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* [PATCH] uml: fix critical typo for TT modePaolo 'Blaisorblade' Giarrusso2006-04-111-1/+1
| | | | | | | | | | | Noticed this for a compilation-time warning, so I'm fixing it even for TT mode - this is not put_user, but copy_to_user, so we need a pointer to sp, not sp itself (we're trying to write the word pointed to by the "sp" var.). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix some double export warningsPaolo 'Blaisorblade' Giarrusso2006-04-111-4/+0
| | | | | | | | | Some functions are exported twice in current code - remove the excess export. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix format errorsPaolo 'Blaisorblade' Giarrusso2006-04-111-1/+1
| | | | | | | | | | Now that GCC warns about format errors, fix them. Nothing able to cause a crash, however. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] UML: TLS fixletsJeff Dike2006-04-111-1/+1
| | | | | | | | | | | | Two small TLS fixes - arch/um/os-Linux/sys-i386/tls.c uses errno and -E* so it should include errno.h __setup_host_supports_tls returns 1, but as an initcall, it should return 0 Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: check for differences in host supportPaolo 'Blaisorblade' Giarrusso2006-03-311-2/+53
| | | | | | | | | | | | | | | | | | If running on a host not supporting TLS (for instance 2.4) we should report that cleanly to the user, instead of printing not comprehensible "error 5" for that. Additionally, i386 and x86_64 support different ranges for user_desc->entry_number, and we must account for that; we couldn't pass ourselves -1 because we need to override previously existing TLS descriptors which glibc has possibly set, so test at startup the range to use. x86 and x86_64 existing ranges are hardcoded. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: add arch_switch_to for newly forked threadPaolo 'Blaisorblade' Giarrusso2006-03-312-4/+18
| | | | | | | | | | | | Newly forked threads have no arch_switch_to_skas() called before their first run, because when schedule() switches to them they're resumed in the body of thread_wait() inside fork_handler() rather than in switch_threads() in switch_to_skas(). Compensate this missing call. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: implement {get,set}_thread_area for i386Paolo 'Blaisorblade' Giarrusso2006-03-315-7/+340
| | | | | | | | | | | | | | | | | | | | | | Implement sys_[gs]et_thread_area and the corresponding ptrace operations for UML. This is the main chunk, additional parts follow. This implementation is now well tested and has run reliably for some time, and we've understood all the previously existing problems. Their implementation saves the new GDT content and then forwards the call to the host when appropriate, i.e. immediately when the target process is running or on context switch otherwise (i.e. on fork and on ptrace() calls). In SKAS mode, we must switch registers on each context switch (because SKAS does not switches tls_array together with current->mm). Also, added get_cpu() locking; this has been done for SKAS mode, since TT does not need it (it does not use smp_processor_id()). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: clean arch_switch usagePaolo 'Blaisorblade' Giarrusso2006-03-312-3/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Call arch_switch also in switch_to_skas, even if it's, for now, a no-op for that case (and mark this in the comment); this will change soon. Also, arch_switch for TT mode is actually useless when the PT proxy (a complicate debugging instrumentation for TT mode) is not enabled. In fact, it only calls update_debugregs, which checks debugregs_seq against seq (to check if the registers are up-to-date - seq here means a "version number" of the registers). If the ptrace proxy is not enabled, debugregs_seq always stays 0 and update_debugregs will be a no-op. So, optimize this out (the compiler can't do it). Also, I've been disappointed by the fact that it would make a lot of sense if, after calling a successful update_debugregs(current->thread.arch.debugregs_seq), current->thread.arch.debugregs_seq were updated with the new debugregs_seq. But this is not done. Is this a bug or a feature? For all purposes, it seems a bug (otherwise the whole mechanism does not make sense, which is also a possibility to check), which causes some performance only problems (not correctness), since we write_debugregs when not needed. Also, as suggested by Jeff, remove a redundant enabling of SIGVTALRM, comprised in the subsequent local_irq_enable(). I'm just a bit dubious if ordering matters there... Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: sparse cleanupsAl Viro2006-03-313-38/+40
| | | | | | | | | | misc sparse annotations Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: clean up remapping code build magicAl Viro2006-03-311-2/+3
| | | | | | | | | | kills unmap magic Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: eliminate symlinks to host archAl Viro2006-03-311-12/+5
| | | | | | | | | | kills symlinks in arch/um/sys-* Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix segfault on signal deliveryJeff Dike2006-03-271-15/+44
| | | | | | | | | | | | | | | | | | | This fixes a process segfault where a signal was being delivered such that a new stack page needed to be allocated to hold the signal frame. This was tripping some logic in the page fault handler which wouldn't allocate the page if the faulting address was more that 32 bytes lower than the current stack pointer. Since a signal frame is greater than 32 bytes, this exercised that case. It's fixed by updating the SP in the pt_regs before starting to copy the signal frame. Since those are the registers that will be copied on to the stack, we have to be careful to put the original SP, not the new one which points to the signal frame, on the stack. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: more carefully test whether we are in a system callBodo Stroesser2006-03-271-3/+12
| | | | | | | | | | | | | | | | | | | | For security reasons, UML in is_syscall() needs to have access to code in vsyscall-page. The current implementation grants this access by explicitly allowing access to vsyscall in access_ok_skas(). With this change, copy_from_user() may be used to read the code. Ptrace access to vsyscall-page for debugging already was implemented in get_user_pages() by mainline. In i386, copy_from_user can't access vsyscall-page, but returns EFAULT. To make UML behave as i386 does, I changed is_syscall to use access_process_vm(current) to read the code from vsyscall-page. This doesn't hurt security, but simplifies the code and prepares implementation of stub-vmas. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: move libc-dependent irq code to os-LinuxJeff Dike2006-03-271-2/+8
| | | | | | | | | | | | The serial UML OS-abstraction layer patch (um/kernel dir). This moves all systemcalls from irq_user.c file under os-Linux dir Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix usage of kernel_errno in place of errnoPaolo 'Blaisorblade' Giarrusso2006-02-241-6/+3
| | | | | | | | | | | | To avoid conflicts, in kernel files errno is expanded to kernel_errno, to distinguish it from glibc errno. In this case, the code wants to use the libc errno but the kernel one is used; in the other usage, we return errno in place of -errno in case of an error. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: compilation fix when MODE_SKAS disabledPekka Enberg2006-02-011-1/+1
| | | | | | | | | | | CC arch/um/sys-i386/ldt.o arch/um/sys-i386/ldt.c:19:21: proc_mm.h: No such file or directory make[1]: *** [arch/um/sys-i386/ldt.o] Error 1 Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: move LDT creationBodo Stroesser2006-01-181-2/+24
| | | | | | | | | | | | | | | s390 doesn't have a LDT. So MM_COPY_SEGMENTS will not be supported on s390. The only user of MM_COPY_SEGMENTS is new_mm(), but that's no longer useful, as arch/sys-i386/ldt.c defines init_new_ldt(), which is called immediately after new_mm(). So we should copy host's LDT in init_new_ldt(), if /proc/mm is available, to have this subarch specific call in subarch code. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix missing KBUILD_BASENAMEJeff Dike2006-01-111-26/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | 2.6.15-mm1 caused kernel-offsets.c to stop compiling with a syntax error in a header. The problem was with KBUILD_BASENAME, which didn't get a definition with the by-hand compilation in the main UML Makefile. This was OK before since the expansion was syntactically the same as the KBUILD_BASENAME token. With -mm1, the expansion is now a quote-delimited string, so there needs to be a definition of it. Since kernel-offsets.c is basically the same as other arches' asm-offsets.c, and those seem to build OK, this patch turns kernel-offsets.c into asm-offsets.c. kernel-offsets.c is in arch/um/sys-$(SUBARCH), i.e. sys-i386 and sys-x86_64, while kbuild expects it to be in arch/um/kernel. kernel-offsets.c is moved to arch/um/include/sysdep-$(SUBARCH)/kernel-offsets.h, which is included by arch/um/kernel/asm-offsets.c. With that, include/asm-um/asm-offsets.h is generated automatically. kernel-offsets.h continues to exist because it needs to be accessible to userspace UML code, and include/asm-um isn't. So, a symlink is made from arch/um/include/kernel-offsets.h to include/asm-um/asm-offsets.h. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: move libc-dependent code from signal_user.cGennady Sharapov2006-01-081-1/+0
| | | | | | | | | | | | The serial UML OS-abstraction layer patch (um/kernel dir). This moves all systemcalls from signal_user.c file under os-Linux dir Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix compilation with CONFIG_MODE_TT disabledPaolo 'Blaisorblade' Giarrusso2005-12-291-3/+5
| | | | | | | | | | | | Fix UML compilation when SKAS mode is disabled. Indeed, we were compiling SKAS-only object files, which failed due to some SKAS-only headers being excluded from the search path. Thanks to the bug report from Pekka J Enberg. Acked-by: Pekka J Enberg <penberg (at) cs ! helsinki ! fi> Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: properly invoke x86_64 system callsJeff Dike2005-11-222-5/+8
| | | | | | | | | | | | | | This patch makes stub_segv use the stub_syscall macros. This was needed anyway, but the bug that prompted this was the discovery that gcc was storing stuff in RCX, which is trashed across a system call. This is exactly the sort of problem that the new macros fix. There is a stub_syscall0 for getpid. stub_segv was changed to be a libc file, and that caused some include changes. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: eliminate anonymous union and clean up symlink lossageJeff Dike2005-11-221-16/+19
| | | | | | | | | | | | This gives a name to the anonymous union introduced in skas-hold-own-ldt, allowing to build on a wider range of gccs. It also removes ldt.h, which somehow became real, and replaces it with a symlink, and creates ldt-x86_64.h as a copy of ldt-i386.h for now. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: maintain own LDT entriesBodo Stroesser2005-11-071-35/+471
| | | | | | | | | | | | | | | | | | | | Patch imlements full LDT handling in SKAS: * UML holds it's own LDT table, used to deliver data on modify_ldt(READ) * UML disables the default_ldt, inherited from the host (SKAS3) or resets LDT entries, set by host's clib and inherited in SKAS0 * A new global variable skas_needs_stub is inserted, that can be used to decide, whether stub-pages must be supported or not. * Uses the syscall-stub to replace missing PTRACE_LDT (therefore, write_ldt_entry needs to be modified) Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Fix sysrq-r support for skas modeAllan Graves2005-10-041-12/+1
| | | | | | | | | | | The old code had the IP and SP coming from the registers in the thread struct, which are completely wrong since those are the userspace registers. This fixes that by pulling the correct values from the jmp_buf in which the kernel state of each thread is stored. Signed-off-by: Allan Graves <allan.graves@oracle.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] UML - Fix Al's build tidyingJeff Dike2005-10-041-1/+1
| | | | | | | | Al's build tidying missed one bit from me - without this UML doesn't boot. Signed-off-by: Jeff Dike <jdike@addtoit.com> Acked-by: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml makefiles sanitizedAl Viro2005-09-296-118/+39
| | | | | | | | | | | | | | | UML makefiles sanitized: - number of generated headers reduced to 2 (from user-offsets.c and kernel-offsets.c resp.). The rest is made constant and simply includes those two. - mk_... helpers are gone now that we don't need to generate these headers - arch/um/include2 removed since everything under arch/um/include/sysdep is constant now and symlink can point straight to source tree. - dependencies seriously simplified. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix modify_ldt - missing break in switchPaolo 'Blaisorblade' Giarrusso2005-09-211-0/+1
| | | | | | | | | | | | | I am a lamer :-(. Luckily, Luo Xin performed LTP testing and found this failure. Btw, the fact that the patch in which I introduced this was merged shows that: a) I'm really trusted by people b) sometimes they're wrong about point a). c) lack of time for reviewers. CC: Luo Xin <luothing@sina.com> Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] bogus symbol used in arch/um/os-Linux/elf_aux.cviro@ZenIV.linux.org.uk2005-09-071-0/+1
| | | | | | | | elf_aux is userland code; it uses symbol (ELF_CLASS) that doesn't exist in userland headers; pulled into kernel-offsets.h, switched elf_aux to using it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: skas0 stubs now check system call return valuesBodo Stroesser2005-09-051-8/+34
| | | | | | | | | | | | | | | | | | | | | Change syscall-stub's data to include a "expected retval". Stub now checks syscalls retval and aborts execution of syscall list, if retval != expected retval. run_syscall_stub prints the data of the failed syscall, using the data pointer and retval written by the stub to the beginning of the stack. one_syscall_stub is removed, to simplify code, because only some instructions are saved by one_syscall_stub, no host-syscall. Using the stub with additional data (modify_ldt via stub) is prepared also. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: build cleanupsAl Viro2005-09-052-7/+2
| | | | | | | | | | | | | | Added missing include list to uml AFLAGS Killed magic for stubs. [So] - it was needed only because of messed AFLAGS Switched segv_stubs.c to kernel CFLAGS sans profile, instead of user ones Killed STUBS_CFLAGS - it's not needed and the only remaining use had been gratitious - it only polluted CFLAGS Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: TLB operation batchingJeff Dike2005-09-051-0/+17
| | | | | | | | | | | | | | | | | | | | | | This adds VM op batching to skas0. Rather than having a context switch to and from the userspace stub for each address space change, we write a number of operations to the stub data page and invoke a different stub which loops over them and executes them all in one go. The operations are stored as [ system call number, arg1, arg2, ... ] tuples. The set is terminated by a system call number of 0. Single operations, i.e. page faults, are handled in the old way, since that is slightly more efficient. For a kernel build, a minority (~1/4) of the operations are part of a set. These sets averaged ~100 in length, so for this quarter, the context switching overhead is greatly reduced. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: build cleanupAl Viro2005-09-051-2/+0
| | | | | | | | | Build cleanups Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix signal frame copy_userAl Viro2005-09-051-1/+1
| | | | | | | | The copy_user stuff in the signal frame code was broke. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Fix skas0 stub returnBodo Stroesser2005-07-281-3/+3
| | | | | | | | | | | | | It's wrong to pop a fixed number of words from stack before calling sigreturn, as the number depends on what code is generated by the compiler for the start of stub_segv_handler(). What we need is esp containing the address of sigcontext. So we explicitly load that pointer into esp. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: consolidate modify_ldtPaolo 'Blaisorblade' Giarrusso2005-07-141-52/+62
| | | | | | | | | | | | | | | | *) Reorganize the two cases of sys_modify_ldt to share all the reasonably common code. *) Avoid memory allocation when unneeded (i.e. when we are writing and the passed buffer size is known), thus not returning ENOMEM (which isn't allowed for this syscall, even if there is no strict "specification"). *) Add copy_{from,to}_user to modify_ldt for TT mode. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: workaround host bug in "TT mode vs. NPTL link fix"Paolo 'Blaisorblade' Giarrusso2005-07-141-1/+1
| | | | | | | | | | | | | | | | | | | A big bug has been diagnosed on hosts running the SKAS patch and built with CONFIG_REGPARM, due to some missing prevent_tail_call(). On these hosts, this workaround is needed to avoid triggering that bug, because "to" is kept by GCC only in EBX, which is corrupted at the return of mmap2(). Since to trigger this bug int 0x80 must be used when doing the call, it rarely manifests itself, so I'd prefer to get this merged to workaround that host bug, since it should cause no functional change. Still, you might prefer to drop it, I'll leave this to you. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: skas0 - separate kernel address space on stock hostsJeff Dike2005-07-073-2/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | UML has had two modes of operation - an insecure, slow mode (tt mode) in which the kernel is mapped into every process address space which requires no host kernel modifications, and a secure, faster mode (skas mode) in which the UML kernel is in a separate host address space, which requires a patch to the host kernel. This patch implements something very close to skas mode for hosts which don't support skas - I'm calling this skas0. It provides the security of the skas host patch, and some of the performance gains. The two main things that are provided by the skas patch, /proc/mm and PTRACE_FAULTINFO, are implemented in a way that require no host patch. For the remote address space changing stuff (mmap, munmap, and mprotect), we set aside two pages in the process above its stack, one of which contains a little bit of code which can call mmap et al. To update the address space, the system call information (system call number and arguments) are written to the stub page above the code. The %esp is set to the beginning of the data, the %eip is set the the start of the stub, and it repeatedly pops the information into its registers and makes the system call until it sees a system call number of zero. This is to amortize the cost of the context switch across multiple address space updates. When the updates are done, it SIGSTOPs itself, and the kernel process continues what it was doing. For a PTRACE_FAULTINFO replacement, we set up a SIGSEGV handler in the child, and let it handle segfaults rather than nullifying them. The handler is in the same page as the mmap stub. The second page is used as the stack. The handler reads cr2 and err from the sigcontext, sticks them at the base of the stack in a faultinfo struct, and SIGSTOPs itself. The kernel then reads the faultinfo and handles the fault. A complication on x86_64 is that this involves resetting the registers to the segfault values when the process is inside the kill system call. This breaks on x86_64 because %rcx will contain %rip because you tell SYSRET where to return to by putting the value in %rcx. So, this corrupts $rcx on return from the segfault. To work around this, I added an arch_finish_segv, which on x86 does nothing, but which on x86_64 ptraces the child back through the sigreturn. This causes %rcx to be restored by sigreturn and avoids the corruption. Ultimately, I think I will replace this with the trick of having it send itself a blocked signal which will be unblocked by the sigreturn. This will allow it to be stopped just after the sigreturn, and PTRACE_SYSCALLed without all the back-and-forth of PTRACE_SYSCALLing it through sigreturn. This runs on a stock host, so theoretically (and hopefully), tt mode isn't needed any more. We need to make sure that this is better in every way than tt mode, though. I'm concerned about the speed of address space updates and page fault handling, since they involve extra round-trips to the child. We can amortize the round-trip cost for large address space updates by writing all of the operations to the data page and having the child execute them all at the same time. This will help fork and exec, but not page faults, since they involve only one page. I can't think of any way to help page faults, except to add something like PTRACE_FAULTINFO to the host. There is PTRACE_SIGINFO, but UML doesn't use siginfo for SIGSEGV (or anything else) because there isn't enough information in the siginfo struct to handle page faults (the faulting operation type is missing). Adding that would make PTRACE_SIGINFO a usable equivalent to PTRACE_FAULTINFO. As for the code itself: - The system call stub is in arch/um/kernel/sys-$(SUBARCH)/stub.S. It is put in its own section of the binary along with stub_segv_handler in arch/um/kernel/skas/process.c. This is manipulated with run_syscall_stub in arch/um/kernel/skas/mem_user.c. syscall_stub will execute any system call at all, but it's only used for mmap, munmap, and mprotect. - The x86_64 stub calls sigreturn by hand rather than allowing the normal sigreturn to happen, because the normal sigreturn is a SA_RESTORER in UML's address space provided by libc. Needless to say, this is not available in the child's address space. Also, it does a couple of odd pops before that which restore the stack to the state it was in at the time the signal handler was called. - There is a new field in the arch mmu_context, which is now a union. This is the pid to be manipulated rather than the /proc/mm file descriptor. Code which deals with this now checks proc_mm to see whether it should use the usual skas code or the new code. - userspace_tramp is now used to create a new host process for every UML process, rather than one per UML processor. It checks proc_mm and ptrace_faultinfo to decide whether to map in the pages above its stack. - start_userspace now makes CLONE_VM conditional on proc_mm since we need separate address spaces now. - switch_mm_skas now just sets userspace_pid[0] to the new pid rather than PTRACE_SWITCH_MM. There is an addition to userspace which updates its idea of the pid being manipulated each time around the loop. This is important on exec, when the pid will change underneath userspace(). - The stub page has a pte, but it can't be mapped in using tlb_flush because it is part of tlb_flush. This is why it's required for it to be mapped in by userspace_tramp. Other random things: - The stub section in uml.lds.S is page aligned. This page is written out to the backing vm file in setup_physmem because it is mapped from there into user processes. - There's some confusion with TASK_SIZE now that there are a couple of extra pages that the process can't use. TASK_SIZE is considered by the elf code to be the usable process memory, which is reasonable, so it is decreased by two pages. This confuses the definition of USER_PGDS_IN_LAST_PML4, making it too small because of the rounding down of the uneven division. So we round it to the nearest PGDIR_SIZE rather than the lower one. - I added a missing PT_SYSCALL_ARG6_OFFSET macro. - um_mmu.h was made into a userspace-usable file. - proc_mm and ptrace_faultinfo are globals which say whether the host supports these features. - There is a bad interaction between the mm.nr_ptes check at the end of exit_mmap, stack randomization, and skas0. exit_mmap will stop freeing pages at the PGDIR_SIZE boundary after the last vma. If the stack isn't on the last page table page, the last pte page won't be freed, as it should be since the stub ptes are there, and exit_mmap will BUG because there is an unfreed page. To get around this, TASK_SIZE is set to the next lowest PGDIR_SIZE boundary and mm->nr_ptes is decremented after the calls to init_stub_pte. This ensures that we know the process stack (and all other process mappings) will be below the top page table page, and thus we know that mm->nr_ptes will be one too many, and can be decremented. Things that need fixing: - We may need better assurrences that the stub code is PIC. - The stub pte is set up in init_new_context_skas. - alloc_pgdir is probably the right place. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fork cleanupJeff Dike2005-06-251-19/+4
| | | | | | | | | | | | | | | | Fix the do_fork calling convention: normal arch pass the regs and the new sp value to do_fork instead of NULL. Currently the arch-independent code ignores these values, while the UML code (actually it's copy_thread) gets the right values by itself. With this patch, things are fixed up. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix sizeof usageAndrew Morton2005-06-251-1/+1
| | | | | | | | | | | Size of pointer doesn't seem right, but maybe my solution isn't either (sig_size maybe?). Signed-off-by: Domen Puncer <domen@coderock.org> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix linkage of tt mode against NPTLPaolo 'Blaisorblade' Giarrusso2005-06-212-0/+27
| | | | | | | | | | | | | | | | | With Al Viro <viro@parcelfarce.linux.theplanet.co.uk> To make sure switcheroo() can execute when we remap all the executable image, we used a trick to make it use a local copy of errno... this trick does not work with NPTL glibc, only with LinuxThreads, so use another (simpler) one to make it work anyway. Hopefully, a lot improved thanks to merging with the version of Al Viro (which had his part of problems, though, i.e. removing a fix to another bug and not fixing the problem on i386). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: stack dump fixPaolo 'Blaisorblade' Giarrusso2005-05-281-1/+79
| | | | | | | | | Copy (and adapt) to UML the stack code dumper used in i386 when CONFIG_FRAME_POINTER is enabled. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Delay loop cleanupsJeff Dike2005-05-201-4/+12
| | | | | | | | | | This patch cleans up the delay implementations a bit, makes the loops unoptimizable, and exports __udelay and __const_udelay. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: small fixes left over from rc4Jeff Dike2005-05-201-2/+2
| | | | | | | | | | | | | | | | | | Some changes that I sent in didn't make 2.6.12-rc4 for some reason. This adds them back. We have an x86_64 definition of TOP_ADDR a reimplementation of the x86_64 csum_partial_copy_from_user some syntax fixes in arch/um/kernel/ptrace.c removal of a CFLAGS definition in the x86_64 Makefile some include changes in the x86_64 ptrace.c and user-offsets.h a syntax fix in elf-x86_64.h Also moved an include in the i386 and x86_64 Makefiles to make the symlinks work, and some small fixes from Al Viro. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: S390 preparation, peekusr/pokeusr defined by subarchBodo Stroesser2005-05-061-0/+40
| | | | | | | | | | | | | | | | | | | | | | | | s390 needs to change some parts of arch/um/kernel/ptrace.c. Thus, the code regarding PEEKUSER and POKEUSER are shifted to arch/um/sys-<subarch>/ptrace.c. Also s390 debug registers need to be updated, when singlestepping is switched on / off. Thus, setting/resetting of singlestepping is centralized in the new function set_singlestep(), which also inserts the macro SUBARCH_SET_SINGLESTEP(mode), if defined. Finally, s390 has the "ieee_instruction_pointer" in its registers, which also is allowed to be read via ptrace( PTRACE_PEEKUSER, getpid(), PT_IEEE_IP, 0); To implement this feature, sys_ptrace inserts the macro SUBARCH_PTRACE_SPECIAL, if defined. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: s390 preparation, delay moved to archBodo Stroesser2005-05-052-0/+23
| | | | | | | | | | | s390 has fast read access to realtime clock (nanosecond resolution). So it makes sense to have an arch-specific implementation not only of __delay, but __udelay also. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: s390 preparation, checksumming done in arch codeBodo Stroesser2005-05-052-5/+4
| | | | | | | | | | | | | | | | | | | | Checksum handling largely depends on the subarch. Thus, I renamed i386 arch_csum_partial in arch/um/sys-i386/checksum.S back to csum_partial, removed csum_partial from arch/um/kernel/checksum.c and shifted EXPORT_SYMBOL(csum_partial) to arch/um/sys-i386/ksyms.c. Then, csum_partial_copy_to and csum_partial_copy_from were shifted from arch/um/kernel/checksum.c to arch/um/include/sysdep-i386/checksum.h and inserted in the calling functions csum_partial_copy_from_user() and csum_and_copy_to_user(). Now, arch/um/kernel/checksum.c is empty and removed. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: S390 preparation, abstract host page fault dataBodo Stroesser2005-05-051-11/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes the arch-specific fault/trap-infos from thread and skas-regs. It adds a new struct faultinfo, that is arch-specific defined in sysdep/faultinfo.h. The structure is inserted in thread.arch and thread.regs.skas and thread.regs.tt Now, segv and other trap-handlers can copy the contents from regs.X.faultinfo to thread.arch.faultinfo with one simple assignment. Also, the number of macros necessary is reduced to FAULT_ADDRESS(struct faultinfo) extracts the faulting address from faultinfo FAULT_WRITE(struct faultinfo) extracts the "is_write" flag SEGV_IS_FIXABLE(struct faultinfo) is true for the fixable segvs, i.e. (TRAP == 14) on i386 UPT_FAULTINFO(regs) result is (struct faultinfo *) to the faultinfo in regs->skas.faultinfo GET_FAULTINFO_FROM_SC(struct faultinfo, struct sigcontext *) copies the relevant parts of the sigcontext to struct faultinfo. On SIGSEGV, call user_signal() instead of handle_segv(), if the architecture provides the information needed in PTRACE_FAULTINFO, or if PTRACE_FAULTINFO is missing, because segv-stub will provide the info. The benefit of the change is, that in case of a non-fixable SIGSEGV, we can give user processes a SIGSEGV, instead of possibly looping on pagefault handling. Since handle_segv() sikked arch_fixup() implicitly by passing ip==0 to segv(), I changed segv() to call arch_fixup() only, if !is_user. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix a ptrace callJeff Dike2005-05-051-2/+3
| | | | | | | | | This fixes write_ldt_entry to treat userspace_pid as an array. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: cross-build support : mk_threadAl Viro2005-05-054-57/+23
| | | | | | | | | | mk_thread converted Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: cross-build support : kernel_offsetsAl Viro2005-05-051-0/+25
| | | | | | | | | | | | | The next group of helpers is a bit trickier - they want the constants similar to those in user-offsets.h, but we need target sc.h for it. So we can't put that into user-offsets (sc.h depends on it) and need the second generated header for that stuff (kernel-offsets.h. BFD... Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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