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Diffstat (limited to 'git-utrace.patch')
| -rw-r--r-- | git-utrace.patch | 6326 |
1 files changed, 6326 insertions, 0 deletions
diff --git a/git-utrace.patch b/git-utrace.patch new file mode 100644 index 000000000..77b5fa749 --- /dev/null +++ b/git-utrace.patch @@ -0,0 +1,6326 @@ +From c2f1645ae87d5b7fc5e5973c3a93a4ae1684a76b Mon Sep 17 00:00:00 2001 +From: Kyle McMartin <kyle@dreadnought.i.jkkm.org> +Date: Tue, 22 Jun 2010 11:31:13 +0100 +Subject: Merge remote branch 'utrace/utrace-ptrace' into rawhide + +% git log --oneline --no-merges 7e27d6e..a91f6b7 +f979955 utrace-ptrace: fix compiling ptrace_regset under CONFIG_UTRACE +b5f196b utrace-ptrace: copy PTRACE_GETREGSET code to utrace-ptrace +d83135e utrace: fix utrace_maybe_reap() vs find_matching_engine() race +9a2c607 utrace: move CONFIG_UTRACE after AUDITSYSCALL in init/Kconfig +62f4621 utrace: s/rmb/mb/ in tracehook_notify_resume() +65f5e9d utrace: fix utrace_maybe_reap logic +ed1f9c2 utrace: fix syntax nit for !CONFIG_UTRACE +71e3f39 ptrace: add utrace comment +e7afc73 utrace: use WARN with text +a8ced33 utrace: cosmetic restructure +4330b80 utrace: remove some inline keywords +d4be40a utrace: remove report_clone special priority for utrace_attach_task on child +8c56566 ptrace: updates for utrace API changes +1900135 utrace: streamline callback API +97662d3 utrace: more cosmetic trivia +fd414cd utrace: more cosmetic cleanup +f30f068 utrace: cosmetic trivia +cfebda7 utrace: fix the comments about rmb() in task_utrace_struct() +875858a utrace: improve the comment in tracehook_notify_resume() +76b49a5 utrace: fix the ->cloning check in utrace_attach_delay() +e0755bb utrace: kill mb() in tracehook_report_death() +9fdc988 fix __must_check warnings +3e02499 kill suppress_sigtrap() +f872e69 utrace: don't set ->ops = utrace_detached_ops lockless +938482e utrace: fix doc typo +7fae049 utrace: avoid BUG_ON when engine leaves bogus si_signo +71b7a85 utrace: trivial, move CONFIG_UTRACE into "General setup" +9c8dbe0 utrace: reset report action for UTRACE_SYSCALL_RESUMED iteration +4c7514e join PTRACE_EVENT_SYSCALL_XXX states +a8f782e export __ptrace_detach() and do_notify_parent_cldstop() +c3473e1 ptrace_signal: check PT_PTRACED before reporting a signal +b396f5e tracehooks: check PT_PTRACED before reporting the single-step +45667dd tracehooks: kill some PT_PTRACED checks +e8a2f23 ptrace: cleanup ptrace_init_task()->ptrace_link() path +611dab8 kill CONFIG_UTRACE_PTRACE +8d3833e rm kernel/ptrace-common.h +494deb7 export __ptrace_detach(), add "ifndef CONFIG_UTRACE" into ptrace.c +05cb325 (upstream) reorder the code in kernel/ptrace.c +eb10f13 restore the old kernel/ptrace.c +ddcc525 utrace_resume: Avoid finish_resume_report() for UTRACE_RESUME +47852f9 mv kernel/ptrace.c kernel/ptrace-utrace.c +de5a46e utrace: fix UTRACE_SYSCALL_RESUMED nits +3bd4be9 stepping, accommodate to utrace-cleanup changes +679be9e Revert "utrace: synthesize SIGTRAP for single-stepping at syscall-exit" +23ab966 utrace: barrier nits +d3800b8 utrace: tracehook_init_task +64daf14 utrace: task_utrace_struct() barrier +f19442c utrace: synthesize SIGTRAP for single-stepping at syscall-exit +2583b32 utrace: nit for utrace-ptrace +a88b467 ptrace: x86: change syscall_trace_leave() to rely on tracehook when stepping +e01acf4 ptrace: x86: implement user_single_step_siginfo() +462a57b ptrace: change tracehook_report_syscall_exit() to handle stepping +172590d ptrace: powerpc: implement user_single_step_siginfo() +d63b43d ptrace: introduce user_single_step_siginfo() helper +c575558 utrace: barriers for initializing struct utrace +89df3c7 utrace: utrace_attach_task() forgets to return when ->utrace == NULL +4d17e95 utrace: finish_report() must never set ->resume = UTRACE_STOP +212f67e utrace: utrace_get_signal() must check ->pending_attach +eff6ca8 change ptrace_report_signal() to use user_single_step_siginfo() +cba1272 don't send the unnecessary SIGTRAP after SYSCALL_EXIT +8aa71a6 revert "turn PTRACE_EVENT_SIGTRAP into PTRACE_EVENT_SIGNAL" +90c8237 utrace-ptrace: minimally handle UTRACE_SYSCALL_RESUMED +a7e9198 utrace: clean up resume-action handling +962eb2f utrace: update after merge +e2ced71 re-introduce utrace_finish_stop() to fix the race with SIGKILL +603e19c turn PTRACE_EVENT_SIGTRAP into PTRACE_EVENT_SIGNAL +ff87f65 introduce suppress_sigtrap() to prevent unwanted send_sigtrap() +6505e3c move ptrace_resume()->send_sigtrap() logic into ptrace_report_signal() +5261baa prepare ptrace_report_signal() to synthesize SIGTRAP +ef9534b ptrace_request: turn ptrace_resume() into default case +f50c776 s/context/ctx/ +228b2e3 ptrace_notify_stop: kill the temporary WARN_ON() +93e866a ptrace_request(PTRACE_KILL) should not(?) return -ESRCH +26fefca utrace: sticky resume action +28b2774b utrace: remove ->stopped field +9e0f357 utrace_set_events: nit clean up +6d0bad3 nits +48bab07 (utrace) utrace_get_signal: don't dequeue_signal() if ->group_stop_count +d4ef551 (upstream) signals: check ->group_stop_count after tracehook_get_signal() +6292daa ptrace_detach_task: don't use valid_signal() +c5a6a82 cosmetic, renames +e422a3f cosmetic, relocate some code in ptrace.c +b96e4db (upstream) introduce kernel/ptrace.h +7665564 (upstream) tracehook_signal_handler: check PT_PTRACED +7d708ca tracehooks: revert utrace-ptrace changes +4104e29 (upstream) ptrace_init_task: cleanup the usage of ptrace_link() +d04ccb7 revert all utrace-ptrace changes in ptrace.h +80786ce revert utrace-ptrace changes in kernel/signal.c +0b02f9e introduce PT_UTRACED to replace PT_PTRACED inside ptrace.c +030ce35 tracehooks: remove some PT_PTRACED checks +4b7b15a revert the clone() related changes in tracehook.h +769030e hack ptrace_check_attach() to make it almost correct +7aa5c3a cosmetic, fold do_ptrace_resume() into ptrace_resume() +d27ebc1 cosmetic, introduce ptrace_resume_action() +35fbca4 turn context->sysemu into PTRACE_O_SYSEMU +38a8c1f PTRACE_SYSEMU_SINGLESTEP support +4367836 PTRACE_SYSEMU support +16819db ptrace_report_clone: minor cleanups + comments +ac1afd8 ptrace_resume: rewrite request processing +6b0d4f6 do_ptrace_resume: always use ptrace_wake_up() +fa92ce3 do_ptrace_resume: consolidate multiple switch stmts +135d780 uglify the code again to report VFORK_DONE after VFORK +4e3f362 fix PTRACE_SYSCALL after PTRACE_EVENT_VFORK_DONE stop +3f95189 ptrace_report_clone: uglify even more to handle TRACEVFORKDONE without TRACEVFORK +66ca8b6 ptrace_report_clone: uglify CLONE_PTRACE/CLONE_UNTRACED behaviour to match upstream +fc82b2c pretend PTRACE_O_TRACEVFORKDONE doesn't exist +28aa15a utrace_set_events: never return -EINPROGRESS unless clearing some event bits +a7f4350 utrace_stop: do ptrace_notify_stop() unconditionally +cb78492 ptrace_report_exit: fix WARN_ON() condition +bb941c3 do_ptrace_notify_stop: document the usage of tracee->exit_code +383ba85 ptrace_wake_up: don't clear tracee->exit_code + update comments +3d5c221 ptrace_wake_up: add "bool force_wakeup" argument for implicit detach +be6862e ptrace_wake_up: clear context->stop_code +bfb40c8 detach: use ptrace_wake_up() instead of utrace_control() +7de148a shift context re-initialization from detach to reuse +464def3 cleanup/optimize reuse/attch in ptrace_attach_task() +50f56b9 ptrace_attach_task: rely on utrace_barrier(), don't check ->ops +03376fd use set_stop_code() in ptrace_report_signal(UTRACE_SIGNAL_HANDLER) +85f8b3a detach should reset the context of self-detaching engine +a27233a attach: try to re-use the self-detaching engine +8667615 ptrace_notify_stop: fix engine leak +3d5d053 ptrace_detach_task: don't use engine ptr before IS_ERR(engine) +01875c7 fold detach_signal() into ptrace_detach_task() +464c2b7 don't detach the engine with the parting signal +97b345c implement the basic detach-with-signal logic +a158247 rework access to context->siginfo +20ea83b introduce set_stop_code() helper +eb222ed cosmetic, misc renames +f83b2ca move "event << 8" into syscall_code() +4c99287 kill context->ev_name +df7c8f2 encode internal stop events in ->ev_code too +3f48297 introduce get_stop_code(context) helper +313bad1 introduce syscall_code(context) helper +47b5e2c don't clear context->ev_code for debugging +4e09fe3 convert ptrace_setsiginfo() to use ptrace_rw_siginfo() +53187be convert ptrace_getsiginfo() to use ptrace_rw_siginfo() +e7ac055 introduce ptrace_rw_siginfo() helper +c625793 move "resume signal" logic into the tracee's context +0768d89 UTRACE_SIGNAL_HANDLER should never see ->siginfo != NULL +e90cb71 don't use task_struct->ptrace_message +842684f do_ptrace_notify_stop: fix the race with SIGKILL +d0ed18d do_ptrace_notify_stop: backport the "sync wakeup" logic +08f4a21 fix the stepping over syscall +a55d174 implement the stacked SYSCALL_EXIT event +ba73824 ptrace_resume: don't ignore "data" argument +fbd4368 kill context->ev_array[] +3c6f822 Revert "ptrace_resume_signal() should use context->siginfo under ->siglock" +ee31432 Revert "UTRACE_SIGNAL_HANDLER should never see ->siginfo != NULL" +a4e5af1 Revert "introduce context_siginfo() helper" +9bc939a revert merge w/s change +6752625 introduce context_siginfo() helper +d43a453 UTRACE_SIGNAL_HANDLER should never see ->siginfo != NULL +e4e48df ptrace_resume_signal() should use context->siginfo under ->siglock +4492770 implement UTRACE_SIGNAL_HANDLER stepping +5f926a5 implement PTRACE_SINGLESTEP/PTRACE_SINGLEBLOCK +8b70ae1 ptrace_request: use ptrace_lookup_engine() +abd580d change ptrace_resume() to have the single "return" +85878ae introduce ptrace_lookup_engine() +74904f1 mv task_struct->last_siginfo ptrace_context->siginfo +2b17f4a pretens ptrace_detach(sig) works +075db41 ptrace_report_quiesce() can't trust fatal_signal_pending() +d583c87 remove the now unneeded code +69a6c83 break ptrace_report_signal() +d6a31ee do_ptrace_notify_stop: kill "->ev_message != 0" check +e194687 convert ptrace_report_exit() +8bf8304 PTRACE_EVENT_VFORK_DONE: set ev_options = PTRACE_O_TRACEVFORKDONE +b8f5e2a make sure PTRACE_SYSCALL reports SYSCALL_EXIT +258b27d make sure PTRACE_CONT "disables" SYSCALL_EXIT report +d26b659 introduce ptrace_event->ev_options +03a0fe3 convert ptrace_report_exec() +bea6139 convert ptrace_report_syscall_entry() +17dd96d cleanup/simplify stop/resume mess +97fc962 utrace: comments +c661ddb utrace: move struct utrace back where it belongs +95dcdee implement stacked stop events +8608da6 ptrace_report_syscall_exit: do not WARN() if killed +95a6b6b ptrace_report_clone: rework the stop/resume logic +25dd723 remove the current PTRACE_EVENT_VFORK_DONE logic +7d8900a ptrace_wake_up: fix the "compatibility bug" logic +9a50d27 ptrace_report_syscall_exit: return UTRACE_STOP, not UTRACE_RESUME +c07370d simplify utrace_add_engine() vs utrace_reap() protection +0f4d918 utrace_add_engine: cleanup +a24e891 fix utrace_reset() vs release_task() theoretical race +dfc0917 change attach/release to avoid unnecessary utrace_reap() +cbed668 utrace_attach_task: do no check ->exit_state +9d114a6 utrace_wakeup: do not check target->state +9368f18 utrace_wakeup: lock ->siglock directly +e9b58e9 convert ptrace_report_syscall_exit() to use ptrace_context +1d47e4d introduce context->resume_stopped() +c34d813 introduce context->stopped_code +b7edb5e introduce ptrace_notify_stop() +93b2e7e utrace_release_task: cosmetic +ac6e19c utrace_reap: loop lockless, do not clear ->ops and ->flags early +7852d10 utrace: slow_path -> pending_attach +c827b15 utrace_add_engine() should set ->utrace_flags |= REAP +2e12892 utrace_reap: fix missing callback +04852f3 utrace: do not force report on attach +37b68f7 kill ptrace_setoptions() and ptrace_update_utrace() +f1b39f3 use context->options instead of "->ptrace & PT_" +d05bf8e ptrace_set_options: use PTRACE_O_ instead of PT_ +167b56a "disable" tracehook_prepare_clone() +5e526f3 introduce ptrace_set_options() +4a50ac1 introduce ptrace_context->options +0457aa8 introduce the empty struct ptrace_context +a2bca6f utrace_reset: do not use "unsafe mode" +eac91f4 utrace_control: don't mark_engine_detached() before engine_wants_stop() +c2916fb utrace_control: fix utrace_reset(safe) usage when ->exit_state != 0 +c36a311 utrace_reset fix +8d2fc04 utrace: remove unused inline +64a8ca3 utrace_reset cleanup +d1a14ce utrace: change UTRACE_STOP bookkeeping +96fe3cc Revert "utrace_stop: fix UTRACE_DETACH race" +ceaae71 utrace: check QUIESCE before reporting UTRACE_SIGNAL_REPORT/HANDLER +fc30d20 utrace_do_stop: move "if (exit_state)" logic to the caller +9b655f7 utrace_do_stop: don't set ->stopped when ->exit_state +9ed6a39 utrace_set_events: never return -EINPROGRESS on a zombie +592d977 utrace_do_stop: cleanup the usage of ->siglock +7f51e58 utrace: fix utrace->signal_handler "leakage" +be5e266 utrace: utrace_finish_vfork: check ->vfork_stop lockless +c3580f1 utrace-ptrace: fix conditions in ptrace_do_detach +00932db utrace_stop: fix UTRACE_DETACH race +b032859 utrace: move utrace_stop down +a62ed15 utrace: consolidate utrace_reset callers +c8315d3 ptrace_do_detach: Fiddle code to avoid warnings. +e3635f1 utrace-ptrace: use WARN_ON(), suppress __must_check warning +8ba59d7 ptrace_attach_task: kill ->ptrace != 0 check +a18378e exit_ptrace: use ptrace_do_detach() +371c69c ptrace_detach: do ptrace_unlink() first +096f3ed ptrace_detach: kill the unconditional wakeup +d999521 ptrace_report_clone: rework auto-attaching +8cefebf move ->ptrace == 0 checks to ptrace_attach_task() +471d6f4 utrace_engine_ops: add release hook +78ca7e7 utrace_control: return -EINVAL for missing UTRACE_EVENT(QUIESCE) +fcb8fa0 change ptrace_traceme() to use the new helpers, kill prepare/finish attach +e82feff rework prepare_ptrace_attach/finish_ptrace_attach +3bea38f do not use engine->data +57cedd0 ptrace_detach_task: always do UTRACE_DETACH +2093f3a shift ptrace_utrace_exit() from tracehook_report_exit() to exit_ptrace() +33fb930 ptrace_resume()->send_sig() can crash +a7b05fd ptrace_check_attach: check child->parent +5ed4eff remove (almost all) !CONFIG_UTRACE_PTRACE code +fb9379c change utrace_stop() to return void +5bbbb41 kill utrace_report->killed +0b57f74 finish_utrace_stop: use __fatal_signal_pending(), dont take ->siglock +113a07e utrace: rework finish_report flag logic +8ad60bb utrace_stop: preserve report/interrupt requests across stop/resume +af3eb44 get_utrace_lock: do not check EXIT_DEAD +d87e8c4 finish_utrace_stop: check ->stopped lockless +3e0a686 utrace_report_jctl/utrace_get_signal: do not play with ->stopped +7d97118 utrace_do_stop: s/STOPPED/TRACED/ to protect against SIGCONT +ad2497a use tracehook_finish_jctl() to clear ->stopped +f99db9f utrace_report_jctl: do not play with the group-stop state +fd89498 introduce tracehook_finish_jctl() helper +ff6be89 do_signal_stop: do not call tracehook_notify_jctl() in TASK_STOPPED state +66e0705 utrace_stop: don't forget about SIGNAL_STOP_STOPPED +2edad7d utrace_wakeup: take ->group_stop_count into account +d4bcb57 utrace_reap: clear engine->flags when finishing detach +cf890ad utrace: fix utrace->reporting left set for no callback +cbe5188 More than one user has hit the -EEXIST problem when using utrace_attach_task and UTRACE_ATTACH_EXCLUSIVE without UTRACE_ATTACH_MATCH_DATA|_OPS. Document that a bit more. +52db080 UTRACE_SYSCALL_RESUMED repeat callback +5e67e22 utrace docbook: s/first/last/ braino +4bd78f8 utrace: reverse engine callback order for report_syscall_entry +1757088 utrace: WARN instead of BUG on misuse of UTRACE_*STEP without arch_has_*_step() check +5d4e97b utrace: restore tracehook_report_death comment misplaced in merges +cb49dcd utrace_report_syscall_entry: remove unnecessary recalc_sigpending() check +c0909b5 utrace_resume: fix potential TIF_SIGPENDING race +f0a1c64 utrace: use \t separator in /proc/pid/status +13a5838 utrace: init_task syntax nit +715d2a1 utrace: cosmetic +42de707 utrace_report_jctl: do splice_attaching +622013d utrace_resume: remove racy BUG_ON +282d685 whitespace fix +bec92f8 signals: tracehook_notify_jctl change +a7181aa utrace: simplify death report condition +4d8a6fd utrace: barrier between TIF_NOTIFY_RESUME check and utrace_flags/utrace->report checks +ae3096f utrace-ptrace: remove unsafe_exec and tracer_task hooks +325fecc utrace: get rid of tracer_task and unsafe_exec hooks +0084fc2 utrace: ensure UTRACE_REPORT callback return leads to callback after utrace_stop +5bdc6f1 utrace: cosmetic: DEAD_FLAGS_MASK macro +5c5bdbe utrace: cosmetic: _UTRACE_DEATH_EVENTS macro +f067223 utrace: make sure utrace_flags is nonzero before set_notify_resume at attach +e2d293e utrace: drop racy unlocked check in utrace_do_stop +68f3899 utrace: fix ->report_jctl @notify argument +c743327 utrace: avoid unnecessary list_for_each_safe +acd516b utrace_stop: trivial, kill the unnecessary assignment +81ed517 utrace_add_engine: add missing 'else' after 'if (utrace->reap)' +215a076 utrace: tracehook.h comment +a584c66 utrace: fix utrace_attach_delay() creator test +827ec3b utrace: comment ->reporting implementation +07732b4 utrace-ptrace: handle -ERESTARTNOINTR from utrace_attach_task +2233b06 utrace: finish utrace_reap conversion after indirect->direct struct utrace +dd30e86 utrace: fix utrace_attach_delay() to loop, remove struct utrace.cloning field +be4f357 get_utrace_lock: kill the bogus engine->kref.refcount check +c367207 utrace: clear struct in utrace_init_task +94f168c utrace: define UTRACE_API_VERSION +742f120 utrace: place struct utrace directly in task_struct +cb25a58 utrace: comment fixes +2b834a5 utrace-ptrace: struct utrace_attached_engine -> struct utrace_engine +6b8306a utrace: struct utrace_attached_engine -> struct utrace_engine +9fe3bac utrace-ptrace: Kconfig doc update +5bb0052 utrace: cosmetic changes +556a7e7 utrace-ptrace: fix resuming with blocked signal +3a9f4c8 utrace: order utrace_control() after callback return value processing +269150d Cosmetic reorganization to further simplify utrace pointer vs embedded-struct. +ea30176 Use task_utrace_struct() helper in utrace_interrupt_pending(). +ed2098a Use task_utrace_struct() helper +97d5cde cosmetic code reorganization +4e8a7ca Remove UTRACE_DEBUG hacks +25fb674 utrace: exclude PTRACE_TRACEME +f286be7 utrace-ptrace: remove utrace_engine_put stub +e0c36bd Disable mutual exclusion if CONFIG_UTRACE_PTRACE +c93d704 utrace/ptrace mutual exclusion +594f22c cond_resched() before race-restart in utrace_attach_task +0da72f3 Clean up utrace_attach_task code. +fd3d457 utrace: ptrace cooperation +f357a74 utrace core +--- + Documentation/DocBook/Makefile | 2 +- + Documentation/DocBook/utrace.tmpl | 590 +++++++++ + fs/proc/array.c | 3 + + include/linux/ptrace.h | 3 +- + include/linux/sched.h | 6 + + include/linux/tracehook.h | 97 ++- + include/linux/utrace.h | 692 +++++++++++ + init/Kconfig | 9 + + kernel/Makefile | 2 + + kernel/fork.c | 3 + + kernel/ptrace-utrace.c | 1127 +++++++++++++++++ + kernel/ptrace.c | 620 +++++----- + kernel/signal.c | 4 +- + kernel/utrace.c | 2452 +++++++++++++++++++++++++++++++++++++ + 14 files changed, 5291 insertions(+), 319 deletions(-) + create mode 100644 Documentation/DocBook/utrace.tmpl + create mode 100644 include/linux/utrace.h + create mode 100644 kernel/ptrace-utrace.c + create mode 100644 kernel/utrace.c + +diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile +index c7e5dc7..e63f889 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 \ + mac80211.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..e149f49 +--- /dev/null ++++ b/Documentation/DocBook/utrace.tmpl +@@ -0,0 +1,590 @@ ++<?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, if ++ you try to clear <constant>UTRACE_EVENT(REAP)</constant> when the ++ <function>report_reap</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 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 9b58d38..c7c7881 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/ptrace.h b/include/linux/ptrace.h +index 4272521..235c1b0 100644 +--- a/include/linux/ptrace.h ++++ b/include/linux/ptrace.h +@@ -99,12 +99,13 @@ + #include <linux/compiler.h> /* For unlikely. */ + #include <linux/sched.h> /* For struct task_struct. */ + +- ++extern void ptrace_notify_stop(struct task_struct *tracee); + extern long arch_ptrace(struct task_struct *child, long request, long addr, long data); + extern int ptrace_traceme(void); + extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len); + extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len); + extern int ptrace_attach(struct task_struct *tsk); ++extern bool __ptrace_detach(struct task_struct *tracer, struct task_struct *tracee); + extern int ptrace_detach(struct task_struct *, unsigned int); + extern void ptrace_disable(struct task_struct *); + extern int ptrace_check_attach(struct task_struct *task, int kill); +diff --git a/include/linux/sched.h b/include/linux/sched.h +index f118809..d3fef7a 100644 +--- a/include/linux/sched.h ++++ b/include/linux/sched.h +@@ -1348,6 +1348,11 @@ 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; +@@ -2033,6 +2038,7 @@ extern int kill_pgrp(struct pid *pid, int sig, int priv); + extern int kill_pid(struct pid *pid, int sig, int priv); + extern int kill_proc_info(int, struct siginfo *, pid_t); + extern int do_notify_parent(struct task_struct *, int); ++extern void do_notify_parent_cldstop(struct task_struct *, int); + extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent); + extern void force_sig(int, struct task_struct *); + extern int send_sig(int, struct task_struct *, int); +diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h +index 10db010..71fa250 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; + } +@@ -134,7 +140,10 @@ static inline __must_check int tracehook_report_syscall_entry( + */ + static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) + { +- if (step) { ++ if (task_utrace_flags(current) & UTRACE_EVENT(SYSCALL_EXIT)) ++ utrace_report_syscall_exit(regs); ++ ++ if (step && (task_ptrace(current) & PT_PTRACED)) { + siginfo_t info; + user_single_step_siginfo(current, regs, &info); + force_sig_info(SIGTRAP, &info, current); +@@ -156,7 +165,7 @@ static inline int tracehook_unsafe_exec(struct task_struct *task) + { + int unsafe = 0; + int ptrace = task_ptrace(task); +- if (ptrace & PT_PTRACED) { ++ if (ptrace) { + if (ptrace & PT_PTRACE_CAP) + unsafe |= LSM_UNSAFE_PTRACE_CAP; + else +@@ -178,7 +187,7 @@ static inline int tracehook_unsafe_exec(struct task_struct *task) + */ + static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk) + { +- if (task_ptrace(tsk) & PT_PTRACED) ++ if (task_ptrace(tsk)) + return rcu_dereference(tsk->parent); + return NULL; + } +@@ -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); + } + + /** +@@ -386,7 +434,9 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, + const struct k_sigaction *ka, + struct pt_regs *regs, int stepping) + { +- if (stepping) ++ if (task_utrace_flags(current)) ++ utrace_signal_handler(current, stepping); ++ if (stepping && (task_ptrace(current) & PT_PTRACED)) + 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; + } + +@@ -492,7 +551,9 @@ static inline int tracehook_get_signal(struct task_struct *task, + */ + static inline int tracehook_notify_jctl(int notify, int why) + { +- return notify ?: (current->ptrace & PT_PTRACED) ? why : 0; ++ if (task_utrace_flags(current) & UTRACE_EVENT(JCTL)) ++ utrace_report_jctl(notify, why); ++ return notify ?: task_ptrace(current) ? why : 0; + } + + /** +@@ -502,6 +563,8 @@ static inline int tracehook_notify_jctl(int notify, int why) + */ + static inline void tracehook_finish_jctl(void) + { ++ if (task_utrace_flags(current)) ++ utrace_finish_stop(); + } + + #define DEATH_REAP -1 +@@ -524,6 +587,8 @@ 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; + +@@ -560,6 +625,15 @@ 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 +@@ -589,10 +663,21 @@ 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 5cff9a9..c0b7f81 100644 +--- a/init/Kconfig ++++ b/init/Kconfig +@@ -328,6 +328,15 @@ config AUDIT_TREE + depends on AUDITSYSCALL + select INOTIFY + ++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. ++ + menu "RCU Subsystem" + + choice +diff --git a/kernel/Makefile b/kernel/Makefile +index 057472f..dfdc01c 100644 +--- a/kernel/Makefile ++++ b/kernel/Makefile +@@ -70,6 +70,8 @@ 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_UTRACE) += ptrace-utrace.o + obj-$(CONFIG_AUDIT) += audit.o auditfilter.o audit_watch.o + obj-$(CONFIG_AUDITSYSCALL) += auditsc.o + obj-$(CONFIG_GCOV_KERNEL) += gcov/ +diff --git a/kernel/fork.c b/kernel/fork.c +index b6cce14..ac4a6ec 100644 +--- a/kernel/fork.c ++++ b/kernel/fork.c +@@ -161,6 +161,7 @@ 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); +@@ -1007,6 +1008,8 @@ 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/ptrace-utrace.c b/kernel/ptrace-utrace.c +new file mode 100644 +index 0000000..86234ee +--- /dev/null ++++ b/kernel/ptrace-utrace.c +@@ -0,0 +1,1127 @@ ++/* ++ * linux/kernel/ptrace.c ++ * ++ * (C) Copyright 1999 Linus Torvalds ++ * ++ * Common interfaces for "ptrace()" which we do not want ++ * to continually duplicate across every architecture. ++ */ ++ ++#include <linux/capability.h> ++#include <linux/module.h> ++#include <linux/sched.h> ++#include <linux/errno.h> ++#include <linux/mm.h> ++#include <linux/highmem.h> ++#include <linux/pagemap.h> ++#include <linux/smp_lock.h> ++#include <linux/ptrace.h> ++#include <linux/utrace.h> ++#include <linux/security.h> ++#include <linux/signal.h> ++#include <linux/audit.h> ++#include <linux/pid_namespace.h> ++#include <linux/syscalls.h> ++#include <linux/uaccess.h> ++ ++/* ++ * ptrace a task: make the debugger its new parent and ++ * move it to the ptrace list. ++ * ++ * Must be called with the tasklist lock write-held. ++ */ ++void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) ++{ ++ BUG_ON(!list_empty(&child->ptrace_entry)); ++ list_add(&child->ptrace_entry, &new_parent->ptraced); ++ child->parent = new_parent; ++} ++ ++/* ++ * unptrace a task: move it back to its original parent and ++ * remove it from the ptrace list. ++ * ++ * Must be called with the tasklist lock write-held. ++ */ ++void __ptrace_unlink(struct task_struct *child) ++{ ++ BUG_ON(!child->ptrace); ++ ++ child->ptrace = 0; ++ child->parent = child->real_parent; ++ list_del_init(&child->ptrace_entry); ++ ++ arch_ptrace_untrace(child); ++} ++ ++struct ptrace_context { ++ int options; ++ ++ int signr; ++ siginfo_t *siginfo; ++ ++ int stop_code; ++ unsigned long eventmsg; ++ ++ enum utrace_resume_action resume; ++}; ++ ++#define PT_UTRACED 0x00001000 ++ ++#define PTRACE_O_SYSEMU 0x100 ++ ++#define PTRACE_EVENT_SYSCALL (1 << 16) ++#define PTRACE_EVENT_SIGTRAP (2 << 16) ++#define PTRACE_EVENT_SIGNAL (3 << 16) ++/* events visible to user-space */ ++#define PTRACE_EVENT_MASK 0xFFFF ++ ++static inline bool ptrace_event_pending(struct ptrace_context *ctx) ++{ ++ return ctx->stop_code != 0; ++} ++ ++static inline int get_stop_event(struct ptrace_context *ctx) ++{ ++ return ctx->stop_code >> 8; ++} ++ ++static inline void set_stop_code(struct ptrace_context *ctx, int event) ++{ ++ ctx->stop_code = (event << 8) | SIGTRAP; ++} ++ ++static inline struct ptrace_context * ++ptrace_context(struct utrace_engine *engine) ++{ ++ return engine->data; ++} ++ ++static const struct utrace_engine_ops ptrace_utrace_ops; /* forward decl */ ++ ++static struct utrace_engine *ptrace_lookup_engine(struct task_struct *tracee) ++{ ++ return utrace_attach_task(tracee, UTRACE_ATTACH_MATCH_OPS, ++ &ptrace_utrace_ops, NULL); ++} ++ ++static struct utrace_engine * ++ptrace_reuse_engine(struct task_struct *tracee) ++{ ++ struct utrace_engine *engine; ++ struct ptrace_context *ctx; ++ int err = -EPERM; ++ ++ engine = ptrace_lookup_engine(tracee); ++ if (IS_ERR(engine)) ++ return engine; ++ ++ ctx = ptrace_context(engine); ++ if (unlikely(ctx->resume == UTRACE_DETACH)) { ++ /* ++ * Try to reuse this self-detaching engine. ++ * The only caller which can hit this case is ptrace_attach(), ++ * it holds ->cred_guard_mutex. ++ */ ++ ctx->options = 0; ++ ctx->eventmsg = 0; ++ ++ /* make sure we don't get unwanted reports */ ++ err = utrace_set_events(tracee, engine, UTRACE_EVENT(QUIESCE)); ++ if (!err || err == -EINPROGRESS) { ++ ctx->resume = UTRACE_RESUME; ++ /* synchronize with ptrace_report_signal() */ ++ err = utrace_barrier(tracee, engine); ++ } ++ WARN_ON(!err != (engine->ops == &ptrace_utrace_ops)); ++ ++ if (!err) ++ return engine; ++ } ++ ++ utrace_engine_put(engine); ++ return ERR_PTR(err); ++} ++ ++static struct utrace_engine * ++ptrace_attach_engine(struct task_struct *tracee) ++{ ++ struct utrace_engine *engine; ++ struct ptrace_context *ctx; ++ ++ if (unlikely(task_utrace_flags(tracee))) { ++ engine = ptrace_reuse_engine(tracee); ++ if (!IS_ERR(engine) || IS_ERR(engine) == -EPERM) ++ return engine; ++ } ++ ++ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); ++ if (unlikely(!ctx)) ++ return ERR_PTR(-ENOMEM); ++ ++ ctx->resume = UTRACE_RESUME; ++ ++ engine = utrace_attach_task(tracee, UTRACE_ATTACH_CREATE | ++ UTRACE_ATTACH_EXCLUSIVE | ++ UTRACE_ATTACH_MATCH_OPS, ++ &ptrace_utrace_ops, ctx); ++ if (unlikely(IS_ERR(engine))) { ++ if (engine != ERR_PTR(-ESRCH) && ++ engine != ERR_PTR(-ERESTARTNOINTR)) ++ engine = ERR_PTR(-EPERM); ++ kfree(ctx); ++ } ++ ++ return engine; ++} ++ ++static inline int ptrace_set_events(struct task_struct *target, ++ struct utrace_engine *engine, ++ unsigned long options) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ /* ++ * We need QUIESCE for resume handling, CLONE to check ++ * for CLONE_PTRACE, other events are always reported. ++ */ ++ unsigned long events = UTRACE_EVENT(QUIESCE) | UTRACE_EVENT(CLONE) | ++ UTRACE_EVENT(EXEC) | UTRACE_EVENT_SIGNAL_ALL; ++ ++ ctx->options = options; ++ if (options & PTRACE_O_TRACEEXIT) ++ events |= UTRACE_EVENT(EXIT); ++ ++ return utrace_set_events(target, engine, events); ++} ++ ++/* ++ * Attach a utrace engine for ptrace and set up its event mask. ++ * Returns error code or 0 on success. ++ */ ++static int ptrace_attach_task(struct task_struct *tracee, int options) ++{ ++ struct utrace_engine *engine; ++ int err; ++ ++ engine = ptrace_attach_engine(tracee); ++ if (IS_ERR(engine)) ++ return PTR_ERR(engine); ++ /* ++ * It can fail only if the tracee is dead, the caller ++ * must notice this before setting PT_UTRACED. ++ */ ++ err = ptrace_set_events(tracee, engine, options); ++ WARN_ON(err && !tracee->exit_state); ++ utrace_engine_put(engine); ++ return 0; ++} ++ ++static int ptrace_wake_up(struct task_struct *tracee, ++ struct utrace_engine *engine, ++ enum utrace_resume_action action, ++ bool force_wakeup) ++{ ++ if (force_wakeup) { ++ unsigned long flags; ++ /* ++ * Preserve the compatibility bug. Historically ptrace ++ * wakes up the tracee even if it should not. Clear ++ * SIGNAL_STOP_STOPPED for utrace_wakeup(). ++ */ ++ if (lock_task_sighand(tracee, &flags)) { ++ tracee->signal->flags &= ~SIGNAL_STOP_STOPPED; ++ unlock_task_sighand(tracee, &flags); ++ } ++ } ++ ++ if (action != UTRACE_REPORT) ++ ptrace_context(engine)->stop_code = 0; ++ ++ return utrace_control(tracee, engine, action); ++} ++ ++static void ptrace_detach_task(struct task_struct *tracee, int sig) ++{ ++ /* ++ * If true, the caller is PTRACE_DETACH, otherwise ++ * the tracer detaches implicitly during exit. ++ */ ++ bool voluntary = (sig >= 0); ++ struct utrace_engine *engine = ptrace_lookup_engine(tracee); ++ enum utrace_resume_action action = UTRACE_DETACH; ++ ++ if (unlikely(IS_ERR(engine))) ++ return; ++ ++ if (sig) { ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ switch (get_stop_event(ctx)) { ++ case PTRACE_EVENT_SYSCALL: ++ if (voluntary) ++ send_sig_info(sig, SEND_SIG_PRIV, tracee); ++ break; ++ ++ case PTRACE_EVENT_SIGNAL: ++ if (voluntary) ++ ctx->signr = sig; ++ ctx->resume = UTRACE_DETACH; ++ action = UTRACE_RESUME; ++ break; ++ } ++ } ++ ++ ptrace_wake_up(tracee, engine, action, voluntary); ++ utrace_engine_put(engine); ++} ++ ++static void ptrace_abort_attach(struct task_struct *tracee) ++{ ++ ptrace_detach_task(tracee, 0); ++} ++ ++static u32 ptrace_report_exit(u32 action, struct utrace_engine *engine, ++ long orig_code, long *code) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ WARN_ON(ptrace_event_pending(ctx) && ++ !signal_group_exit(current->signal)); ++ ++ set_stop_code(ctx, PTRACE_EVENT_EXIT); ++ ctx->eventmsg = *code; ++ ++ return UTRACE_STOP; ++} ++ ++static void ptrace_clone_attach(struct task_struct *child, ++ int options) ++{ ++ struct task_struct *parent = current; ++ struct task_struct *tracer; ++ bool abort = true; ++ ++ if (unlikely(ptrace_attach_task(child, options))) { ++ WARN_ON(1); ++ return; ++ } ++ ++ write_lock_irq(&tasklist_lock); ++ tracer = parent->parent; ++ if (!(tracer->flags & PF_EXITING) && parent->ptrace) { ++ child->ptrace = parent->ptrace; ++ __ptrace_link(child, tracer); ++ abort = false; ++ } ++ write_unlock_irq(&tasklist_lock); ++ if (unlikely(abort)) { ++ ptrace_abort_attach(child); ++ return; ++ } ++ ++ sigaddset(&child->pending.signal, SIGSTOP); ++ set_tsk_thread_flag(child, TIF_SIGPENDING); ++} ++ ++static u32 ptrace_report_clone(u32 action, struct utrace_engine *engine, ++ unsigned long clone_flags, ++ struct task_struct *child) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ int event = 0; ++ ++ WARN_ON(ptrace_event_pending(ctx)); ++ ++ if (clone_flags & CLONE_UNTRACED) { ++ /* no events reported */ ++ } else if (clone_flags & CLONE_VFORK) { ++ if (ctx->options & PTRACE_O_TRACEVFORK) ++ event = PTRACE_EVENT_VFORK; ++ else if (ctx->options & PTRACE_O_TRACEVFORKDONE) ++ event = PTRACE_EVENT_VFORK_DONE; ++ } else if ((clone_flags & CSIGNAL) != SIGCHLD) { ++ if (ctx->options & PTRACE_O_TRACECLONE) ++ event = PTRACE_EVENT_CLONE; ++ } else if (ctx->options & PTRACE_O_TRACEFORK) { ++ event = PTRACE_EVENT_FORK; ++ } ++ /* ++ * Any of these reports implies auto-attaching the new child. ++ * So does CLONE_PTRACE, even with no event to report. ++ */ ++ if ((event && event != PTRACE_EVENT_VFORK_DONE) || ++ (clone_flags & CLONE_PTRACE)) ++ ptrace_clone_attach(child, ctx->options); ++ ++ if (!event) ++ return UTRACE_RESUME; ++ ++ set_stop_code(ctx, event); ++ ctx->eventmsg = child->pid; ++ /* ++ * We shouldn't stop now, inside the do_fork() path. ++ * We will stop later, before return to user-mode. ++ */ ++ if (event == PTRACE_EVENT_VFORK_DONE) ++ return UTRACE_REPORT; ++ else ++ return UTRACE_STOP; ++} ++ ++static inline void set_syscall_code(struct ptrace_context *ctx) ++{ ++ set_stop_code(ctx, PTRACE_EVENT_SYSCALL); ++ if (ctx->options & PTRACE_O_TRACESYSGOOD) ++ ctx->stop_code |= 0x80; ++} ++ ++static u32 ptrace_report_syscall_entry(u32 action, struct utrace_engine *engine, ++ struct pt_regs *regs) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ if (action & UTRACE_SYSCALL_RESUMED) { ++ /* ++ * We already reported the first time. ++ * Nothing more to do now. ++ */ ++ if (unlikely(ctx->options & PTRACE_O_SYSEMU)) ++ return UTRACE_SYSCALL_ABORT | UTRACE_REPORT; ++ return utrace_syscall_action(action) | UTRACE_RESUME; ++ } ++ ++ WARN_ON(ptrace_event_pending(ctx)); ++ ++ set_syscall_code(ctx); ++ ++ if (unlikely(ctx->options & PTRACE_O_SYSEMU)) ++ return UTRACE_SYSCALL_ABORT | UTRACE_REPORT; ++ /* ++ * Stop now to report. We will get another callback after ++ * we resume, with the UTRACE_SYSCALL_RESUMED flag set. ++ */ ++ return UTRACE_SYSCALL_RUN | UTRACE_STOP; ++} ++ ++static u32 ptrace_report_syscall_exit(u32 action, struct utrace_engine *engine, ++ struct pt_regs *regs) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ if (ptrace_event_pending(ctx)) ++ return UTRACE_STOP; ++ ++ if (ctx->resume != UTRACE_RESUME) { ++ WARN_ON(ctx->resume != UTRACE_BLOCKSTEP && ++ ctx->resume != UTRACE_SINGLESTEP); ++ ctx->resume = UTRACE_RESUME; ++ ++ ctx->signr = SIGTRAP; ++ return UTRACE_INTERRUPT; ++ } ++ ++ set_syscall_code(ctx); ++ return UTRACE_STOP; ++} ++ ++static u32 ptrace_report_exec(u32 action, struct utrace_engine *engine, ++ const struct linux_binfmt *fmt, ++ const struct linux_binprm *bprm, ++ struct pt_regs *regs) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ WARN_ON(ptrace_event_pending(ctx)); ++ ++ if (!(ctx->options & PTRACE_O_TRACEEXEC)) { ++ /* ++ * Old-fashioned ptrace'd exec just posts a plain signal. ++ */ ++ send_sig(SIGTRAP, current, 0); ++ return UTRACE_RESUME; ++ } ++ ++ set_stop_code(ctx, PTRACE_EVENT_EXEC); ++ return UTRACE_STOP; ++} ++ ++static enum utrace_signal_action resume_signal(struct ptrace_context *ctx, ++ struct k_sigaction *return_ka) ++{ ++ siginfo_t *info = ctx->siginfo; ++ int signr = ctx->signr; ++ ++ ctx->siginfo = NULL; ++ ctx->signr = 0; ++ ++ /* Did the debugger cancel the sig? */ ++ if (!signr) ++ return UTRACE_SIGNAL_IGN; ++ /* ++ * Update the siginfo structure if the signal has changed. ++ * If the debugger wanted something specific in the siginfo ++ * then it should have updated *info via PTRACE_SETSIGINFO. ++ */ ++ if (info->si_signo != signr) { ++ info->si_signo = signr; ++ info->si_errno = 0; ++ info->si_code = SI_USER; ++ info->si_pid = task_pid_vnr(current->parent); ++ info->si_uid = task_uid(current->parent); ++ } ++ ++ /* If the (new) signal is now blocked, requeue it. */ ++ if (sigismember(¤t->blocked, signr)) { ++ send_sig_info(signr, info, current); ++ return UTRACE_SIGNAL_IGN; ++ } ++ ++ spin_lock_irq(¤t->sighand->siglock); ++ *return_ka = current->sighand->action[signr - 1]; ++ spin_unlock_irq(¤t->sighand->siglock); ++ ++ return UTRACE_SIGNAL_DELIVER; ++} ++ ++static u32 ptrace_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) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ enum utrace_resume_action resume = ctx->resume; ++ ++ if (ptrace_event_pending(ctx)) { ++ action = utrace_signal_action(action); ++ WARN_ON(action != UTRACE_SIGNAL_REPORT); ++ return action | UTRACE_STOP; ++ } ++ ++ switch (utrace_signal_action(action)) { ++ case UTRACE_SIGNAL_HANDLER: ++ if (WARN_ON(ctx->siginfo)) ++ ctx->siginfo = NULL; ++ ++ if (resume != UTRACE_RESUME) { ++ WARN_ON(resume != UTRACE_BLOCKSTEP && ++ resume != UTRACE_SINGLESTEP); ++ ++ set_stop_code(ctx, PTRACE_EVENT_SIGTRAP); ++ return UTRACE_STOP | UTRACE_SIGNAL_IGN; ++ } ++ ++ case UTRACE_SIGNAL_REPORT: ++ if (!ctx->siginfo) { ++ if (ctx->signr) { ++ /* set by ptrace_resume(SYSCALL_EXIT) */ ++ WARN_ON(ctx->signr != SIGTRAP); ++ user_single_step_siginfo(current, regs, info); ++ force_sig_info(SIGTRAP, info, current); ++ } ++ ++ return resume | UTRACE_SIGNAL_IGN; ++ } ++ ++ if (WARN_ON(ctx->siginfo != info)) ++ return resume | UTRACE_SIGNAL_IGN; ++ ++ return resume | resume_signal(ctx, return_ka); ++ ++ default: ++ break; ++ } ++ ++ WARN_ON(ctx->siginfo); ++ ctx->siginfo = info; ++ /* ++ * ctx->siginfo points to the caller's stack. ++ * Make sure the subsequent UTRACE_SIGNAL_REPORT clears ++ * ->siginfo before return from get_signal_to_deliver(). ++ */ ++ if (utrace_control(current, engine, UTRACE_INTERRUPT)) ++ WARN_ON(1); ++ ++ ctx->signr = info->si_signo; ++ ctx->stop_code = (PTRACE_EVENT_SIGNAL << 8) | ctx->signr; ++ ++ return UTRACE_STOP | UTRACE_SIGNAL_IGN; ++} ++ ++static u32 ptrace_report_quiesce(u32 action, struct utrace_engine *engine, ++ unsigned long event) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ ++ if (ptrace_event_pending(ctx)) ++ return UTRACE_STOP; ++ ++ return event ? UTRACE_RESUME : ctx->resume; ++} ++ ++static void ptrace_release(void *data) ++{ ++ kfree(data); ++} ++ ++static const struct utrace_engine_ops ptrace_utrace_ops = { ++ .report_signal = ptrace_report_signal, ++ .report_quiesce = ptrace_report_quiesce, ++ .report_exec = ptrace_report_exec, ++ .report_exit = ptrace_report_exit, ++ .report_clone = ptrace_report_clone, ++ .report_syscall_entry = ptrace_report_syscall_entry, ++ .report_syscall_exit = ptrace_report_syscall_exit, ++ .release = ptrace_release, ++}; ++ ++int ptrace_check_attach(struct task_struct *child, int kill) ++{ ++ struct utrace_engine *engine; ++ struct utrace_examiner exam; ++ int ret = -ESRCH; ++ ++ engine = ptrace_lookup_engine(child); ++ if (IS_ERR(engine)) ++ return ret; ++ ++ if (child->parent != current) ++ goto out; ++ ++ if (unlikely(kill)) ++ ret = 0; ++ ++ if (!task_is_stopped_or_traced(child)) ++ goto out; ++ /* ++ * Make sure our engine has already stopped the child. ++ * Then wait for it to be off the CPU. ++ */ ++ if (!utrace_control(child, engine, UTRACE_STOP) && ++ !utrace_prepare_examine(child, engine, &exam)) ++ ret = 0; ++out: ++ utrace_engine_put(engine); ++ return ret; ++} ++ ++int ptrace_attach(struct task_struct *task) ++{ ++ int retval; ++ ++ audit_ptrace(task); ++ ++ retval = -EPERM; ++ if (unlikely(task->flags & PF_KTHREAD)) ++ goto out; ++ if (same_thread_group(task, current)) ++ goto out; ++ ++ /* ++ * Protect exec's credential calculations against our interference; ++ * interference; SUID, SGID and LSM creds get determined differently ++ * under ptrace. ++ */ ++ retval = -ERESTARTNOINTR; ++ if (mutex_lock_interruptible(&task->cred_guard_mutex)) ++ goto out; ++ ++ task_lock(task); ++ retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH); ++ task_unlock(task); ++ if (retval) ++ goto unlock_creds; ++ ++ retval = ptrace_attach_task(task, 0); ++ if (unlikely(retval)) ++ goto unlock_creds; ++ ++ write_lock_irq(&tasklist_lock); ++ retval = -EPERM; ++ if (unlikely(task->exit_state)) ++ goto unlock_tasklist; ++ ++ BUG_ON(task->ptrace); ++ task->ptrace = PT_UTRACED; ++ if (capable(CAP_SYS_PTRACE)) ++ task->ptrace |= PT_PTRACE_CAP; ++ ++ __ptrace_link(task, current); ++ send_sig_info(SIGSTOP, SEND_SIG_FORCED, task); ++ ++ retval = 0; ++unlock_tasklist: ++ write_unlock_irq(&tasklist_lock); ++unlock_creds: ++ mutex_unlock(&task->cred_guard_mutex); ++out: ++ return retval; ++} ++ ++/* ++ * Performs checks and sets PT_UTRACED. ++ * Should be used by all ptrace implementations for PTRACE_TRACEME. ++ */ ++int ptrace_traceme(void) ++{ ++ bool detach = true; ++ int ret = ptrace_attach_task(current, 0); ++ ++ if (unlikely(ret)) ++ return ret; ++ ++ ret = -EPERM; ++ write_lock_irq(&tasklist_lock); ++ BUG_ON(current->ptrace); ++ ret = security_ptrace_traceme(current->parent); ++ /* ++ * Check PF_EXITING to ensure ->real_parent has not passed ++ * exit_ptrace(). Otherwise we don't report the error but ++ * pretend ->real_parent untraces us right after return. ++ */ ++ if (!ret && !(current->real_parent->flags & PF_EXITING)) { ++ current->ptrace = PT_UTRACED; ++ __ptrace_link(current, current->real_parent); ++ detach = false; ++ } ++ write_unlock_irq(&tasklist_lock); ++ ++ if (detach) ++ ptrace_abort_attach(current); ++ return ret; ++} ++ ++static void ptrace_do_detach(struct task_struct *tracee, unsigned int data) ++{ ++ bool detach, release; ++ ++ write_lock_irq(&tasklist_lock); ++ /* ++ * This tracee can be already killed. Make sure de_thread() or ++ * our sub-thread doing do_wait() didn't do release_task() yet. ++ */ ++ detach = tracee->ptrace != 0; ++ release = false; ++ if (likely(detach)) ++ release = __ptrace_detach(current, tracee); ++ write_unlock_irq(&tasklist_lock); ++ ++ if (unlikely(release)) ++ release_task(tracee); ++ else if (likely(detach)) ++ ptrace_detach_task(tracee, data); ++} ++ ++int ptrace_detach(struct task_struct *child, unsigned int data) ++{ ++ if (!valid_signal(data)) ++ return -EIO; ++ ++ ptrace_do_detach(child, data); ++ ++ return 0; ++} ++ ++/* ++ * Detach all tasks we were using ptrace on. ++ */ ++void exit_ptrace(struct task_struct *tracer) ++{ ++ for (;;) { ++ struct task_struct *tracee = NULL; ++ ++ read_lock(&tasklist_lock); ++ if (!list_empty(&tracer->ptraced)) { ++ tracee = list_first_entry(&tracer->ptraced, ++ struct task_struct, ptrace_entry); ++ get_task_struct(tracee); ++ } ++ read_unlock(&tasklist_lock); ++ if (!tracee) ++ break; ++ ++ ptrace_do_detach(tracee, -1); ++ put_task_struct(tracee); ++ } ++} ++ ++static int ptrace_set_options(struct task_struct *tracee, ++ struct utrace_engine *engine, long data) ++{ ++ BUILD_BUG_ON(PTRACE_O_MASK & PTRACE_O_SYSEMU); ++ ++ ptrace_set_events(tracee, engine, data & PTRACE_O_MASK); ++ return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; ++} ++ ++static int ptrace_rw_siginfo(struct task_struct *tracee, ++ struct ptrace_context *ctx, ++ siginfo_t *info, bool write) ++{ ++ unsigned long flags; ++ int err; ++ ++ switch (get_stop_event(ctx)) { ++ case 0: /* jctl stop */ ++ return -EINVAL; ++ ++ case PTRACE_EVENT_SIGNAL: ++ err = -ESRCH; ++ if (lock_task_sighand(tracee, &flags)) { ++ if (likely(task_is_traced(tracee))) { ++ if (write) ++ *ctx->siginfo = *info; ++ else ++ *info = *ctx->siginfo; ++ err = 0; ++ } ++ unlock_task_sighand(tracee, &flags); ++ } ++ ++ return err; ++ ++ default: ++ if (!write) { ++ memset(info, 0, sizeof(*info)); ++ info->si_signo = SIGTRAP; ++ info->si_code = ctx->stop_code & PTRACE_EVENT_MASK; ++ info->si_pid = task_pid_vnr(tracee); ++ info->si_uid = task_uid(tracee); ++ } ++ ++ return 0; ++ } ++} ++ ++static void do_ptrace_notify_stop(struct ptrace_context *ctx, ++ struct task_struct *tracee) ++{ ++ /* ++ * This can race with SIGKILL, but we borrow this race from ++ * the old ptrace implementation. ->exit_code is only needed ++ * for wait_task_stopped()->task_stopped_code(), we should ++ * change it to use ptrace_context. ++ */ ++ tracee->exit_code = ctx->stop_code & PTRACE_EVENT_MASK; ++ WARN_ON(!tracee->exit_code); ++ ++ read_lock(&tasklist_lock); ++ /* ++ * Don't want to allow preemption here, because ++ * sys_ptrace() needs this task to be inactive. ++ */ ++ preempt_disable(); ++ /* ++ * It can be killed and then released by our subthread, ++ * or ptrace_attach() has not completed yet. ++ */ ++ if (task_ptrace(tracee)) ++ do_notify_parent_cldstop(tracee, CLD_TRAPPED); ++ read_unlock(&tasklist_lock); ++ preempt_enable_no_resched(); ++} ++ ++void ptrace_notify_stop(struct task_struct *tracee) ++{ ++ struct utrace_engine *engine = ptrace_lookup_engine(tracee); ++ ++ if (IS_ERR(engine)) ++ return; ++ ++ do_ptrace_notify_stop(ptrace_context(engine), tracee); ++ utrace_engine_put(engine); ++} ++ ++static int ptrace_resume_action(struct task_struct *tracee, ++ struct utrace_engine *engine, long request) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ unsigned long events; ++ int action; ++ ++ ctx->options &= ~PTRACE_O_SYSEMU; ++ events = engine->flags & ~UTRACE_EVENT_SYSCALL; ++ action = UTRACE_RESUME; ++ ++ switch (request) { ++#ifdef PTRACE_SINGLEBLOCK ++ case PTRACE_SINGLEBLOCK: ++ if (unlikely(!arch_has_block_step())) ++ return -EIO; ++ action = UTRACE_BLOCKSTEP; ++ events |= UTRACE_EVENT(SYSCALL_EXIT); ++ break; ++#endif ++ ++#ifdef PTRACE_SINGLESTEP ++ case PTRACE_SINGLESTEP: ++ if (unlikely(!arch_has_single_step())) ++ return -EIO; ++ action = UTRACE_SINGLESTEP; ++ events |= UTRACE_EVENT(SYSCALL_EXIT); ++ break; ++#endif ++ ++#ifdef PTRACE_SYSEMU ++ case PTRACE_SYSEMU_SINGLESTEP: ++ if (unlikely(!arch_has_single_step())) ++ return -EIO; ++ action = UTRACE_SINGLESTEP; ++ case PTRACE_SYSEMU: ++ ctx->options |= PTRACE_O_SYSEMU; ++ events |= UTRACE_EVENT(SYSCALL_ENTRY); ++ break; ++#endif ++ ++ case PTRACE_SYSCALL: ++ events |= UTRACE_EVENT_SYSCALL; ++ break; ++ ++ case PTRACE_CONT: ++ break; ++ default: ++ return -EIO; ++ } ++ ++ if (events != engine->flags && ++ utrace_set_events(tracee, engine, events)) ++ return -ESRCH; ++ ++ return action; ++} ++ ++static int ptrace_resume(struct task_struct *tracee, ++ struct utrace_engine *engine, ++ long request, long data) ++{ ++ struct ptrace_context *ctx = ptrace_context(engine); ++ int action; ++ ++ if (!valid_signal(data)) ++ return -EIO; ++ ++ action = ptrace_resume_action(tracee, engine, request); ++ if (action < 0) ++ return action; ++ ++ switch (get_stop_event(ctx)) { ++ case PTRACE_EVENT_VFORK: ++ if (ctx->options & PTRACE_O_TRACEVFORKDONE) { ++ set_stop_code(ctx, PTRACE_EVENT_VFORK_DONE); ++ action = UTRACE_REPORT; ++ } ++ break; ++ ++ case PTRACE_EVENT_EXEC: ++ case PTRACE_EVENT_FORK: ++ case PTRACE_EVENT_CLONE: ++ case PTRACE_EVENT_VFORK_DONE: ++ if (request == PTRACE_SYSCALL) { ++ set_syscall_code(ctx); ++ do_ptrace_notify_stop(ctx, tracee); ++ return 0; ++ } ++ ++ if (action != UTRACE_RESUME) { ++ /* ++ * single-stepping. UTRACE_SIGNAL_REPORT will ++ * synthesize a trap to follow the syscall insn. ++ */ ++ ctx->signr = SIGTRAP; ++ action = UTRACE_INTERRUPT; ++ } ++ break; ++ ++ case PTRACE_EVENT_SYSCALL: ++ if (data) ++ send_sig_info(data, SEND_SIG_PRIV, tracee); ++ break; ++ ++ case PTRACE_EVENT_SIGNAL: ++ ctx->signr = data; ++ break; ++ } ++ ++ ctx->resume = action; ++ ptrace_wake_up(tracee, engine, action, true); ++ return 0; ++} ++ ++extern int ptrace_regset(struct task_struct *task, int req, unsigned int type, ++ struct iovec *kiov); ++ ++int ptrace_request(struct task_struct *child, long request, ++ long addr, long data) ++{ ++ struct utrace_engine *engine = ptrace_lookup_engine(child); ++ siginfo_t siginfo; ++ int ret; ++ ++ if (unlikely(IS_ERR(engine))) ++ return -ESRCH; ++ ++ switch (request) { ++ case PTRACE_PEEKTEXT: ++ case PTRACE_PEEKDATA: ++ ret = generic_ptrace_peekdata(child, addr, data); ++ break; ++ case PTRACE_POKETEXT: ++ case PTRACE_POKEDATA: ++ ret = generic_ptrace_pokedata(child, addr, data); ++ break; ++ ++#ifdef PTRACE_OLDSETOPTIONS ++ case PTRACE_OLDSETOPTIONS: ++#endif ++ case PTRACE_SETOPTIONS: ++ ret = ptrace_set_options(child, engine, data); ++ break; ++ case PTRACE_GETEVENTMSG: ++ ret = put_user(ptrace_context(engine)->eventmsg, ++ (unsigned long __user *) data); ++ break; ++ ++ case PTRACE_GETSIGINFO: ++ ret = ptrace_rw_siginfo(child, ptrace_context(engine), ++ &siginfo, false); ++ if (!ret) ++ ret = copy_siginfo_to_user((siginfo_t __user *) data, ++ &siginfo); ++ break; ++ ++ case PTRACE_SETSIGINFO: ++ if (copy_from_user(&siginfo, (siginfo_t __user *) data, ++ sizeof siginfo)) ++ ret = -EFAULT; ++ else ++ ret = ptrace_rw_siginfo(child, ptrace_context(engine), ++ &siginfo, true); ++ break; ++ ++ case PTRACE_DETACH: /* detach a process that was attached. */ ++ ret = ptrace_detach(child, data); ++ break; ++ ++ case PTRACE_KILL: ++ /* Ugly historical behaviour. */ ++ if (task_is_traced(child)) ++ ptrace_resume(child, engine, PTRACE_CONT, SIGKILL); ++ ret = 0; ++ break; ++ ++ case PTRACE_GETREGSET: ++ case PTRACE_SETREGSET: ++ { ++ struct iovec kiov; ++ struct iovec __user *uiov = (struct iovec __user *) data; ++ ++ if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) ++ return -EFAULT; ++ ++ if (__get_user(kiov.iov_base, &uiov->iov_base) || ++ __get_user(kiov.iov_len, &uiov->iov_len)) ++ return -EFAULT; ++ ++ ret = ptrace_regset(child, request, addr, &kiov); ++ if (!ret) ++ ret = __put_user(kiov.iov_len, &uiov->iov_len); ++ break; ++ } ++ ++ default: ++ ret = ptrace_resume(child, engine, request, data); ++ break; ++ } ++ ++ utrace_engine_put(engine); ++ return ret; ++} ++ ++#if defined CONFIG_COMPAT ++#include <linux/compat.h> ++ ++int compat_ptrace_request(struct task_struct *child, compat_long_t request, ++ compat_ulong_t addr, compat_ulong_t data) ++{ ++ struct utrace_engine *engine = ptrace_lookup_engine(child); ++ compat_ulong_t __user *datap = compat_ptr(data); ++ compat_ulong_t word; ++ siginfo_t siginfo; ++ int ret; ++ ++ if (unlikely(IS_ERR(engine))) ++ return -ESRCH; ++ ++ switch (request) { ++ case PTRACE_PEEKTEXT: ++ case PTRACE_PEEKDATA: ++ ret = access_process_vm(child, addr, &word, sizeof(word), 0); ++ if (ret != sizeof(word)) ++ ret = -EIO; ++ else ++ ret = put_user(word, datap); ++ break; ++ ++ case PTRACE_POKETEXT: ++ case PTRACE_POKEDATA: ++ ret = access_process_vm(child, addr, &data, sizeof(data), 1); ++ ret = (ret != sizeof(data) ? -EIO : 0); ++ break; ++ ++ case PTRACE_GETEVENTMSG: ++ ret = put_user((compat_ulong_t)ptrace_context(engine)->eventmsg, ++ datap); ++ break; ++ ++ case PTRACE_GETSIGINFO: ++ ret = ptrace_rw_siginfo(child, ptrace_context(engine), ++ &siginfo, false); ++ if (!ret) ++ ret = copy_siginfo_to_user32( ++ (struct compat_siginfo __user *) datap, ++ &siginfo); ++ break; ++ ++ case PTRACE_SETSIGINFO: ++ memset(&siginfo, 0, sizeof siginfo); ++ if (copy_siginfo_from_user32( ++ &siginfo, (struct compat_siginfo __user *) datap)) ++ ret = -EFAULT; ++ else ++ ret = ptrace_rw_siginfo(child, ptrace_context(engine), ++ &siginfo, true); ++ break; ++ ++ case PTRACE_GETREGSET: ++ case PTRACE_SETREGSET: ++ { ++ struct iovec kiov; ++ struct compat_iovec __user *uiov = ++ (struct compat_iovec __user *) datap; ++ compat_uptr_t ptr; ++ compat_size_t len; ++ ++ if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) ++ return -EFAULT; ++ ++ if (__get_user(ptr, &uiov->iov_base) || ++ __get_user(len, &uiov->iov_len)) ++ return -EFAULT; ++ ++ kiov.iov_base = compat_ptr(ptr); ++ kiov.iov_len = len; ++ ++ ret = ptrace_regset(child, request, addr, &kiov); ++ if (!ret) ++ ret = __put_user(kiov.iov_len, &uiov->iov_len); ++ break; ++ } ++ ++ default: ++ ret = ptrace_request(child, request, addr, data); ++ } ++ ++ utrace_engine_put(engine); ++ return ret; ++} ++#endif /* CONFIG_COMPAT */ +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 74a3d69..c77f9bf 100644 +--- a/kernel/ptrace.c ++++ b/kernel/ptrace.c +@@ -23,7 +23,317 @@ + #include <linux/uaccess.h> + #include <linux/regset.h> + ++int __ptrace_may_access(struct task_struct *task, unsigned int mode) ++{ ++ const struct cred *cred = current_cred(), *tcred; ++ ++ /* May we inspect the given task? ++ * This check is used both for attaching with ptrace ++ * and for allowing access to sensitive information in /proc. ++ * ++ * ptrace_attach denies several cases that /proc allows ++ * because setting up the necessary parent/child relationship ++ * or halting the specified task is impossible. ++ */ ++ int dumpable = 0; ++ /* Don't let security modules deny introspection */ ++ if (task == current) ++ return 0; ++ rcu_read_lock(); ++ tcred = __task_cred(task); ++ if ((cred->uid != tcred->euid || ++ cred->uid != tcred->suid || ++ cred->uid != tcred->uid || ++ cred->gid != tcred->egid || ++ cred->gid != tcred->sgid || ++ cred->gid != tcred->gid) && ++ !capable(CAP_SYS_PTRACE)) { ++ rcu_read_unlock(); ++ return -EPERM; ++ } ++ rcu_read_unlock(); ++ smp_rmb(); ++ if (task->mm) ++ dumpable = get_dumpable(task->mm); ++ if (!dumpable && !capable(CAP_SYS_PTRACE)) ++ return -EPERM; ++ ++ return security_ptrace_access_check(task, mode); ++} ++ ++bool ptrace_may_access(struct task_struct *task, unsigned int mode) ++{ ++ int err; ++ task_lock(task); ++ err = __ptrace_may_access(task, mode); ++ task_unlock(task); ++ return !err; ++} ++ ++/* ++ * Called with irqs disabled, returns true if childs should reap themselves. ++ */ ++static int ignoring_children(struct sighand_struct *sigh) ++{ ++ int ret; ++ spin_lock(&sigh->siglock); ++ ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || ++ (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); ++ spin_unlock(&sigh->siglock); ++ return ret; ++} ++ ++/* ++ * Called with tasklist_lock held for writing. ++ * Unlink a traced task, and clean it up if it was a traced zombie. ++ * Return true if it needs to be reaped with release_task(). ++ * (We can't call release_task() here because we already hold tasklist_lock.) ++ * ++ * If it's a zombie, our attachedness prevented normal parent notification ++ * or self-reaping. Do notification now if it would have happened earlier. ++ * If it should reap itself, return true. ++ * ++ * If it's our own child, there is no notification to do. But if our normal ++ * children self-reap, then this child was prevented by ptrace and we must ++ * reap it now, in that case we must also wake up sub-threads sleeping in ++ * do_wait(). ++ */ ++bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) ++{ ++ __ptrace_unlink(p); ++ ++ if (p->exit_state == EXIT_ZOMBIE) { ++ if (!task_detached(p) && thread_group_empty(p)) { ++ if (!same_thread_group(p->real_parent, tracer)) ++ do_notify_parent(p, p->exit_signal); ++ else if (ignoring_children(tracer->sighand)) { ++ __wake_up_parent(p, tracer); ++ p->exit_signal = -1; ++ } ++ } ++ if (task_detached(p)) { ++ /* Mark it as in the process of being reaped. */ ++ p->exit_state = EXIT_DEAD; ++ return true; ++ } ++ } ++ ++ return false; ++} ++ ++int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) ++{ ++ int copied = 0; ++ ++ while (len > 0) { ++ char buf[128]; ++ int this_len, retval; ++ ++ this_len = (len > sizeof(buf)) ? sizeof(buf) : len; ++ retval = access_process_vm(tsk, src, buf, this_len, 0); ++ if (!retval) { ++ if (copied) ++ break; ++ return -EIO; ++ } ++ if (copy_to_user(dst, buf, retval)) ++ return -EFAULT; ++ copied += retval; ++ src += retval; ++ dst += retval; ++ len -= retval; ++ } ++ return copied; ++} ++ ++int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) ++{ ++ int copied = 0; ++ ++ while (len > 0) { ++ char buf[128]; ++ int this_len, retval; ++ ++ this_len = (len > sizeof(buf)) ? sizeof(buf) : len; ++ if (copy_from_user(buf, src, this_len)) ++ return -EFAULT; ++ retval = access_process_vm(tsk, dst, buf, this_len, 1); ++ if (!retval) { ++ if (copied) ++ break; ++ return -EIO; ++ } ++ copied += retval; ++ src += retval; ++ dst += retval; ++ len -= retval; ++ } ++ return copied; ++} ++ ++#ifdef CONFIG_HAVE_ARCH_TRACEHOOK ++ ++static const struct user_regset * ++find_regset(const struct user_regset_view *view, unsigned int type) ++{ ++ const struct user_regset *regset; ++ int n; ++ ++ for (n = 0; n < view->n; ++n) { ++ regset = view->regsets + n; ++ if (regset->core_note_type == type) ++ return regset; ++ } ++ ++ return NULL; ++} ++ ++int ptrace_regset(struct task_struct *task, int req, unsigned int type, ++ struct iovec *kiov) ++{ ++ const struct user_regset_view *view = task_user_regset_view(task); ++ const struct user_regset *regset = find_regset(view, type); ++ int regset_no; ++ ++ if (!regset || (kiov->iov_len % regset->size) != 0) ++ return -EINVAL; ++ ++ regset_no = regset - view->regsets; ++ kiov->iov_len = min(kiov->iov_len, ++ (__kernel_size_t) (regset->n * regset->size)); ++ ++ if (req == PTRACE_GETREGSET) ++ return copy_regset_to_user(task, view, regset_no, 0, ++ kiov->iov_len, kiov->iov_base); ++ else ++ return copy_regset_from_user(task, view, regset_no, 0, ++ kiov->iov_len, kiov->iov_base); ++} ++ ++#endif ++ ++static struct task_struct *ptrace_get_task_struct(pid_t pid) ++{ ++ struct task_struct *child; ++ ++ rcu_read_lock(); ++ child = find_task_by_vpid(pid); ++ if (child) ++ get_task_struct(child); ++ rcu_read_unlock(); ++ ++ if (!child) ++ return ERR_PTR(-ESRCH); ++ return child; ++} ++ ++#ifndef arch_ptrace_attach ++#define arch_ptrace_attach(child) do { } while (0) ++#endif ++ ++SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data) ++{ ++ struct task_struct *child; ++ long ret; ++ ++ if (request == PTRACE_TRACEME) { ++ ret = ptrace_traceme(); ++ if (!ret) ++ arch_ptrace_attach(current); ++ goto out; ++ } ++ ++ child = ptrace_get_task_struct(pid); ++ if (IS_ERR(child)) { ++ ret = PTR_ERR(child); ++ goto out; ++ } ++ ++ if (request == PTRACE_ATTACH) { ++ ret = ptrace_attach(child); ++ /* ++ * Some architectures need to do book-keeping after ++ * a ptrace attach. ++ */ ++ if (!ret) ++ arch_ptrace_attach(child); ++ goto out_put_task_struct; ++ } ++ ++ ret = ptrace_check_attach(child, request == PTRACE_KILL); ++ if (ret < 0) ++ goto out_put_task_struct; ++ ++ ret = arch_ptrace(child, request, addr, data); ++ ++ out_put_task_struct: ++ put_task_struct(child); ++ out: ++ return ret; ++} ++ ++int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data) ++{ ++ unsigned long tmp; ++ int copied; ++ ++ copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); ++ if (copied != sizeof(tmp)) ++ return -EIO; ++ return put_user(tmp, (unsigned long __user *)data); ++} ++ ++int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data) ++{ ++ int copied; ++ ++ copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); ++ return (copied == sizeof(data)) ? 0 : -EIO; ++} ++ ++#if defined CONFIG_COMPAT ++#include <linux/compat.h> ++ ++asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, ++ compat_long_t addr, compat_long_t data) ++{ ++ struct task_struct *child; ++ long ret; ++ ++ if (request == PTRACE_TRACEME) { ++ ret = ptrace_traceme(); ++ goto out; ++ } ++ ++ child = ptrace_get_task_struct(pid); ++ if (IS_ERR(child)) { ++ ret = PTR_ERR(child); ++ goto out; ++ } ++ ++ if (request == PTRACE_ATTACH) { ++ ret = ptrace_attach(child); ++ /* ++ * Some architectures need to do book-keeping after ++ * a ptrace attach. ++ */ ++ if (!ret) ++ arch_ptrace_attach(child); ++ goto out_put_task_struct; ++ } ++ ++ ret = ptrace_check_attach(child, request == PTRACE_KILL); ++ if (!ret) ++ ret = compat_arch_ptrace(child, request, addr, data); ++ ++ out_put_task_struct: ++ put_task_struct(child); ++ out: ++ return ret; ++} ++#endif /* CONFIG_COMPAT */ + ++#ifndef CONFIG_UTRACE + /* + * ptrace a task: make the debugger its new parent and + * move it to the ptrace list. +@@ -116,53 +426,6 @@ int ptrace_check_attach(struct task_struct *child, int kill) + return ret; + } + +-int __ptrace_may_access(struct task_struct *task, unsigned int mode) +-{ +- const struct cred *cred = current_cred(), *tcred; +- +- /* May we inspect the given task? +- * This check is used both for attaching with ptrace +- * and for allowing access to sensitive information in /proc. +- * +- * ptrace_attach denies several cases that /proc allows +- * because setting up the necessary parent/child relationship +- * or halting the specified task is impossible. +- */ +- int dumpable = 0; +- /* Don't let security modules deny introspection */ +- if (task == current) +- return 0; +- rcu_read_lock(); +- tcred = __task_cred(task); +- if ((cred->uid != tcred->euid || +- cred->uid != tcred->suid || +- cred->uid != tcred->uid || +- cred->gid != tcred->egid || +- cred->gid != tcred->sgid || +- cred->gid != tcred->gid) && +- !capable(CAP_SYS_PTRACE)) { +- rcu_read_unlock(); +- return -EPERM; +- } +- rcu_read_unlock(); +- smp_rmb(); +- if (task->mm) +- dumpable = get_dumpable(task->mm); +- if (!dumpable && !capable(CAP_SYS_PTRACE)) +- return -EPERM; +- +- return security_ptrace_access_check(task, mode); +-} +- +-bool ptrace_may_access(struct task_struct *task, unsigned int mode) +-{ +- int err; +- task_lock(task); +- err = __ptrace_may_access(task, mode); +- task_unlock(task); +- return !err; +-} +- + int ptrace_attach(struct task_struct *task) + { + int retval; +@@ -242,57 +505,6 @@ int ptrace_traceme(void) + return ret; + } + +-/* +- * Called with irqs disabled, returns true if childs should reap themselves. +- */ +-static int ignoring_children(struct sighand_struct *sigh) +-{ +- int ret; +- spin_lock(&sigh->siglock); +- ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || +- (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); +- spin_unlock(&sigh->siglock); +- return ret; +-} +- +-/* +- * Called with tasklist_lock held for writing. +- * Unlink a traced task, and clean it up if it was a traced zombie. +- * Return true if it needs to be reaped with release_task(). +- * (We can't call release_task() here because we already hold tasklist_lock.) +- * +- * If it's a zombie, our attachedness prevented normal parent notification +- * or self-reaping. Do notification now if it would have happened earlier. +- * If it should reap itself, return true. +- * +- * If it's our own child, there is no notification to do. But if our normal +- * children self-reap, then this child was prevented by ptrace and we must +- * reap it now, in that case we must also wake up sub-threads sleeping in +- * do_wait(). +- */ +-static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) +-{ +- __ptrace_unlink(p); +- +- if (p->exit_state == EXIT_ZOMBIE) { +- if (!task_detached(p) && thread_group_empty(p)) { +- if (!same_thread_group(p->real_parent, tracer)) +- do_notify_parent(p, p->exit_signal); +- else if (ignoring_children(tracer->sighand)) { +- __wake_up_parent(p, tracer); +- p->exit_signal = -1; +- } +- } +- if (task_detached(p)) { +- /* Mark it as in the process of being reaped. */ +- p->exit_state = EXIT_DEAD; +- return true; +- } +- } +- +- return false; +-} +- + int ptrace_detach(struct task_struct *child, unsigned int data) + { + bool dead = false; +@@ -346,56 +558,6 @@ void exit_ptrace(struct task_struct *tracer) + } + } + +-int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) +-{ +- int copied = 0; +- +- while (len > 0) { +- char buf[128]; +- int this_len, retval; +- +- this_len = (len > sizeof(buf)) ? sizeof(buf) : len; +- retval = access_process_vm(tsk, src, buf, this_len, 0); +- if (!retval) { +- if (copied) +- break; +- return -EIO; +- } +- if (copy_to_user(dst, buf, retval)) +- return -EFAULT; +- copied += retval; +- src += retval; +- dst += retval; +- len -= retval; +- } +- return copied; +-} +- +-int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) +-{ +- int copied = 0; +- +- while (len > 0) { +- char buf[128]; +- int this_len, retval; +- +- this_len = (len > sizeof(buf)) ? sizeof(buf) : len; +- if (copy_from_user(buf, src, this_len)) +- return -EFAULT; +- retval = access_process_vm(tsk, dst, buf, this_len, 1); +- if (!retval) { +- if (copied) +- break; +- return -EIO; +- } +- copied += retval; +- src += retval; +- dst += retval; +- len -= retval; +- } +- return copied; +-} +- + static int ptrace_setoptions(struct task_struct *child, long data) + { + child->ptrace &= ~PT_TRACE_MASK; +@@ -456,7 +618,6 @@ static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) + return error; + } + +- + #ifdef PTRACE_SINGLESTEP + #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP) + #else +@@ -510,47 +671,6 @@ static int ptrace_resume(struct task_struct *child, long request, long data) + return 0; + } + +-#ifdef CONFIG_HAVE_ARCH_TRACEHOOK +- +-static const struct user_regset * +-find_regset(const struct user_regset_view *view, unsigned int type) +-{ +- const struct user_regset *regset; +- int n; +- +- for (n = 0; n < view->n; ++n) { +- regset = view->regsets + n; +- if (regset->core_note_type == type) +- return regset; +- } +- +- return NULL; +-} +- +-static int ptrace_regset(struct task_struct *task, int req, unsigned int type, +- struct iovec *kiov) +-{ +- const struct user_regset_view *view = task_user_regset_view(task); +- const struct user_regset *regset = find_regset(view, type); +- int regset_no; +- +- if (!regset || (kiov->iov_len % regset->size) != 0) +- return -EINVAL; +- +- regset_no = regset - view->regsets; +- kiov->iov_len = min(kiov->iov_len, +- (__kernel_size_t) (regset->n * regset->size)); +- +- if (req == PTRACE_GETREGSET) +- return copy_regset_to_user(task, view, regset_no, 0, +- kiov->iov_len, kiov->iov_base); +- else +- return copy_regset_from_user(task, view, regset_no, 0, +- kiov->iov_len, kiov->iov_base); +-} +- +-#endif +- + int ptrace_request(struct task_struct *child, long request, + long addr, long data) + { +@@ -666,88 +786,7 @@ int ptrace_request(struct task_struct *child, long request, + return ret; + } + +-static struct task_struct *ptrace_get_task_struct(pid_t pid) +-{ +- struct task_struct *child; +- +- rcu_read_lock(); +- child = find_task_by_vpid(pid); +- if (child) +- get_task_struct(child); +- rcu_read_unlock(); +- +- if (!child) +- return ERR_PTR(-ESRCH); +- return child; +-} +- +-#ifndef arch_ptrace_attach +-#define arch_ptrace_attach(child) do { } while (0) +-#endif +- +-SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data) +-{ +- struct task_struct *child; +- long ret; +- +- if (request == PTRACE_TRACEME) { +- ret = ptrace_traceme(); +- if (!ret) +- arch_ptrace_attach(current); +- goto out; +- } +- +- child = ptrace_get_task_struct(pid); +- if (IS_ERR(child)) { +- ret = PTR_ERR(child); +- goto out; +- } +- +- if (request == PTRACE_ATTACH) { +- ret = ptrace_attach(child); +- /* +- * Some architectures need to do book-keeping after +- * a ptrace attach. +- */ +- if (!ret) +- arch_ptrace_attach(child); +- goto out_put_task_struct; +- } +- +- ret = ptrace_check_attach(child, request == PTRACE_KILL); +- if (ret < 0) +- goto out_put_task_struct; +- +- ret = arch_ptrace(child, request, addr, data); +- +- out_put_task_struct: +- put_task_struct(child); +- out: +- return ret; +-} +- +-int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data) +-{ +- unsigned long tmp; +- int copied; +- +- copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); +- if (copied != sizeof(tmp)) +- return -EIO; +- return put_user(tmp, (unsigned long __user *)data); +-} +- +-int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data) +-{ +- int copied; +- +- copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); +- return (copied == sizeof(data)) ? 0 : -EIO; +-} +- + #if defined CONFIG_COMPAT +-#include <linux/compat.h> +- + int compat_ptrace_request(struct task_struct *child, compat_long_t request, + compat_ulong_t addr, compat_ulong_t data) + { +@@ -825,42 +864,5 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request, + + return ret; + } +- +-asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, +- compat_long_t addr, compat_long_t data) +-{ +- struct task_struct *child; +- long ret; +- +- if (request == PTRACE_TRACEME) { +- ret = ptrace_traceme(); +- goto out; +- } +- +- child = ptrace_get_task_struct(pid); +- if (IS_ERR(child)) { +- ret = PTR_ERR(child); +- goto out; +- } +- +- if (request == PTRACE_ATTACH) { +- ret = ptrace_attach(child); +- /* +- * Some architectures need to do book-keeping after +- * a ptrace attach. +- */ +- if (!ret) +- arch_ptrace_attach(child); +- goto out_put_task_struct; +- } +- +- ret = ptrace_check_attach(child, request == PTRACE_KILL); +- if (!ret) +- ret = compat_arch_ptrace(child, request, addr, data); +- +- out_put_task_struct: +- put_task_struct(child); +- out: +- return ret; +-} + #endif /* CONFIG_COMPAT */ ++#endif /* CONFIG_UTRACE */ +diff --git a/kernel/signal.c b/kernel/signal.c +index 906ae5a..8087f13 100644 +--- a/kernel/signal.c ++++ b/kernel/signal.c +@@ -1518,7 +1518,7 @@ int do_notify_parent(struct task_struct *tsk, int sig) + return ret; + } + +-static void do_notify_parent_cldstop(struct task_struct *tsk, int why) ++void do_notify_parent_cldstop(struct task_struct *tsk, int why) + { + struct siginfo info; + unsigned long flags; +@@ -1788,7 +1788,7 @@ static int do_signal_stop(int signr) + static int ptrace_signal(int signr, siginfo_t *info, + struct pt_regs *regs, void *cookie) + { +- if (!task_ptrace(current)) ++ if (!(task_ptrace(current) & PT_PTRACED)) + return signr; + + ptrace_signal_deliver(regs, cookie); +diff --git a/kernel/utrace.c b/kernel/utrace.c +new file mode 100644 +index 0000000..f5a9e2c +--- /dev/null ++++ b/kernel/utrace.c +@@ -0,0 +1,2452 @@ ++/* ++ * 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; ++ 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 two ++ * refs: one ref to return, and one ref for being attached. ++ */ ++ kref_set(&engine->kref, 2); ++ 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(!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, if you try to clear %UTRACE_EVENT(%REAP) when the @report_reap ++ * 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 can fail with -%ESRCH 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; ++ ++ /* ++ * 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 (target->exit_state && ++ (((events & ~old_flags) & _UTRACE_DEATH_EVENTS) || ++ (utrace->death && ++ ((old_flags & ~events) & _UTRACE_DEATH_EVENTS)) || ++ (utrace->reap && ((old_flags & ~events) & UTRACE_EVENT(REAP))))) { ++ spin_unlock(&utrace->lock); ++ return -EALREADY; ++ } ++ ++ /* ++ * 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_utrace_flags) & _UTRACE_DEATH_EVENTS) { ++ read_lock(&tasklist_lock); ++ if (unlikely(target->exit_state)) { ++ read_unlock(&tasklist_lock); ++ spin_unlock(&utrace->lock); ++ return -EALREADY; ++ } ++ 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; ++ } ++ ++ 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)) ++ 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); ++ ++ /* ++ * If ptrace is among the reasons for this stop, do its ++ * notification now. This could not just be done in ++ * ptrace's own event report callbacks because it has to ++ * be done after we are in TASK_TRACED. This makes the ++ * synchronization with ptrace_do_wait() work right. ++ * ++ * It's only because of the bad old overloading of the do_wait() ++ * logic for handling ptrace stops that we need this special case ++ * here. One day we will clean up ptrace so it does not need to ++ * work this way. New things that are designed sensibly don't need ++ * a wakeup that synchronizes with tasklist_lock and ->state, so ++ * the proper utrace API does not try to support this weirdness. ++ */ ++ ptrace_notify_stop(task); ++ ++ 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: ++ /* ++ * This and all other cases imply resuming if stopped. ++ * There might not be another report before it just ++ * resumes, so make sure single-step is not left set. ++ */ ++ clear_engine_wants_stop(engine); ++ if (likely(reset)) ++ user_disable_single_step(target); ++ 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)) { ++ if (finish_callback(task, utrace, report, engine, ++ (*ops->report_quiesce)(report->action, ++ engine, event))) ++ 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->signal->flags |= SIGNAL_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); ++} +-- +1.7.0.1 + |