diff options
| -rw-r--r-- | config-generic | 2 | ||||
| -rw-r--r-- | kernel.spec | 8 | ||||
| -rw-r--r-- | utrace.patch | 6166 |
3 files changed, 6176 insertions, 0 deletions
diff --git a/config-generic b/config-generic index 755c7c621..e93ccee1b 100644 --- a/config-generic +++ b/config-generic @@ -4220,6 +4220,8 @@ CONFIG_ASYNC_TX_DMA=y CONFIG_UNUSED_SYMBOLS=y +CONFIG_UTRACE=y + CONFIG_FTRACE=y CONFIG_DYNAMIC_FTRACE=y # CONFIG_IRQSOFF_TRACER is not set diff --git a/kernel.spec b/kernel.spec index 924805458..fcb9284a2 100644 --- a/kernel.spec +++ b/kernel.spec @@ -696,6 +696,8 @@ Patch12205: runtime_pm_fixups.patch Patch12303: dmar-disable-when-ricoh-multifunction.patch +Patch20000: utrace.patch + %endif BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root @@ -1274,6 +1276,9 @@ ApplyPatch linux-2.6-rt2x00-Add-device-ID-for-RT539F-device.patch # rhbz#605888 ApplyPatch dmar-disable-when-ricoh-multifunction.patch +# utrace. +ApplyPatch utrace.patch + # END OF PATCH APPLICATIONS %endif @@ -1884,6 +1889,9 @@ fi # and build. %changelog +* Fri Jul 15 2011 Dave Jones <davej@redhat.com> +- Bring back utrace until uprobes gets merged upstream. + * Wed Jul 13 2011 Kyle McMartin <kmcmartin@redhat.com> 3.0-0.rc7.git1.1 - Update to snapshot 3.0-rc7-git1 for intel drm fixes. diff --git a/utrace.patch b/utrace.patch new file mode 100644 index 000000000..55d0b3c1b --- /dev/null +++ b/utrace.patch @@ -0,0 +1,6166 @@ +From davej Thu Jun 30 20:27:03 2011 +Return-Path: oleg@redhat.com +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:03 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:00 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 10DAED812A; + Thu, 30 Jun 2011 20:23:00 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id fiwBBweCuo8A; Thu, 30 Jun 2011 20:22:59 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id E7CA2D810F; + Thu, 30 Jun 2011 20:22:59 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610MpCP015143; + Thu, 30 Jun 2011 20:22:52 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:20:59 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:20:57 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 01/19] utrace core +Message-ID: <20110701002057.GA25776@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 148213 +Lines: 4119 + +From: Roland McGrath <roland@redhat.com> + +This adds the utrace facility, a new modular interface in the kernel for +implementing user thread tracing and debugging. This fits on top of the +tracehook_* layer, so the new code is well-isolated. + +The new interface is in <linux/utrace.h> and the DocBook utrace book +describes it. It allows for multiple separate tracing engines to work in +parallel without interfering with each other. Higher-level tracing +facilities can be implemented as loadable kernel modules using this layer. + +The new facility is made optional under CONFIG_UTRACE. +When this is not enabled, no new code is added. +It can only be enabled on machines that have all the +prerequisites and select CONFIG_HAVE_ARCH_TRACEHOOK. + +In this initial version, utrace and ptrace do not play together at all, +the next patches try to fix this. + +This is is same/old utrace-core patch except: + + - use group_stop/GROUP_STOP_DEQUEUED instead of removed + signal->flags/SIGNAL_STOP_DEQUEUED in utrace_get_signal() + + - rediff the changes in tracehook.h against the current code + without PT_PTRACED tweaks which were needed for ptrace-utrace + +Signed-off-by: Roland McGrath <roland@redhat.com> +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + Documentation/DocBook/Makefile | 2 +- + Documentation/DocBook/utrace.tmpl | 589 +++++++++ + fs/proc/array.c | 3 + + include/linux/sched.h | 5 + + include/linux/tracehook.h | 85 ++- + include/linux/utrace.h | 692 +++++++++++ + init/Kconfig | 9 + + kernel/Makefile | 1 + + kernel/fork.c | 3 + + kernel/utrace.c | 2440 +++++++++++++++++++++++++++++++++++++ + 10 files changed, 3827 insertions(+), 2 deletions(-) + create mode 100644 Documentation/DocBook/utrace.tmpl + create mode 100644 include/linux/utrace.h + create mode 100644 kernel/utrace.c + +diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile +index 3cebfa0..86c288b 100644 +--- a/Documentation/DocBook/Makefile ++++ b/Documentation/DocBook/Makefile +@@ -14,7 +14,7 @@ DOCBOOKS := z8530book.xml mcabook.xml device-drivers.xml \ + genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \ + 80211.xml debugobjects.xml sh.xml regulator.xml \ + alsa-driver-api.xml writing-an-alsa-driver.xml \ +- tracepoint.xml media.xml drm.xml ++ tracepoint.xml utrace.xml media.xml drm.xml + + ### + # The build process is as follows (targets): +diff --git a/Documentation/DocBook/utrace.tmpl b/Documentation/DocBook/utrace.tmpl +new file mode 100644 +index 0000000..0c40add +--- /dev/null ++++ b/Documentation/DocBook/utrace.tmpl +@@ -0,0 +1,589 @@ ++<?xml version="1.0" encoding="UTF-8"?> ++<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" ++"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> ++ ++<book id="utrace"> ++ <bookinfo> ++ <title>The utrace User Debugging Infrastructure</title> ++ </bookinfo> ++ ++ <toc></toc> ++ ++ <chapter id="concepts"><title>utrace concepts</title> ++ ++ <sect1 id="intro"><title>Introduction</title> ++ ++ <para> ++ <application>utrace</application> is infrastructure code for tracing ++ and controlling user threads. This is the foundation for writing ++ tracing engines, which can be loadable kernel modules. ++ </para> ++ ++ <para> ++ The basic actors in <application>utrace</application> are the thread ++ and the tracing engine. A tracing engine is some body of code that ++ calls into the <filename><linux/utrace.h></filename> ++ interfaces, represented by a <structname>struct ++ utrace_engine_ops</structname>. (Usually it's a kernel module, ++ though the legacy <function>ptrace</function> support is a tracing ++ engine that is not in a kernel module.) The interface operates on ++ individual threads (<structname>struct task_struct</structname>). ++ If an engine wants to treat several threads as a group, that is up ++ to its higher-level code. ++ </para> ++ ++ <para> ++ Tracing begins by attaching an engine to a thread, using ++ <function>utrace_attach_task</function> or ++ <function>utrace_attach_pid</function>. If successful, it returns a ++ pointer that is the handle used in all other calls. ++ </para> ++ ++ </sect1> ++ ++ <sect1 id="callbacks"><title>Events and Callbacks</title> ++ ++ <para> ++ An attached engine does nothing by default. An engine makes something ++ happen by requesting callbacks via <function>utrace_set_events</function> ++ and poking the thread with <function>utrace_control</function>. ++ The synchronization issues related to these two calls ++ are discussed further below in <xref linkend="teardown"/>. ++ </para> ++ ++ <para> ++ Events are specified using the macro ++ <constant>UTRACE_EVENT(<replaceable>type</replaceable>)</constant>. ++ Each event type is associated with a callback in <structname>struct ++ utrace_engine_ops</structname>. A tracing engine can leave unused ++ callbacks <constant>NULL</constant>. The only callbacks required ++ are those used by the event flags it sets. ++ </para> ++ ++ <para> ++ Many engines can be attached to each thread. When a thread has an ++ event, each engine gets a callback if it has set the event flag for ++ that event type. For most events, engines are called in the order they ++ attached. Engines that attach after the event has occurred do not get ++ callbacks for that event. This includes any new engines just attached ++ by an existing engine's callback function. Once the sequence of ++ callbacks for that one event has completed, such new engines are then ++ eligible in the next sequence that starts when there is another event. ++ </para> ++ ++ <para> ++ Event reporting callbacks have details particular to the event type, ++ but are all called in similar environments and have the same ++ constraints. Callbacks are made from safe points, where no locks ++ are held, no special resources are pinned (usually), and the ++ user-mode state of the thread is accessible. So, callback code has ++ a pretty free hand. But to be a good citizen, callback code should ++ never block for long periods. It is fine to block in ++ <function>kmalloc</function> and the like, but never wait for i/o or ++ for user mode to do something. If you need the thread to wait, use ++ <constant>UTRACE_STOP</constant> and return from the callback ++ quickly. When your i/o finishes or whatever, you can use ++ <function>utrace_control</function> to resume the thread. ++ </para> ++ ++ <para> ++ The <constant>UTRACE_EVENT(SYSCALL_ENTRY)</constant> event is a special ++ case. While other events happen in the kernel when it will return to ++ user mode soon, this event happens when entering the kernel before it ++ will proceed with the work requested from user mode. Because of this ++ difference, the <function>report_syscall_entry</function> callback is ++ special in two ways. For this event, engines are called in reverse of ++ the normal order (this includes the <function>report_quiesce</function> ++ call that precedes a <function>report_syscall_entry</function> call). ++ This preserves the semantics that the last engine to attach is called ++ "closest to user mode"--the engine that is first to see a thread's user ++ state when it enters the kernel is also the last to see that state when ++ the thread returns to user mode. For the same reason, if these ++ callbacks use <constant>UTRACE_STOP</constant> (see the next section), ++ the thread stops immediately after callbacks rather than only when it's ++ ready to return to user mode; when allowed to resume, it will actually ++ attempt the system call indicated by the register values at that time. ++ </para> ++ ++ </sect1> ++ ++ <sect1 id="safely"><title>Stopping Safely</title> ++ ++ <sect2 id="well-behaved"><title>Writing well-behaved callbacks</title> ++ ++ <para> ++ Well-behaved callbacks are important to maintain two essential ++ properties of the interface. The first of these is that unrelated ++ tracing engines should not interfere with each other. If your engine's ++ event callback does not return quickly, then another engine won't get ++ the event notification in a timely manner. The second important ++ property is that tracing should be as noninvasive as possible to the ++ normal operation of the system overall and of the traced thread in ++ particular. That is, attached tracing engines should not perturb a ++ thread's behavior, except to the extent that changing its user-visible ++ state is explicitly what you want to do. (Obviously some perturbation ++ is unavoidable, primarily timing changes, ranging from small delays due ++ to the overhead of tracing, to arbitrary pauses in user code execution ++ when a user stops a thread with a debugger for examination.) Even when ++ you explicitly want the perturbation of making the traced thread block, ++ just blocking directly in your callback has more unwanted effects. For ++ example, the <constant>CLONE</constant> event callbacks are called when ++ the new child thread has been created but not yet started running; the ++ child can never be scheduled until the <constant>CLONE</constant> ++ tracing callbacks return. (This allows engines tracing the parent to ++ attach to the child.) If a <constant>CLONE</constant> event callback ++ blocks the parent thread, it also prevents the child thread from ++ running (even to process a <constant>SIGKILL</constant>). If what you ++ want is to make both the parent and child block, then use ++ <function>utrace_attach_task</function> on the child and then use ++ <constant>UTRACE_STOP</constant> on both threads. A more crucial ++ problem with blocking in callbacks is that it can prevent ++ <constant>SIGKILL</constant> from working. A thread that is blocking ++ due to <constant>UTRACE_STOP</constant> will still wake up and die ++ immediately when sent a <constant>SIGKILL</constant>, as all threads ++ should. Relying on the <application>utrace</application> ++ infrastructure rather than on private synchronization calls in event ++ callbacks is an important way to help keep tracing robustly ++ noninvasive. ++ </para> ++ ++ </sect2> ++ ++ <sect2 id="UTRACE_STOP"><title>Using <constant>UTRACE_STOP</constant></title> ++ ++ <para> ++ To control another thread and access its state, it must be stopped ++ with <constant>UTRACE_STOP</constant>. This means that it is ++ stopped and won't start running again while we access it. When a ++ thread is not already stopped, <function>utrace_control</function> ++ returns <constant>-EINPROGRESS</constant> and an engine must wait ++ for an event callback when the thread is ready to stop. The thread ++ may be running on another CPU or may be blocked. When it is ready ++ to be examined, it will make callbacks to engines that set the ++ <constant>UTRACE_EVENT(QUIESCE)</constant> event bit. To wake up an ++ interruptible wait, use <constant>UTRACE_INTERRUPT</constant>. ++ </para> ++ ++ <para> ++ As long as some engine has used <constant>UTRACE_STOP</constant> and ++ not called <function>utrace_control</function> to resume the thread, ++ then the thread will remain stopped. <constant>SIGKILL</constant> ++ will wake it up, but it will not run user code. When the stop is ++ cleared with <function>utrace_control</function> or a callback ++ return value, the thread starts running again. ++ (See also <xref linkend="teardown"/>.) ++ </para> ++ ++ </sect2> ++ ++ </sect1> ++ ++ <sect1 id="teardown"><title>Tear-down Races</title> ++ ++ <sect2 id="SIGKILL"><title>Primacy of <constant>SIGKILL</constant></title> ++ <para> ++ Ordinarily synchronization issues for tracing engines are kept fairly ++ straightforward by using <constant>UTRACE_STOP</constant>. You ask a ++ thread to stop, and then once it makes the ++ <function>report_quiesce</function> callback it cannot do anything else ++ that would result in another callback, until you let it with a ++ <function>utrace_control</function> call. This simple arrangement ++ avoids complex and error-prone code in each one of a tracing engine's ++ event callbacks to keep them serialized with the engine's other ++ operations done on that thread from another thread of control. ++ However, giving tracing engines complete power to keep a traced thread ++ stuck in place runs afoul of a more important kind of simplicity that ++ the kernel overall guarantees: nothing can prevent or delay ++ <constant>SIGKILL</constant> from making a thread die and release its ++ resources. To preserve this important property of ++ <constant>SIGKILL</constant>, it as a special case can break ++ <constant>UTRACE_STOP</constant> like nothing else normally can. This ++ includes both explicit <constant>SIGKILL</constant> signals and the ++ implicit <constant>SIGKILL</constant> sent to each other thread in the ++ same thread group by a thread doing an exec, or processing a fatal ++ signal, or making an <function>exit_group</function> system call. A ++ tracing engine can prevent a thread from beginning the exit or exec or ++ dying by signal (other than <constant>SIGKILL</constant>) if it is ++ attached to that thread, but once the operation begins, no tracing ++ engine can prevent or delay all other threads in the same thread group ++ dying. ++ </para> ++ </sect2> ++ ++ <sect2 id="reap"><title>Final callbacks</title> ++ <para> ++ The <function>report_reap</function> callback is always the final event ++ in the life cycle of a traced thread. Tracing engines can use this as ++ the trigger to clean up their own data structures. The ++ <function>report_death</function> callback is always the penultimate ++ event a tracing engine might see; it's seen unless the thread was ++ already in the midst of dying when the engine attached. Many tracing ++ engines will have no interest in when a parent reaps a dead process, ++ and nothing they want to do with a zombie thread once it dies; for ++ them, the <function>report_death</function> callback is the natural ++ place to clean up data structures and detach. To facilitate writing ++ such engines robustly, given the asynchrony of ++ <constant>SIGKILL</constant>, and without error-prone manual ++ implementation of synchronization schemes, the ++ <application>utrace</application> infrastructure provides some special ++ guarantees about the <function>report_death</function> and ++ <function>report_reap</function> callbacks. It still takes some care ++ to be sure your tracing engine is robust to tear-down races, but these ++ rules make it reasonably straightforward and concise to handle a lot of ++ corner cases correctly. ++ </para> ++ </sect2> ++ ++ <sect2 id="refcount"><title>Engine and task pointers</title> ++ <para> ++ The first sort of guarantee concerns the core data structures ++ themselves. <structname>struct utrace_engine</structname> is ++ a reference-counted data structure. While you hold a reference, an ++ engine pointer will always stay valid so that you can safely pass it to ++ any <application>utrace</application> call. Each call to ++ <function>utrace_attach_task</function> or ++ <function>utrace_attach_pid</function> returns an engine pointer with a ++ reference belonging to the caller. You own that reference until you ++ drop it using <function>utrace_engine_put</function>. There is an ++ implicit reference on the engine while it is attached. So if you drop ++ your only reference, and then use ++ <function>utrace_attach_task</function> without ++ <constant>UTRACE_ATTACH_CREATE</constant> to look up that same engine, ++ you will get the same pointer with a new reference to replace the one ++ you dropped, just like calling <function>utrace_engine_get</function>. ++ When an engine has been detached, either explicitly with ++ <constant>UTRACE_DETACH</constant> or implicitly after ++ <function>report_reap</function>, then any references you hold are all ++ that keep the old engine pointer alive. ++ </para> ++ ++ <para> ++ There is nothing a kernel module can do to keep a <structname>struct ++ task_struct</structname> alive outside of ++ <function>rcu_read_lock</function>. When the task dies and is reaped ++ by its parent (or itself), that structure can be freed so that any ++ dangling pointers you have stored become invalid. ++ <application>utrace</application> will not prevent this, but it can ++ help you detect it safely. By definition, a task that has been reaped ++ has had all its engines detached. All ++ <application>utrace</application> calls can be safely called on a ++ detached engine if the caller holds a reference on that engine pointer, ++ even if the task pointer passed in the call is invalid. All calls ++ return <constant>-ESRCH</constant> for a detached engine, which tells ++ you that the task pointer you passed could be invalid now. Since ++ <function>utrace_control</function> and ++ <function>utrace_set_events</function> do not block, you can call those ++ inside a <function>rcu_read_lock</function> section and be sure after ++ they don't return <constant>-ESRCH</constant> that the task pointer is ++ still valid until <function>rcu_read_unlock</function>. The ++ infrastructure never holds task references of its own. Though neither ++ <function>rcu_read_lock</function> nor any other lock is held while ++ making a callback, it's always guaranteed that the <structname>struct ++ task_struct</structname> and the <structname>struct ++ utrace_engine</structname> passed as arguments remain valid ++ until the callback function returns. ++ </para> ++ ++ <para> ++ The common means for safely holding task pointers that is available to ++ kernel modules is to use <structname>struct pid</structname>, which ++ permits <function>put_pid</function> from kernel modules. When using ++ that, the calls <function>utrace_attach_pid</function>, ++ <function>utrace_control_pid</function>, ++ <function>utrace_set_events_pid</function>, and ++ <function>utrace_barrier_pid</function> are available. ++ </para> ++ </sect2> ++ ++ <sect2 id="reap-after-death"> ++ <title> ++ Serialization of <constant>DEATH</constant> and <constant>REAP</constant> ++ </title> ++ <para> ++ The second guarantee is the serialization of ++ <constant>DEATH</constant> and <constant>REAP</constant> event ++ callbacks for a given thread. The actual reaping by the parent ++ (<function>release_task</function> call) can occur simultaneously ++ while the thread is still doing the final steps of dying, including ++ the <function>report_death</function> callback. If a tracing engine ++ has requested both <constant>DEATH</constant> and ++ <constant>REAP</constant> event reports, it's guaranteed that the ++ <function>report_reap</function> callback will not be made until ++ after the <function>report_death</function> callback has returned. ++ If the <function>report_death</function> callback itself detaches ++ from the thread, then the <function>report_reap</function> callback ++ will never be made. Thus it is safe for a ++ <function>report_death</function> callback to clean up data ++ structures and detach. ++ </para> ++ </sect2> ++ ++ <sect2 id="interlock"><title>Interlock with final callbacks</title> ++ <para> ++ The final sort of guarantee is that a tracing engine will know for sure ++ whether or not the <function>report_death</function> and/or ++ <function>report_reap</function> callbacks will be made for a certain ++ thread. These tear-down races are disambiguated by the error return ++ values of <function>utrace_set_events</function> and ++ <function>utrace_control</function>. Normally ++ <function>utrace_control</function> called with ++ <constant>UTRACE_DETACH</constant> returns zero, and this means that no ++ more callbacks will be made. If the thread is in the midst of dying, ++ it returns <constant>-EALREADY</constant> to indicate that the ++ <constant>report_death</constant> callback may already be in progress; ++ when you get this error, you know that any cleanup your ++ <function>report_death</function> callback does is about to happen or ++ has just happened--note that if the <function>report_death</function> ++ callback does not detach, the engine remains attached until the thread ++ gets reaped. If the thread is in the midst of being reaped, ++ <function>utrace_control</function> returns <constant>-ESRCH</constant> ++ to indicate that the <function>report_reap</function> callback may ++ already be in progress; this means the engine is implicitly detached ++ when the callback completes. This makes it possible for a tracing ++ engine that has decided asynchronously to detach from a thread to ++ safely clean up its data structures, knowing that no ++ <function>report_death</function> or <function>report_reap</function> ++ callback will try to do the same. <constant>utrace_detach</constant> ++ returns <constant>-ESRCH</constant> when the <structname>struct ++ utrace_engine</structname> has already been detached, but is ++ still a valid pointer because of its reference count. A tracing engine ++ can use this to safely synchronize its own independent multiple threads ++ of control with each other and with its event callbacks that detach. ++ </para> ++ ++ <para> ++ In the same vein, <function>utrace_set_events</function> normally ++ returns zero; if the target thread was stopped before the call, then ++ after a successful call, no event callbacks not requested in the new ++ flags will be made. It fails with <constant>-EALREADY</constant> if ++ you try to clear <constant>UTRACE_EVENT(DEATH)</constant> when the ++ <function>report_death</function> callback may already have begun, or if ++ you try to newly set <constant>UTRACE_EVENT(DEATH)</constant> or ++ <constant>UTRACE_EVENT(QUIESCE)</constant> when the target is already ++ dead or dying. Like <function>utrace_control</function>, it returns ++ <constant>-ESRCH</constant> when the <function>report_reap</function> ++ callback may already have begun, or the thread has already been detached ++ (including forcible detach on reaping). This lets the tracing engine ++ know for sure which event callbacks it will or won't see after ++ <function>utrace_set_events</function> has returned. By checking for ++ errors, it can know whether to clean up its data structures immediately ++ or to let its callbacks do the work. ++ </para> ++ </sect2> ++ ++ <sect2 id="barrier"><title>Using <function>utrace_barrier</function></title> ++ <para> ++ When a thread is safely stopped, calling ++ <function>utrace_control</function> with <constant>UTRACE_DETACH</constant> ++ or calling <function>utrace_set_events</function> to disable some events ++ ensures synchronously that your engine won't get any more of the callbacks ++ that have been disabled (none at all when detaching). But these can also ++ be used while the thread is not stopped, when it might be simultaneously ++ making a callback to your engine. For this situation, these calls return ++ <constant>-EINPROGRESS</constant> when it's possible a callback is in ++ progress. If you are not prepared to have your old callbacks still run, ++ then you can synchronize to be sure all the old callbacks are finished, ++ using <function>utrace_barrier</function>. This is necessary if the ++ kernel module containing your callback code is going to be unloaded. ++ </para> ++ <para> ++ After using <constant>UTRACE_DETACH</constant> once, further calls to ++ <function>utrace_control</function> with the same engine pointer will ++ return <constant>-ESRCH</constant>. In contrast, after getting ++ <constant>-EINPROGRESS</constant> from ++ <function>utrace_set_events</function>, you can call ++ <function>utrace_set_events</function> again later and if it returns zero ++ then know the old callbacks have finished. ++ </para> ++ <para> ++ Unlike all other calls, <function>utrace_barrier</function> (and ++ <function>utrace_barrier_pid</function>) will accept any engine pointer you ++ hold a reference on, even if <constant>UTRACE_DETACH</constant> has already ++ been used. After any <function>utrace_control</function> or ++ <function>utrace_set_events</function> call (these do not block), you can ++ call <function>utrace_barrier</function> to block until callbacks have ++ finished. This returns <constant>-ESRCH</constant> only if the engine is ++ completely detached (finished all callbacks). Otherwise it waits ++ until the thread is definitely not in the midst of a callback to this ++ engine and then returns zero, but can return ++ <constant>-ERESTARTSYS</constant> if its wait is interrupted. ++ </para> ++ </sect2> ++ ++</sect1> ++ ++</chapter> ++ ++<chapter id="core"><title>utrace core API</title> ++ ++<para> ++ The utrace API is declared in <filename><linux/utrace.h></filename>. ++</para> ++ ++!Iinclude/linux/utrace.h ++!Ekernel/utrace.c ++ ++</chapter> ++ ++<chapter id="machine"><title>Machine State</title> ++ ++<para> ++ The <function>task_current_syscall</function> function can be used on any ++ valid <structname>struct task_struct</structname> at any time, and does ++ not even require that <function>utrace_attach_task</function> was used at all. ++</para> ++ ++<para> ++ The other ways to access the registers and other machine-dependent state of ++ a task can only be used on a task that is at a known safe point. The safe ++ points are all the places where <function>utrace_set_events</function> can ++ request callbacks (except for the <constant>DEATH</constant> and ++ <constant>REAP</constant> events). So at any event callback, it is safe to ++ examine <varname>current</varname>. ++</para> ++ ++<para> ++ One task can examine another only after a callback in the target task that ++ returns <constant>UTRACE_STOP</constant> so that task will not return to user ++ mode after the safe point. This guarantees that the task will not resume ++ until the same engine uses <function>utrace_control</function>, unless the ++ task dies suddenly. To examine safely, one must use a pair of calls to ++ <function>utrace_prepare_examine</function> and ++ <function>utrace_finish_examine</function> surrounding the calls to ++ <structname>struct user_regset</structname> functions or direct examination ++ of task data structures. <function>utrace_prepare_examine</function> returns ++ an error if the task is not properly stopped, or is dead. After a ++ successful examination, the paired <function>utrace_finish_examine</function> ++ call returns an error if the task ever woke up during the examination. If ++ so, any data gathered may be scrambled and should be discarded. This means ++ there was a spurious wake-up (which should not happen), or a sudden death. ++</para> ++ ++<sect1 id="regset"><title><structname>struct user_regset</structname></title> ++ ++<para> ++ The <structname>struct user_regset</structname> API ++ is declared in <filename><linux/regset.h></filename>. ++</para> ++ ++!Finclude/linux/regset.h ++ ++</sect1> ++ ++<sect1 id="task_current_syscall"> ++ <title><filename>System Call Information</filename></title> ++ ++<para> ++ This function is declared in <filename><linux/ptrace.h></filename>. ++</para> ++ ++!Elib/syscall.c ++ ++</sect1> ++ ++<sect1 id="syscall"><title><filename>System Call Tracing</filename></title> ++ ++<para> ++ The arch API for system call information is declared in ++ <filename><asm/syscall.h></filename>. ++ Each of these calls can be used only at system call entry tracing, ++ or can be used only at system call exit and the subsequent safe points ++ before returning to user mode. ++ At system call entry tracing means either during a ++ <structfield>report_syscall_entry</structfield> callback, ++ or any time after that callback has returned <constant>UTRACE_STOP</constant>. ++</para> ++ ++!Finclude/asm-generic/syscall.h ++ ++</sect1> ++ ++</chapter> ++ ++<chapter id="internals"><title>Kernel Internals</title> ++ ++<para> ++ This chapter covers the interface to the tracing infrastructure ++ from the core of the kernel and the architecture-specific code. ++ This is for maintainers of the kernel and arch code, and not relevant ++ to using the tracing facilities described in preceding chapters. ++</para> ++ ++<sect1 id="tracehook"><title>Core Calls In</title> ++ ++<para> ++ These calls are declared in <filename><linux/tracehook.h></filename>. ++ The core kernel calls these functions at various important places. ++</para> ++ ++!Finclude/linux/tracehook.h ++ ++</sect1> ++ ++<sect1 id="arch"><title>Architecture Calls Out</title> ++ ++<para> ++ An arch that has done all these things sets ++ <constant>CONFIG_HAVE_ARCH_TRACEHOOK</constant>. ++ This is required to enable the <application>utrace</application> code. ++</para> ++ ++<sect2 id="arch-ptrace"><title><filename><asm/ptrace.h></filename></title> ++ ++<para> ++ An arch defines these in <filename><asm/ptrace.h></filename> ++ if it supports hardware single-step or block-step features. ++</para> ++ ++!Finclude/linux/ptrace.h arch_has_single_step arch_has_block_step ++!Finclude/linux/ptrace.h user_enable_single_step user_enable_block_step ++!Finclude/linux/ptrace.h user_disable_single_step ++ ++</sect2> ++ ++<sect2 id="arch-syscall"> ++ <title><filename><asm/syscall.h></filename></title> ++ ++ <para> ++ An arch provides <filename><asm/syscall.h></filename> that ++ defines these as inlines, or declares them as exported functions. ++ These interfaces are described in <xref linkend="syscall"/>. ++ </para> ++ ++</sect2> ++ ++<sect2 id="arch-tracehook"> ++ <title><filename><linux/tracehook.h></filename></title> ++ ++ <para> ++ An arch must define <constant>TIF_NOTIFY_RESUME</constant> ++ and <constant>TIF_SYSCALL_TRACE</constant> ++ in its <filename><asm/thread_info.h></filename>. ++ The arch code must call the following functions, all declared ++ in <filename><linux/tracehook.h></filename> and ++ described in <xref linkend="tracehook"/>: ++ ++ <itemizedlist> ++ <listitem> ++ <para><function>tracehook_notify_resume</function></para> ++ </listitem> ++ <listitem> ++ <para><function>tracehook_report_syscall_entry</function></para> ++ </listitem> ++ <listitem> ++ <para><function>tracehook_report_syscall_exit</function></para> ++ </listitem> ++ <listitem> ++ <para><function>tracehook_signal_handler</function></para> ++ </listitem> ++ </itemizedlist> ++ ++ </para> ++ ++</sect2> ++ ++</sect1> ++ ++</chapter> ++ ++</book> +diff --git a/fs/proc/array.c b/fs/proc/array.c +index 9b45ee8..496fef3 100644 +--- a/fs/proc/array.c ++++ b/fs/proc/array.c +@@ -81,6 +81,7 @@ + #include <linux/pid_namespace.h> + #include <linux/ptrace.h> + #include <linux/tracehook.h> ++#include <linux/utrace.h> + + #include <asm/pgtable.h> + #include <asm/processor.h> +@@ -192,6 +193,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, + cred->uid, cred->euid, cred->suid, cred->fsuid, + cred->gid, cred->egid, cred->sgid, cred->fsgid); + ++ task_utrace_proc_status(m, p); ++ + task_lock(p); + if (p->files) + fdt = files_fdtable(p->files); +diff --git a/include/linux/sched.h b/include/linux/sched.h +index a837b20..b87de83 100644 +--- a/include/linux/sched.h ++++ b/include/linux/sched.h +@@ -1397,6 +1397,11 @@ struct task_struct { + #endif + seccomp_t seccomp; + ++#ifdef CONFIG_UTRACE ++ struct utrace *utrace; ++ unsigned long utrace_flags; ++#endif ++ + /* Thread group tracking */ + u32 parent_exec_id; + u32 self_exec_id; +diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h +index e95f523..7d7bdde 100644 +--- a/include/linux/tracehook.h ++++ b/include/linux/tracehook.h +@@ -49,6 +49,7 @@ + #include <linux/sched.h> + #include <linux/ptrace.h> + #include <linux/security.h> ++#include <linux/utrace.h> + struct linux_binprm; + + /** +@@ -63,6 +64,8 @@ struct linux_binprm; + */ + static inline int tracehook_expect_breakpoints(struct task_struct *task) + { ++ if (unlikely(task_utrace_flags(task) & UTRACE_EVENT(SIGNAL_CORE))) ++ return 1; + return (task_ptrace(task) & PT_PTRACED) != 0; + } + +@@ -111,6 +114,9 @@ static inline void ptrace_report_syscall(struct pt_regs *regs) + static inline __must_check int tracehook_report_syscall_entry( + struct pt_regs *regs) + { ++ if ((task_utrace_flags(current) & UTRACE_EVENT(SYSCALL_ENTRY)) && ++ utrace_report_syscall_entry(regs)) ++ return 1; + ptrace_report_syscall(regs); + return 0; + } +@@ -134,6 +140,9 @@ static inline __must_check int tracehook_report_syscall_entry( + */ + static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) + { ++ if (task_utrace_flags(current) & UTRACE_EVENT(SYSCALL_EXIT)) ++ utrace_report_syscall_exit(regs); ++ + if (step) { + siginfo_t info; + user_single_step_siginfo(current, regs, &info); +@@ -201,6 +210,8 @@ static inline void tracehook_report_exec(struct linux_binfmt *fmt, + struct linux_binprm *bprm, + struct pt_regs *regs) + { ++ if (unlikely(task_utrace_flags(current) & UTRACE_EVENT(EXEC))) ++ utrace_report_exec(fmt, bprm, regs); + if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) && + unlikely(task_ptrace(current) & PT_PTRACED)) + send_sig(SIGTRAP, current, 0); +@@ -218,10 +229,37 @@ static inline void tracehook_report_exec(struct linux_binfmt *fmt, + */ + static inline void tracehook_report_exit(long *exit_code) + { ++ if (unlikely(task_utrace_flags(current) & UTRACE_EVENT(EXIT))) ++ utrace_report_exit(exit_code); + ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code); + } + + /** ++ * tracehook_init_task - task_struct has just been copied ++ * @task: new &struct task_struct just copied from parent ++ * ++ * Called from do_fork() when @task has just been duplicated. ++ * After this, @task will be passed to tracehook_free_task() ++ * even if the rest of its setup fails before it is fully created. ++ */ ++static inline void tracehook_init_task(struct task_struct *task) ++{ ++ utrace_init_task(task); ++} ++ ++/** ++ * tracehook_free_task - task_struct is being freed ++ * @task: dead &struct task_struct being freed ++ * ++ * Called from free_task() when @task is no longer in use. ++ */ ++static inline void tracehook_free_task(struct task_struct *task) ++{ ++ if (task_utrace_struct(task)) ++ utrace_free_task(task); ++} ++ ++/** + * tracehook_prepare_clone - prepare for new child to be cloned + * @clone_flags: %CLONE_* flags from clone/fork/vfork system call + * +@@ -285,6 +323,8 @@ static inline void tracehook_report_clone(struct pt_regs *regs, + unsigned long clone_flags, + pid_t pid, struct task_struct *child) + { ++ if (unlikely(task_utrace_flags(current) & UTRACE_EVENT(CLONE))) ++ utrace_report_clone(clone_flags, child); + if (unlikely(task_ptrace(child))) { + /* + * It doesn't matter who attached/attaching to this +@@ -317,6 +357,9 @@ static inline void tracehook_report_clone_complete(int trace, + pid_t pid, + struct task_struct *child) + { ++ if (unlikely(task_utrace_flags(current) & UTRACE_EVENT(CLONE)) && ++ (clone_flags & CLONE_VFORK)) ++ utrace_finish_vfork(current); + if (unlikely(trace)) + ptrace_event(0, trace, pid); + } +@@ -351,6 +394,10 @@ static inline void tracehook_report_vfork_done(struct task_struct *child, + */ + static inline void tracehook_prepare_release_task(struct task_struct *task) + { ++ /* see utrace_add_engine() about this barrier */ ++ smp_mb(); ++ if (task_utrace_flags(task)) ++ utrace_maybe_reap(task, task_utrace_struct(task), true); + } + + /** +@@ -365,6 +412,7 @@ static inline void tracehook_prepare_release_task(struct task_struct *task) + static inline void tracehook_finish_release_task(struct task_struct *task) + { + ptrace_release_task(task); ++ BUG_ON(task->exit_state != EXIT_DEAD); + } + + /** +@@ -386,6 +434,8 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, + const struct k_sigaction *ka, + struct pt_regs *regs, int stepping) + { ++ if (task_utrace_flags(current)) ++ utrace_signal_handler(current, stepping); + if (stepping) + ptrace_notify(SIGTRAP); + } +@@ -403,6 +453,8 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, + static inline int tracehook_consider_ignored_signal(struct task_struct *task, + int sig) + { ++ if (unlikely(task_utrace_flags(task) & UTRACE_EVENT(SIGNAL_IGN))) ++ return 1; + return (task_ptrace(task) & PT_PTRACED) != 0; + } + +@@ -422,6 +474,9 @@ static inline int tracehook_consider_ignored_signal(struct task_struct *task, + static inline int tracehook_consider_fatal_signal(struct task_struct *task, + int sig) + { ++ if (unlikely(task_utrace_flags(task) & (UTRACE_EVENT(SIGNAL_TERM) | ++ UTRACE_EVENT(SIGNAL_CORE)))) ++ return 1; + return (task_ptrace(task) & PT_PTRACED) != 0; + } + +@@ -436,6 +491,8 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task, + */ + static inline int tracehook_force_sigpending(void) + { ++ if (unlikely(task_utrace_flags(current))) ++ return utrace_interrupt_pending(); + return 0; + } + +@@ -465,6 +522,8 @@ static inline int tracehook_get_signal(struct task_struct *task, + siginfo_t *info, + struct k_sigaction *return_ka) + { ++ if (unlikely(task_utrace_flags(task))) ++ return utrace_get_signal(task, regs, info, return_ka); + return 0; + } + +@@ -475,6 +534,8 @@ static inline int tracehook_get_signal(struct task_struct *task, + */ + static inline void tracehook_finish_jctl(void) + { ++ if (task_utrace_flags(current)) ++ utrace_finish_stop(); + } + + #define DEATH_REAP -1 +@@ -497,6 +558,8 @@ static inline void tracehook_finish_jctl(void) + static inline int tracehook_notify_death(struct task_struct *task, + void **death_cookie, int group_dead) + { ++ *death_cookie = task_utrace_struct(task); ++ + if (task_detached(task)) + return task->ptrace ? SIGCHLD : DEATH_REAP; + +@@ -533,6 +596,15 @@ static inline void tracehook_report_death(struct task_struct *task, + int signal, void *death_cookie, + int group_dead) + { ++ /* ++ * If utrace_set_events() was just called to enable ++ * UTRACE_EVENT(DEATH), then we are obliged to call ++ * utrace_report_death() and not miss it. utrace_set_events() ++ * checks @task->exit_state under tasklist_lock to synchronize ++ * with exit_notify(), the caller. ++ */ ++ if (task_utrace_flags(task) & _UTRACE_DEATH_EVENTS) ++ utrace_report_death(task, death_cookie, group_dead, signal); + } + + #ifdef TIF_NOTIFY_RESUME +@@ -562,10 +634,21 @@ static inline void set_notify_resume(struct task_struct *task) + * asynchronously, this will be called again before we return to + * user mode. + * +- * Called without locks. ++ * Called without locks. However, on some machines this may be ++ * called with interrupts disabled. + */ + static inline void tracehook_notify_resume(struct pt_regs *regs) + { ++ struct task_struct *task = current; ++ /* ++ * Prevent the following store/load from getting ahead of the ++ * caller which clears TIF_NOTIFY_RESUME. This pairs with the ++ * implicit mb() before setting TIF_NOTIFY_RESUME in ++ * set_notify_resume(). ++ */ ++ smp_mb(); ++ if (task_utrace_flags(task)) ++ utrace_resume(task, regs); + } + #endif /* TIF_NOTIFY_RESUME */ + +diff --git a/include/linux/utrace.h b/include/linux/utrace.h +new file mode 100644 +index 0000000..f251efe +--- /dev/null ++++ b/include/linux/utrace.h +@@ -0,0 +1,692 @@ ++/* ++ * utrace infrastructure interface for debugging user processes ++ * ++ * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved. ++ * ++ * This copyrighted material is made available to anyone wishing to use, ++ * modify, copy, or redistribute it subject to the terms and conditions ++ * of the GNU General Public License v.2. ++ * ++ * Red Hat Author: Roland McGrath. ++ * ++ * This interface allows for notification of interesting events in a ++ * thread. It also mediates access to thread state such as registers. ++ * Multiple unrelated users can be associated with a single thread. ++ * We call each of these a tracing engine. ++ * ++ * A tracing engine starts by calling utrace_attach_task() or ++ * utrace_attach_pid() on the chosen thread, passing in a set of hooks ++ * (&struct utrace_engine_ops), and some associated data. This produces a ++ * &struct utrace_engine, which is the handle used for all other ++ * operations. An attached engine has its ops vector, its data, and an ++ * event mask controlled by utrace_set_events(). ++ * ++ * For each event bit that is set, that engine will get the ++ * appropriate ops->report_*() callback when the event occurs. The ++ * &struct utrace_engine_ops need not provide callbacks for an event ++ * unless the engine sets one of the associated event bits. ++ */ ++ ++#ifndef _LINUX_UTRACE_H ++#define _LINUX_UTRACE_H 1 ++ ++#include <linux/list.h> ++#include <linux/kref.h> ++#include <linux/signal.h> ++#include <linux/sched.h> ++ ++struct linux_binprm; ++struct pt_regs; ++struct utrace; ++struct user_regset; ++struct user_regset_view; ++ ++/* ++ * Event bits passed to utrace_set_events(). ++ * These appear in &struct task_struct.@utrace_flags ++ * and &struct utrace_engine.@flags. ++ */ ++enum utrace_events { ++ _UTRACE_EVENT_QUIESCE, /* Thread is available for examination. */ ++ _UTRACE_EVENT_REAP, /* Zombie reaped, no more tracing possible. */ ++ _UTRACE_EVENT_CLONE, /* Successful clone/fork/vfork just done. */ ++ _UTRACE_EVENT_EXEC, /* Successful execve just completed. */ ++ _UTRACE_EVENT_EXIT, /* Thread exit in progress. */ ++ _UTRACE_EVENT_DEATH, /* Thread has died. */ ++ _UTRACE_EVENT_SYSCALL_ENTRY, /* User entered kernel for system call. */ ++ _UTRACE_EVENT_SYSCALL_EXIT, /* Returning to user after system call. */ ++ _UTRACE_EVENT_SIGNAL, /* Signal delivery will run a user handler. */ ++ _UTRACE_EVENT_SIGNAL_IGN, /* No-op signal to be delivered. */ ++ _UTRACE_EVENT_SIGNAL_STOP, /* Signal delivery will suspend. */ ++ _UTRACE_EVENT_SIGNAL_TERM, /* Signal delivery will terminate. */ ++ _UTRACE_EVENT_SIGNAL_CORE, /* Signal delivery will dump core. */ ++ _UTRACE_EVENT_JCTL, /* Job control stop or continue completed. */ ++ _UTRACE_NEVENTS ++}; ++#define UTRACE_EVENT(type) (1UL << _UTRACE_EVENT_##type) ++ ++/* ++ * All the kinds of signal events. ++ * These all use the @report_signal() callback. ++ */ ++#define UTRACE_EVENT_SIGNAL_ALL (UTRACE_EVENT(SIGNAL) \ ++ | UTRACE_EVENT(SIGNAL_IGN) \ ++ | UTRACE_EVENT(SIGNAL_STOP) \ ++ | UTRACE_EVENT(SIGNAL_TERM) \ ++ | UTRACE_EVENT(SIGNAL_CORE)) ++/* ++ * Both kinds of syscall events; these call the @report_syscall_entry() ++ * and @report_syscall_exit() callbacks, respectively. ++ */ ++#define UTRACE_EVENT_SYSCALL \ ++ (UTRACE_EVENT(SYSCALL_ENTRY) | UTRACE_EVENT(SYSCALL_EXIT)) ++ ++/* ++ * The event reports triggered synchronously by task death. ++ */ ++#define _UTRACE_DEATH_EVENTS (UTRACE_EVENT(DEATH) | UTRACE_EVENT(QUIESCE)) ++ ++/* ++ * Hooks in <linux/tracehook.h> call these entry points to the utrace dispatch. ++ */ ++void utrace_free_task(struct task_struct *); ++bool utrace_interrupt_pending(void); ++void utrace_resume(struct task_struct *, struct pt_regs *); ++void utrace_finish_stop(void); ++void utrace_maybe_reap(struct task_struct *, struct utrace *, bool); ++int utrace_get_signal(struct task_struct *, struct pt_regs *, ++ siginfo_t *, struct k_sigaction *); ++void utrace_report_clone(unsigned long, struct task_struct *); ++void utrace_finish_vfork(struct task_struct *); ++void utrace_report_exit(long *exit_code); ++void utrace_report_death(struct task_struct *, struct utrace *, bool, int); ++void utrace_report_jctl(int notify, int type); ++void utrace_report_exec(struct linux_binfmt *, struct linux_binprm *, ++ struct pt_regs *regs); ++bool utrace_report_syscall_entry(struct pt_regs *); ++void utrace_report_syscall_exit(struct pt_regs *); ++void utrace_signal_handler(struct task_struct *, int); ++ ++#ifndef CONFIG_UTRACE ++ ++/* ++ * <linux/tracehook.h> uses these accessors to avoid #ifdef CONFIG_UTRACE. ++ */ ++static inline unsigned long task_utrace_flags(struct task_struct *task) ++{ ++ return 0; ++} ++static inline struct utrace *task_utrace_struct(struct task_struct *task) ++{ ++ return NULL; ++} ++static inline void utrace_init_task(struct task_struct *child) ++{ ++} ++ ++static inline void task_utrace_proc_status(struct seq_file *m, ++ struct task_struct *p) ++{ ++} ++ ++#else /* CONFIG_UTRACE */ ++ ++static inline unsigned long task_utrace_flags(struct task_struct *task) ++{ ++ return task->utrace_flags; ++} ++ ++static inline struct utrace *task_utrace_struct(struct task_struct *task) ++{ ++ struct utrace *utrace; ++ ++ /* ++ * This barrier ensures that any prior load of task->utrace_flags ++ * is ordered before this load of task->utrace. We use those ++ * utrace_flags checks in the hot path to decide to call into ++ * the utrace code. The first attach installs task->utrace before ++ * setting task->utrace_flags nonzero with implicit barrier in ++ * between, see utrace_add_engine(). ++ */ ++ smp_rmb(); ++ utrace = task->utrace; ++ ++ smp_read_barrier_depends(); /* See utrace_task_alloc(). */ ++ return utrace; ++} ++ ++static inline void utrace_init_task(struct task_struct *task) ++{ ++ task->utrace_flags = 0; ++ task->utrace = NULL; ++} ++ ++void task_utrace_proc_status(struct seq_file *m, struct task_struct *p); ++ ++ ++/* ++ * Version number of the API defined in this file. This will change ++ * whenever a tracing engine's code would need some updates to keep ++ * working. We maintain this here for the benefit of tracing engine code ++ * that is developed concurrently with utrace API improvements before they ++ * are merged into the kernel, making LINUX_VERSION_CODE checks unwieldy. ++ */ ++#define UTRACE_API_VERSION 20091216 ++ ++/** ++ * enum utrace_resume_action - engine's choice of action for a traced task ++ * @UTRACE_STOP: Stay quiescent after callbacks. ++ * @UTRACE_INTERRUPT: Make @report_signal() callback soon. ++ * @UTRACE_REPORT: Make some callback soon. ++ * @UTRACE_SINGLESTEP: Resume in user mode for one instruction. ++ * @UTRACE_BLOCKSTEP: Resume in user mode until next branch. ++ * @UTRACE_RESUME: Resume normally in user mode. ++ * @UTRACE_DETACH: Detach my engine (implies %UTRACE_RESUME). ++ * ++ * See utrace_control() for detailed descriptions of each action. This is ++ * encoded in the @action argument and the return value for every callback ++ * with a &u32 return value. ++ * ++ * The order of these is important. When there is more than one engine, ++ * each supplies its choice and the smallest value prevails. ++ */ ++enum utrace_resume_action { ++ UTRACE_STOP, ++ UTRACE_INTERRUPT, ++ UTRACE_REPORT, ++ UTRACE_SINGLESTEP, ++ UTRACE_BLOCKSTEP, ++ UTRACE_RESUME, ++ UTRACE_DETACH, ++ UTRACE_RESUME_MAX ++}; ++#define UTRACE_RESUME_BITS (ilog2(UTRACE_RESUME_MAX) + 1) ++#define UTRACE_RESUME_MASK ((1 << UTRACE_RESUME_BITS) - 1) ++ ++/** ++ * utrace_resume_action - &enum utrace_resume_action from callback action ++ * @action: &u32 callback @action argument or return value ++ * ++ * This extracts the &enum utrace_resume_action from @action, ++ * which is the @action argument to a &struct utrace_engine_ops ++ * callback or the return value from one. ++ */ ++static inline enum utrace_resume_action utrace_resume_action(u32 action) ++{ ++ return action & UTRACE_RESUME_MASK; ++} ++ ++/** ++ * enum utrace_signal_action - disposition of signal ++ * @UTRACE_SIGNAL_DELIVER: Deliver according to sigaction. ++ * @UTRACE_SIGNAL_IGN: Ignore the signal. ++ * @UTRACE_SIGNAL_TERM: Terminate the process. ++ * @UTRACE_SIGNAL_CORE: Terminate with core dump. ++ * @UTRACE_SIGNAL_STOP: Deliver as absolute stop. ++ * @UTRACE_SIGNAL_TSTP: Deliver as job control stop. ++ * @UTRACE_SIGNAL_REPORT: Reporting before pending signals. ++ * @UTRACE_SIGNAL_HANDLER: Reporting after signal handler setup. ++ * ++ * This is encoded in the @action argument and the return value for ++ * a @report_signal() callback. It says what will happen to the ++ * signal described by the &siginfo_t parameter to the callback. ++ * ++ * The %UTRACE_SIGNAL_REPORT value is used in an @action argument when ++ * a tracing report is being made before dequeuing any pending signal. ++ * If this is immediately after a signal handler has been set up, then ++ * %UTRACE_SIGNAL_HANDLER is used instead. A @report_signal callback ++ * that uses %UTRACE_SIGNAL_DELIVER|%UTRACE_SINGLESTEP will ensure ++ * it sees a %UTRACE_SIGNAL_HANDLER report. ++ */ ++enum utrace_signal_action { ++ UTRACE_SIGNAL_DELIVER = 0x00, ++ UTRACE_SIGNAL_IGN = 0x10, ++ UTRACE_SIGNAL_TERM = 0x20, ++ UTRACE_SIGNAL_CORE = 0x30, ++ UTRACE_SIGNAL_STOP = 0x40, ++ UTRACE_SIGNAL_TSTP = 0x50, ++ UTRACE_SIGNAL_REPORT = 0x60, ++ UTRACE_SIGNAL_HANDLER = 0x70 ++}; ++#define UTRACE_SIGNAL_MASK 0xf0 ++#define UTRACE_SIGNAL_HOLD 0x100 /* Flag, push signal back on queue. */ ++ ++/** ++ * utrace_signal_action - &enum utrace_signal_action from callback action ++ * @action: @report_signal callback @action argument or return value ++ * ++ * This extracts the &enum utrace_signal_action from @action, which ++ * is the @action argument to a @report_signal callback or the ++ * return value from one. ++ */ ++static inline enum utrace_signal_action utrace_signal_action(u32 action) ++{ ++ return action & UTRACE_SIGNAL_MASK; ++} ++ ++/** ++ * enum utrace_syscall_action - disposition of system call attempt ++ * @UTRACE_SYSCALL_RUN: Run the system call. ++ * @UTRACE_SYSCALL_ABORT: Don't run the system call. ++ * ++ * This is encoded in the @action argument and the return value for ++ * a @report_syscall_entry callback. ++ */ ++enum utrace_syscall_action { ++ UTRACE_SYSCALL_RUN = 0x00, ++ UTRACE_SYSCALL_ABORT = 0x10 ++}; ++#define UTRACE_SYSCALL_MASK 0xf0 ++#define UTRACE_SYSCALL_RESUMED 0x100 /* Flag, report_syscall_entry() repeats */ ++ ++/** ++ * utrace_syscall_action - &enum utrace_syscall_action from callback action ++ * @action: @report_syscall_entry callback @action or return value ++ * ++ * This extracts the &enum utrace_syscall_action from @action, which ++ * is the @action argument to a @report_syscall_entry callback or the ++ * return value from one. ++ */ ++static inline enum utrace_syscall_action utrace_syscall_action(u32 action) ++{ ++ return action & UTRACE_SYSCALL_MASK; ++} ++ ++/* ++ * Flags for utrace_attach_task() and utrace_attach_pid(). ++ */ ++#define UTRACE_ATTACH_MATCH_OPS 0x0001 /* Match engines on ops. */ ++#define UTRACE_ATTACH_MATCH_DATA 0x0002 /* Match engines on data. */ ++#define UTRACE_ATTACH_MATCH_MASK 0x000f ++#define UTRACE_ATTACH_CREATE 0x0010 /* Attach a new engine. */ ++#define UTRACE_ATTACH_EXCLUSIVE 0x0020 /* Refuse if existing match. */ ++ ++/** ++ * struct utrace_engine - per-engine structure ++ * @ops: &struct utrace_engine_ops pointer passed to utrace_attach_task() ++ * @data: engine-private &void * passed to utrace_attach_task() ++ * @flags: event mask set by utrace_set_events() plus internal flag bits ++ * ++ * The task itself never has to worry about engines detaching while ++ * it's doing event callbacks. These structures are removed from the ++ * task's active list only when it's stopped, or by the task itself. ++ * ++ * utrace_engine_get() and utrace_engine_put() maintain a reference count. ++ * When it drops to zero, the structure is freed. One reference is held ++ * implicitly while the engine is attached to its task. ++ */ ++struct utrace_engine { ++/* private: */ ++ struct kref kref; ++ void (*release)(void *); ++ struct list_head entry; ++ ++/* public: */ ++ const struct utrace_engine_ops *ops; ++ void *data; ++ ++ unsigned long flags; ++}; ++ ++/** ++ * utrace_engine_get - acquire a reference on a &struct utrace_engine ++ * @engine: &struct utrace_engine pointer ++ * ++ * You must hold a reference on @engine, and you get another. ++ */ ++static inline void utrace_engine_get(struct utrace_engine *engine) ++{ ++ kref_get(&engine->kref); ++} ++ ++void __utrace_engine_release(struct kref *); ++ ++/** ++ * utrace_engine_put - release a reference on a &struct utrace_engine ++ * @engine: &struct utrace_engine pointer ++ * ++ * You must hold a reference on @engine, and you lose that reference. ++ * If it was the last one, @engine becomes an invalid pointer. ++ */ ++static inline void utrace_engine_put(struct utrace_engine *engine) ++{ ++ kref_put(&engine->kref, __utrace_engine_release); ++} ++ ++/** ++ * struct utrace_engine_ops - tracing engine callbacks ++ * ++ * Each @report_*() callback corresponds to an %UTRACE_EVENT(*) bit. ++ * utrace_set_events() calls on @engine choose which callbacks will ++ * be made to @engine from @task. ++ * ++ * Most callbacks take an @action argument, giving the resume action ++ * chosen by other tracing engines. All callbacks take an @engine ++ * argument. The @report_reap callback takes a @task argument that ++ * might or might not be @current. All other @report_* callbacks ++ * report an event in the @current task. ++ * ++ * For some calls, @action also includes bits specific to that event ++ * and utrace_resume_action() is used to extract the resume action. ++ * This shows what would happen if @engine wasn't there, or will if ++ * the callback's return value uses %UTRACE_RESUME. This always ++ * starts as %UTRACE_RESUME when no other tracing is being done on ++ * this task. ++ * ++ * All return values contain &enum utrace_resume_action bits. For ++ * some calls, other bits specific to that kind of event are added to ++ * the resume action bits with OR. These are the same bits used in ++ * the @action argument. The resume action returned by a callback ++ * does not override previous engines' choices, it only says what ++ * @engine wants done. What @current actually does is the action that's ++ * most constrained among the choices made by all attached engines. ++ * See utrace_control() for more information on the actions. ++ * ++ * When %UTRACE_STOP is used in @report_syscall_entry, then @current ++ * stops before attempting the system call. In this case, another ++ * @report_syscall_entry callback will follow after @current resumes if ++ * %UTRACE_REPORT or %UTRACE_INTERRUPT was returned by some callback ++ * or passed to utrace_control(). In a second or later callback, ++ * %UTRACE_SYSCALL_RESUMED is set in the @action argument to indicate ++ * a repeat callback still waiting to attempt the same system call ++ * invocation. This repeat callback gives each engine an opportunity ++ * to reexamine registers another engine might have changed while ++ * @current was held in %UTRACE_STOP. ++ * ++ * In other cases, the resume action does not take effect until @current ++ * is ready to check for signals and return to user mode. If there ++ * are more callbacks to be made, the last round of calls determines ++ * the final action. A @report_quiesce callback with @event zero, or ++ * a @report_signal callback, will always be the last one made before ++ * @current resumes. Only %UTRACE_STOP is "sticky"--if @engine returned ++ * %UTRACE_STOP then @current stays stopped unless @engine returns ++ * different from a following callback. ++ * ++ * The report_death() and report_reap() callbacks do not take @action ++ * arguments, and only %UTRACE_DETACH is meaningful in the return value ++ * from a report_death() callback. None of the resume actions applies ++ * to a dead thread. ++ * ++ * All @report_*() hooks are called with no locks held, in a generally ++ * safe environment when we will be returning to user mode soon (or just ++ * entered the kernel). It is fine to block for memory allocation and ++ * the like, but all hooks are asynchronous and must not block on ++ * external events! If you want the thread to block, use %UTRACE_STOP ++ * in your hook's return value; then later wake it up with utrace_control(). ++ * ++ * @report_quiesce: ++ * Requested by %UTRACE_EVENT(%QUIESCE). ++ * This does not indicate any event, but just that @current is in a ++ * safe place for examination. This call is made before each specific ++ * event callback, except for @report_reap. The @event argument gives ++ * the %UTRACE_EVENT(@which) value for the event occurring. This ++ * callback might be made for events @engine has not requested, if ++ * some other engine is tracing the event; calling utrace_set_events() ++ * call here can request the immediate callback for this occurrence of ++ * @event. @event is zero when there is no other event, @current is ++ * now ready to check for signals and return to user mode, and some ++ * engine has used %UTRACE_REPORT or %UTRACE_INTERRUPT to request this ++ * callback. For this case, if @report_signal is not %NULL, the ++ * @report_quiesce callback may be replaced with a @report_signal ++ * callback passing %UTRACE_SIGNAL_REPORT in its @action argument, ++ * whenever @current is entering the signal-check path anyway. ++ * ++ * @report_signal: ++ * Requested by %UTRACE_EVENT(%SIGNAL_*) or %UTRACE_EVENT(%QUIESCE). ++ * Use utrace_signal_action() and utrace_resume_action() on @action. ++ * The signal action is %UTRACE_SIGNAL_REPORT when some engine has ++ * used %UTRACE_REPORT or %UTRACE_INTERRUPT; the callback can choose ++ * to stop or to deliver an artificial signal, before pending signals. ++ * It's %UTRACE_SIGNAL_HANDLER instead when signal handler setup just ++ * finished (after a previous %UTRACE_SIGNAL_DELIVER return); this ++ * serves in lieu of any %UTRACE_SIGNAL_REPORT callback requested by ++ * %UTRACE_REPORT or %UTRACE_INTERRUPT, and is also implicitly ++ * requested by %UTRACE_SINGLESTEP or %UTRACE_BLOCKSTEP into the ++ * signal delivery. The other signal actions indicate a signal about ++ * to be delivered; the previous engine's return value sets the signal ++ * action seen by the the following engine's callback. The @info data ++ * can be changed at will, including @info->si_signo. The settings in ++ * @return_ka determines what %UTRACE_SIGNAL_DELIVER does. @orig_ka ++ * is what was in force before other tracing engines intervened, and ++ * it's %NULL when this report began as %UTRACE_SIGNAL_REPORT or ++ * %UTRACE_SIGNAL_HANDLER. For a report without a new signal, @info ++ * is left uninitialized and must be set completely by an engine that ++ * chooses to deliver a signal; if there was a previous @report_signal ++ * callback ending in %UTRACE_STOP and it was just resumed using ++ * %UTRACE_REPORT or %UTRACE_INTERRUPT, then @info is left unchanged ++ * from the previous callback. In this way, the original signal can ++ * be left in @info while returning %UTRACE_STOP|%UTRACE_SIGNAL_IGN ++ * and then found again when resuming with %UTRACE_INTERRUPT. ++ * The %UTRACE_SIGNAL_HOLD flag bit can be OR'd into the return value, ++ * and might be in @action if the previous engine returned it. This ++ * flag asks that the signal in @info be pushed back on @current's queue ++ * so that it will be seen again after whatever action is taken now. ++ * ++ * @report_clone: ++ * Requested by %UTRACE_EVENT(%CLONE). ++ * Event reported for parent, before the new task @child might run. ++ * @clone_flags gives the flags used in the clone system call, or ++ * equivalent flags for a fork() or vfork() system call. This ++ * function can use utrace_attach_task() on @child. Then passing ++ * %UTRACE_STOP to utrace_control() on @child here keeps the child ++ * stopped before it ever runs in user mode, %UTRACE_REPORT or ++ * %UTRACE_INTERRUPT ensures a callback from @child before it ++ * starts in user mode. ++ * ++ * @report_jctl: ++ * Requested by %UTRACE_EVENT(%JCTL). ++ * Job control event; @type is %CLD_STOPPED or %CLD_CONTINUED, ++ * indicating whether we are stopping or resuming now. If @notify ++ * is nonzero, @current is the last thread to stop and so will send ++ * %SIGCHLD to its parent after this callback; @notify reflects ++ * what the parent's %SIGCHLD has in @si_code, which can sometimes ++ * be %CLD_STOPPED even when @type is %CLD_CONTINUED. ++ * ++ * @report_exec: ++ * Requested by %UTRACE_EVENT(%EXEC). ++ * An execve system call has succeeded and the new program is about to ++ * start running. The initial user register state is handy to be tweaked ++ * directly in @regs. @fmt and @bprm gives the details of this exec. ++ * ++ * @report_syscall_entry: ++ * Requested by %UTRACE_EVENT(%SYSCALL_ENTRY). ++ * Thread has entered the kernel to request a system call. ++ * The user register state is handy to be tweaked directly in @regs. ++ * The @action argument contains an &enum utrace_syscall_action, ++ * use utrace_syscall_action() to extract it. The return value ++ * overrides the last engine's action for the system call. ++ * If the final action is %UTRACE_SYSCALL_ABORT, no system call ++ * is made. The details of the system call being attempted can ++ * be fetched here with syscall_get_nr() and syscall_get_arguments(). ++ * The parameter registers can be changed with syscall_set_arguments(). ++ * See above about the %UTRACE_SYSCALL_RESUMED flag in @action. ++ * Use %UTRACE_REPORT in the return value to guarantee you get ++ * another callback (with %UTRACE_SYSCALL_RESUMED flag) in case ++ * @current stops with %UTRACE_STOP before attempting the system call. ++ * ++ * @report_syscall_exit: ++ * Requested by %UTRACE_EVENT(%SYSCALL_EXIT). ++ * Thread is about to leave the kernel after a system call request. ++ * The user register state is handy to be tweaked directly in @regs. ++ * The results of the system call attempt can be examined here using ++ * syscall_get_error() and syscall_get_return_value(). It is safe ++ * here to call syscall_set_return_value() or syscall_rollback(). ++ * ++ * @report_exit: ++ * Requested by %UTRACE_EVENT(%EXIT). ++ * Thread is exiting and cannot be prevented from doing so, ++ * but all its state is still live. The @code value will be ++ * the wait result seen by the parent, and can be changed by ++ * this engine or others. The @orig_code value is the real ++ * status, not changed by any tracing engine. Returning %UTRACE_STOP ++ * here keeps @current stopped before it cleans up its state and dies, ++ * so it can be examined by other processes. When @current is allowed ++ * to run, it will die and get to the @report_death callback. ++ * ++ * @report_death: ++ * Requested by %UTRACE_EVENT(%DEATH). ++ * Thread is really dead now. It might be reaped by its parent at ++ * any time, or self-reap immediately. Though the actual reaping ++ * may happen in parallel, a report_reap() callback will always be ++ * ordered after a report_death() callback. ++ * ++ * @report_reap: ++ * Requested by %UTRACE_EVENT(%REAP). ++ * Called when someone reaps the dead task (parent, init, or self). ++ * This means the parent called wait, or else this was a detached ++ * thread or a process whose parent ignores SIGCHLD. ++ * No more callbacks are made after this one. ++ * The engine is always detached. ++ * There is nothing more a tracing engine can do about this thread. ++ * After this callback, the @engine pointer will become invalid. ++ * The @task pointer may become invalid if get_task_struct() hasn't ++ * been used to keep it alive. ++ * An engine should always request this callback if it stores the ++ * @engine pointer or stores any pointer in @engine->data, so it ++ * can clean up its data structures. ++ * Unlike other callbacks, this can be called from the parent's context ++ * rather than from the traced thread itself--it must not delay the ++ * parent by blocking. ++ * ++ * @release: ++ * If not %NULL, this is called after the last utrace_engine_put() ++ * call for a &struct utrace_engine, which could be implicit after ++ * a %UTRACE_DETACH return from another callback. Its argument is ++ * the engine's @data member. ++ */ ++struct utrace_engine_ops { ++ u32 (*report_quiesce)(u32 action, struct utrace_engine *engine, ++ unsigned long event); ++ u32 (*report_signal)(u32 action, struct utrace_engine *engine, ++ struct pt_regs *regs, ++ siginfo_t *info, ++ const struct k_sigaction *orig_ka, ++ struct k_sigaction *return_ka); ++ u32 (*report_clone)(u32 action, struct utrace_engine *engine, ++ unsigned long clone_flags, ++ struct task_struct *child); ++ u32 (*report_jctl)(u32 action, struct utrace_engine *engine, ++ int type, int notify); ++ u32 (*report_exec)(u32 action, struct utrace_engine *engine, ++ const struct linux_binfmt *fmt, ++ const struct linux_binprm *bprm, ++ struct pt_regs *regs); ++ u32 (*report_syscall_entry)(u32 action, struct utrace_engine *engine, ++ struct pt_regs *regs); ++ u32 (*report_syscall_exit)(u32 action, struct utrace_engine *engine, ++ struct pt_regs *regs); ++ u32 (*report_exit)(u32 action, struct utrace_engine *engine, ++ long orig_code, long *code); ++ u32 (*report_death)(struct utrace_engine *engine, ++ bool group_dead, int signal); ++ void (*report_reap)(struct utrace_engine *engine, ++ struct task_struct *task); ++ void (*release)(void *data); ++}; ++ ++/** ++ * struct utrace_examiner - private state for using utrace_prepare_examine() ++ * ++ * The members of &struct utrace_examiner are private to the implementation. ++ * This data type holds the state from a call to utrace_prepare_examine() ++ * to be used by a call to utrace_finish_examine(). ++ */ ++struct utrace_examiner { ++/* private: */ ++ long state; ++ unsigned long ncsw; ++}; ++ ++/* ++ * These are the exported entry points for tracing engines to use. ++ * See kernel/utrace.c for their kerneldoc comments with interface details. ++ */ ++struct utrace_engine *utrace_attach_task(struct task_struct *, int, ++ const struct utrace_engine_ops *, ++ void *); ++struct utrace_engine *utrace_attach_pid(struct pid *, int, ++ const struct utrace_engine_ops *, ++ void *); ++int __must_check utrace_control(struct task_struct *, ++ struct utrace_engine *, ++ enum utrace_resume_action); ++int __must_check utrace_set_events(struct task_struct *, ++ struct utrace_engine *, ++ unsigned long eventmask); ++int __must_check utrace_barrier(struct task_struct *, ++ struct utrace_engine *); ++int __must_check utrace_prepare_examine(struct task_struct *, ++ struct utrace_engine *, ++ struct utrace_examiner *); ++int __must_check utrace_finish_examine(struct task_struct *, ++ struct utrace_engine *, ++ struct utrace_examiner *); ++ ++/** ++ * utrace_control_pid - control a thread being traced by a tracing engine ++ * @pid: thread to affect ++ * @engine: attached engine to affect ++ * @action: &enum utrace_resume_action for thread to do ++ * ++ * This is the same as utrace_control(), but takes a &struct pid ++ * pointer rather than a &struct task_struct pointer. The caller must ++ * hold a ref on @pid, but does not need to worry about the task ++ * staying valid. If it's been reaped so that @pid points nowhere, ++ * then this call returns -%ESRCH. ++ */ ++static inline __must_check int utrace_control_pid( ++ struct pid *pid, struct utrace_engine *engine, ++ enum utrace_resume_action action) ++{ ++ /* ++ * We don't bother with rcu_read_lock() here to protect the ++ * task_struct pointer, because utrace_control will return ++ * -ESRCH without looking at that pointer if the engine is ++ * already detached. A task_struct pointer can't die before ++ * all the engines are detached in release_task() first. ++ */ ++ struct task_struct *task = pid_task(pid, PIDTYPE_PID); ++ return unlikely(!task) ? -ESRCH : utrace_control(task, engine, action); ++} ++ ++/** ++ * utrace_set_events_pid - choose which event reports a tracing engine gets ++ * @pid: thread to affect ++ * @engine: attached engine to affect ++ * @eventmask: new event mask ++ * ++ * This is the same as utrace_set_events(), but takes a &struct pid ++ * pointer rather than a &struct task_struct pointer. The caller must ++ * hold a ref on @pid, but does not need to worry about the task ++ * staying valid. If it's been reaped so that @pid points nowhere, ++ * then this call returns -%ESRCH. ++ */ ++static inline __must_check int utrace_set_events_pid( ++ struct pid *pid, struct utrace_engine *engine, unsigned long eventmask) ++{ ++ struct task_struct *task = pid_task(pid, PIDTYPE_PID); ++ return unlikely(!task) ? -ESRCH : ++ utrace_set_events(task, engine, eventmask); ++} ++ ++/** ++ * utrace_barrier_pid - synchronize with simultaneous tracing callbacks ++ * @pid: thread to affect ++ * @engine: engine to affect (can be detached) ++ * ++ * This is the same as utrace_barrier(), but takes a &struct pid ++ * pointer rather than a &struct task_struct pointer. The caller must ++ * hold a ref on @pid, but does not need to worry about the task ++ * staying valid. If it's been reaped so that @pid points nowhere, ++ * then this call returns -%ESRCH. ++ */ ++static inline __must_check int utrace_barrier_pid(struct pid *pid, ++ struct utrace_engine *engine) ++{ ++ struct task_struct *task = pid_task(pid, PIDTYPE_PID); ++ return unlikely(!task) ? -ESRCH : utrace_barrier(task, engine); ++} ++ ++#endif /* CONFIG_UTRACE */ ++ ++#endif /* linux/utrace.h */ +diff --git a/init/Kconfig b/init/Kconfig +index 412c21b..a03ae51 100644 +--- a/init/Kconfig ++++ b/init/Kconfig +@@ -372,6 +372,15 @@ config AUDIT_TREE + depends on AUDITSYSCALL + select FSNOTIFY + ++config UTRACE ++ bool "Infrastructure for tracing and debugging user processes" ++ depends on EXPERIMENTAL ++ depends on HAVE_ARCH_TRACEHOOK ++ help ++ Enable the utrace process tracing interface. This is an internal ++ kernel interface exported to kernel modules, to track events in ++ user threads, extract and change user thread state. ++ + source "kernel/irq/Kconfig" + + menu "RCU Subsystem" +diff --git a/kernel/Makefile b/kernel/Makefile +index 2d64cfc..4a22e81 100644 +--- a/kernel/Makefile ++++ b/kernel/Makefile +@@ -68,6 +68,7 @@ obj-$(CONFIG_IKCONFIG) += configs.o + obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o + obj-$(CONFIG_SMP) += stop_machine.o + obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o ++obj-$(CONFIG_UTRACE) += utrace.o + obj-$(CONFIG_AUDIT) += audit.o auditfilter.o + obj-$(CONFIG_AUDITSYSCALL) += auditsc.o + obj-$(CONFIG_AUDIT_WATCH) += audit_watch.o +diff --git a/kernel/fork.c b/kernel/fork.c +index 0276c30..62caf3d 100644 +--- a/kernel/fork.c ++++ b/kernel/fork.c +@@ -168,6 +168,7 @@ void free_task(struct task_struct *tsk) + free_thread_info(tsk->stack); + rt_mutex_debug_task_free(tsk); + ftrace_graph_exit_task(tsk); ++ tracehook_free_task(tsk); + free_task_struct(tsk); + } + EXPORT_SYMBOL(free_task); +@@ -1095,6 +1096,8 @@ static struct task_struct *copy_process(unsigned long clone_flags, + if (!p) + goto fork_out; + ++ tracehook_init_task(p); ++ + ftrace_graph_init_task(p); + + rt_mutex_init_task(p); +diff --git a/kernel/utrace.c b/kernel/utrace.c +new file mode 100644 +index 0000000..f332d65 +--- /dev/null ++++ b/kernel/utrace.c +@@ -0,0 +1,2440 @@ ++/* ++ * utrace infrastructure interface for debugging user processes ++ * ++ * Copyright (C) 2006-2010 Red Hat, Inc. All rights reserved. ++ * ++ * This copyrighted material is made available to anyone wishing to use, ++ * modify, copy, or redistribute it subject to the terms and conditions ++ * of the GNU General Public License v.2. ++ * ++ * Red Hat Author: Roland McGrath. ++ */ ++ ++#include <linux/utrace.h> ++#include <linux/tracehook.h> ++#include <linux/regset.h> ++#include <asm/syscall.h> ++#include <linux/ptrace.h> ++#include <linux/err.h> ++#include <linux/sched.h> ++#include <linux/freezer.h> ++#include <linux/module.h> ++#include <linux/init.h> ++#include <linux/slab.h> ++#include <linux/seq_file.h> ++ ++ ++/* ++ * Per-thread structure private to utrace implementation. ++ * If task_struct.utrace_flags is nonzero, task_struct.utrace ++ * has always been allocated first. Once allocated, it is ++ * never freed until free_task(). ++ * ++ * The common event reporting loops are done by the task making the ++ * report without ever taking any locks. To facilitate this, the two ++ * lists @attached and @attaching work together for smooth asynchronous ++ * attaching with low overhead. Modifying either list requires @lock. ++ * The @attaching list can be modified any time while holding @lock. ++ * New engines being attached always go on this list. ++ * ++ * The @attached list is what the task itself uses for its reporting ++ * loops. When the task itself is not quiescent, it can use the ++ * @attached list without taking any lock. Nobody may modify the list ++ * when the task is not quiescent. When it is quiescent, that means ++ * that it won't run again without taking @lock itself before using ++ * the list. ++ * ++ * At each place where we know the task is quiescent (or it's current), ++ * while holding @lock, we call splice_attaching(), below. This moves ++ * the @attaching list members on to the end of the @attached list. ++ * Since this happens at the start of any reporting pass, any new ++ * engines attached asynchronously go on the stable @attached list ++ * in time to have their callbacks seen. ++ */ ++struct utrace { ++ spinlock_t lock; ++ struct list_head attached, attaching; ++ ++ struct task_struct *cloning; ++ ++ struct utrace_engine *reporting; ++ ++ enum utrace_resume_action resume:UTRACE_RESUME_BITS; ++ unsigned int signal_handler:1; ++ unsigned int vfork_stop:1; /* need utrace_stop() before vfork wait */ ++ unsigned int death:1; /* in utrace_report_death() now */ ++ unsigned int reap:1; /* release_task() has run */ ++ unsigned int pending_attach:1; /* need splice_attaching() */ ++}; ++ ++static struct kmem_cache *utrace_cachep; ++static struct kmem_cache *utrace_engine_cachep; ++static const struct utrace_engine_ops utrace_detached_ops; /* forward decl */ ++ ++static int __init utrace_init(void) ++{ ++ utrace_cachep = KMEM_CACHE(utrace, SLAB_PANIC); ++ utrace_engine_cachep = KMEM_CACHE(utrace_engine, SLAB_PANIC); ++ return 0; ++} ++module_init(utrace_init); ++ ++/* ++ * Set up @task.utrace for the first time. We can have races ++ * between two utrace_attach_task() calls here. The task_lock() ++ * governs installing the new pointer. If another one got in first, ++ * we just punt the new one we allocated. ++ * ++ * This returns false only in case of a memory allocation failure. ++ */ ++static bool utrace_task_alloc(struct task_struct *task) ++{ ++ struct utrace *utrace = kmem_cache_zalloc(utrace_cachep, GFP_KERNEL); ++ if (unlikely(!utrace)) ++ return false; ++ spin_lock_init(&utrace->lock); ++ INIT_LIST_HEAD(&utrace->attached); ++ INIT_LIST_HEAD(&utrace->attaching); ++ utrace->resume = UTRACE_RESUME; ++ task_lock(task); ++ if (likely(!task->utrace)) { ++ /* ++ * This barrier makes sure the initialization of the struct ++ * precedes the installation of the pointer. This pairs ++ * with smp_read_barrier_depends() in task_utrace_struct(). ++ */ ++ smp_wmb(); ++ task->utrace = utrace; ++ } ++ task_unlock(task); ++ ++ if (unlikely(task->utrace != utrace)) ++ kmem_cache_free(utrace_cachep, utrace); ++ return true; ++} ++ ++/* ++ * This is called via tracehook_free_task() from free_task() ++ * when @task is being deallocated. ++ */ ++void utrace_free_task(struct task_struct *task) ++{ ++ kmem_cache_free(utrace_cachep, task->utrace); ++} ++ ++/* ++ * This is calledwhen the task is safely quiescent, i.e. it won't consult ++ * utrace->attached without the lock. Move any engines attached ++ * asynchronously from @utrace->attaching onto the @utrace->attached list. ++ */ ++static void splice_attaching(struct utrace *utrace) ++{ ++ lockdep_assert_held(&utrace->lock); ++ list_splice_tail_init(&utrace->attaching, &utrace->attached); ++ utrace->pending_attach = 0; ++} ++ ++/* ++ * This is the exported function used by the utrace_engine_put() inline. ++ */ ++void __utrace_engine_release(struct kref *kref) ++{ ++ struct utrace_engine *engine = container_of(kref, struct utrace_engine, ++ kref); ++ BUG_ON(!list_empty(&engine->entry)); ++ if (engine->release) ++ (*engine->release)(engine->data); ++ kmem_cache_free(utrace_engine_cachep, engine); ++} ++EXPORT_SYMBOL_GPL(__utrace_engine_release); ++ ++static bool engine_matches(struct utrace_engine *engine, int flags, ++ const struct utrace_engine_ops *ops, void *data) ++{ ++ if ((flags & UTRACE_ATTACH_MATCH_OPS) && engine->ops != ops) ++ return false; ++ if ((flags & UTRACE_ATTACH_MATCH_DATA) && engine->data != data) ++ return false; ++ return engine->ops && engine->ops != &utrace_detached_ops; ++} ++ ++static struct utrace_engine *find_matching_engine( ++ struct utrace *utrace, int flags, ++ const struct utrace_engine_ops *ops, void *data) ++{ ++ struct utrace_engine *engine; ++ list_for_each_entry(engine, &utrace->attached, entry) ++ if (engine_matches(engine, flags, ops, data)) ++ return engine; ++ list_for_each_entry(engine, &utrace->attaching, entry) ++ if (engine_matches(engine, flags, ops, data)) ++ return engine; ++ return NULL; ++} ++ ++/* ++ * Enqueue @engine, or maybe don't if UTRACE_ATTACH_EXCLUSIVE. ++ */ ++static int utrace_add_engine(struct task_struct *target, ++ struct utrace *utrace, ++ struct utrace_engine *engine, ++ int flags, ++ const struct utrace_engine_ops *ops, ++ void *data) ++{ ++ int ret; ++ ++ spin_lock(&utrace->lock); ++ ++ ret = -EEXIST; ++ if ((flags & UTRACE_ATTACH_EXCLUSIVE) && ++ unlikely(find_matching_engine(utrace, flags, ops, data))) ++ goto unlock; ++ ++ /* ++ * In case we had no engines before, make sure that ++ * utrace_flags is not zero. Since we did unlock+lock ++ * at least once after utrace_task_alloc() installed ++ * ->utrace, we have the necessary barrier which pairs ++ * with rmb() in task_utrace_struct(). ++ */ ++ ret = -ESRCH; ++ if (!target->utrace_flags) { ++ target->utrace_flags = UTRACE_EVENT(REAP); ++ /* ++ * If we race with tracehook_prepare_release_task() ++ * make sure that either it sees utrace_flags != 0 ++ * or we see exit_state == EXIT_DEAD. ++ */ ++ smp_mb(); ++ if (unlikely(target->exit_state == EXIT_DEAD)) { ++ target->utrace_flags = 0; ++ goto unlock; ++ } ++ } ++ ++ /* ++ * Put the new engine on the pending ->attaching list. ++ * Make sure it gets onto the ->attached list by the next ++ * time it's examined. Setting ->pending_attach ensures ++ * that start_report() takes the lock and splices the lists ++ * before the next new reporting pass. ++ * ++ * When target == current, it would be safe just to call ++ * splice_attaching() right here. But if we're inside a ++ * callback, that would mean the new engine also gets ++ * notified about the event that precipitated its own ++ * creation. This is not what the user wants. ++ */ ++ list_add_tail(&engine->entry, &utrace->attaching); ++ utrace->pending_attach = 1; ++ utrace_engine_get(engine); ++ ret = 0; ++unlock: ++ spin_unlock(&utrace->lock); ++ ++ return ret; ++} ++ ++/** ++ * utrace_attach_task - attach new engine, or look up an attached engine ++ * @target: thread to attach to ++ * @flags: flag bits combined with OR, see below ++ * @ops: callback table for new engine ++ * @data: engine private data pointer ++ * ++ * The caller must ensure that the @target thread does not get freed, ++ * i.e. hold a ref or be its parent. It is always safe to call this ++ * on @current, or on the @child pointer in a @report_clone callback. ++ * For most other cases, it's easier to use utrace_attach_pid() instead. ++ * ++ * UTRACE_ATTACH_CREATE: ++ * Create a new engine. If %UTRACE_ATTACH_CREATE is not specified, you ++ * only look up an existing engine already attached to the thread. ++ * ++ * UTRACE_ATTACH_EXCLUSIVE: ++ * Attempting to attach a second (matching) engine fails with -%EEXIST. ++ * ++ * UTRACE_ATTACH_MATCH_OPS: Only consider engines matching @ops. ++ * UTRACE_ATTACH_MATCH_DATA: Only consider engines matching @data. ++ * ++ * Calls with neither %UTRACE_ATTACH_MATCH_OPS nor %UTRACE_ATTACH_MATCH_DATA ++ * match the first among any engines attached to @target. That means that ++ * %UTRACE_ATTACH_EXCLUSIVE in such a call fails with -%EEXIST if there ++ * are any engines on @target at all. ++ */ ++struct utrace_engine *utrace_attach_task( ++ struct task_struct *target, int flags, ++ const struct utrace_engine_ops *ops, void *data) ++{ ++ struct utrace *utrace = task_utrace_struct(target); ++ struct utrace_engine *engine; ++ int ret; ++ ++ if (!(flags & UTRACE_ATTACH_CREATE)) { ++ if (unlikely(!utrace)) ++ return ERR_PTR(-ENOENT); ++ spin_lock(&utrace->lock); ++ engine = find_matching_engine(utrace, flags, ops, data); ++ if (engine) ++ utrace_engine_get(engine); ++ spin_unlock(&utrace->lock); ++ return engine ?: ERR_PTR(-ENOENT); ++ } ++ ++ if (unlikely(!ops) || unlikely(ops == &utrace_detached_ops)) ++ return ERR_PTR(-EINVAL); ++ ++ if (unlikely(target->flags & PF_KTHREAD)) ++ /* ++ * Silly kernel, utrace is for users! ++ */ ++ return ERR_PTR(-EPERM); ++ ++ if (!utrace) { ++ if (unlikely(!utrace_task_alloc(target))) ++ return ERR_PTR(-ENOMEM); ++ utrace = task_utrace_struct(target); ++ } ++ ++ engine = kmem_cache_alloc(utrace_engine_cachep, GFP_KERNEL); ++ if (unlikely(!engine)) ++ return ERR_PTR(-ENOMEM); ++ ++ /* ++ * Initialize the new engine structure. It starts out with one ref ++ * to return. utrace_add_engine() adds another for being attached. ++ */ ++ kref_init(&engine->kref); ++ engine->flags = 0; ++ engine->ops = ops; ++ engine->data = data; ++ engine->release = ops->release; ++ ++ ret = utrace_add_engine(target, utrace, engine, flags, ops, data); ++ ++ if (unlikely(ret)) { ++ kmem_cache_free(utrace_engine_cachep, engine); ++ engine = ERR_PTR(ret); ++ } ++ ++ ++ return engine; ++} ++EXPORT_SYMBOL_GPL(utrace_attach_task); ++ ++/** ++ * utrace_attach_pid - attach new engine, or look up an attached engine ++ * @pid: &struct pid pointer representing thread to attach to ++ * @flags: flag bits combined with OR, see utrace_attach_task() ++ * @ops: callback table for new engine ++ * @data: engine private data pointer ++ * ++ * This is the same as utrace_attach_task(), but takes a &struct pid ++ * pointer rather than a &struct task_struct pointer. The caller must ++ * hold a ref on @pid, but does not need to worry about the task ++ * staying valid. If it's been reaped so that @pid points nowhere, ++ * then this call returns -%ESRCH. ++ */ ++struct utrace_engine *utrace_attach_pid( ++ struct pid *pid, int flags, ++ const struct utrace_engine_ops *ops, void *data) ++{ ++ struct utrace_engine *engine = ERR_PTR(-ESRCH); ++ struct task_struct *task = get_pid_task(pid, PIDTYPE_PID); ++ if (task) { ++ engine = utrace_attach_task(task, flags, ops, data); ++ put_task_struct(task); ++ } ++ return engine; ++} ++EXPORT_SYMBOL_GPL(utrace_attach_pid); ++ ++/* ++ * When an engine is detached, the target thread may still see it and ++ * make callbacks until it quiesces. We install a special ops vector ++ * with these two callbacks. When the target thread quiesces, it can ++ * safely free the engine itself. For any event we will always get ++ * the report_quiesce() callback first, so we only need this one ++ * pointer to be set. The only exception is report_reap(), so we ++ * supply that callback too. ++ */ ++static u32 utrace_detached_quiesce(u32 action, struct utrace_engine *engine, ++ unsigned long event) ++{ ++ return UTRACE_DETACH; ++} ++ ++static void utrace_detached_reap(struct utrace_engine *engine, ++ struct task_struct *task) ++{ ++} ++ ++static const struct utrace_engine_ops utrace_detached_ops = { ++ .report_quiesce = &utrace_detached_quiesce, ++ .report_reap = &utrace_detached_reap ++}; ++ ++/* ++ * The caller has to hold a ref on the engine. If the attached flag is ++ * true (all but utrace_barrier() calls), the engine is supposed to be ++ * attached. If the attached flag is false (utrace_barrier() only), ++ * then return -ERESTARTSYS for an engine marked for detach but not yet ++ * fully detached. The task pointer can be invalid if the engine is ++ * detached. ++ * ++ * Get the utrace lock for the target task. ++ * Returns the struct if locked, or ERR_PTR(-errno). ++ * ++ * This has to be robust against races with: ++ * utrace_control(target, UTRACE_DETACH) calls ++ * UTRACE_DETACH after reports ++ * utrace_report_death ++ * utrace_release_task ++ */ ++static struct utrace *get_utrace_lock(struct task_struct *target, ++ struct utrace_engine *engine, ++ bool attached) ++ __acquires(utrace->lock) ++{ ++ struct utrace *utrace; ++ ++ rcu_read_lock(); ++ ++ /* ++ * If this engine was already detached, bail out before we look at ++ * the task_struct pointer at all. If it's detached after this ++ * check, then RCU is still keeping this task_struct pointer valid. ++ * ++ * The ops pointer is NULL when the engine is fully detached. ++ * It's &utrace_detached_ops when it's marked detached but still ++ * on the list. In the latter case, utrace_barrier() still works, ++ * since the target might be in the middle of an old callback. ++ */ ++ if (unlikely(!engine->ops)) { ++ rcu_read_unlock(); ++ return ERR_PTR(-ESRCH); ++ } ++ ++ if (unlikely(engine->ops == &utrace_detached_ops)) { ++ rcu_read_unlock(); ++ return attached ? ERR_PTR(-ESRCH) : ERR_PTR(-ERESTARTSYS); ++ } ++ ++ utrace = task_utrace_struct(target); ++ spin_lock(&utrace->lock); ++ if (unlikely(utrace->reap) || unlikely(!engine->ops) || ++ unlikely(engine->ops == &utrace_detached_ops)) { ++ /* ++ * By the time we got the utrace lock, ++ * it had been reaped or detached already. ++ */ ++ spin_unlock(&utrace->lock); ++ utrace = ERR_PTR(-ESRCH); ++ if (!attached && engine->ops == &utrace_detached_ops) ++ utrace = ERR_PTR(-ERESTARTSYS); ++ } ++ rcu_read_unlock(); ++ ++ return utrace; ++} ++ ++/* ++ * Now that we don't hold any locks, run through any ++ * detached engines and free their references. Each ++ * engine had one implicit ref while it was attached. ++ */ ++static void put_detached_list(struct list_head *list) ++{ ++ struct utrace_engine *engine, *next; ++ list_for_each_entry_safe(engine, next, list, entry) { ++ list_del_init(&engine->entry); ++ utrace_engine_put(engine); ++ } ++} ++ ++/* ++ * We use an extra bit in utrace_engine.flags past the event bits, ++ * to record whether the engine is keeping the target thread stopped. ++ * ++ * This bit is set in task_struct.utrace_flags whenever it is set in any ++ * engine's flags. Only utrace_reset() resets it in utrace_flags. ++ */ ++#define ENGINE_STOP (1UL << _UTRACE_NEVENTS) ++ ++static void mark_engine_wants_stop(struct task_struct *task, ++ struct utrace_engine *engine) ++{ ++ engine->flags |= ENGINE_STOP; ++ task->utrace_flags |= ENGINE_STOP; ++} ++ ++static void clear_engine_wants_stop(struct utrace_engine *engine) ++{ ++ engine->flags &= ~ENGINE_STOP; ++} ++ ++static bool engine_wants_stop(struct utrace_engine *engine) ++{ ++ return (engine->flags & ENGINE_STOP) != 0; ++} ++ ++/** ++ * utrace_set_events - choose which event reports a tracing engine gets ++ * @target: thread to affect ++ * @engine: attached engine to affect ++ * @events: new event mask ++ * ++ * This changes the set of events for which @engine wants callbacks made. ++ * ++ * This fails with -%EALREADY and does nothing if you try to clear ++ * %UTRACE_EVENT(%DEATH) when the @report_death callback may already have ++ * begun, or if you try to newly set %UTRACE_EVENT(%DEATH) or ++ * %UTRACE_EVENT(%QUIESCE) when @target is already dead or dying. ++ * ++ * This fails with -%ESRCH if you try to clear %UTRACE_EVENT(%REAP) when ++ * the @report_reap callback may already have begun, or when @target has ++ * already been detached, including forcible detach on reaping. ++ * ++ * If @target was stopped before the call, then after a successful call, ++ * no event callbacks not requested in @events will be made; if ++ * %UTRACE_EVENT(%QUIESCE) is included in @events, then a ++ * @report_quiesce callback will be made when @target resumes. ++ * ++ * If @target was not stopped and @events excludes some bits that were ++ * set before, this can return -%EINPROGRESS to indicate that @target ++ * may have been making some callback to @engine. When this returns ++ * zero, you can be sure that no event callbacks you've disabled in ++ * @events can be made. If @events only sets new bits that were not set ++ * before on @engine, then -%EINPROGRESS will never be returned. ++ * ++ * To synchronize after an -%EINPROGRESS return, see utrace_barrier(). ++ * ++ * When @target is @current, -%EINPROGRESS is not returned. But note ++ * that a newly-created engine will not receive any callbacks related to ++ * an event notification already in progress. This call enables @events ++ * callbacks to be made as soon as @engine becomes eligible for any ++ * callbacks, see utrace_attach_task(). ++ * ++ * These rules provide for coherent synchronization based on %UTRACE_STOP, ++ * even when %SIGKILL is breaking its normal simple rules. ++ */ ++int utrace_set_events(struct task_struct *target, ++ struct utrace_engine *engine, ++ unsigned long events) ++{ ++ struct utrace *utrace; ++ unsigned long old_flags, old_utrace_flags; ++ int ret = -EALREADY; ++ ++ /* ++ * We just ignore the internal bit, so callers can use ++ * engine->flags to seed bitwise ops for our argument. ++ */ ++ events &= ~ENGINE_STOP; ++ ++ utrace = get_utrace_lock(target, engine, true); ++ if (unlikely(IS_ERR(utrace))) ++ return PTR_ERR(utrace); ++ ++ old_utrace_flags = target->utrace_flags; ++ old_flags = engine->flags & ~ENGINE_STOP; ++ ++ /* ++ * If utrace_report_death() is already progress now, ++ * it's too late to clear the death event bits. ++ */ ++ if (((old_flags & ~events) & _UTRACE_DEATH_EVENTS) && utrace->death) ++ goto unlock; ++ ++ /* ++ * When setting these flags, it's essential that we really ++ * synchronize with exit_notify(). They cannot be set after ++ * exit_notify() takes the tasklist_lock. By holding the read ++ * lock here while setting the flags, we ensure that the calls ++ * to tracehook_notify_death() and tracehook_report_death() will ++ * see the new flags. This ensures that utrace_release_task() ++ * knows positively that utrace_report_death() will be called or ++ * that it won't. ++ */ ++ if ((events & ~old_flags) & _UTRACE_DEATH_EVENTS) { ++ read_lock(&tasklist_lock); ++ if (unlikely(target->exit_state)) { ++ read_unlock(&tasklist_lock); ++ goto unlock; ++ } ++ target->utrace_flags |= events; ++ read_unlock(&tasklist_lock); ++ } ++ ++ engine->flags = events | (engine->flags & ENGINE_STOP); ++ target->utrace_flags |= events; ++ ++ if ((events & UTRACE_EVENT_SYSCALL) && ++ !(old_utrace_flags & UTRACE_EVENT_SYSCALL)) ++ set_tsk_thread_flag(target, TIF_SYSCALL_TRACE); ++ ++ ret = 0; ++ if ((old_flags & ~events) && target != current && ++ !task_is_stopped_or_traced(target) && !target->exit_state) { ++ /* ++ * This barrier ensures that our engine->flags changes ++ * have hit before we examine utrace->reporting, ++ * pairing with the barrier in start_callback(). If ++ * @target has not yet hit finish_callback() to clear ++ * utrace->reporting, we might be in the middle of a ++ * callback to @engine. ++ */ ++ smp_mb(); ++ if (utrace->reporting == engine) ++ ret = -EINPROGRESS; ++ } ++unlock: ++ spin_unlock(&utrace->lock); ++ ++ return ret; ++} ++EXPORT_SYMBOL_GPL(utrace_set_events); ++ ++/* ++ * Asynchronously mark an engine as being detached. ++ * ++ * This must work while the target thread races with us doing ++ * start_callback(), defined below. It uses smp_rmb() between checking ++ * @engine->flags and using @engine->ops. Here we change @engine->ops ++ * first, then use smp_wmb() before changing @engine->flags. This ensures ++ * it can check the old flags before using the old ops, or check the old ++ * flags before using the new ops, or check the new flags before using the ++ * new ops, but can never check the new flags before using the old ops. ++ * Hence, utrace_detached_ops might be used with any old flags in place. ++ * It has report_quiesce() and report_reap() callbacks to handle all cases. ++ */ ++static void mark_engine_detached(struct utrace_engine *engine) ++{ ++ engine->ops = &utrace_detached_ops; ++ smp_wmb(); ++ engine->flags = UTRACE_EVENT(QUIESCE); ++} ++ ++/* ++ * Get @target to stop and return true if it is already stopped now. ++ * If we return false, it will make some event callback soonish. ++ * Called with @utrace locked. ++ */ ++static bool utrace_do_stop(struct task_struct *target, struct utrace *utrace) ++{ ++ if (task_is_stopped(target)) { ++ /* ++ * Stopped is considered quiescent; when it wakes up, it will ++ * go through utrace_finish_stop() before doing anything else. ++ */ ++ spin_lock_irq(&target->sighand->siglock); ++ if (likely(task_is_stopped(target))) ++ __set_task_state(target, TASK_TRACED); ++ spin_unlock_irq(&target->sighand->siglock); ++ } else if (utrace->resume > UTRACE_REPORT) { ++ utrace->resume = UTRACE_REPORT; ++ set_notify_resume(target); ++ } ++ ++ return task_is_traced(target); ++} ++ ++/* ++ * If the target is not dead it should not be in tracing ++ * stop any more. Wake it unless it's in job control stop. ++ */ ++static void utrace_wakeup(struct task_struct *target, struct utrace *utrace) ++{ ++ lockdep_assert_held(&utrace->lock); ++ spin_lock_irq(&target->sighand->siglock); ++ if (target->signal->flags & SIGNAL_STOP_STOPPED || ++ target->signal->group_stop_count) ++ target->state = TASK_STOPPED; ++ else ++ wake_up_state(target, __TASK_TRACED); ++ spin_unlock_irq(&target->sighand->siglock); ++} ++ ++/* ++ * This is called when there might be some detached engines on the list or ++ * some stale bits in @task->utrace_flags. Clean them up and recompute the ++ * flags. Returns true if we're now fully detached. ++ * ++ * Called with @utrace->lock held, returns with it released. ++ * After this returns, @utrace might be freed if everything detached. ++ */ ++static bool utrace_reset(struct task_struct *task, struct utrace *utrace) ++ __releases(utrace->lock) ++{ ++ struct utrace_engine *engine, *next; ++ unsigned long flags = 0; ++ LIST_HEAD(detached); ++ ++ splice_attaching(utrace); ++ ++ /* ++ * Update the set of events of interest from the union ++ * of the interests of the remaining tracing engines. ++ * For any engine marked detached, remove it from the list. ++ * We'll collect them on the detached list. ++ */ ++ list_for_each_entry_safe(engine, next, &utrace->attached, entry) { ++ if (engine->ops == &utrace_detached_ops) { ++ engine->ops = NULL; ++ list_move(&engine->entry, &detached); ++ } else { ++ flags |= engine->flags | UTRACE_EVENT(REAP); ++ } ++ } ++ ++ if (task->exit_state) { ++ /* ++ * Once it's already dead, we never install any flags ++ * except REAP. When ->exit_state is set and events ++ * like DEATH are not set, then they never can be set. ++ * This ensures that utrace_release_task() knows ++ * positively that utrace_report_death() can never run. ++ */ ++ BUG_ON(utrace->death); ++ flags &= UTRACE_EVENT(REAP); ++ } else if (!(flags & UTRACE_EVENT_SYSCALL) && ++ test_tsk_thread_flag(task, TIF_SYSCALL_TRACE)) { ++ clear_tsk_thread_flag(task, TIF_SYSCALL_TRACE); ++ } ++ ++ if (!flags) { ++ /* ++ * No more engines, cleared out the utrace. ++ */ ++ utrace->resume = UTRACE_RESUME; ++ utrace->signal_handler = 0; ++ } ++ ++ /* ++ * If no more engines want it stopped, wake it up. ++ */ ++ if (task_is_traced(task) && !(flags & ENGINE_STOP)) { ++ /* ++ * It just resumes, so make sure single-step ++ * is not left set. ++ */ ++ if (utrace->resume == UTRACE_RESUME) ++ user_disable_single_step(task); ++ utrace_wakeup(task, utrace); ++ } ++ ++ /* ++ * In theory spin_lock() doesn't imply rcu_read_lock(). ++ * Once we clear ->utrace_flags this task_struct can go away ++ * because tracehook_prepare_release_task() path does not take ++ * utrace->lock when ->utrace_flags == 0. ++ */ ++ rcu_read_lock(); ++ task->utrace_flags = flags; ++ spin_unlock(&utrace->lock); ++ rcu_read_unlock(); ++ ++ put_detached_list(&detached); ++ ++ return !flags; ++} ++ ++void utrace_finish_stop(void) ++{ ++ /* ++ * If we were task_is_traced() and then SIGKILL'ed, make ++ * sure we do nothing until the tracer drops utrace->lock. ++ */ ++ if (unlikely(__fatal_signal_pending(current))) { ++ struct utrace *utrace = task_utrace_struct(current); ++ spin_unlock_wait(&utrace->lock); ++ } ++} ++ ++/* ++ * Perform %UTRACE_STOP, i.e. block in TASK_TRACED until woken up. ++ * @task == current, @utrace == current->utrace, which is not locked. ++ * Return true if we were woken up by SIGKILL even though some utrace ++ * engine may still want us to stay stopped. ++ */ ++static void utrace_stop(struct task_struct *task, struct utrace *utrace, ++ enum utrace_resume_action action) ++{ ++relock: ++ spin_lock(&utrace->lock); ++ ++ if (action < utrace->resume) { ++ /* ++ * Ensure a reporting pass when we're resumed. ++ */ ++ utrace->resume = action; ++ if (action == UTRACE_INTERRUPT) ++ set_thread_flag(TIF_SIGPENDING); ++ else ++ set_thread_flag(TIF_NOTIFY_RESUME); ++ } ++ ++ /* ++ * If the ENGINE_STOP bit is clear in utrace_flags, that means ++ * utrace_reset() ran after we processed some UTRACE_STOP return ++ * values from callbacks to get here. If all engines have detached ++ * or resumed us, we don't stop. This check doesn't require ++ * siglock, but it should follow the interrupt/report bookkeeping ++ * steps (this can matter for UTRACE_RESUME but not UTRACE_DETACH). ++ */ ++ if (unlikely(!(task->utrace_flags & ENGINE_STOP))) { ++ utrace_reset(task, utrace); ++ if (task->utrace_flags & ENGINE_STOP) ++ goto relock; ++ return; ++ } ++ ++ /* ++ * The siglock protects us against signals. As well as SIGKILL ++ * waking us up, we must synchronize with the signal bookkeeping ++ * for stop signals and SIGCONT. ++ */ ++ spin_lock_irq(&task->sighand->siglock); ++ ++ if (unlikely(__fatal_signal_pending(task))) { ++ spin_unlock_irq(&task->sighand->siglock); ++ spin_unlock(&utrace->lock); ++ return; ++ } ++ ++ __set_current_state(TASK_TRACED); ++ ++ /* ++ * If there is a group stop in progress, ++ * we must participate in the bookkeeping. ++ */ ++ if (unlikely(task->signal->group_stop_count) && ++ !--task->signal->group_stop_count) ++ task->signal->flags = SIGNAL_STOP_STOPPED; ++ ++ spin_unlock_irq(&task->sighand->siglock); ++ spin_unlock(&utrace->lock); ++ ++ schedule(); ++ ++ utrace_finish_stop(); ++ ++ /* ++ * While in TASK_TRACED, we were considered "frozen enough". ++ * Now that we woke up, it's crucial if we're supposed to be ++ * frozen that we freeze now before running anything substantial. ++ */ ++ try_to_freeze(); ++ ++ /* ++ * While we were in TASK_TRACED, complete_signal() considered ++ * us "uninterested" in signal wakeups. Now make sure our ++ * TIF_SIGPENDING state is correct for normal running. ++ */ ++ spin_lock_irq(&task->sighand->siglock); ++ recalc_sigpending(); ++ spin_unlock_irq(&task->sighand->siglock); ++} ++ ++/* ++ * Called by release_task() with @reap set to true. ++ * Called by utrace_report_death() with @reap set to false. ++ * On reap, make report_reap callbacks and clean out @utrace ++ * unless still making callbacks. On death, update bookkeeping ++ * and handle the reap work if release_task() came in first. ++ */ ++void utrace_maybe_reap(struct task_struct *target, struct utrace *utrace, ++ bool reap) ++{ ++ struct utrace_engine *engine, *next; ++ struct list_head attached; ++ ++ spin_lock(&utrace->lock); ++ ++ if (reap) { ++ /* ++ * If the target will do some final callbacks but hasn't ++ * finished them yet, we know because it clears these event ++ * bits after it's done. Instead of cleaning up here and ++ * requiring utrace_report_death() to cope with it, we ++ * delay the REAP report and the teardown until after the ++ * target finishes its death reports. ++ */ ++ utrace->reap = 1; ++ ++ if (target->utrace_flags & _UTRACE_DEATH_EVENTS) { ++ spin_unlock(&utrace->lock); ++ return; ++ } ++ } else { ++ /* ++ * After we unlock with this flag clear, any competing ++ * utrace_control/utrace_set_events calls know that we've ++ * finished our callbacks and any detach bookkeeping. ++ */ ++ utrace->death = 0; ++ ++ if (!utrace->reap) { ++ /* ++ * We're just dead, not reaped yet. This will ++ * reset @target->utrace_flags so the later call ++ * with @reap set won't hit the check above. ++ */ ++ utrace_reset(target, utrace); ++ return; ++ } ++ } ++ ++ /* ++ * utrace_add_engine() checks ->utrace_flags != 0. Since ++ * @utrace->reap is set, nobody can set or clear UTRACE_EVENT(REAP) ++ * in @engine->flags or change @engine->ops and nobody can change ++ * @utrace->attached after we drop the lock. ++ */ ++ target->utrace_flags = 0; ++ ++ /* ++ * We clear out @utrace->attached before we drop the lock so ++ * that find_matching_engine() can't come across any old engine ++ * while we are busy tearing it down. ++ */ ++ list_replace_init(&utrace->attached, &attached); ++ list_splice_tail_init(&utrace->attaching, &attached); ++ ++ spin_unlock(&utrace->lock); ++ ++ list_for_each_entry_safe(engine, next, &attached, entry) { ++ if (engine->flags & UTRACE_EVENT(REAP)) ++ engine->ops->report_reap(engine, target); ++ ++ engine->ops = NULL; ++ engine->flags = 0; ++ list_del_init(&engine->entry); ++ ++ utrace_engine_put(engine); ++ } ++} ++ ++/* ++ * You can't do anything to a dead task but detach it. ++ * If release_task() has been called, you can't do that. ++ * ++ * On the exit path, DEATH and QUIESCE event bits are set only ++ * before utrace_report_death() has taken the lock. At that point, ++ * the death report will come soon, so disallow detach until it's ++ * done. This prevents us from racing with it detaching itself. ++ * ++ * Called only when @target->exit_state is nonzero. ++ */ ++static inline int utrace_control_dead(struct task_struct *target, ++ struct utrace *utrace, ++ enum utrace_resume_action action) ++{ ++ lockdep_assert_held(&utrace->lock); ++ ++ if (action != UTRACE_DETACH || unlikely(utrace->reap)) ++ return -ESRCH; ++ ++ if (unlikely(utrace->death)) ++ /* ++ * We have already started the death report. We can't ++ * prevent the report_death and report_reap callbacks, ++ * so tell the caller they will happen. ++ */ ++ return -EALREADY; ++ ++ return 0; ++} ++ ++/** ++ * utrace_control - control a thread being traced by a tracing engine ++ * @target: thread to affect ++ * @engine: attached engine to affect ++ * @action: &enum utrace_resume_action for thread to do ++ * ++ * This is how a tracing engine asks a traced thread to do something. ++ * This call is controlled by the @action argument, which has the ++ * same meaning as the &enum utrace_resume_action value returned by ++ * event reporting callbacks. ++ * ++ * If @target is already dead (@target->exit_state nonzero), ++ * all actions except %UTRACE_DETACH fail with -%ESRCH. ++ * ++ * The following sections describe each option for the @action argument. ++ * ++ * UTRACE_DETACH: ++ * ++ * After this, the @engine data structure is no longer accessible, ++ * and the thread might be reaped. The thread will start running ++ * again if it was stopped and no longer has any attached engines ++ * that want it stopped. ++ * ++ * If the @report_reap callback may already have begun, this fails ++ * with -%ESRCH. If the @report_death callback may already have ++ * begun, this fails with -%EALREADY. ++ * ++ * If @target is not already stopped, then a callback to this engine ++ * might be in progress or about to start on another CPU. If so, ++ * then this returns -%EINPROGRESS; the detach happens as soon as ++ * the pending callback is finished. To synchronize after an ++ * -%EINPROGRESS return, see utrace_barrier(). ++ * ++ * If @target is properly stopped before utrace_control() is called, ++ * then after successful return it's guaranteed that no more callbacks ++ * to the @engine->ops vector will be made. ++ * ++ * The only exception is %SIGKILL (and exec or group-exit by another ++ * thread in the group), which can cause asynchronous @report_death ++ * and/or @report_reap callbacks even when %UTRACE_STOP was used. ++ * (In that event, this fails with -%ESRCH or -%EALREADY, see above.) ++ * ++ * UTRACE_STOP: ++ * ++ * This asks that @target stop running. This returns 0 only if ++ * @target is already stopped, either for tracing or for job ++ * control. Then @target will remain stopped until another ++ * utrace_control() call is made on @engine; @target can be woken ++ * only by %SIGKILL (or equivalent, such as exec or termination by ++ * another thread in the same thread group). ++ * ++ * This returns -%EINPROGRESS if @target is not already stopped. ++ * Then the effect is like %UTRACE_REPORT. A @report_quiesce or ++ * @report_signal callback will be made soon. Your callback can ++ * then return %UTRACE_STOP to keep @target stopped. ++ * ++ * This does not interrupt system calls in progress, including ones ++ * that sleep for a long time. For that, use %UTRACE_INTERRUPT. ++ * To interrupt system calls and then keep @target stopped, your ++ * @report_signal callback can return %UTRACE_STOP. ++ * ++ * UTRACE_RESUME: ++ * ++ * Just let @target continue running normally, reversing the effect ++ * of a previous %UTRACE_STOP. If another engine is keeping @target ++ * stopped, then it remains stopped until all engines let it resume. ++ * If @target was not stopped, this has no effect. ++ * ++ * UTRACE_REPORT: ++ * ++ * This is like %UTRACE_RESUME, but also ensures that there will be ++ * a @report_quiesce or @report_signal callback made soon. If ++ * @target had been stopped, then there will be a callback before it ++ * resumes running normally. If another engine is keeping @target ++ * stopped, then there might be no callbacks until all engines let ++ * it resume. ++ * ++ * Since this is meaningless unless @report_quiesce callbacks will ++ * be made, it returns -%EINVAL if @engine lacks %UTRACE_EVENT(%QUIESCE). ++ * ++ * UTRACE_INTERRUPT: ++ * ++ * This is like %UTRACE_REPORT, but ensures that @target will make a ++ * @report_signal callback before it resumes or delivers signals. ++ * If @target was in a system call or about to enter one, work in ++ * progress will be interrupted as if by %SIGSTOP. If another ++ * engine is keeping @target stopped, then there might be no ++ * callbacks until all engines let it resume. ++ * ++ * This gives @engine an opportunity to introduce a forced signal ++ * disposition via its @report_signal callback. ++ * ++ * UTRACE_SINGLESTEP: ++ * ++ * It's invalid to use this unless arch_has_single_step() returned true. ++ * This is like %UTRACE_RESUME, but resumes for one user instruction only. ++ * ++ * Note that passing %UTRACE_SINGLESTEP or %UTRACE_BLOCKSTEP to ++ * utrace_control() or returning it from an event callback alone does ++ * not necessarily ensure that stepping will be enabled. If there are ++ * more callbacks made to any engine before returning to user mode, ++ * then the resume action is chosen only by the last set of callbacks. ++ * To be sure, enable %UTRACE_EVENT(%QUIESCE) and look for the ++ * @report_quiesce callback with a zero event mask, or the ++ * @report_signal callback with %UTRACE_SIGNAL_REPORT. ++ * ++ * Since this is not robust unless @report_quiesce callbacks will ++ * be made, it returns -%EINVAL if @engine lacks %UTRACE_EVENT(%QUIESCE). ++ * ++ * UTRACE_BLOCKSTEP: ++ * ++ * It's invalid to use this unless arch_has_block_step() returned true. ++ * This is like %UTRACE_SINGLESTEP, but resumes for one whole basic ++ * block of user instructions. ++ * ++ * Since this is not robust unless @report_quiesce callbacks will ++ * be made, it returns -%EINVAL if @engine lacks %UTRACE_EVENT(%QUIESCE). ++ * ++ * %UTRACE_BLOCKSTEP devolves to %UTRACE_SINGLESTEP when another ++ * tracing engine is using %UTRACE_SINGLESTEP at the same time. ++ */ ++int utrace_control(struct task_struct *target, ++ struct utrace_engine *engine, ++ enum utrace_resume_action action) ++{ ++ struct utrace *utrace; ++ bool reset; ++ int ret; ++ ++ if (unlikely(action >= UTRACE_RESUME_MAX)) { ++ WARN(1, "invalid action argument to utrace_control()!"); ++ return -EINVAL; ++ } ++ ++ /* ++ * This is a sanity check for a programming error in the caller. ++ * Their request can only work properly in all cases by relying on ++ * a follow-up callback, but they didn't set one up! This check ++ * doesn't do locking, but it shouldn't matter. The caller has to ++ * be synchronously sure the callback is set up to be operating the ++ * interface properly. ++ */ ++ if (action >= UTRACE_REPORT && action < UTRACE_RESUME && ++ unlikely(!(engine->flags & UTRACE_EVENT(QUIESCE)))) { ++ WARN(1, "utrace_control() with no QUIESCE callback in place!"); ++ return -EINVAL; ++ } ++ ++ utrace = get_utrace_lock(target, engine, true); ++ if (unlikely(IS_ERR(utrace))) ++ return PTR_ERR(utrace); ++ ++ reset = task_is_traced(target); ++ ret = 0; ++ ++ /* ++ * ->exit_state can change under us, this doesn't matter. ++ * We do not care about ->exit_state in fact, but we do ++ * care about ->reap and ->death. If either flag is set, ++ * we must also see ->exit_state != 0. ++ */ ++ if (unlikely(target->exit_state)) { ++ ret = utrace_control_dead(target, utrace, action); ++ if (ret) { ++ spin_unlock(&utrace->lock); ++ return ret; ++ } ++ reset = true; ++ } ++ ++ switch (action) { ++ case UTRACE_STOP: ++ mark_engine_wants_stop(target, engine); ++ if (!reset && !utrace_do_stop(target, utrace)) ++ ret = -EINPROGRESS; ++ reset = false; ++ break; ++ ++ case UTRACE_DETACH: ++ if (engine_wants_stop(engine)) ++ target->utrace_flags &= ~ENGINE_STOP; ++ mark_engine_detached(engine); ++ reset = reset || utrace_do_stop(target, utrace); ++ if (!reset) { ++ /* ++ * As in utrace_set_events(), this barrier ensures ++ * that our engine->flags changes have hit before we ++ * examine utrace->reporting, pairing with the barrier ++ * in start_callback(). If @target has not yet hit ++ * finish_callback() to clear utrace->reporting, we ++ * might be in the middle of a callback to @engine. ++ */ ++ smp_mb(); ++ if (utrace->reporting == engine) ++ ret = -EINPROGRESS; ++ } ++ break; ++ ++ case UTRACE_RESUME: ++ clear_engine_wants_stop(engine); ++ break; ++ ++ case UTRACE_BLOCKSTEP: ++ /* ++ * Resume from stopped, step one block. ++ * We fall through to treat it like UTRACE_SINGLESTEP. ++ */ ++ if (unlikely(!arch_has_block_step())) { ++ WARN(1, "UTRACE_BLOCKSTEP when !arch_has_block_step()"); ++ action = UTRACE_SINGLESTEP; ++ } ++ ++ case UTRACE_SINGLESTEP: ++ /* ++ * Resume from stopped, step one instruction. ++ * We fall through to the UTRACE_REPORT case. ++ */ ++ if (unlikely(!arch_has_single_step())) { ++ WARN(1, ++ "UTRACE_SINGLESTEP when !arch_has_single_step()"); ++ reset = false; ++ ret = -EOPNOTSUPP; ++ break; ++ } ++ ++ case UTRACE_REPORT: ++ /* ++ * Make the thread call tracehook_notify_resume() soon. ++ * But don't bother if it's already been interrupted. ++ * In that case, utrace_get_signal() will be reporting soon. ++ */ ++ clear_engine_wants_stop(engine); ++ if (action < utrace->resume) { ++ utrace->resume = action; ++ set_notify_resume(target); ++ } ++ break; ++ ++ case UTRACE_INTERRUPT: ++ /* ++ * Make the thread call tracehook_get_signal() soon. ++ */ ++ clear_engine_wants_stop(engine); ++ if (utrace->resume == UTRACE_INTERRUPT) ++ break; ++ utrace->resume = UTRACE_INTERRUPT; ++ ++ /* ++ * If it's not already stopped, interrupt it now. We need ++ * the siglock here in case it calls recalc_sigpending() ++ * and clears its own TIF_SIGPENDING. By taking the lock, ++ * we've serialized any later recalc_sigpending() after our ++ * setting of utrace->resume to force it on. ++ */ ++ if (reset) { ++ /* ++ * This is really just to keep the invariant that ++ * TIF_SIGPENDING is set with UTRACE_INTERRUPT. ++ * When it's stopped, we know it's always going ++ * through utrace_get_signal() and will recalculate. ++ */ ++ set_tsk_thread_flag(target, TIF_SIGPENDING); ++ } else { ++ struct sighand_struct *sighand; ++ unsigned long irqflags; ++ sighand = lock_task_sighand(target, &irqflags); ++ if (likely(sighand)) { ++ signal_wake_up(target, 0); ++ unlock_task_sighand(target, &irqflags); ++ } ++ } ++ break; ++ ++ default: ++ BUG(); /* We checked it on entry. */ ++ } ++ ++ /* ++ * Let the thread resume running. If it's not stopped now, ++ * there is nothing more we need to do. ++ */ ++ if (reset) ++ utrace_reset(target, utrace); ++ else ++ spin_unlock(&utrace->lock); ++ ++ return ret; ++} ++EXPORT_SYMBOL_GPL(utrace_control); ++ ++/** ++ * utrace_barrier - synchronize with simultaneous tracing callbacks ++ * @target: thread to affect ++ * @engine: engine to affect (can be detached) ++ * ++ * This blocks while @target might be in the midst of making a callback to ++ * @engine. It can be interrupted by signals and will return -%ERESTARTSYS. ++ * A return value of zero means no callback from @target to @engine was ++ * in progress. Any effect of its return value (such as %UTRACE_STOP) has ++ * already been applied to @engine. ++ * ++ * It's not necessary to keep the @target pointer alive for this call. ++ * It's only necessary to hold a ref on @engine. This will return ++ * safely even if @target has been reaped and has no task refs. ++ * ++ * A successful return from utrace_barrier() guarantees its ordering ++ * with respect to utrace_set_events() and utrace_control() calls. If ++ * @target was not properly stopped, event callbacks just disabled might ++ * still be in progress; utrace_barrier() waits until there is no chance ++ * an unwanted callback can be in progress. ++ */ ++int utrace_barrier(struct task_struct *target, struct utrace_engine *engine) ++{ ++ struct utrace *utrace; ++ int ret = -ERESTARTSYS; ++ ++ if (unlikely(target == current)) ++ return 0; ++ ++ do { ++ utrace = get_utrace_lock(target, engine, false); ++ if (unlikely(IS_ERR(utrace))) { ++ ret = PTR_ERR(utrace); ++ if (ret != -ERESTARTSYS) ++ break; ++ } else { ++ /* ++ * All engine state changes are done while ++ * holding the lock, i.e. before we get here. ++ * Since we have the lock, we only need to ++ * worry about @target making a callback. ++ * When it has entered start_callback() but ++ * not yet gotten to finish_callback(), we ++ * will see utrace->reporting == @engine. ++ * When @target doesn't take the lock, it uses ++ * barriers to order setting utrace->reporting ++ * before it examines the engine state. ++ */ ++ if (utrace->reporting != engine) ++ ret = 0; ++ spin_unlock(&utrace->lock); ++ if (!ret) ++ break; ++ } ++ schedule_timeout_interruptible(1); ++ } while (!signal_pending(current)); ++ ++ return ret; ++} ++EXPORT_SYMBOL_GPL(utrace_barrier); ++ ++/* ++ * This is local state used for reporting loops, perhaps optimized away. ++ */ ++struct utrace_report { ++ u32 result; ++ enum utrace_resume_action action; ++ enum utrace_resume_action resume_action; ++ bool detaches; ++ bool spurious; ++}; ++ ++#define INIT_REPORT(var) \ ++ struct utrace_report var = { \ ++ .action = UTRACE_RESUME, \ ++ .resume_action = UTRACE_RESUME, \ ++ .spurious = true \ ++ } ++ ++/* ++ * We are now making the report, so clear the flag saying we need one. ++ * When there is a new attach, ->pending_attach is set just so we will ++ * know to do splice_attaching() here before the callback loop. ++ */ ++static enum utrace_resume_action start_report(struct utrace *utrace) ++{ ++ enum utrace_resume_action resume = utrace->resume; ++ if (utrace->pending_attach || ++ (resume > UTRACE_INTERRUPT && resume < UTRACE_RESUME)) { ++ spin_lock(&utrace->lock); ++ splice_attaching(utrace); ++ resume = utrace->resume; ++ if (resume > UTRACE_INTERRUPT) ++ utrace->resume = UTRACE_RESUME; ++ spin_unlock(&utrace->lock); ++ } ++ return resume; ++} ++ ++static inline void finish_report_reset(struct task_struct *task, ++ struct utrace *utrace, ++ struct utrace_report *report) ++{ ++ if (unlikely(report->spurious || report->detaches)) { ++ spin_lock(&utrace->lock); ++ if (utrace_reset(task, utrace)) ++ report->action = UTRACE_RESUME; ++ } ++} ++ ++/* ++ * Complete a normal reporting pass, pairing with a start_report() call. ++ * This handles any UTRACE_DETACH or UTRACE_REPORT or UTRACE_INTERRUPT ++ * returns from engine callbacks. If @will_not_stop is true and any ++ * engine's last callback used UTRACE_STOP, we do UTRACE_REPORT here to ++ * ensure we stop before user mode. If there were no callbacks made, it ++ * will recompute @task->utrace_flags to avoid another false-positive. ++ */ ++static void finish_report(struct task_struct *task, struct utrace *utrace, ++ struct utrace_report *report, bool will_not_stop) ++{ ++ enum utrace_resume_action resume = report->action; ++ ++ if (resume == UTRACE_STOP) ++ resume = will_not_stop ? UTRACE_REPORT : UTRACE_RESUME; ++ ++ if (resume < utrace->resume) { ++ spin_lock(&utrace->lock); ++ utrace->resume = resume; ++ if (resume == UTRACE_INTERRUPT) ++ set_tsk_thread_flag(task, TIF_SIGPENDING); ++ else ++ set_tsk_thread_flag(task, TIF_NOTIFY_RESUME); ++ spin_unlock(&utrace->lock); ++ } ++ ++ finish_report_reset(task, utrace, report); ++} ++ ++static void finish_callback_report(struct task_struct *task, ++ struct utrace *utrace, ++ struct utrace_report *report, ++ struct utrace_engine *engine, ++ enum utrace_resume_action action) ++{ ++ if (action == UTRACE_DETACH) { ++ /* ++ * By holding the lock here, we make sure that ++ * utrace_barrier() (really get_utrace_lock()) sees the ++ * effect of this detach. Otherwise utrace_barrier() could ++ * return 0 after this callback had returned UTRACE_DETACH. ++ * This way, a 0 return is an unambiguous indicator that any ++ * callback returning UTRACE_DETACH has indeed caused detach. ++ */ ++ spin_lock(&utrace->lock); ++ engine->ops = &utrace_detached_ops; ++ spin_unlock(&utrace->lock); ++ } ++ ++ /* ++ * If utrace_control() was used, treat that like UTRACE_DETACH here. ++ */ ++ if (engine->ops == &utrace_detached_ops) { ++ report->detaches = true; ++ return; ++ } ++ ++ if (action < report->action) ++ report->action = action; ++ ++ if (action != UTRACE_STOP) { ++ if (action < report->resume_action) ++ report->resume_action = action; ++ ++ if (engine_wants_stop(engine)) { ++ spin_lock(&utrace->lock); ++ clear_engine_wants_stop(engine); ++ spin_unlock(&utrace->lock); ++ } ++ ++ return; ++ } ++ ++ if (!engine_wants_stop(engine)) { ++ spin_lock(&utrace->lock); ++ /* ++ * If utrace_control() came in and detached us ++ * before we got the lock, we must not stop now. ++ */ ++ if (unlikely(engine->ops == &utrace_detached_ops)) ++ report->detaches = true; ++ else ++ mark_engine_wants_stop(task, engine); ++ spin_unlock(&utrace->lock); ++ } ++} ++ ++/* ++ * Apply the return value of one engine callback to @report. ++ * Returns true if @engine detached and should not get any more callbacks. ++ */ ++static bool finish_callback(struct task_struct *task, struct utrace *utrace, ++ struct utrace_report *report, ++ struct utrace_engine *engine, ++ u32 ret) ++{ ++ report->result = ret & ~UTRACE_RESUME_MASK; ++ finish_callback_report(task, utrace, report, engine, ++ utrace_resume_action(ret)); ++ ++ /* ++ * Now that we have applied the effect of the return value, ++ * clear this so that utrace_barrier() can stop waiting. ++ * A subsequent utrace_control() can stop or resume @engine ++ * and know this was ordered after its callback's action. ++ * ++ * We don't need any barriers here because utrace_barrier() ++ * takes utrace->lock. If we touched engine->flags above, ++ * the lock guaranteed this change was before utrace_barrier() ++ * examined utrace->reporting. ++ */ ++ utrace->reporting = NULL; ++ ++ /* ++ * We've just done an engine callback. These are allowed to sleep, ++ * though all well-behaved ones restrict that to blocking kalloc() ++ * or quickly-acquired mutex_lock() and the like. This is a good ++ * place to make sure tracing engines don't introduce too much ++ * latency under voluntary preemption. ++ */ ++ might_sleep(); ++ ++ return engine->ops == &utrace_detached_ops; ++} ++ ++/* ++ * Start the callbacks for @engine to consider @event (a bit mask). ++ * This makes the report_quiesce() callback first. If @engine wants ++ * a specific callback for @event, we return the ops vector to use. ++ * If not, we return NULL. The return value from the ops->callback ++ * function called should be passed to finish_callback(). ++ */ ++static const struct utrace_engine_ops *start_callback( ++ struct utrace *utrace, struct utrace_report *report, ++ struct utrace_engine *engine, struct task_struct *task, ++ unsigned long event) ++{ ++ const struct utrace_engine_ops *ops; ++ unsigned long want; ++ ++ /* ++ * This barrier ensures that we've set utrace->reporting before ++ * we examine engine->flags or engine->ops. utrace_barrier() ++ * relies on this ordering to indicate that the effect of any ++ * utrace_control() and utrace_set_events() calls is in place ++ * by the time utrace->reporting can be seen to be NULL. ++ */ ++ utrace->reporting = engine; ++ smp_mb(); ++ ++ /* ++ * This pairs with the barrier in mark_engine_detached(). ++ * It makes sure that we never see the old ops vector with ++ * the new flags, in case the original vector had no report_quiesce. ++ */ ++ want = engine->flags; ++ smp_rmb(); ++ ops = engine->ops; ++ ++ if ((want & UTRACE_EVENT(QUIESCE)) || ops == &utrace_detached_ops) { ++ if (finish_callback(task, utrace, report, engine, ++ (*ops->report_quiesce)(report->action, ++ engine, event))) ++ return NULL; ++ ++ if (!event) { ++ /* We only got here to report QUIESCE */ ++ report->spurious = false; ++ return NULL; ++ } ++ ++ /* ++ * finish_callback() reset utrace->reporting after the ++ * quiesce callback. Now we set it again (as above) ++ * before re-examining engine->flags, which could have ++ * been changed synchronously by ->report_quiesce or ++ * asynchronously by utrace_control() or utrace_set_events(). ++ */ ++ utrace->reporting = engine; ++ smp_mb(); ++ want = engine->flags; ++ } ++ ++ if (want & ENGINE_STOP) ++ report->action = UTRACE_STOP; ++ ++ if (want & event) { ++ report->spurious = false; ++ return ops; ++ } ++ ++ utrace->reporting = NULL; ++ return NULL; ++} ++ ++/* ++ * Do a normal reporting pass for engines interested in @event. ++ * @callback is the name of the member in the ops vector, and remaining ++ * args are the extras it takes after the standard three args. ++ */ ++#define REPORT_CALLBACKS(rev, task, utrace, report, event, callback, ...) \ ++ do { \ ++ struct utrace_engine *engine; \ ++ const struct utrace_engine_ops *ops; \ ++ list_for_each_entry##rev(engine, &utrace->attached, entry) { \ ++ ops = start_callback(utrace, report, engine, task, \ ++ event); \ ++ if (!ops) \ ++ continue; \ ++ finish_callback(task, utrace, report, engine, \ ++ (*ops->callback)(__VA_ARGS__)); \ ++ } \ ++ } while (0) ++#define REPORT(task, utrace, report, event, callback, ...) \ ++ do { \ ++ start_report(utrace); \ ++ REPORT_CALLBACKS(, task, utrace, report, event, callback, \ ++ (report)->action, engine, ## __VA_ARGS__); \ ++ finish_report(task, utrace, report, true); \ ++ } while (0) ++ ++/* ++ * Called iff UTRACE_EVENT(EXEC) flag is set. ++ */ ++void utrace_report_exec(struct linux_binfmt *fmt, struct linux_binprm *bprm, ++ struct pt_regs *regs) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ ++ REPORT(task, utrace, &report, UTRACE_EVENT(EXEC), ++ report_exec, fmt, bprm, regs); ++} ++ ++static u32 do_report_syscall_entry(struct pt_regs *regs, ++ struct task_struct *task, ++ struct utrace *utrace, ++ struct utrace_report *report, ++ u32 resume_report) ++{ ++ start_report(utrace); ++ REPORT_CALLBACKS(_reverse, task, utrace, report, ++ UTRACE_EVENT(SYSCALL_ENTRY), report_syscall_entry, ++ resume_report | report->result | report->action, ++ engine, regs); ++ finish_report(task, utrace, report, false); ++ ++ if (report->action != UTRACE_STOP) ++ return 0; ++ ++ utrace_stop(task, utrace, report->resume_action); ++ ++ if (fatal_signal_pending(task)) { ++ /* ++ * We are continuing despite UTRACE_STOP because of a ++ * SIGKILL. Don't let the system call actually proceed. ++ */ ++ report->result = UTRACE_SYSCALL_ABORT; ++ } else if (utrace->resume <= UTRACE_REPORT) { ++ /* ++ * If we've been asked for another report after our stop, ++ * go back to report (and maybe stop) again before we run ++ * the system call. The second (and later) reports are ++ * marked with the UTRACE_SYSCALL_RESUMED flag so that ++ * engines know this is a second report at the same ++ * entry. This gives them the chance to examine the ++ * registers anew after they might have been changed ++ * while we were stopped. ++ */ ++ report->detaches = false; ++ report->spurious = true; ++ report->action = report->resume_action = UTRACE_RESUME; ++ return UTRACE_SYSCALL_RESUMED; ++ } ++ ++ return 0; ++} ++ ++/* ++ * Called iff UTRACE_EVENT(SYSCALL_ENTRY) flag is set. ++ * Return true to prevent the system call. ++ */ ++bool utrace_report_syscall_entry(struct pt_regs *regs) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ u32 resume_report = 0; ++ ++ do { ++ resume_report = do_report_syscall_entry(regs, task, utrace, ++ &report, resume_report); ++ } while (resume_report); ++ ++ return utrace_syscall_action(report.result) == UTRACE_SYSCALL_ABORT; ++} ++ ++/* ++ * Called iff UTRACE_EVENT(SYSCALL_EXIT) flag is set. ++ */ ++void utrace_report_syscall_exit(struct pt_regs *regs) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ ++ REPORT(task, utrace, &report, UTRACE_EVENT(SYSCALL_EXIT), ++ report_syscall_exit, regs); ++} ++ ++/* ++ * Called iff UTRACE_EVENT(CLONE) flag is set. ++ * This notification call blocks the wake_up_new_task call on the child. ++ * So we must not quiesce here. tracehook_report_clone_complete will do ++ * a quiescence check momentarily. ++ */ ++void utrace_report_clone(unsigned long clone_flags, struct task_struct *child) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ ++ /* ++ * We don't use the REPORT() macro here, because we need ++ * to clear utrace->cloning before finish_report(). ++ * After finish_report(), utrace can be a stale pointer ++ * in cases when report.action is still UTRACE_RESUME. ++ */ ++ start_report(utrace); ++ utrace->cloning = child; ++ ++ REPORT_CALLBACKS(, task, utrace, &report, ++ UTRACE_EVENT(CLONE), report_clone, ++ report.action, engine, clone_flags, child); ++ ++ utrace->cloning = NULL; ++ finish_report(task, utrace, &report, !(clone_flags & CLONE_VFORK)); ++ ++ /* ++ * For a vfork, we will go into an uninterruptible block waiting ++ * for the child. We need UTRACE_STOP to happen before this, not ++ * after. For CLONE_VFORK, utrace_finish_vfork() will be called. ++ */ ++ if (report.action == UTRACE_STOP && (clone_flags & CLONE_VFORK)) { ++ spin_lock(&utrace->lock); ++ utrace->vfork_stop = 1; ++ spin_unlock(&utrace->lock); ++ } ++} ++ ++/* ++ * We're called after utrace_report_clone() for a CLONE_VFORK. ++ * If UTRACE_STOP was left from the clone report, we stop here. ++ * After this, we'll enter the uninterruptible wait_for_completion() ++ * waiting for the child. ++ */ ++void utrace_finish_vfork(struct task_struct *task) ++{ ++ struct utrace *utrace = task_utrace_struct(task); ++ ++ if (utrace->vfork_stop) { ++ spin_lock(&utrace->lock); ++ utrace->vfork_stop = 0; ++ spin_unlock(&utrace->lock); ++ utrace_stop(task, utrace, UTRACE_RESUME); /* XXX */ ++ } ++} ++ ++/* ++ * Called iff UTRACE_EVENT(JCTL) flag is set. ++ * ++ * Called with siglock held. ++ */ ++void utrace_report_jctl(int notify, int what) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ ++ spin_unlock_irq(&task->sighand->siglock); ++ ++ REPORT(task, utrace, &report, UTRACE_EVENT(JCTL), ++ report_jctl, what, notify); ++ ++ spin_lock_irq(&task->sighand->siglock); ++} ++ ++/* ++ * Called iff UTRACE_EVENT(EXIT) flag is set. ++ */ ++void utrace_report_exit(long *exit_code) ++{ ++ struct task_struct *task = current; ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ long orig_code = *exit_code; ++ ++ REPORT(task, utrace, &report, UTRACE_EVENT(EXIT), ++ report_exit, orig_code, exit_code); ++ ++ if (report.action == UTRACE_STOP) ++ utrace_stop(task, utrace, report.resume_action); ++} ++ ++/* ++ * Called iff UTRACE_EVENT(DEATH) or UTRACE_EVENT(QUIESCE) flag is set. ++ * ++ * It is always possible that we are racing with utrace_release_task here. ++ * For this reason, utrace_release_task checks for the event bits that get ++ * us here, and delays its cleanup for us to do. ++ */ ++void utrace_report_death(struct task_struct *task, struct utrace *utrace, ++ bool group_dead, int signal) ++{ ++ INIT_REPORT(report); ++ ++ BUG_ON(!task->exit_state); ++ ++ /* ++ * We are presently considered "quiescent"--which is accurate ++ * inasmuch as we won't run any more user instructions ever again. ++ * But for utrace_control and utrace_set_events to be robust, they ++ * must be sure whether or not we will run any more callbacks. If ++ * a call comes in before we do, taking the lock here synchronizes ++ * us so we don't run any callbacks just disabled. Calls that come ++ * in while we're running the callbacks will see the exit.death ++ * flag and know that we are not yet fully quiescent for purposes ++ * of detach bookkeeping. ++ */ ++ spin_lock(&utrace->lock); ++ BUG_ON(utrace->death); ++ utrace->death = 1; ++ utrace->resume = UTRACE_RESUME; ++ splice_attaching(utrace); ++ spin_unlock(&utrace->lock); ++ ++ REPORT_CALLBACKS(, task, utrace, &report, UTRACE_EVENT(DEATH), ++ report_death, engine, group_dead, signal); ++ ++ utrace_maybe_reap(task, utrace, false); ++} ++ ++/* ++ * Finish the last reporting pass before returning to user mode. ++ */ ++static void finish_resume_report(struct task_struct *task, ++ struct utrace *utrace, ++ struct utrace_report *report) ++{ ++ finish_report_reset(task, utrace, report); ++ ++ switch (report->action) { ++ case UTRACE_STOP: ++ utrace_stop(task, utrace, report->resume_action); ++ break; ++ ++ case UTRACE_INTERRUPT: ++ if (!signal_pending(task)) ++ set_tsk_thread_flag(task, TIF_SIGPENDING); ++ break; ++ ++ case UTRACE_BLOCKSTEP: ++ if (likely(arch_has_block_step())) { ++ user_enable_block_step(task); ++ break; ++ } ++ ++ /* ++ * This means some callback is to blame for failing ++ * to check arch_has_block_step() itself. Warn and ++ * then fall through to treat it as SINGLESTEP. ++ */ ++ WARN(1, "UTRACE_BLOCKSTEP when !arch_has_block_step()"); ++ ++ case UTRACE_SINGLESTEP: ++ if (likely(arch_has_single_step())) { ++ user_enable_single_step(task); ++ } else { ++ /* ++ * This means some callback is to blame for failing ++ * to check arch_has_single_step() itself. Spew ++ * about it so the loser will fix his module. ++ */ ++ WARN(1, ++ "UTRACE_SINGLESTEP when !arch_has_single_step()"); ++ } ++ break; ++ ++ case UTRACE_REPORT: ++ case UTRACE_RESUME: ++ default: ++ user_disable_single_step(task); ++ break; ++ } ++} ++ ++/* ++ * This is called when TIF_NOTIFY_RESUME had been set (and is now clear). ++ * We are close to user mode, and this is the place to report or stop. ++ * When we return, we're going to user mode or into the signals code. ++ */ ++void utrace_resume(struct task_struct *task, struct pt_regs *regs) ++{ ++ struct utrace *utrace = task_utrace_struct(task); ++ INIT_REPORT(report); ++ struct utrace_engine *engine; ++ ++ /* ++ * Some machines get here with interrupts disabled. The same arch ++ * code path leads to calling into get_signal_to_deliver(), which ++ * implicitly reenables them by virtue of spin_unlock_irq. ++ */ ++ local_irq_enable(); ++ ++ /* ++ * If this flag is still set it's because there was a signal ++ * handler setup done but no report_signal following it. Clear ++ * the flag before we get to user so it doesn't confuse us later. ++ */ ++ if (unlikely(utrace->signal_handler)) { ++ spin_lock(&utrace->lock); ++ utrace->signal_handler = 0; ++ spin_unlock(&utrace->lock); ++ } ++ ++ /* ++ * Update our bookkeeping even if there are no callbacks made here. ++ */ ++ report.action = start_report(utrace); ++ ++ switch (report.action) { ++ case UTRACE_RESUME: ++ /* ++ * Anything we might have done was already handled by ++ * utrace_get_signal(), or this is an entirely spurious ++ * call. (The arch might use TIF_NOTIFY_RESUME for other ++ * purposes as well as calling us.) ++ */ ++ return; ++ case UTRACE_REPORT: ++ if (unlikely(!(task->utrace_flags & UTRACE_EVENT(QUIESCE)))) ++ break; ++ /* ++ * Do a simple reporting pass, with no specific ++ * callback after report_quiesce. ++ */ ++ report.action = UTRACE_RESUME; ++ list_for_each_entry(engine, &utrace->attached, entry) ++ start_callback(utrace, &report, engine, task, 0); ++ break; ++ default: ++ /* ++ * Even if this report was truly spurious, there is no need ++ * for utrace_reset() now. TIF_NOTIFY_RESUME was already ++ * cleared--it doesn't stay spuriously set. ++ */ ++ report.spurious = false; ++ break; ++ } ++ ++ /* ++ * Finish the report and either stop or get ready to resume. ++ * If utrace->resume was not UTRACE_REPORT, this applies its ++ * effect now (i.e. step or interrupt). ++ */ ++ finish_resume_report(task, utrace, &report); ++} ++ ++/* ++ * Return true if current has forced signal_pending(). ++ * ++ * This is called only when current->utrace_flags is nonzero, so we know ++ * that current->utrace must be set. It's not inlined in tracehook.h ++ * just so that struct utrace can stay opaque outside this file. ++ */ ++bool utrace_interrupt_pending(void) ++{ ++ return task_utrace_struct(current)->resume == UTRACE_INTERRUPT; ++} ++ ++/* ++ * Take the siglock and push @info back on our queue. ++ * Returns with @task->sighand->siglock held. ++ */ ++static void push_back_signal(struct task_struct *task, siginfo_t *info) ++ __acquires(task->sighand->siglock) ++{ ++ struct sigqueue *q; ++ ++ if (unlikely(!info->si_signo)) { /* Oh, a wise guy! */ ++ spin_lock_irq(&task->sighand->siglock); ++ return; ++ } ++ ++ q = sigqueue_alloc(); ++ if (likely(q)) { ++ q->flags = 0; ++ copy_siginfo(&q->info, info); ++ } ++ ++ spin_lock_irq(&task->sighand->siglock); ++ ++ sigaddset(&task->pending.signal, info->si_signo); ++ if (likely(q)) ++ list_add(&q->list, &task->pending.list); ++ ++ set_tsk_thread_flag(task, TIF_SIGPENDING); ++} ++ ++/* ++ * This is the hook from the signals code, called with the siglock held. ++ * Here is the ideal place to stop. We also dequeue and intercept signals. ++ */ ++int utrace_get_signal(struct task_struct *task, struct pt_regs *regs, ++ siginfo_t *info, struct k_sigaction *return_ka) ++ __releases(task->sighand->siglock) ++ __acquires(task->sighand->siglock) ++{ ++ struct utrace *utrace; ++ struct k_sigaction *ka; ++ INIT_REPORT(report); ++ struct utrace_engine *engine; ++ const struct utrace_engine_ops *ops; ++ unsigned long event, want; ++ u32 ret; ++ int signr; ++ ++ utrace = task_utrace_struct(task); ++ if (utrace->resume < UTRACE_RESUME || ++ utrace->pending_attach || utrace->signal_handler) { ++ enum utrace_resume_action resume; ++ ++ /* ++ * We've been asked for an explicit report before we ++ * even check for pending signals. ++ */ ++ ++ spin_unlock_irq(&task->sighand->siglock); ++ ++ spin_lock(&utrace->lock); ++ ++ splice_attaching(utrace); ++ ++ report.result = utrace->signal_handler ? ++ UTRACE_SIGNAL_HANDLER : UTRACE_SIGNAL_REPORT; ++ utrace->signal_handler = 0; ++ ++ resume = utrace->resume; ++ utrace->resume = UTRACE_RESUME; ++ ++ spin_unlock(&utrace->lock); ++ ++ /* ++ * Make sure signal_pending() only returns true ++ * if there are real signals pending. ++ */ ++ if (signal_pending(task)) { ++ spin_lock_irq(&task->sighand->siglock); ++ recalc_sigpending(); ++ spin_unlock_irq(&task->sighand->siglock); ++ } ++ ++ if (resume > UTRACE_REPORT) { ++ /* ++ * We only got here to process utrace->resume. ++ * Despite no callbacks, this report is not spurious. ++ */ ++ report.action = resume; ++ report.spurious = false; ++ finish_resume_report(task, utrace, &report); ++ return -1; ++ } else if (!(task->utrace_flags & UTRACE_EVENT(QUIESCE))) { ++ /* ++ * We only got here to clear utrace->signal_handler. ++ */ ++ return -1; ++ } ++ ++ /* ++ * Do a reporting pass for no signal, just for EVENT(QUIESCE). ++ * The engine callbacks can fill in *info and *return_ka. ++ * We'll pass NULL for the @orig_ka argument to indicate ++ * that there was no original signal. ++ */ ++ event = 0; ++ ka = NULL; ++ memset(return_ka, 0, sizeof *return_ka); ++ } else if (!(task->utrace_flags & UTRACE_EVENT_SIGNAL_ALL) || ++ unlikely(task->signal->group_stop_count)) { ++ /* ++ * If no engine is interested in intercepting signals or ++ * we must stop, let the caller just dequeue them normally ++ * or participate in group-stop. ++ */ ++ return 0; ++ } else { ++ /* ++ * Steal the next signal so we can let tracing engines ++ * examine it. From the signal number and sigaction, ++ * determine what normal delivery would do. If no ++ * engine perturbs it, we'll do that by returning the ++ * signal number after setting *return_ka. ++ */ ++ signr = dequeue_signal(task, &task->blocked, info); ++ if (signr == 0) ++ return signr; ++ BUG_ON(signr != info->si_signo); ++ ++ ka = &task->sighand->action[signr - 1]; ++ *return_ka = *ka; ++ ++ /* ++ * We are never allowed to interfere with SIGKILL. ++ * Just punt after filling in *return_ka for our caller. ++ */ ++ if (signr == SIGKILL) ++ return signr; ++ ++ if (ka->sa.sa_handler == SIG_IGN) { ++ event = UTRACE_EVENT(SIGNAL_IGN); ++ report.result = UTRACE_SIGNAL_IGN; ++ } else if (ka->sa.sa_handler != SIG_DFL) { ++ event = UTRACE_EVENT(SIGNAL); ++ report.result = UTRACE_SIGNAL_DELIVER; ++ } else if (sig_kernel_coredump(signr)) { ++ event = UTRACE_EVENT(SIGNAL_CORE); ++ report.result = UTRACE_SIGNAL_CORE; ++ } else if (sig_kernel_ignore(signr)) { ++ event = UTRACE_EVENT(SIGNAL_IGN); ++ report.result = UTRACE_SIGNAL_IGN; ++ } else if (signr == SIGSTOP) { ++ event = UTRACE_EVENT(SIGNAL_STOP); ++ report.result = UTRACE_SIGNAL_STOP; ++ } else if (sig_kernel_stop(signr)) { ++ event = UTRACE_EVENT(SIGNAL_STOP); ++ report.result = UTRACE_SIGNAL_TSTP; ++ } else { ++ event = UTRACE_EVENT(SIGNAL_TERM); ++ report.result = UTRACE_SIGNAL_TERM; ++ } ++ ++ /* ++ * Now that we know what event type this signal is, we ++ * can short-circuit if no engines care about those. ++ */ ++ if ((task->utrace_flags & (event | UTRACE_EVENT(QUIESCE))) == 0) ++ return signr; ++ ++ /* ++ * We have some interested engines, so tell them about ++ * the signal and let them change its disposition. ++ */ ++ spin_unlock_irq(&task->sighand->siglock); ++ } ++ ++ /* ++ * This reporting pass chooses what signal disposition we'll act on. ++ */ ++ list_for_each_entry(engine, &utrace->attached, entry) { ++ /* ++ * See start_callback() comment about this barrier. ++ */ ++ utrace->reporting = engine; ++ smp_mb(); ++ ++ /* ++ * This pairs with the barrier in mark_engine_detached(), ++ * see start_callback() comments. ++ */ ++ want = engine->flags; ++ smp_rmb(); ++ ops = engine->ops; ++ ++ if ((want & (event | UTRACE_EVENT(QUIESCE))) == 0) { ++ utrace->reporting = NULL; ++ continue; ++ } ++ ++ if (ops->report_signal) ++ ret = (*ops->report_signal)( ++ report.result | report.action, engine, ++ regs, info, ka, return_ka); ++ else ++ ret = (report.result | (*ops->report_quiesce)( ++ report.action, engine, event)); ++ ++ /* ++ * Avoid a tight loop reporting again and again if some ++ * engine is too stupid. ++ */ ++ switch (utrace_resume_action(ret)) { ++ default: ++ break; ++ case UTRACE_INTERRUPT: ++ case UTRACE_REPORT: ++ ret = (ret & ~UTRACE_RESUME_MASK) | UTRACE_RESUME; ++ break; ++ } ++ ++ finish_callback(task, utrace, &report, engine, ret); ++ } ++ ++ /* ++ * We express the chosen action to the signals code in terms ++ * of a representative signal whose default action does it. ++ * Our caller uses our return value (signr) to decide what to ++ * do, but uses info->si_signo as the signal number to report. ++ */ ++ switch (utrace_signal_action(report.result)) { ++ case UTRACE_SIGNAL_TERM: ++ signr = SIGTERM; ++ break; ++ ++ case UTRACE_SIGNAL_CORE: ++ signr = SIGQUIT; ++ break; ++ ++ case UTRACE_SIGNAL_STOP: ++ signr = SIGSTOP; ++ break; ++ ++ case UTRACE_SIGNAL_TSTP: ++ signr = SIGTSTP; ++ break; ++ ++ case UTRACE_SIGNAL_DELIVER: ++ signr = info->si_signo; ++ ++ if (return_ka->sa.sa_handler == SIG_DFL) { ++ /* ++ * We'll do signr's normal default action. ++ * For ignore, we'll fall through below. ++ * For stop/death, break locks and returns it. ++ */ ++ if (likely(signr) && !sig_kernel_ignore(signr)) ++ break; ++ } else if (return_ka->sa.sa_handler != SIG_IGN && ++ likely(signr)) { ++ /* ++ * Complete the bookkeeping after the report. ++ * The handler will run. If an engine wanted to ++ * stop or step, then make sure we do another ++ * report after signal handler setup. ++ */ ++ if (report.action != UTRACE_RESUME) ++ report.action = UTRACE_INTERRUPT; ++ finish_report(task, utrace, &report, true); ++ ++ if (unlikely(report.result & UTRACE_SIGNAL_HOLD)) ++ push_back_signal(task, info); ++ else ++ spin_lock_irq(&task->sighand->siglock); ++ ++ /* ++ * We do the SA_ONESHOT work here since the ++ * normal path will only touch *return_ka now. ++ */ ++ if (unlikely(return_ka->sa.sa_flags & SA_ONESHOT)) { ++ return_ka->sa.sa_flags &= ~SA_ONESHOT; ++ if (likely(valid_signal(signr))) { ++ ka = &task->sighand->action[signr - 1]; ++ ka->sa.sa_handler = SIG_DFL; ++ } ++ } ++ ++ return signr; ++ } ++ ++ /* Fall through for an ignored signal. */ ++ ++ case UTRACE_SIGNAL_IGN: ++ case UTRACE_SIGNAL_REPORT: ++ default: ++ /* ++ * If the signal is being ignored, then we are on the way ++ * directly back to user mode. We can stop here, or step, ++ * as in utrace_resume(), above. After we've dealt with that, ++ * our caller will relock and come back through here. ++ */ ++ finish_resume_report(task, utrace, &report); ++ ++ if (unlikely(fatal_signal_pending(task))) { ++ /* ++ * The only reason we woke up now was because of a ++ * SIGKILL. Don't do normal dequeuing in case it ++ * might get a signal other than SIGKILL. That would ++ * perturb the death state so it might differ from ++ * what the debugger would have allowed to happen. ++ * Instead, pluck out just the SIGKILL to be sure ++ * we'll die immediately with nothing else different ++ * from the quiescent state the debugger wanted us in. ++ */ ++ sigset_t sigkill_only; ++ siginitsetinv(&sigkill_only, sigmask(SIGKILL)); ++ spin_lock_irq(&task->sighand->siglock); ++ signr = dequeue_signal(task, &sigkill_only, info); ++ BUG_ON(signr != SIGKILL); ++ *return_ka = task->sighand->action[SIGKILL - 1]; ++ return signr; ++ } ++ ++ if (unlikely(report.result & UTRACE_SIGNAL_HOLD)) { ++ push_back_signal(task, info); ++ spin_unlock_irq(&task->sighand->siglock); ++ } ++ ++ return -1; ++ } ++ ++ /* ++ * Complete the bookkeeping after the report. ++ * This sets utrace->resume if UTRACE_STOP was used. ++ */ ++ finish_report(task, utrace, &report, true); ++ ++ return_ka->sa.sa_handler = SIG_DFL; ++ ++ /* ++ * If this signal is fatal, si_signo gets through as exit_code. ++ * We can't allow a completely bogus value there or else core ++ * kernel code can freak out. (If an engine wants to control ++ * the exit_code value exactly, it can do so in report_exit.) ++ * We'll produce a big complaint in dmesg, but won't crash. ++ * That's nicer for debugging your utrace engine. ++ */ ++ if (unlikely(info->si_signo & 0x80)) { ++ WARN(1, "utrace engine left bogus si_signo value!"); ++ info->si_signo = SIGTRAP; ++ } ++ ++ if (unlikely(report.result & UTRACE_SIGNAL_HOLD)) ++ push_back_signal(task, info); ++ else ++ spin_lock_irq(&task->sighand->siglock); ++ ++ if (sig_kernel_stop(signr)) ++ task->group_stop |= GROUP_STOP_DEQUEUED; ++ ++ return signr; ++} ++ ++/* ++ * This gets called after a signal handler has been set up. ++ * We set a flag so the next report knows it happened. ++ * If we're already stepping, make sure we do a report_signal. ++ * If not, make sure we get into utrace_resume() where we can ++ * clear the signal_handler flag before resuming. ++ */ ++void utrace_signal_handler(struct task_struct *task, int stepping) ++{ ++ struct utrace *utrace = task_utrace_struct(task); ++ ++ spin_lock(&utrace->lock); ++ ++ utrace->signal_handler = 1; ++ if (utrace->resume > UTRACE_INTERRUPT) { ++ if (stepping) { ++ utrace->resume = UTRACE_INTERRUPT; ++ set_tsk_thread_flag(task, TIF_SIGPENDING); ++ } else if (utrace->resume == UTRACE_RESUME) { ++ set_tsk_thread_flag(task, TIF_NOTIFY_RESUME); ++ } ++ } ++ ++ spin_unlock(&utrace->lock); ++} ++ ++/** ++ * utrace_prepare_examine - prepare to examine thread state ++ * @target: thread of interest, a &struct task_struct pointer ++ * @engine: engine pointer returned by utrace_attach_task() ++ * @exam: temporary state, a &struct utrace_examiner pointer ++ * ++ * This call prepares to safely examine the thread @target using ++ * &struct user_regset calls, or direct access to thread-synchronous fields. ++ * ++ * When @target is current, this call is superfluous. When @target is ++ * another thread, it must be held stopped via %UTRACE_STOP by @engine. ++ * ++ * This call may block the caller until @target stays stopped, so it must ++ * be called only after the caller is sure @target is about to unschedule. ++ * This means a zero return from a utrace_control() call on @engine giving ++ * %UTRACE_STOP, or a report_quiesce() or report_signal() callback to ++ * @engine that used %UTRACE_STOP in its return value. ++ * ++ * Returns -%ESRCH if @target is dead or -%EINVAL if %UTRACE_STOP was ++ * not used. If @target has started running again despite %UTRACE_STOP ++ * (for %SIGKILL or a spurious wakeup), this call returns -%EAGAIN. ++ * ++ * When this call returns zero, it's safe to use &struct user_regset ++ * calls and task_user_regset_view() on @target and to examine some of ++ * its fields directly. When the examination is complete, a ++ * utrace_finish_examine() call must follow to check whether it was ++ * completed safely. ++ */ ++int utrace_prepare_examine(struct task_struct *target, ++ struct utrace_engine *engine, ++ struct utrace_examiner *exam) ++{ ++ int ret = 0; ++ ++ if (unlikely(target == current)) ++ return 0; ++ ++ rcu_read_lock(); ++ if (unlikely(!engine_wants_stop(engine))) ++ ret = -EINVAL; ++ else if (unlikely(target->exit_state)) ++ ret = -ESRCH; ++ else { ++ exam->state = target->state; ++ if (unlikely(exam->state == TASK_RUNNING)) ++ ret = -EAGAIN; ++ else ++ get_task_struct(target); ++ } ++ rcu_read_unlock(); ++ ++ if (likely(!ret)) { ++ exam->ncsw = wait_task_inactive(target, exam->state); ++ put_task_struct(target); ++ if (unlikely(!exam->ncsw)) ++ ret = -EAGAIN; ++ } ++ ++ return ret; ++} ++EXPORT_SYMBOL_GPL(utrace_prepare_examine); ++ ++/** ++ * utrace_finish_examine - complete an examination of thread state ++ * @target: thread of interest, a &struct task_struct pointer ++ * @engine: engine pointer returned by utrace_attach_task() ++ * @exam: pointer passed to utrace_prepare_examine() call ++ * ++ * This call completes an examination on the thread @target begun by a ++ * paired utrace_prepare_examine() call with the same arguments that ++ * returned success (zero). ++ * ++ * When @target is current, this call is superfluous. When @target is ++ * another thread, this returns zero if @target has remained unscheduled ++ * since the paired utrace_prepare_examine() call returned zero. ++ * ++ * When this returns an error, any examination done since the paired ++ * utrace_prepare_examine() call is unreliable and the data extracted ++ * should be discarded. The error is -%EINVAL if @engine is not ++ * keeping @target stopped, or -%EAGAIN if @target woke up unexpectedly. ++ */ ++int utrace_finish_examine(struct task_struct *target, ++ struct utrace_engine *engine, ++ struct utrace_examiner *exam) ++{ ++ int ret = 0; ++ ++ if (unlikely(target == current)) ++ return 0; ++ ++ rcu_read_lock(); ++ if (unlikely(!engine_wants_stop(engine))) ++ ret = -EINVAL; ++ else if (unlikely(target->state != exam->state)) ++ ret = -EAGAIN; ++ else ++ get_task_struct(target); ++ rcu_read_unlock(); ++ ++ if (likely(!ret)) { ++ unsigned long ncsw = wait_task_inactive(target, exam->state); ++ if (unlikely(ncsw != exam->ncsw)) ++ ret = -EAGAIN; ++ put_task_struct(target); ++ } ++ ++ return ret; ++} ++EXPORT_SYMBOL_GPL(utrace_finish_examine); ++ ++/* ++ * This is declared in linux/regset.h and defined in machine-dependent ++ * code. We put the export here to ensure no machine forgets it. ++ */ ++EXPORT_SYMBOL_GPL(task_user_regset_view); ++ ++/* ++ * Called with rcu_read_lock() held. ++ */ ++void task_utrace_proc_status(struct seq_file *m, struct task_struct *p) ++{ ++ seq_printf(m, "Utrace:\t%lx\n", p->utrace_flags); ++} +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:04 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:04 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:03 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 2259ED812A; + Thu, 30 Jun 2011 20:23:03 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id Ex9fFDzwy1Zb; Thu, 30 Jun 2011 20:23:03 -0400 (EDT) +Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 0EF28D810F; + Thu, 30 Jun 2011 20:23:03 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610Mt6X021086; + Thu, 30 Jun 2011 20:22:56 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:03 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:01 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 02/19] utrace: remove jobctl bits +Message-ID: <20110701002101.GA25779@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 +Status: RO +Content-Length: 1890 +Lines: 56 + +- change utrace_get_signal() to check GROUP_STOP_PENDING instead of + signal->group_stop_count. With the recent changes group_stop_count + doesn't necessarily mean this task should participate in group stop. + +- remove the "participate in group stop" code from utrace_wakeup() and + utrace_stop(), this is no longer needed and wrong. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/utrace.c | 16 ++-------------- + 1 files changed, 2 insertions(+), 14 deletions(-) + +diff --git a/kernel/utrace.c b/kernel/utrace.c +index f332d65..6e7fafb 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -648,11 +648,7 @@ static void utrace_wakeup(struct task_struct *target, struct utrace *utrace) + { + lockdep_assert_held(&utrace->lock); + spin_lock_irq(&target->sighand->siglock); +- if (target->signal->flags & SIGNAL_STOP_STOPPED || +- target->signal->group_stop_count) +- target->state = TASK_STOPPED; +- else +- wake_up_state(target, __TASK_TRACED); ++ wake_up_state(target, __TASK_TRACED); + spin_unlock_irq(&target->sighand->siglock); + } + +@@ -805,14 +801,6 @@ relock: + + __set_current_state(TASK_TRACED); + +- /* +- * If there is a group stop in progress, +- * we must participate in the bookkeeping. +- */ +- if (unlikely(task->signal->group_stop_count) && +- !--task->signal->group_stop_count) +- task->signal->flags = SIGNAL_STOP_STOPPED; +- + spin_unlock_irq(&task->sighand->siglock); + spin_unlock(&utrace->lock); + +@@ -2036,7 +2024,7 @@ int utrace_get_signal(struct task_struct *task, struct pt_regs *regs, + ka = NULL; + memset(return_ka, 0, sizeof *return_ka); + } else if (!(task->utrace_flags & UTRACE_EVENT_SIGNAL_ALL) || +- unlikely(task->signal->group_stop_count)) { ++ unlikely(task->group_stop & GROUP_STOP_PENDING)) { + /* + * If no engine is interested in intercepting signals or + * we must stop, let the caller just dequeue them normally +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:05 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:05 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:06 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 6B38AD812A; + Thu, 30 Jun 2011 20:23:06 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id f4153Z6E7KGl; Thu, 30 Jun 2011 20:23:06 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 55D4AD810F; + Thu, 30 Jun 2011 20:23:06 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610Mwi2015168; + Thu, 30 Jun 2011 20:22:59 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:06 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:04 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 03/19] ptrace: take ->siglock around s/TRACED/RUNNING/ +Message-ID: <20110701002104.GA25787@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 1624 +Lines: 56 + +change ptrace_resume() and ptrace_stop() to take ->siglock around changing +task->state from TRACED to RUNNING. + +With this patch __TASK_TRACED/STOPPED bits are fully protected by ->siglock, +nobody can set or clear these bits without ->siglock held. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/ptrace.c | 8 +++++++- + kernel/signal.c | 3 +++ + 2 files changed, 10 insertions(+), 1 deletions(-) + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 2df1157..9988b13 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -534,6 +534,8 @@ static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) + static int ptrace_resume(struct task_struct *child, long request, + unsigned long data) + { ++ unsigned long flags; ++ + if (!valid_signal(data)) + return -EIO; + +@@ -562,7 +564,11 @@ static int ptrace_resume(struct task_struct *child, long request, + } + + child->exit_code = data; +- wake_up_state(child, __TASK_TRACED); ++ ++ if (lock_task_sighand(child, &flags)) { ++ wake_up_state(child, __TASK_TRACED); ++ unlock_task_sighand(child, &flags); ++ } + + return 0; + } +diff --git a/kernel/signal.c b/kernel/signal.c +index ff76786..2138cee 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -1799,7 +1799,10 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) + if (gstop_done) + do_notify_parent_cldstop(current, false, why); + ++ spin_lock_irq(¤t->sighand->siglock); + __set_current_state(TASK_RUNNING); ++ spin_unlock_irq(¤t->sighand->siglock); ++ + if (clear_code) + current->exit_code = 0; + read_unlock(&tasklist_lock); +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:06 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:06 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:09 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id E1AB7D812A; + Thu, 30 Jun 2011 20:23:09 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id QhOnA49nS3Vp; Thu, 30 Jun 2011 20:23:09 -0400 (EDT) +Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id C5E15D810F; + Thu, 30 Jun 2011 20:23:09 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610N2Kd007635; + Thu, 30 Jun 2011 20:23:02 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:10 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:07 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 04/19] introduce wake_up_quiescent() +Message-ID: <20110701002107.GA25790@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 +Status: RO +Content-Length: 3104 +Lines: 93 + +No functional changes. Add the new helper, wake_up_quiescent(task, state), +which simply returns wake_up_state(task, state). Change all callers which +do wake_up_state(STOPPED/TRACED) to use the new helper. ptrace_stop() is +a bit special, it does __set_current_state(RUNNING) in the very unlikely +case, change it as well. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + include/linux/signal.h | 2 ++ + kernel/ptrace.c | 2 +- + kernel/signal.c | 12 ++++++++++-- + kernel/utrace.c | 2 +- + 4 files changed, 14 insertions(+), 4 deletions(-) + +diff --git a/include/linux/signal.h b/include/linux/signal.h +index a822300..2be3712 100644 +--- a/include/linux/signal.h ++++ b/include/linux/signal.h +@@ -239,6 +239,8 @@ static inline int valid_signal(unsigned long sig) + struct timespec; + struct pt_regs; + ++extern int wake_up_quiescent(struct task_struct *p, unsigned int state); ++ + extern int next_signal(struct sigpending *pending, sigset_t *mask); + extern int do_send_sig_info(int sig, struct siginfo *info, + struct task_struct *p, bool group); +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 9988b13..26ae214 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -566,7 +566,7 @@ static int ptrace_resume(struct task_struct *child, long request, + child->exit_code = data; + + if (lock_task_sighand(child, &flags)) { +- wake_up_state(child, __TASK_TRACED); ++ wake_up_quiescent(child, __TASK_TRACED); + unlock_task_sighand(child, &flags); + } + +diff --git a/kernel/signal.c b/kernel/signal.c +index 2138cee..4fcf1c7 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -652,6 +652,14 @@ void signal_wake_up(struct task_struct *t, int resume) + } + + /* ++ * wakes up the STOPPED/TRACED task, must be called with ->siglock held. ++ */ ++int wake_up_quiescent(struct task_struct *p, unsigned int state) ++{ ++ return wake_up_state(p, state); ++} ++ ++/* + * Remove signals in mask from the pending set and queue. + * Returns 1 if any signals were found. + * +@@ -811,7 +819,7 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) + do { + task_clear_group_stop_pending(t); + rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); +- wake_up_state(t, __TASK_STOPPED); ++ wake_up_quiescent(t, __TASK_STOPPED); + } while_each_thread(p, t); + + /* +@@ -1800,7 +1808,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) + do_notify_parent_cldstop(current, false, why); + + spin_lock_irq(¤t->sighand->siglock); +- __set_current_state(TASK_RUNNING); ++ wake_up_quiescent(current, __TASK_TRACED); + spin_unlock_irq(¤t->sighand->siglock); + + if (clear_code) +diff --git a/kernel/utrace.c b/kernel/utrace.c +index 6e7fafb..d7c547c 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -648,7 +648,7 @@ static void utrace_wakeup(struct task_struct *target, struct utrace *utrace) + { + lockdep_assert_held(&utrace->lock); + spin_lock_irq(&target->sighand->siglock); +- wake_up_state(target, __TASK_TRACED); ++ wake_up_quiescent(target, __TASK_TRACED); + spin_unlock_irq(&target->sighand->siglock); + } + +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:07 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:07 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com (LHLO + zmta02.collab.prod.int.phx2.redhat.com) (10.5.5.32) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:13 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 2CF811287F3; + Thu, 30 Jun 2011 20:23:13 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta02.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id dNPA3WxO-7pp; Thu, 30 Jun 2011 20:23:13 -0400 (EDT) +Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 154D61287DD; + Thu, 30 Jun 2011 20:23:13 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610N5nY021107; + Thu, 30 Jun 2011 20:23:06 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:13 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:11 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 05/19] introduce ptrace_signal_wake_up() +Message-ID: <20110701002111.GA25797@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 +Status: RO +Content-Length: 1975 +Lines: 68 + +Add the new helper, ptrace_signal_wake_up(), change ptrace.c to use +it instead of signal_wake_up(). + +The new helper does almost the same, except: + + - it doesn't use the TASK_WAKEKILL bit to wake up the TRACED + or STOPPED task, it uses __TASK_STOPPED | __TASK_TRACED + explicitly. This is what ptrace actually wants, it should + never wake up a TASK_KILLABLE task. + + This should be cleanuped upatream, signal_wake_up() should + take the state as an argument, not a boolean. Until then + we add a new static helper. + + - it uses wake_up_quiescent() instead of wake_up_state(). + +Thereafter every change from STOPPED/TRACED to RUNNING is done via +wake_up_quiescent(). + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/ptrace.c | 16 ++++++++++++++-- + 1 files changed, 14 insertions(+), 2 deletions(-) + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 26ae214..0b2aba5 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -24,6 +24,18 @@ + #include <linux/regset.h> + #include <linux/hw_breakpoint.h> + ++static void ptrace_signal_wake_up(struct task_struct *p, int quiescent) ++{ ++ unsigned int state; ++ ++ set_tsk_thread_flag(p, TIF_SIGPENDING); ++ ++ state = TASK_INTERRUPTIBLE; ++ if (quiescent) ++ state |= (__TASK_STOPPED | __TASK_TRACED); ++ if (!wake_up_quiescent(p, state)) ++ kick_process(p); ++} + + /* + * ptrace a task: make the debugger its new parent and +@@ -92,7 +104,7 @@ void __ptrace_unlink(struct task_struct *child) + * TASK_KILLABLE sleeps. + */ + if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child)) +- signal_wake_up(child, task_is_traced(child)); ++ ptrace_signal_wake_up(child, task_is_traced(child)); + + spin_unlock(&child->sighand->siglock); + } +@@ -245,7 +257,7 @@ static int ptrace_attach(struct task_struct *task) + */ + if (task_is_stopped(task)) { + task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING; +- signal_wake_up(task, 1); ++ ptrace_signal_wake_up(task, 1); + wait_trap = true; + } + +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:08 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:08 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:16 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 6FB379C0CB; + Thu, 30 Jun 2011 20:23:16 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id IYB64KKErOyI; Thu, 30 Jun 2011 20:23:16 -0400 (EDT) +Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 597119C0C5; + Thu, 30 Jun 2011 20:23:16 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610N8bE032569; + Thu, 30 Jun 2011 20:23:09 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:16 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:14 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 06/19] wait_task_inactive: treat task->state and + match_state as bitmasks +Message-ID: <20110701002114.GA25804@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 +Status: RO +Content-Length: 1558 +Lines: 39 + +Change wait_task_inactive() to check "state & match_state" instead of +"state == match_state". This should not make any difference, but this +allows us to add more "stopped" bits which can be set or cleared +independently. + +IOW. wait_task_inactive() assumes that if task->state != 0, it can +only be changed to TASK_RUNNING. Currently this is true, and in this +case "state & match_state" continues to work. But, unlike the current +check, it also works if task->state has other bits set while the caller +is only interested in, say, __TASK_TRACED. + +Note: I think wait_task_inactive() should be cleanuped upstrean anyway, +nowadays we have TASK_WAKING and task->state != 0 doesn't necessarily +mean it is TASK_RUNNING. It also makes sense to exclude the !TASK_REPORT +bits during the check. Finally, probably this patch makes sense anyway +even without utrace. For example, a stopped _and_ traced thread could +have task->state = TASK_STOPPED | TASK_TRACED, this can be useful. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/sched.c | 2 +- + 1 files changed, 1 insertions(+), 1 deletions(-) + +diff --git a/kernel/sched.c b/kernel/sched.c +index 3f2e502..ade7997 100644 +--- a/kernel/sched.c ++++ b/kernel/sched.c +@@ -2277,7 +2277,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state) + * is actually now running somewhere else! + */ + while (task_running(rq, p)) { +- if (match_state && unlikely(p->state != match_state)) ++ if (match_state && !likely(p->state & match_state)) + return 0; + cpu_relax(); + } +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:09 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:09 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:19 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id A6BD4D810F; + Thu, 30 Jun 2011 20:23:19 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 2ovLSk6W1SGg; Thu, 30 Jun 2011 20:23:19 -0400 (EDT) +Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 8DBABD812A; + Thu, 30 Jun 2011 20:23:19 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610NCUq026299; + Thu, 30 Jun 2011 20:23:12 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:19 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:17 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 07/19] introduce TASK_UTRACED state +Message-ID: <20110701002117.GA25807@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 +Status: RO +Content-Length: 2913 +Lines: 84 + +Introduce TASK_UTRACED state, will be used by utrace instead of TASK_TRACED. + +Note: this state is reported as "t (tracing stop)" to the user-space to +avoid the confusion. IOW, it looks like TASK_TRACED in /proc/pid/status. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + fs/proc/array.c | 11 ++++++----- + include/linux/sched.h | 20 +++++++++++--------- + 2 files changed, 17 insertions(+), 14 deletions(-) + +diff --git a/fs/proc/array.c b/fs/proc/array.c +index 496fef3..bfaa998 100644 +--- a/fs/proc/array.c ++++ b/fs/proc/array.c +@@ -138,11 +138,12 @@ static const char * const task_state_array[] = { + "D (disk sleep)", /* 2 */ + "T (stopped)", /* 4 */ + "t (tracing stop)", /* 8 */ +- "Z (zombie)", /* 16 */ +- "X (dead)", /* 32 */ +- "x (dead)", /* 64 */ +- "K (wakekill)", /* 128 */ +- "W (waking)", /* 256 */ ++ "t (tracing stop)", /* 16 (stopped by utrace) */ ++ "Z (zombie)", /* 32 */ ++ "X (dead)", /* 64 */ ++ "x (dead)", /* 128 */ ++ "K (wakekill)", /* 256 */ ++ "W (waking)", /* 512 */ + }; + + static inline const char *get_task_state(struct task_struct *tsk) +diff --git a/include/linux/sched.h b/include/linux/sched.h +index b87de83..7a0008c 100644 +--- a/include/linux/sched.h ++++ b/include/linux/sched.h +@@ -184,16 +184,17 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) + #define TASK_UNINTERRUPTIBLE 2 + #define __TASK_STOPPED 4 + #define __TASK_TRACED 8 ++#define __TASK_UTRACED 16 + /* in tsk->exit_state */ +-#define EXIT_ZOMBIE 16 +-#define EXIT_DEAD 32 ++#define EXIT_ZOMBIE 32 ++#define EXIT_DEAD 64 + /* in tsk->state again */ +-#define TASK_DEAD 64 +-#define TASK_WAKEKILL 128 +-#define TASK_WAKING 256 +-#define TASK_STATE_MAX 512 ++#define TASK_DEAD 128 ++#define TASK_WAKEKILL 256 ++#define TASK_WAKING 512 ++#define TASK_STATE_MAX 1024 + +-#define TASK_STATE_TO_CHAR_STR "RSDTtZXxKW" ++#define TASK_STATE_TO_CHAR_STR "RSDTtUZXxKW" + + extern char ___assert_task_state[1 - 2*!!( + sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1)]; +@@ -202,15 +203,16 @@ extern char ___assert_task_state[1 - 2*!!( + #define TASK_KILLABLE (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE) + #define TASK_STOPPED (TASK_WAKEKILL | __TASK_STOPPED) + #define TASK_TRACED (TASK_WAKEKILL | __TASK_TRACED) ++#define TASK_UTRACED (TASK_WAKEKILL | __TASK_UTRACED) + + /* Convenience macros for the sake of wake_up */ + #define TASK_NORMAL (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE) +-#define TASK_ALL (TASK_NORMAL | __TASK_STOPPED | __TASK_TRACED) ++#define TASK_ALL (TASK_NORMAL | __TASK_STOPPED | __TASK_TRACED | __TASK_UTRACED) + + /* get_task_state() */ + #define TASK_REPORT (TASK_RUNNING | TASK_INTERRUPTIBLE | \ + TASK_UNINTERRUPTIBLE | __TASK_STOPPED | \ +- __TASK_TRACED) ++ __TASK_TRACED | __TASK_UTRACED) + + #define task_is_traced(task) ((task->state & __TASK_TRACED) != 0) + #define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0) +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:10 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:10 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:23 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 1A66AD812A; + Thu, 30 Jun 2011 20:23:23 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id fctUcQ+-lYpk; Thu, 30 Jun 2011 20:23:23 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id F2D35D810F; + Thu, 30 Jun 2011 20:23:22 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NF1u015200; + Thu, 30 Jun 2011 20:23:15 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:23 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:20 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 08/19] utrace: use TASK_UTRACED instead of TASK_TRACED +Message-ID: <20110701002120.GA25814@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 4316 +Lines: 130 + +Change utrace.c to use TASK_UTRACED instead of TASK_TRACED. + +- utrace_stop/utrace_wakeup: simply use the new state + +- utrace_do_stop: do not clear STOPPED/TRACED, but add the new + __TASK_UTRACED bit to state the fact that both ptrace and utrace + want this task to be stopped + +- naturally, do not use task_is_traced() to check if this task was + stopped by utrace, use the new task_is_utraced() helper which + checks __TASK_UTRACED. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/utrace.c | 26 ++++++++++++++------------ + 1 files changed, 14 insertions(+), 12 deletions(-) + +diff --git a/kernel/utrace.c b/kernel/utrace.c +index d7c547c..be98607 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -462,6 +462,8 @@ static void put_detached_list(struct list_head *list) + */ + #define ENGINE_STOP (1UL << _UTRACE_NEVENTS) + ++#define task_is_utraced(task) ((task->state & __TASK_UTRACED) != 0) ++ + static void mark_engine_wants_stop(struct task_struct *task, + struct utrace_engine *engine) + { +@@ -576,7 +578,7 @@ int utrace_set_events(struct task_struct *target, + + ret = 0; + if ((old_flags & ~events) && target != current && +- !task_is_stopped_or_traced(target) && !target->exit_state) { ++ !task_is_utraced(target) && !target->exit_state) { + /* + * This barrier ensures that our engine->flags changes + * have hit before we examine utrace->reporting, +@@ -623,21 +625,21 @@ static void mark_engine_detached(struct utrace_engine *engine) + */ + static bool utrace_do_stop(struct task_struct *target, struct utrace *utrace) + { +- if (task_is_stopped(target)) { ++ if (task_is_stopped_or_traced(target)) { + /* + * Stopped is considered quiescent; when it wakes up, it will + * go through utrace_finish_stop() before doing anything else. + */ + spin_lock_irq(&target->sighand->siglock); +- if (likely(task_is_stopped(target))) +- __set_task_state(target, TASK_TRACED); ++ if (likely(task_is_stopped_or_traced(target))) ++ target->state |= TASK_UTRACED; + spin_unlock_irq(&target->sighand->siglock); + } else if (utrace->resume > UTRACE_REPORT) { + utrace->resume = UTRACE_REPORT; + set_notify_resume(target); + } + +- return task_is_traced(target); ++ return task_is_utraced(target); + } + + /* +@@ -648,7 +650,7 @@ static void utrace_wakeup(struct task_struct *target, struct utrace *utrace) + { + lockdep_assert_held(&utrace->lock); + spin_lock_irq(&target->sighand->siglock); +- wake_up_quiescent(target, __TASK_TRACED); ++ wake_up_quiescent(target, __TASK_UTRACED); + spin_unlock_irq(&target->sighand->siglock); + } + +@@ -710,7 +712,7 @@ static bool utrace_reset(struct task_struct *task, struct utrace *utrace) + /* + * If no more engines want it stopped, wake it up. + */ +- if (task_is_traced(task) && !(flags & ENGINE_STOP)) { ++ if (task_is_utraced(task) && !(flags & ENGINE_STOP)) { + /* + * It just resumes, so make sure single-step + * is not left set. +@@ -749,7 +751,7 @@ void utrace_finish_stop(void) + } + + /* +- * Perform %UTRACE_STOP, i.e. block in TASK_TRACED until woken up. ++ * Perform %UTRACE_STOP, i.e. block in TASK_UTRACED until woken up. + * @task == current, @utrace == current->utrace, which is not locked. + * Return true if we were woken up by SIGKILL even though some utrace + * engine may still want us to stay stopped. +@@ -799,7 +801,7 @@ relock: + return; + } + +- __set_current_state(TASK_TRACED); ++ __set_current_state(TASK_UTRACED); + + spin_unlock_irq(&task->sighand->siglock); + spin_unlock(&utrace->lock); +@@ -809,14 +811,14 @@ relock: + utrace_finish_stop(); + + /* +- * While in TASK_TRACED, we were considered "frozen enough". ++ * While in TASK_UTRACED, we were considered "frozen enough". + * Now that we woke up, it's crucial if we're supposed to be + * frozen that we freeze now before running anything substantial. + */ + try_to_freeze(); + + /* +- * While we were in TASK_TRACED, complete_signal() considered ++ * While we were in TASK_UTRACED, complete_signal() considered + * us "uninterested" in signal wakeups. Now make sure our + * TIF_SIGPENDING state is correct for normal running. + */ +@@ -1087,7 +1089,7 @@ int utrace_control(struct task_struct *target, + if (unlikely(IS_ERR(utrace))) + return PTR_ERR(utrace); + +- reset = task_is_traced(target); ++ reset = task_is_utraced(target); + ret = 0; + + /* +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:12 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:12 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:26 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 289969C0C5; + Thu, 30 Jun 2011 20:23:26 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id q99JSaVz2X1O; Thu, 30 Jun 2011 20:23:26 -0400 (EDT) +Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 143F89C0C3; + Thu, 30 Jun 2011 20:23:26 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610NI9T021133; + Thu, 30 Jun 2011 20:23:19 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:26 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:24 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 09/19] tracehooks: kill tracehook_finish_jctl(), add + tracehook_finish_stop() +Message-ID: <20110701002124.GA25817@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 +Status: RO +Content-Length: 2782 +Lines: 86 + +tracehook_finish_jctl() is needed to avoid the races with SIGKILL +which wakes up UTRACED task, and thus it should be called every time +after the STOPPED/TRACED/UTRACED returns from schedule(), remember +that TASK_UTRACED can be added while the task is STOPPED/UTRACED. + +- rename it to tracehook_finish_stop(),jctl no longer matches the + reality. + +- change do_signal_state() to call this helper right after schedule(), + otherwise this logic is broken by the upstream changes + +- now that utrace doesn't control TASK_TRACED bit, ptrace_stop() must + call this helper too. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + include/linux/tracehook.h | 6 +++--- + kernel/signal.c | 5 +++-- + kernel/utrace.c | 2 +- + 3 files changed, 7 insertions(+), 6 deletions(-) + +diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h +index 7d7bdde..3c7b6b3 100644 +--- a/include/linux/tracehook.h ++++ b/include/linux/tracehook.h +@@ -528,11 +528,11 @@ static inline int tracehook_get_signal(struct task_struct *task, + } + + /** +- * tracehook_finish_jctl - report about return from job control stop ++ * tracehook_finish_stop - report about return from STOPPED/TRACED + * +- * This is called by do_signal_stop() after wakeup. ++ * This is called by do_signal_stop() and ptrace_stop after wakeup. + */ +-static inline void tracehook_finish_jctl(void) ++static inline void tracehook_finish_stop(void) + { + if (task_utrace_flags(current)) + utrace_finish_stop(); +diff --git a/kernel/signal.c b/kernel/signal.c +index 4fcf1c7..a7979ad 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -1816,6 +1816,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) + read_unlock(&tasklist_lock); + } + ++ tracehook_finish_stop(); + /* + * While in TASK_TRACED, we were considered "frozen enough". + * Now that we woke up, it's crucial if we're supposed to be +@@ -1952,6 +1953,8 @@ retry: + /* Now we don't run again until woken by SIGCONT or SIGKILL */ + schedule(); + ++ tracehook_finish_stop(); ++ + spin_lock_irq(¤t->sighand->siglock); + } else { + ptrace_stop(current->group_stop & GROUP_STOP_SIGMASK, +@@ -1974,8 +1977,6 @@ retry: + + spin_unlock_irq(¤t->sighand->siglock); + +- tracehook_finish_jctl(); +- + return 1; + } + +diff --git a/kernel/utrace.c b/kernel/utrace.c +index be98607..daa96b9 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -741,7 +741,7 @@ static bool utrace_reset(struct task_struct *task, struct utrace *utrace) + void utrace_finish_stop(void) + { + /* +- * If we were task_is_traced() and then SIGKILL'ed, make ++ * If we were task_is_utraced() and then SIGKILL'ed, make + * sure we do nothing until the tracer drops utrace->lock. + */ + if (unlikely(__fatal_signal_pending(current))) { +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:13 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:13 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:29 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id A748FD813B; + Thu, 30 Jun 2011 20:23:29 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id EwbxGxAU7ASi; Thu, 30 Jun 2011 20:23:29 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 72761D810F; + Thu, 30 Jun 2011 20:23:29 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NMAW015213; + Thu, 30 Jun 2011 20:23:22 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:29 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:27 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 10/19] teach wake_up_quiescent() to do "selective" wake_up +Message-ID: <20110701002127.GA25824@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 1335 +Lines: 46 + +Both utrace and ptrace can want the same thread to be quiescent, in this +case its state is TASK_TRACED | TASK_UTRACED. And this also means that +this task must not run unless both utrace and ptrace resume it. + +Change wake_up_quiescent(p, state) to do "p->state &= ~state" and return +false unless there is no more "quiescent" bits in task->state. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/signal.c | 15 +++++++++++++++ + 1 files changed, 15 insertions(+), 0 deletions(-) + +diff --git a/kernel/signal.c b/kernel/signal.c +index a7979ad..57552e6 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -651,11 +651,26 @@ void signal_wake_up(struct task_struct *t, int resume) + kick_process(t); + } + ++#define STATE_QUIESCENT (__TASK_STOPPED | __TASK_TRACED | __TASK_UTRACED) + /* + * wakes up the STOPPED/TRACED task, must be called with ->siglock held. + */ + int wake_up_quiescent(struct task_struct *p, unsigned int state) + { ++ unsigned int quiescent = (p->state & STATE_QUIESCENT); ++ ++ WARN_ON(state & ~(STATE_QUIESCENT | TASK_INTERRUPTIBLE)); ++ ++ if (quiescent) { ++ state &= ~TASK_INTERRUPTIBLE; ++ if ((quiescent & ~state) != 0) { ++ p->state &= ~state; ++ WARN_ON(!(p->state & STATE_QUIESCENT)); ++ WARN_ON(!(p->state & TASK_WAKEKILL)); ++ return 0; ++ } ++ } ++ + return wake_up_state(p, state); + } + +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:14 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:14 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:32 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id C94CF9C0C5; + Thu, 30 Jun 2011 20:23:32 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 9R-z4gQXQITf; Thu, 30 Jun 2011 20:23:32 -0400 (EDT) +Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id B55759C0C3; + Thu, 30 Jun 2011 20:23:32 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610NPe5021144; + Thu, 30 Jun 2011 20:23:25 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:33 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:30 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 11/19] ptrace_stop: do not assume the task is running after + wake_up_quiescent() +Message-ID: <20110701002130.GA25827@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 +Status: RO +Content-Length: 962 +Lines: 31 + +If ptrace_stop() sets TASK_TRACED and then detects we should not stop, +it can race with utrace_do_stop() which can see TASK_TRACED and add +TASK_UTRACED. In this case we should stop for utrace needs. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/signal.c | 8 ++++++++ + 1 files changed, 8 insertions(+), 0 deletions(-) + +diff --git a/kernel/signal.c b/kernel/signal.c +index 57552e6..89e691d 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -1829,6 +1829,14 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) + if (clear_code) + current->exit_code = 0; + read_unlock(&tasklist_lock); ++ ++ /* ++ * It is possible that __TASK_UTRACED was added by utrace ++ * while we were __TASK_TRACED and before we take ->siglock ++ * for wake_up_quiescent(), we need to block in this case. ++ * Otherwise this is unnecessary but absolutely harmless. ++ */ ++ schedule(); + } + + tracehook_finish_stop(); +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:17 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:17 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com (LHLO + zmta02.collab.prod.int.phx2.redhat.com) (10.5.5.32) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:36 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 4390F1287F3; + Thu, 30 Jun 2011 20:23:36 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta02.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id v5mzxCjpefBI; Thu, 30 Jun 2011 20:23:36 -0400 (EDT) +Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 283B21287DD; + Thu, 30 Jun 2011 20:23:36 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NSc9032626; + Thu, 30 Jun 2011 20:23:29 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:36 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:34 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 12/19] get_signal_to_deliver: restructure utrace/ptrace + signal reporting +Message-ID: <20110701002134.GA25834@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 +Status: RO +Content-Length: 2012 +Lines: 73 + +get_signal_to_deliver() assumes that either tracehook_get_signal() does +nothing (without CONFIG_UTRACE), or it also reports the signal to ptrace +engine implemented on top of utrace. Now that ptrace works independently +this doesn't work. + +Change the code to call ptrace_signal() after tracehook_get_signal(). + +Move ->ptrace check from ptrace_signal() to get_signal_to_deliver(), +we do not want to change *return_ka if it was initialized by utrace +and the task is not traced. + +IOW, roughly, ptrace acts as if it is the last attached engine, it +takes the final decision about the signal. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/signal.c | 24 +++++++++++------------- + 1 files changed, 11 insertions(+), 13 deletions(-) + +diff --git a/kernel/signal.c b/kernel/signal.c +index 89e691d..d0e0c67 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -2006,9 +2006,6 @@ retry: + static int ptrace_signal(int signr, siginfo_t *info, + struct pt_regs *regs, void *cookie) + { +- if (!task_ptrace(current)) +- return signr; +- + ptrace_signal_deliver(regs, cookie); + + /* Let the debugger run. */ +@@ -2110,6 +2107,7 @@ relock: + signr = tracehook_get_signal(current, regs, info, return_ka); + if (unlikely(signr < 0)) + goto relock; ++ + if (unlikely(signr != 0)) + ka = return_ka; + else { +@@ -2117,18 +2115,18 @@ relock: + GROUP_STOP_PENDING) && do_signal_stop(0)) + goto relock; + +- signr = dequeue_signal(current, ¤t->blocked, +- info); ++ signr = dequeue_signal(current, ¤t->blocked, info); + +- if (!signr) +- break; /* will return 0 */ ++ ka = &sighand->action[signr-1]; ++ } + +- if (signr != SIGKILL) { +- signr = ptrace_signal(signr, info, +- regs, cookie); +- if (!signr) +- continue; +- } ++ if (!signr) ++ break; /* will return 0 */ ++ ++ if (signr != SIGKILL && current->ptrace) { ++ signr = ptrace_signal(signr, info, regs, cookie); ++ if (!signr) ++ continue; + + ka = &sighand->action[signr-1]; + } +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:18 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:18 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:39 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 74BDFD813B; + Thu, 30 Jun 2011 20:23:39 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id tAGkG+GCPdeN; Thu, 30 Jun 2011 20:23:39 -0400 (EDT) +Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 5B728D812A; + Thu, 30 Jun 2011 20:23:39 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NWY1032629; + Thu, 30 Jun 2011 20:23:32 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:39 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:37 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 13/19] introduce ptrace_set_syscall_trace() +Message-ID: <20110701002137.GA25837@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 +Status: RO +Content-Length: 1581 +Lines: 52 + +No functional changes. Add the new helper, ptrace_set_syscall_trace(), +which should be used to set/clear TIF_SYSCALL_TRACE in ptrace code. +Currently it does nothing more. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/ptrace.c | 15 ++++++++++----- + 1 files changed, 10 insertions(+), 5 deletions(-) + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 0b2aba5..b6fd922 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -37,6 +37,14 @@ static void ptrace_signal_wake_up(struct task_struct *p, int quiescent) + kick_process(p); + } + ++static void ptrace_set_syscall_trace(struct task_struct *p, bool on) ++{ ++ if (on) ++ set_tsk_thread_flag(p, TIF_SYSCALL_TRACE); ++ else ++ clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); ++} ++ + /* + * ptrace a task: make the debugger its new parent and + * move it to the ptrace list. +@@ -364,7 +372,7 @@ static int ptrace_detach(struct task_struct *child, unsigned int data) + + /* Architecture-specific hardware disable .. */ + ptrace_disable(child); +- clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); ++ ptrace_set_syscall_trace(child, false); + + write_lock_irq(&tasklist_lock); + /* +@@ -551,10 +559,7 @@ static int ptrace_resume(struct task_struct *child, long request, + if (!valid_signal(data)) + return -EIO; + +- if (request == PTRACE_SYSCALL) +- set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); +- else +- clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); ++ ptrace_set_syscall_trace(child, request == PTRACE_SYSCALL); + + #ifdef TIF_SYSCALL_EMU + if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP) +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:20 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:20 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:42 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id CFC3F9C0C5; + Thu, 30 Jun 2011 20:23:42 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id vS4KlM5ek+bt; Thu, 30 Jun 2011 20:23:42 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id B28CA9C0C3; + Thu, 30 Jun 2011 20:23:42 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NZvo015255; + Thu, 30 Jun 2011 20:23:35 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:43 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:40 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 14/19] introduce PT_SYSCALL_TRACE flag +Message-ID: <20110701002140.GA25844@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 2236 +Lines: 73 + +Currently tracehooks assume that if the ptraced task has +TIF_SYSCALL_TRACE set, the tracee should report the syscall. +This is not true, this thread flag can be set by utrace. + +Add the new internal ptrace flag, PT_SYSCALL_TRACE. Change +ptrace_set_syscall_trace() to set/clear this bit along with +TIF_SYSCALL_TRACE, change ptrace_report_syscall() to check +this flag instead of PT_PTRACED. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + include/linux/ptrace.h | 3 +++ + include/linux/tracehook.h | 2 +- + kernel/ptrace.c | 7 +++++-- + 3 files changed, 9 insertions(+), 3 deletions(-) + +diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h +index 9178d5c..98d995d 100644 +--- a/include/linux/ptrace.h ++++ b/include/linux/ptrace.h +@@ -90,6 +90,8 @@ + + #define PT_TRACE_MASK 0x000003f4 + ++#define PT_SYSCALL_TRACE 0x00010000 ++ + /* single stepping state bits (used on ARM and PA-RISC) */ + #define PT_SINGLESTEP_BIT 31 + #define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT) +@@ -187,6 +189,7 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) + child->ptrace = 0; + if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) { + child->ptrace = current->ptrace; ++ child->ptrace &= ~PT_SYSCALL_TRACE; + __ptrace_link(child, current->parent); + } + +diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h +index 3c7b6b3..6ce7a37 100644 +--- a/include/linux/tracehook.h ++++ b/include/linux/tracehook.h +@@ -76,7 +76,7 @@ static inline void ptrace_report_syscall(struct pt_regs *regs) + { + int ptrace = task_ptrace(current); + +- if (!(ptrace & PT_PTRACED)) ++ if (!(ptrace & PT_SYSCALL_TRACE)) + return; + + ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0)); +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index b6fd922..0825a01 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -39,10 +39,13 @@ static void ptrace_signal_wake_up(struct task_struct *p, int quiescent) + + static void ptrace_set_syscall_trace(struct task_struct *p, bool on) + { +- if (on) ++ if (on) { ++ p->ptrace |= PT_SYSCALL_TRACE; + set_tsk_thread_flag(p, TIF_SYSCALL_TRACE); +- else ++ } else { ++ p->ptrace &= ~PT_SYSCALL_TRACE; + clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); ++ } + } + + /* +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:21 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:21 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:46 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 35A70D812A; + Thu, 30 Jun 2011 20:23:46 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id L06hkGLA8FQs; Thu, 30 Jun 2011 20:23:46 -0400 (EDT) +Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 21C2BD810F; + Thu, 30 Jun 2011 20:23:46 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610Nc7k007721; + Thu, 30 Jun 2011 20:23:39 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:46 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:44 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 15/19] utrace: don't clear TIF_SYSCALL_TRACE if it is + needed by ptrace +Message-ID: <20110701002144.GA25847@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 +Status: RO +Content-Length: 797 +Lines: 24 + +TIF_SYSCALL_TRACE should be cleared only if both ptrace and utrace do +not want it, change utrace_reset() to check PT_SYSCALL_TRACE before +clear_tsk_thread_flag(TIF_SYSCALL_TRACE). + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/utrace.c | 1 + + 1 files changed, 1 insertions(+), 0 deletions(-) + +diff --git a/kernel/utrace.c b/kernel/utrace.c +index daa96b9..a824ac3 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -697,6 +697,7 @@ static bool utrace_reset(struct task_struct *task, struct utrace *utrace) + BUG_ON(utrace->death); + flags &= UTRACE_EVENT(REAP); + } else if (!(flags & UTRACE_EVENT_SYSCALL) && ++ !(task->ptrace & PT_SYSCALL_TRACE) && + test_tsk_thread_flag(task, TIF_SYSCALL_TRACE)) { + clear_tsk_thread_flag(task, TIF_SYSCALL_TRACE); + } +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:22 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:22 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:49 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 72E0C9C0C3; + Thu, 30 Jun 2011 20:23:49 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id o3ezwgloxuCS; Thu, 30 Jun 2011 20:23:49 -0400 (EDT) +Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 5DD6A9C0C5; + Thu, 30 Jun 2011 20:23:49 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610NglX026379; + Thu, 30 Jun 2011 20:23:42 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:49 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:47 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 16/19] introduce task_utrace_lock/task_utrace_unlock +Message-ID: <20110701002147.GA25854@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 +Status: RO +Content-Length: 2190 +Lines: 81 + +- Add task_utrace_lock(task). It simply takes task->utrace->lock if + this task was ever utraced. Otherwise it takes task_lock(), this + serializes with utrace_attach_task()->utrace_task_alloc(). In both + case the caller can be sure it can't race with anything which needs + utrace->lock. + +- Add task_utrace_unlock(task), it releases the corresponding lock. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + include/linux/utrace.h | 9 +++++++++ + kernel/utrace.c | 26 ++++++++++++++++++++++++++ + 2 files changed, 35 insertions(+), 0 deletions(-) + +diff --git a/include/linux/utrace.h b/include/linux/utrace.h +index f251efe..5176f5f 100644 +--- a/include/linux/utrace.h ++++ b/include/linux/utrace.h +@@ -109,6 +109,12 @@ void utrace_signal_handler(struct task_struct *, int); + + #ifndef CONFIG_UTRACE + ++static inline void task_utrace_lock(struct task_struct *task) ++{ ++} ++static inline void task_utrace_unlock(struct task_struct *task) ++{ ++} + /* + * <linux/tracehook.h> uses these accessors to avoid #ifdef CONFIG_UTRACE. + */ +@@ -131,6 +137,9 @@ static inline void task_utrace_proc_status(struct seq_file *m, + + #else /* CONFIG_UTRACE */ + ++extern void task_utrace_lock(struct task_struct *task); ++extern void task_utrace_unlock(struct task_struct *task); ++ + static inline unsigned long task_utrace_flags(struct task_struct *task) + { + return task->utrace_flags; +diff --git a/kernel/utrace.c b/kernel/utrace.c +index a824ac3..508c13c 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -79,6 +79,32 @@ static int __init utrace_init(void) + } + module_init(utrace_init); + ++void task_utrace_lock(struct task_struct *task) ++{ ++ struct utrace *utrace = task_utrace_struct(task); ++ ++ if (!utrace) { ++ task_lock(task); ++ utrace = task_utrace_struct(task); ++ if (!utrace) ++ return; ++ ++ task_unlock(task); ++ } ++ ++ spin_lock(&utrace->lock); ++} ++ ++void task_utrace_unlock(struct task_struct *task) ++{ ++ struct utrace *utrace = task_utrace_struct(task); ++ ++ if (utrace) ++ spin_unlock(&utrace->lock); ++ else ++ task_unlock(task); ++} ++ + /* + * Set up @task.utrace for the first time. We can have races + * between two utrace_attach_task() calls here. The task_lock() +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:24 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:24 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com (LHLO + zmta03.collab.prod.int.phx2.redhat.com) (10.5.5.33) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:52 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id DB8D8D812A; + Thu, 30 Jun 2011 20:23:52 -0400 (EDT) +Received: from zmta03.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta03.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 74TDLZXBCl6s; Thu, 30 Jun 2011 20:23:52 -0400 (EDT) +Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) + by zmta03.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id C6776D810F; + Thu, 30 Jun 2011 20:23:52 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NjAl015271; + Thu, 30 Jun 2011 20:23:45 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:53 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:50 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 17/19] teach ptrace_set_syscall_trace() to play well with + utrace +Message-ID: <20110701002150.GA25861@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 +Status: RO +Content-Length: 1513 +Lines: 49 + +1. ptrace_set_syscall_trace(true)->set_tsk_thread_flag(TIF_SYSCALL_TRACE) + can race with utrace_control()->utrace_reset() path which can miss + PT_SYSCALL_TRACE and clear TIF_SYSCALL_TRACE after it was already set. + +2. ptrace_set_syscall_trace(false) clears TIF_SYSCALL_TRACE and this is + not utrace-friendly, it can need this flag. + +Change ptrace_set_syscall_trace() to take task_utrace_lock(), this is +enough to fix the 1st problem. Check task_utrace_flags() before clearing +TIF_SYSCALL_TRACE, this fixes 2. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/ptrace.c | 6 +++++- + 1 files changed, 5 insertions(+), 1 deletions(-) + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 0825a01..209ea2d 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -23,6 +23,7 @@ + #include <linux/uaccess.h> + #include <linux/regset.h> + #include <linux/hw_breakpoint.h> ++#include <linux/utrace.h> + + static void ptrace_signal_wake_up(struct task_struct *p, int quiescent) + { +@@ -39,13 +40,16 @@ static void ptrace_signal_wake_up(struct task_struct *p, int quiescent) + + static void ptrace_set_syscall_trace(struct task_struct *p, bool on) + { ++ task_utrace_lock(p); + if (on) { + p->ptrace |= PT_SYSCALL_TRACE; + set_tsk_thread_flag(p, TIF_SYSCALL_TRACE); + } else { + p->ptrace &= ~PT_SYSCALL_TRACE; +- clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); ++ if (!(task_utrace_flags(p) & UTRACE_EVENT_SYSCALL)) ++ clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); + } ++ task_utrace_unlock(p); + } + + /* +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:24 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:24 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com (LHLO + zmta02.collab.prod.int.phx2.redhat.com) (10.5.5.32) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:56 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 6CD231287F3; + Thu, 30 Jun 2011 20:23:56 -0400 (EDT) +Received: from zmta02.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta02.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id XX9YNcTcP1Ny; Thu, 30 Jun 2011 20:23:56 -0400 (EDT) +Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) + by zmta02.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 504BF1287DD; + Thu, 30 Jun 2011 20:23:56 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id p610NmjB032686; + Thu, 30 Jun 2011 20:23:49 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:56 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:54 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 18/19] introduce PT_SINGLE_STEP and PT_SINGLE_BLOCK +Message-ID: <20110701002154.GA25864@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 +Status: RO +Content-Length: 3725 +Lines: 108 + +Add the new internal ptrace flags, PT_SINGLE_STEP and PT_SINGLE_BLOCK. + +Like PT_SYSCALL_TRACE, this is needed to avoid the unnecessary ptrace +reports when TIF_SINGLESTEP was set by another engine, not by ptrace. +Also, we need these bits to coordinate the user_*_single_step() calls +from ptrace and utrace. + +TODO: update the !x86 ptrace code which does user_disable_single_step(). + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + arch/x86/kernel/ptrace.c | 1 + + include/linux/ptrace.h | 5 ++++- + include/linux/tracehook.h | 7 +++++-- + kernel/ptrace.c | 3 +++ + 4 files changed, 13 insertions(+), 3 deletions(-) + +diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c +index 807c2a2..7ab475f 100644 +--- a/arch/x86/kernel/ptrace.c ++++ b/arch/x86/kernel/ptrace.c +@@ -807,6 +807,7 @@ static int ioperm_get(struct task_struct *target, + */ + void ptrace_disable(struct task_struct *child) + { ++ child->ptrace &= ~(PT_SINGLE_STEP | PT_SINGLE_BLOCK); + user_disable_single_step(child); + #ifdef TIF_SYSCALL_EMU + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); +diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h +index 98d995d..65b1e4f 100644 +--- a/include/linux/ptrace.h ++++ b/include/linux/ptrace.h +@@ -91,6 +91,8 @@ + #define PT_TRACE_MASK 0x000003f4 + + #define PT_SYSCALL_TRACE 0x00010000 ++#define PT_SINGLE_STEP 0x00020000 ++#define PT_SINGLE_BLOCK 0x00040000 + + /* single stepping state bits (used on ARM and PA-RISC) */ + #define PT_SINGLESTEP_BIT 31 +@@ -189,7 +191,8 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) + child->ptrace = 0; + if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) { + child->ptrace = current->ptrace; +- child->ptrace &= ~PT_SYSCALL_TRACE; ++ child->ptrace &= ++ ~(PT_SYSCALL_TRACE | PT_SINGLE_STEP | PT_SINGLE_BLOCK); + __ptrace_link(child, current->parent); + } + +diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h +index 6ce7a37..06edb52 100644 +--- a/include/linux/tracehook.h ++++ b/include/linux/tracehook.h +@@ -121,6 +121,9 @@ static inline __must_check int tracehook_report_syscall_entry( + return 0; + } + ++#define ptrace_wants_step() \ ++ (current->ptrace & (PT_SINGLE_STEP | PT_SINGLE_BLOCK)) ++ + /** + * tracehook_report_syscall_exit - task has just finished a system call + * @regs: user register state of current task +@@ -143,7 +146,7 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) + if (task_utrace_flags(current) & UTRACE_EVENT(SYSCALL_EXIT)) + utrace_report_syscall_exit(regs); + +- if (step) { ++ if (step && ptrace_wants_step()) { + siginfo_t info; + user_single_step_siginfo(current, regs, &info); + force_sig_info(SIGTRAP, &info, current); +@@ -436,7 +439,7 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, + { + if (task_utrace_flags(current)) + utrace_signal_handler(current, stepping); +- if (stepping) ++ if (stepping && ptrace_wants_step()) + ptrace_notify(SIGTRAP); + } + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 209ea2d..44908d0 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -575,13 +575,16 @@ static int ptrace_resume(struct task_struct *child, long request, + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); + #endif + ++ child->ptrace &= ~(PT_SINGLE_STEP | PT_SINGLE_BLOCK); + if (is_singleblock(request)) { + if (unlikely(!arch_has_block_step())) + return -EIO; ++ child->ptrace |= PT_SINGLE_BLOCK; + user_enable_block_step(child); + } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { + if (unlikely(!arch_has_single_step())) + return -EIO; ++ child->ptrace |= PT_SINGLE_STEP; + user_enable_single_step(child); + } else { + user_disable_single_step(child); +-- +1.5.5.1 + + +From davej Thu Jun 30 20:27:26 2011 +Return-Path: oleg@redhat.com +X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on + gelk.kernelslacker.org +X-Spam-Level: +X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD, + UNPARSEABLE_RELAY autolearn=ham version=3.3.2 +Received: from mail.corp.redhat.com [10.5.5.51] + by gelk with IMAP (fetchmail-6.3.20) + for <davej@localhost> (single-drop); Thu, 30 Jun 2011 20:27:26 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com (LHLO + zmta01.collab.prod.int.phx2.redhat.com) (10.5.5.31) by + mail04.corp.redhat.com with LMTP; Thu, 30 Jun 2011 20:23:59 -0400 (EDT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 8FF6B9C0C5; + Thu, 30 Jun 2011 20:23:59 -0400 (EDT) +Received: from zmta01.collab.prod.int.phx2.redhat.com ([127.0.0.1]) + by localhost (zmta01.collab.prod.int.phx2.redhat.com [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id pNFtYrppMjXf; Thu, 30 Jun 2011 20:23:59 -0400 (EDT) +Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) + by zmta01.collab.prod.int.phx2.redhat.com (Postfix) with ESMTP id 7C2B89C0C3; + Thu, 30 Jun 2011 20:23:59 -0400 (EDT) +Received: from tranklukator.englab.brq.redhat.com (dhcp-1-232.brq.redhat.com [10.34.1.232]) + by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p610Nqpd026408; + Thu, 30 Jun 2011 20:23:52 -0400 +Received: by tranklukator.englab.brq.redhat.com (nbSMTP-1.00) for uid 500 + oleg@redhat.com; Fri, 1 Jul 2011 02:21:59 +0200 (CEST) +Date: Fri, 1 Jul 2011 02:21:57 +0200 +From: Oleg Nesterov <oleg@redhat.com> +To: "Frank Ch. Eigler" <fche@redhat.com>, Kyle McMartin <kmcmartin@redhat.com>, + Dave Jones <davej@redhat.com>, Josh Stone <jistone@redhat.com>, + Matthew Garrett <mjg@redhat.com>, David Smith <dsmith@redhat.com> +Cc: kernel@lists.fedoraproject.org, utrace-devel@redhat.com +Subject: [PATCH 19/19] utrace: consult PT_SINGLE_STEP/PT_SINGLE_BLOCK + before user_disable_single_step() +Message-ID: <20110701002157.GA25871@redhat.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.18 (2008-05-17) +X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 +Status: RO +Content-Length: 1150 +Lines: 41 + +- do not do user_enable_block_step() if PT_SINGLE_STEP is set, in this + case ptrace has already called user_enable_single_step() + +- do not do user_disable_single_step() if PT_*_STEP is set, ptrace needs + the stepping + +Unless the tracee is killed this can't race with ptrace, this is called +by the tracee itself. + +Signed-off-by: Oleg Nesterov <oleg@redhat.com> +--- + kernel/utrace.c | 6 ++++-- + 1 files changed, 4 insertions(+), 2 deletions(-) + +diff --git a/kernel/utrace.c b/kernel/utrace.c +index 508c13c..d6607cb 100644 +--- a/kernel/utrace.c ++++ b/kernel/utrace.c +@@ -1828,7 +1828,8 @@ static void finish_resume_report(struct task_struct *task, + + case UTRACE_BLOCKSTEP: + if (likely(arch_has_block_step())) { +- user_enable_block_step(task); ++ if (!(current->ptrace & PT_SINGLE_STEP)) ++ user_enable_block_step(task); + break; + } + +@@ -1856,7 +1857,8 @@ static void finish_resume_report(struct task_struct *task, + case UTRACE_REPORT: + case UTRACE_RESUME: + default: +- user_disable_single_step(task); ++ if (!(current->ptrace & (PT_SINGLE_STEP | PT_SINGLE_BLOCK))) ++ user_disable_single_step(task); + break; + } + } +-- +1.5.5.1 + + |