| Message ID | 20171207174057.GA32196@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] Linux/x86: Update cancel_jmp_buf to match __jmp_buf_tag [BZ #22563] | expand |
On Thu, 7 Dec 2017, H.J. Lu wrote: > On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer > to support shadow stack in Intel Control-flow Enforcemen Technology. > Since the cancel_jmp_buf array is passed to setjmp and longjmp by > casting it to pointer to struct __jmp_buf_tag, it should be as large > as struct __jmp_buf_tag. This patch adds pthread.h, pthreaddef.h and > pthreadP.h for Linux/x86 to define a new cancel_jmp_buf to match > struct __jmp_buf_tag. Duplicating the installed pthread.h is a bad idea (in general, we should avoid having architecture-specific variants of installed headers as much as possible, and, especially, define APIs in architecture-independent headers and limit architecture-specific variants to as few constants or structures as possible, those going in bits/ headers that at least people expect to have multiple variants). Thus, we should aim to eliminate the hppa-specific variant of pthread.h by creating a bits/ header that has the minimum information required to encapsulate the hppa variations (or putting such information in an existing bits/ header, if appropriate), and likewise for whatever the differences are in your x86 variant. We should certainly not create a new x86 variant of the whole of pthread.h.
On 12/07/2017 06:40 PM, H.J. Lu wrote: > On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer > to support shadow stack in Intel Control-flow Enforcemen Technology. > Since the cancel_jmp_buf array is passed to setjmp and longjmp by > casting it to pointer to struct __jmp_buf_tag, it should be as large > as struct __jmp_buf_tag. This patch adds pthread.h, pthreaddef.h and > pthreadP.h for Linux/x86 to define a new cancel_jmp_buf to match > struct __jmp_buf_tag. This seems the wrong thing to do. I don't think cancellation needs the shadow stack because none of the functions on the existing stack return during cancellation processing. Furthermore, SJLJ-style cancellation appears to defeat CET anyway, so I'm puzzled why aren't trying to get rid of this type of cancellation implementation instead because it looks like a fairly significant weakness (similar to SEH on Windows). If you want to preserve SJLJ-style cancellation as-is, __pthread_unwind_buf_t has sufficient padding, and you could simply use that. Thanks, Florian
On Thu, Dec 7, 2017 at 10:36 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/07/2017 06:40 PM, H.J. Lu wrote: >> >> On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer >> to support shadow stack in Intel Control-flow Enforcemen Technology. >> Since the cancel_jmp_buf array is passed to setjmp and longjmp by >> casting it to pointer to struct __jmp_buf_tag, it should be as large >> as struct __jmp_buf_tag. This patch adds pthread.h, pthreaddef.h and >> pthreadP.h for Linux/x86 to define a new cancel_jmp_buf to match >> struct __jmp_buf_tag. > > > This seems the wrong thing to do. > > I don't think cancellation needs the shadow stack because none of the > functions on the existing stack return during cancellation processing. > > Furthermore, SJLJ-style cancellation appears to defeat CET anyway, so I'm > puzzled why aren't trying to get rid of this type of cancellation > implementation instead because it looks like a fairly significant weakness > (similar to SEH on Windows). > > If you want to preserve SJLJ-style cancellation as-is, > __pthread_unwind_buf_t has sufficient padding, and you could simply use > that. > No, shadow stack doesn't work that way. Once it is turned on, it is on until the process exits. There is no such a thing of that cancellation doesn't need shadow stack.
On 12/07/2017 07:59 PM, H.J. Lu wrote: > On Thu, Dec 7, 2017 at 10:36 AM, Florian Weimer <fweimer@redhat.com> wrote: >> On 12/07/2017 06:40 PM, H.J. Lu wrote: >>> >>> On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer >>> to support shadow stack in Intel Control-flow Enforcemen Technology. >>> Since the cancel_jmp_buf array is passed to setjmp and longjmp by >>> casting it to pointer to struct __jmp_buf_tag, it should be as large >>> as struct __jmp_buf_tag. This patch adds pthread.h, pthreaddef.h and >>> pthreadP.h for Linux/x86 to define a new cancel_jmp_buf to match >>> struct __jmp_buf_tag. >> >> >> This seems the wrong thing to do. >> >> I don't think cancellation needs the shadow stack because none of the >> functions on the existing stack return during cancellation processing. >> >> Furthermore, SJLJ-style cancellation appears to defeat CET anyway, so I'm >> puzzled why aren't trying to get rid of this type of cancellation >> implementation instead because it looks like a fairly significant weakness >> (similar to SEH on Windows). >> >> If you want to preserve SJLJ-style cancellation as-is, >> __pthread_unwind_buf_t has sufficient padding, and you could simply use >> that. >> > > No, shadow stack doesn't work that way. Once it is turned on, it is on > until the process exits. There is no such a thing of that cancellation > doesn't need shadow stack. Sorry, what exactly is stored on the shadow stack? I assumed it was for verification of the targets of ret instructions. In this case, don't need to unwind the shadow stack (or preserve its contents) because there are no returns from existing stack frames once cancellation has started. Florian
On Thu, Dec 7, 2017 at 11:09 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/07/2017 07:59 PM, H.J. Lu wrote: >> >> On Thu, Dec 7, 2017 at 10:36 AM, Florian Weimer <fweimer@redhat.com> >> wrote: >>> >>> On 12/07/2017 06:40 PM, H.J. Lu wrote: >>>> >>>> >>>> On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer >>>> to support shadow stack in Intel Control-flow Enforcemen Technology. >>>> Since the cancel_jmp_buf array is passed to setjmp and longjmp by >>>> casting it to pointer to struct __jmp_buf_tag, it should be as large >>>> as struct __jmp_buf_tag. This patch adds pthread.h, pthreaddef.h and >>>> pthreadP.h for Linux/x86 to define a new cancel_jmp_buf to match >>>> struct __jmp_buf_tag. >>> >>> >>> >>> This seems the wrong thing to do. >>> >>> I don't think cancellation needs the shadow stack because none of the >>> functions on the existing stack return during cancellation processing. >>> >>> Furthermore, SJLJ-style cancellation appears to defeat CET anyway, so I'm >>> puzzled why aren't trying to get rid of this type of cancellation >>> implementation instead because it looks like a fairly significant >>> weakness >>> (similar to SEH on Windows). >>> >>> If you want to preserve SJLJ-style cancellation as-is, >>> __pthread_unwind_buf_t has sufficient padding, and you could simply use >>> that. >>> >> >> No, shadow stack doesn't work that way. Once it is turned on, it is on >> until the process exits. There is no such a thing of that cancellation >> doesn't need shadow stack. > > > Sorry, what exactly is stored on the shadow stack? I assumed it was for > verification of the targets of ret instructions. > > In this case, don't need to unwind the shadow stack (or preserve its > contents) because there are no returns from existing stack frames once > cancellation has started. > Shadow stack is the similar to normal call stack without local variables. SHSTK checks the return address of EACH "RET" instruction against shadow stack.
On 12/07/2017 08:12 PM, H.J. Lu wrote: >> Sorry, what exactly is stored on the shadow stack? I assumed it was for >> verification of the targets of ret instructions. >> >> In this case, don't need to unwind the shadow stack (or preserve its >> contents) because there are no returns from existing stack frames once >> cancellation has started. >> > Shadow stack is the similar to normal call stack without local variables. > SHSTK checks the return address of EACH "RET" instruction against > shadow stack. Then the shadow stack contents at the time of cancellation does not matter because all future RET instructions on this thread will match CALLs which happened *after* cancellation. (In other words, I still think I'm right about this.) Thanks, Florian
On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/07/2017 08:12 PM, H.J. Lu wrote: >>> >>> Sorry, what exactly is stored on the shadow stack? I assumed it was for >>> verification of the targets of ret instructions. >>> >>> In this case, don't need to unwind the shadow stack (or preserve its >>> contents) because there are no returns from existing stack frames once >>> cancellation has started. >>> >> Shadow stack is the similar to normal call stack without local variables. >> SHSTK checks the return address of EACH "RET" instruction against >> shadow stack. > > > Then the shadow stack contents at the time of cancellation does not matter > because all future RET instructions on this thread will match CALLs which > happened *after* cancellation. (In other words, I still think I'm right > about this.) > We are updating setjmp/lonjmp to save and restore shadow stack pointer: https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f
On 12/07/2017 08:19 PM, H.J. Lu wrote: > On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> wrote: >> On 12/07/2017 08:12 PM, H.J. Lu wrote: >>>> >>>> Sorry, what exactly is stored on the shadow stack? I assumed it was for >>>> verification of the targets of ret instructions. >>>> >>>> In this case, don't need to unwind the shadow stack (or preserve its >>>> contents) because there are no returns from existing stack frames once >>>> cancellation has started. >>>> >>> Shadow stack is the similar to normal call stack without local variables. >>> SHSTK checks the return address of EACH "RET" instruction against >>> shadow stack. >> >> >> Then the shadow stack contents at the time of cancellation does not matter >> because all future RET instructions on this thread will match CALLs which >> happened *after* cancellation. (In other words, I still think I'm right >> about this.) >> > > We are updating setjmp/lonjmp to save and restore shadow stack pointer: > > https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f Please try to understand what I wrote. You don't need the restore during cancellation handling: if (__glibc_unlikely (__not_first_call)) \ { \ __cancel_routine (__cancel_arg); \ __pthread_unwind_next (&__cancel_buf); \ /* NOTREACHED */ \ } \ Florian
On Thu, Dec 7, 2017 at 11:25 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/07/2017 08:19 PM, H.J. Lu wrote: >> >> On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> >> wrote: >>> >>> On 12/07/2017 08:12 PM, H.J. Lu wrote: >>>>> >>>>> >>>>> Sorry, what exactly is stored on the shadow stack? I assumed it was >>>>> for >>>>> verification of the targets of ret instructions. >>>>> >>>>> In this case, don't need to unwind the shadow stack (or preserve its >>>>> contents) because there are no returns from existing stack frames once >>>>> cancellation has started. >>>>> >>>> Shadow stack is the similar to normal call stack without local >>>> variables. >>>> SHSTK checks the return address of EACH "RET" instruction against >>>> shadow stack. >>> >>> >>> >>> Then the shadow stack contents at the time of cancellation does not >>> matter >>> because all future RET instructions on this thread will match CALLs which >>> happened *after* cancellation. (In other words, I still think I'm right >>> about this.) >>> >> >> We are updating setjmp/lonjmp to save and restore shadow stack pointer: >> >> >> https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f > > > Please try to understand what I wrote. You don't need the restore during > cancellation handling: > > if (__glibc_unlikely (__not_first_call)) \ > { \ > __cancel_routine (__cancel_arg); \ > __pthread_unwind_next (&__cancel_buf); \ > /* NOTREACHED */ \ > } \ > Who will sync shadow stack with call stack?
On Thu, Dec 7, 2017 at 11:35 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Thu, Dec 7, 2017 at 11:25 AM, Florian Weimer <fweimer@redhat.com> wrote: >> On 12/07/2017 08:19 PM, H.J. Lu wrote: >>> >>> On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> >>> wrote: >>>> >>>> On 12/07/2017 08:12 PM, H.J. Lu wrote: >>>>>> >>>>>> >>>>>> Sorry, what exactly is stored on the shadow stack? I assumed it was >>>>>> for >>>>>> verification of the targets of ret instructions. >>>>>> >>>>>> In this case, don't need to unwind the shadow stack (or preserve its >>>>>> contents) because there are no returns from existing stack frames once >>>>>> cancellation has started. >>>>>> >>>>> Shadow stack is the similar to normal call stack without local >>>>> variables. >>>>> SHSTK checks the return address of EACH "RET" instruction against >>>>> shadow stack. >>>> >>>> >>>> >>>> Then the shadow stack contents at the time of cancellation does not >>>> matter >>>> because all future RET instructions on this thread will match CALLs which >>>> happened *after* cancellation. (In other words, I still think I'm right >>>> about this.) >>>> >>> >>> We are updating setjmp/lonjmp to save and restore shadow stack pointer: >>> >>> >>> https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f >> >> >> Please try to understand what I wrote. You don't need the restore during >> cancellation handling: >> >> if (__glibc_unlikely (__not_first_call)) \ >> { \ >> __cancel_routine (__cancel_arg); \ >> __pthread_unwind_next (&__cancel_buf); \ >> /* NOTREACHED */ \ >> } \ >> > > Who will sync shadow stack with call stack? > Here is call stack during stack unwind: (gdb) bt #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800da0, val=val@entry=1) at longjmp.c:39 #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, actions=<optimized out>, exc_class=<optimized out>, exc_obj=<optimized out>, context=<optimized out>, stop_parameter=0x7ffff7800da0) at unwind.c:94 #3 0x00007ffff6df9b6e in _Unwind_ForcedUnwind_Phase2 ( exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff78005d0, frames_p=frames_p@entry=0x7ffff78004d8) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 #4 0x00007ffff6dfa1c0 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, stop_argument=<optimized out>) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) at unwind.c:121 #6 0x00007ffff7bbe46a in __do_cancel () at ./pthreadP.h:297 #7 sigcancel_handler (sig=<optimized out>, si=0x7ffff7800870, ctx=<optimized out>) at nptl-init.c:216 #8 <signal handler called> #9 0x00007ffff7bc8f04 in __libc_read (fd=fd@entry=3, buf=buf@entry=0x7ffff7800d30, nbytes=nbytes@entry=100) ---Type <return> to continue, or q <return> to quit--- sv/linux/read.c:27 #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 #11 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) at pthread_create.c:463 #12 0x00007ffff78f5f73 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) f 10 #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 102 s = read (fd, buf, sizeof (buf)); (gdb) list 97 98 ssize_t s; 99 pthread_cleanup_push (cl, NULL); 100 101 char buf[100]; 102 s = read (fd, buf, sizeof (buf)); 103 104 pthread_cleanup_pop (0); 105 106 FAIL_EXIT1 ("read returns with %zd", s); (gdb) # define pthread_cleanup_push(routine, arg) \ do { \ __pthread_unwind_buf_t __cancel_buf; \ void (*__cancel_routine) (void *) = (routine); \ void *__cancel_arg = (arg); \ int __not_first_call = __sigsetjmp ((struct __jmp_buf_tag *) (void *) \ __cancel_buf.__cancel_jmp_buf, 0); \ if (__glibc_unlikely (__not_first_call)) \ { \ __cancel_routine (__cancel_arg); \ __pthread_unwind_next (&__cancel_buf); \ /* NOTREACHED */ \ } To unwind shadow stack, we need to save shadow stack pointer in __cancel_buf. This updated patch adds bits/types/__cancel_jmp_buf_tag.h to define struct __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to __cancel_jmp_buf. We will check if shadow stack is enabled before saving and restoring shadow stack pointer so that it works with the old smaller cancel_jmp_buf which doesn't have space for shadow stack pointer.
On Thu, Dec 7, 2017 at 6:25 PM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Thu, Dec 7, 2017 at 11:35 AM, H.J. Lu <hjl.tools@gmail.com> wrote: >> On Thu, Dec 7, 2017 at 11:25 AM, Florian Weimer <fweimer@redhat.com> wrote: >>> On 12/07/2017 08:19 PM, H.J. Lu wrote: >>>> >>>> On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> >>>> wrote: >>>>> >>>>> On 12/07/2017 08:12 PM, H.J. Lu wrote: >>>>>>> >>>>>>> >>>>>>> Sorry, what exactly is stored on the shadow stack? I assumed it was >>>>>>> for >>>>>>> verification of the targets of ret instructions. >>>>>>> >>>>>>> In this case, don't need to unwind the shadow stack (or preserve its >>>>>>> contents) because there are no returns from existing stack frames once >>>>>>> cancellation has started. >>>>>>> >>>>>> Shadow stack is the similar to normal call stack without local >>>>>> variables. >>>>>> SHSTK checks the return address of EACH "RET" instruction against >>>>>> shadow stack. >>>>> >>>>> >>>>> >>>>> Then the shadow stack contents at the time of cancellation does not >>>>> matter >>>>> because all future RET instructions on this thread will match CALLs which >>>>> happened *after* cancellation. (In other words, I still think I'm right >>>>> about this.) >>>>> >>>> >>>> We are updating setjmp/lonjmp to save and restore shadow stack pointer: >>>> >>>> >>>> https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f >>> >>> >>> Please try to understand what I wrote. You don't need the restore during >>> cancellation handling: >>> >>> if (__glibc_unlikely (__not_first_call)) \ >>> { \ >>> __cancel_routine (__cancel_arg); \ >>> __pthread_unwind_next (&__cancel_buf); \ >>> /* NOTREACHED */ \ >>> } \ >>> >> >> Who will sync shadow stack with call stack? >> > > Here is call stack during stack unwind: > > (gdb) bt > #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 > #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800da0, > val=val@entry=1) at longjmp.c:39 > #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, > actions=<optimized out>, exc_class=<optimized out>, > exc_obj=<optimized out>, context=<optimized out>, > stop_parameter=0x7ffff7800da0) at unwind.c:94 > #3 0x00007ffff6df9b6e in _Unwind_ForcedUnwind_Phase2 ( > exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff78005d0, > frames_p=frames_p@entry=0x7ffff78004d8) > at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 > #4 0x00007ffff6dfa1c0 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, > stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, > stop_argument=<optimized out>) > at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 > #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) > at unwind.c:121 > #6 0x00007ffff7bbe46a in __do_cancel () at ./pthreadP.h:297 > #7 sigcancel_handler (sig=<optimized out>, si=0x7ffff7800870, > ctx=<optimized out>) at nptl-init.c:216 > #8 <signal handler called> > #9 0x00007ffff7bc8f04 in __libc_read (fd=fd@entry=3, > buf=buf@entry=0x7ffff7800d30, nbytes=nbytes@entry=100) > ---Type <return> to continue, or q <return> to quit--- > sv/linux/read.c:27 > #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 > #11 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) > at pthread_create.c:463 > #12 0x00007ffff78f5f73 in clone () > at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 > (gdb) f 10 > #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 > 102 s = read (fd, buf, sizeof (buf)); > (gdb) list > 97 > 98 ssize_t s; > 99 pthread_cleanup_push (cl, NULL); > 100 > 101 char buf[100]; > 102 s = read (fd, buf, sizeof (buf)); > 103 > 104 pthread_cleanup_pop (0); > 105 > 106 FAIL_EXIT1 ("read returns with %zd", s); > (gdb) > > # define pthread_cleanup_push(routine, arg) \ > do { \ > __pthread_unwind_buf_t __cancel_buf; \ > void (*__cancel_routine) (void *) = (routine); \ > void *__cancel_arg = (arg); \ > int __not_first_call = __sigsetjmp ((struct __jmp_buf_tag *) (void *) \ > __cancel_buf.__cancel_jmp_buf, 0); \ > if (__glibc_unlikely (__not_first_call)) \ > { \ > __cancel_routine (__cancel_arg); \ > __pthread_unwind_next (&__cancel_buf); \ > /* NOTREACHED */ \ > } > > To unwind shadow stack, we need to save shadow stack pointer in > __cancel_buf. This updated patch adds bits/types/__cancel_jmp_buf_tag.h > to define struct __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask > to __cancel_jmp_buf. We will check if shadow stack is enabled before saving > and restoring shadow stack pointer so that it works with the old smaller > cancel_jmp_buf which doesn't have space for shadow stack pointer. > Any comments?
On Thu, Dec 14, 2017 at 5:06 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Thu, Dec 7, 2017 at 6:25 PM, H.J. Lu <hjl.tools@gmail.com> wrote: >> On Thu, Dec 7, 2017 at 11:35 AM, H.J. Lu <hjl.tools@gmail.com> wrote: >>> On Thu, Dec 7, 2017 at 11:25 AM, Florian Weimer <fweimer@redhat.com> wrote: >>>> On 12/07/2017 08:19 PM, H.J. Lu wrote: >>>>> >>>>> On Thu, Dec 7, 2017 at 11:14 AM, Florian Weimer <fweimer@redhat.com> >>>>> wrote: >>>>>> >>>>>> On 12/07/2017 08:12 PM, H.J. Lu wrote: >>>>>>>> >>>>>>>> >>>>>>>> Sorry, what exactly is stored on the shadow stack? I assumed it was >>>>>>>> for >>>>>>>> verification of the targets of ret instructions. >>>>>>>> >>>>>>>> In this case, don't need to unwind the shadow stack (or preserve its >>>>>>>> contents) because there are no returns from existing stack frames once >>>>>>>> cancellation has started. >>>>>>>> >>>>>>> Shadow stack is the similar to normal call stack without local >>>>>>> variables. >>>>>>> SHSTK checks the return address of EACH "RET" instruction against >>>>>>> shadow stack. >>>>>> >>>>>> >>>>>> >>>>>> Then the shadow stack contents at the time of cancellation does not >>>>>> matter >>>>>> because all future RET instructions on this thread will match CALLs which >>>>>> happened *after* cancellation. (In other words, I still think I'm right >>>>>> about this.) >>>>>> >>>>> >>>>> We are updating setjmp/lonjmp to save and restore shadow stack pointer: >>>>> >>>>> >>>>> https://sourceware.org/git/?p=glibc.git;a=commit;h=ac195a2d554e3fb577e44474faf3ed7f4521de9f >>>> >>>> >>>> Please try to understand what I wrote. You don't need the restore during >>>> cancellation handling: >>>> >>>> if (__glibc_unlikely (__not_first_call)) \ >>>> { \ >>>> __cancel_routine (__cancel_arg); \ >>>> __pthread_unwind_next (&__cancel_buf); \ >>>> /* NOTREACHED */ \ >>>> } \ >>>> >>> >>> Who will sync shadow stack with call stack? >>> >> >> Here is call stack during stack unwind: >> >> (gdb) bt >> #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 >> #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800da0, >> val=val@entry=1) at longjmp.c:39 >> #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, >> actions=<optimized out>, exc_class=<optimized out>, >> exc_obj=<optimized out>, context=<optimized out>, >> stop_parameter=0x7ffff7800da0) at unwind.c:94 >> #3 0x00007ffff6df9b6e in _Unwind_ForcedUnwind_Phase2 ( >> exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff78005d0, >> frames_p=frames_p@entry=0x7ffff78004d8) >> at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 >> #4 0x00007ffff6dfa1c0 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, >> stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, >> stop_argument=<optimized out>) >> at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 >> #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) >> at unwind.c:121 >> #6 0x00007ffff7bbe46a in __do_cancel () at ./pthreadP.h:297 >> #7 sigcancel_handler (sig=<optimized out>, si=0x7ffff7800870, >> ctx=<optimized out>) at nptl-init.c:216 >> #8 <signal handler called> >> #9 0x00007ffff7bc8f04 in __libc_read (fd=fd@entry=3, >> buf=buf@entry=0x7ffff7800d30, nbytes=nbytes@entry=100) >> ---Type <return> to continue, or q <return> to quit--- >> sv/linux/read.c:27 >> #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 >> #11 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) >> at pthread_create.c:463 >> #12 0x00007ffff78f5f73 in clone () >> at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 >> (gdb) f 10 >> #10 0x00000000004064a0 in tf_read (arg=<optimized out>) at tst-cancel4.c:102 >> 102 s = read (fd, buf, sizeof (buf)); >> (gdb) list >> 97 >> 98 ssize_t s; >> 99 pthread_cleanup_push (cl, NULL); >> 100 >> 101 char buf[100]; >> 102 s = read (fd, buf, sizeof (buf)); >> 103 >> 104 pthread_cleanup_pop (0); >> 105 >> 106 FAIL_EXIT1 ("read returns with %zd", s); >> (gdb) >> >> # define pthread_cleanup_push(routine, arg) \ >> do { \ >> __pthread_unwind_buf_t __cancel_buf; \ >> void (*__cancel_routine) (void *) = (routine); \ >> void *__cancel_arg = (arg); \ >> int __not_first_call = __sigsetjmp ((struct __jmp_buf_tag *) (void *) \ >> __cancel_buf.__cancel_jmp_buf, 0); \ >> if (__glibc_unlikely (__not_first_call)) \ >> { \ >> __cancel_routine (__cancel_arg); \ >> __pthread_unwind_next (&__cancel_buf); \ >> /* NOTREACHED */ \ >> } >> >> To unwind shadow stack, we need to save shadow stack pointer in >> __cancel_buf. This updated patch adds bits/types/__cancel_jmp_buf_tag.h >> to define struct __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask >> to __cancel_jmp_buf. We will check if shadow stack is enabled before saving >> and restoring shadow stack pointer so that it works with the old smaller >> cancel_jmp_buf which doesn't have space for shadow stack pointer. >> > > Any comments? > I will check it in next Monday.
On 12/08/2017 03:25 AM, H.J. Lu wrote: > Here is call stack during stack unwind: > > (gdb) bt (snip) > To unwind shadow stack, we need to save shadow stack pointer in > __cancel_buf. This updated patch adds bits/types/__cancel_jmp_buf_tag.h > to define struct __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask > to __cancel_jmp_buf. We will check if shadow stack is enabled before saving > and restoring shadow stack pointer so that it works with the old smaller > cancel_jmp_buf which doesn't have space for shadow stack pointer. I still don't understand why you think you have to reset the shadow stack. I used this test program: #include <err.h> #include <errno.h> #include <pthread.h> #include <stdbool.h> #include <stdio.h> #include <unistd.h> __attribute__ ((noinline, noclone, weak)) void handler1 (void *closure) { printf ("handler1 called\n"); } __attribute__ ((noinline, noclone, weak)) void handler2 (void *closure) { printf ("handler2 called\n"); } __attribute__ ((noinline, noclone, weak)) void pausefunc (void) { while (true) pause (); } __attribute__ ((noinline, noclone, weak)) void handlerfunc (void) { pthread_cleanup_push (handler2, NULL); pausefunc (); pthread_cleanup_pop (1); } __attribute__ ((noinline, noclone, weak)) void * threadfunc (void *closure) { pthread_cleanup_push (handler1, NULL); handlerfunc (); pthread_cleanup_pop (0); return NULL; } int main (void) { pthread_t thr; int ret = pthread_create (&thr, NULL, threadfunc, NULL); if (ret != 0) { errno = ret; err (1, "pthread_create"); } ret = pthread_cancel (thr); if (ret != 0) { errno = ret; err (1, "pthread_cancel"); } void *result; ret = pthread_join (thr, &result); if (ret != 0) { errno = ret; err (1, "pthread_join"); } if (result != PTHREAD_CANCELED) errx (1, "pthread_join did not return PTHREAD_CANCEL, but %p", result); return 0; } See the attached GDB log. As you can see, I set breakpoints on all pre-existing RET instructions on the call stack (which would be protected by the shadow stack with CET). None of the RET instructions actually execute, ergo we do not have to restore the shadow stack. Thanks, Florian gdb ./simple-cancel GNU gdb (GDB) Fedora 8.0.1-33.fc26 Copyright (C) 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from ./simple-cancel...done. (gdb) r Starting program: /home/fweimer/tmp/simple-cancel [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". [New Thread 0x7ffff77e1700 (LWP 12256)] handler2 called handler1 called [Thread 0x7ffff77e1700 (LWP 12256) exited] [Inferior 1 (process 12252) exited normally] Missing separate debuginfos, use: dnf debuginfo-install libgcc-7.2.1-2.fc26.x86_64 (gdb) break sigcancel_handler Breakpoint 1 at 0x7ffff7bbc960: file nptl-init.c, line 187. (gdb) r Starting program: /home/fweimer/tmp/simple-cancel [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". [New Thread 0x7ffff77e1700 (LWP 12258)] [Switching to Thread 0x7ffff77e1700 (LWP 12258)] Thread 2 "simple-cancel" hit Breakpoint 1, sigcancel_handler (sig=32, si=0x7ffff77e09b0, ctx=0x7ffff77e0880) at nptl-init.c:187 187 if (sig != SIGCANCEL (gdb) bt #0 sigcancel_handler (sig=32, si=0x7ffff77e09b0, ctx=0x7ffff77e0880) at nptl-init.c:187 #1 <signal handler called> #2 0x00007ffff7bc89ed in pause () at ../sysdeps/unix/syscall-template.S:84 #3 0x000000000040098d in pausefunc () at simple-cancel.c:27 #4 0x00000000004009af in handlerfunc () at simple-cancel.c:35 #5 0x00000000004009ff in threadfunc (closure=<optimized out>) at simple-cancel.c:45 #6 0x00007ffff7bbe36d in start_thread (arg=0x7ffff77e1700) at pthread_create.c:456 #7 0x00007ffff78f2e1f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 (gdb) up #1 <signal handler called> (gdb) down #0 sigcancel_handler (sig=32, si=0x7ffff77e09b0, ctx=0x7ffff77e0880) at nptl-init.c:187 187 if (sig != SIGCANCEL (gdb) disas Dump of assembler code for function sigcancel_handler: => 0x00007ffff7bbc960 <+0>: cmp $0x20,%edi 0x00007ffff7bbc963 <+3>: je 0x7ffff7bbc970 <sigcancel_handler+16> 0x00007ffff7bbc965 <+5>: repz retq 0x00007ffff7bbc967 <+7>: nopw 0x0(%rax,%rax,1) 0x00007ffff7bbc970 <+16>: push %rbp 0x00007ffff7bbc971 <+17>: push %rbx 0x00007ffff7bbc972 <+18>: mov %rsi,%rbx 0x00007ffff7bbc975 <+21>: sub $0x8,%rsp 0x00007ffff7bbc979 <+25>: mov 0x10(%rsi),%ebp 0x00007ffff7bbc97c <+28>: callq 0x7ffff7bbc670 0x00007ffff7bbc981 <+33>: cmp %eax,%ebp 0x00007ffff7bbc983 <+35>: je 0x7ffff7bbc990 <sigcancel_handler+48> 0x00007ffff7bbc985 <+37>: add $0x8,%rsp 0x00007ffff7bbc989 <+41>: pop %rbx 0x00007ffff7bbc98a <+42>: pop %rbp 0x00007ffff7bbc98b <+43>: retq 0x00007ffff7bbc98c <+44>: nopl 0x0(%rax) 0x00007ffff7bbc990 <+48>: cmpl $0xfffffffa,0x8(%rbx) 0x00007ffff7bbc994 <+52>: jne 0x7ffff7bbc985 <sigcancel_handler+37> 0x00007ffff7bbc996 <+54>: mov %fs:0x308,%edx 0x00007ffff7bbc99e <+62>: jmp 0x7ffff7bbc9b7 <sigcancel_handler+87> 0x00007ffff7bbc9a0 <+64>: test $0x10,%dl 0x00007ffff7bbc9a3 <+67>: jne 0x7ffff7bbc985 <sigcancel_handler+37> 0x00007ffff7bbc9a5 <+69>: mov %edx,%eax 0x00007ffff7bbc9a7 <+71>: lock cmpxchg %ecx,%fs:0x308 0x00007ffff7bbc9b1 <+81>: cmp %eax,%edx 0x00007ffff7bbc9b3 <+83>: je 0x7ffff7bbc9c8 <sigcancel_handler+104> 0x00007ffff7bbc9b5 <+85>: mov %eax,%edx 0x00007ffff7bbc9b7 <+87>: mov %edx,%ecx 0x00007ffff7bbc9b9 <+89>: or $0xc,%ecx 0x00007ffff7bbc9bc <+92>: cmp %ecx,%edx 0x00007ffff7bbc9be <+94>: jne 0x7ffff7bbc9a0 <sigcancel_handler+64> 0x00007ffff7bbc9c0 <+96>: jmp 0x7ffff7bbc985 <sigcancel_handler+37> 0x00007ffff7bbc9c2 <+98>: nopw 0x0(%rax,%rax,1) 0x00007ffff7bbc9c8 <+104>: movq $0xffffffffffffffff,%fs:0x630 0x00007ffff7bbc9d5 <+117>: and $0x2,%edx 0x00007ffff7bbc9d8 <+120>: je 0x7ffff7bbc985 <sigcancel_handler+37> 0x00007ffff7bbc9da <+122>: lock orl $0x10,%fs:0x308 0x00007ffff7bbc9e4 <+132>: mov %fs:0x300,%rdi 0x00007ffff7bbc9ed <+141>: callq 0x7ffff7bc7e60 <__GI___pthread_unwind> End of assembler dump. (gdb) break *0x00007ffff7bbc965 Breakpoint 2 at 0x7ffff7bbc965: file nptl-init.c, line 187. (gdb) break *0x00007ffff7bbc98b Breakpoint 3 at 0x7ffff7bbc98b: file nptl-init.c, line 223. (gdb) up #1 <signal handler called> (gdb) disas Dump of assembler code for function __restore_rt: => 0x00007ffff7bc93b0 <+0>: mov $0xf,%rax 0x00007ffff7bc93b7 <+7>: syscall 0x00007ffff7bc93b9 <+9>: nopl 0x0(%rax) End of assembler dump. (gdb) up #2 0x00007ffff7bc89ed in pause () at ../sysdeps/unix/syscall-template.S:84 84 T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS) (gdb) disas Dump of assembler code for function pause: 0x00007ffff7bc89c0 <+0>: cmpl $0x0,0x20c7b9(%rip) # 0x7ffff7dd5180 <__pthread_multiple_threads> 0x00007ffff7bc89c7 <+7>: jne 0x7ffff7bc89d9 <pause+25> 0x00007ffff7bc89c9 <+0>: mov $0x22,%eax 0x00007ffff7bc89ce <+5>: syscall 0x00007ffff7bc89d0 <+7>: cmp $0xfffffffffffff001,%rax 0x00007ffff7bc89d6 <+13>: jae 0x7ffff7bc8a09 <pause+73> 0x00007ffff7bc89d8 <+15>: retq 0x00007ffff7bc89d9 <+25>: sub $0x8,%rsp 0x00007ffff7bc89dd <+29>: callq 0x7ffff7bc7f90 <__pthread_enable_asynccancel> 0x00007ffff7bc89e2 <+34>: mov %rax,(%rsp) 0x00007ffff7bc89e6 <+38>: mov $0x22,%eax 0x00007ffff7bc89eb <+43>: syscall => 0x00007ffff7bc89ed <+45>: mov (%rsp),%rdi 0x00007ffff7bc89f1 <+49>: mov %rax,%rdx 0x00007ffff7bc89f4 <+52>: callq 0x7ffff7bc7ff0 <__pthread_disable_asynccancel> 0x00007ffff7bc89f9 <+57>: mov %rdx,%rax 0x00007ffff7bc89fc <+60>: add $0x8,%rsp 0x00007ffff7bc8a00 <+64>: cmp $0xfffffffffffff001,%rax 0x00007ffff7bc8a06 <+70>: jae 0x7ffff7bc8a09 <pause+73> 0x00007ffff7bc8a08 <+72>: retq 0x00007ffff7bc8a09 <+73>: mov 0x208370(%rip),%rcx # 0x7ffff7dd0d80 0x00007ffff7bc8a10 <+80>: neg %eax 0x00007ffff7bc8a12 <+82>: mov %eax,%fs:(%rcx) 0x00007ffff7bc8a15 <+85>: or $0xffffffffffffffff,%rax 0x00007ffff7bc8a19 <+89>: retq End of assembler dump. (gdb) break *0x00007ffff7bc89d8 Breakpoint 4 at 0x7ffff7bc89d8: file ../sysdeps/unix/syscall-template.S, line 84. (gdb) break *0x00007ffff7bc8a08 Breakpoint 5 at 0x7ffff7bc8a08: file ../sysdeps/unix/syscall-template.S, line 85. (gdb) break *0x00007ffff7bc8a19 Breakpoint 6 at 0x7ffff7bc8a19: file ../sysdeps/unix/syscall-template.S, line 86. (gdb) up #3 0x000000000040098d in pausefunc () at simple-cancel.c:27 27 pause (); (gdb) disas Dump of assembler code for function pausefunc: 0x0000000000400980 <+0>: sub $0x8,%rsp 0x0000000000400984 <+4>: nopl 0x0(%rax) 0x0000000000400988 <+8>: callq 0x400780 <pause@plt> => 0x000000000040098d <+13>: jmp 0x400988 <pausefunc+8> End of assembler dump. (gdb) up #4 0x00000000004009af in handlerfunc () at simple-cancel.c:35 35 pausefunc (); (gdb) disas Dump of assembler code for function handlerfunc: 0x0000000000400990 <+0>: sub $0x78,%rsp 0x0000000000400994 <+4>: xor %esi,%esi 0x0000000000400996 <+6>: mov %rsp,%rdi 0x0000000000400999 <+9>: callq 0x4007c0 <__sigsetjmp@plt> 0x000000000040099e <+14>: test %eax,%eax 0x00000000004009a0 <+16>: jne 0x4009c8 <handlerfunc+56> 0x00000000004009a2 <+18>: mov %rsp,%rdi 0x00000000004009a5 <+21>: callq 0x400750 <__pthread_register_cancel@plt> 0x00000000004009aa <+26>: callq 0x400980 <pausefunc> => 0x00000000004009af <+31>: mov %rsp,%rdi 0x00000000004009b2 <+34>: callq 0x400770 <__pthread_unregister_cancel@plt> 0x00000000004009b7 <+39>: xor %edi,%edi 0x00000000004009b9 <+41>: callq 0x400970 <handler2> 0x00000000004009be <+46>: add $0x78,%rsp 0x00000000004009c2 <+50>: retq 0x00000000004009c3 <+51>: nopl 0x0(%rax,%rax,1) 0x00000000004009c8 <+56>: xor %edi,%edi 0x00000000004009ca <+58>: callq 0x400970 <handler2> 0x00000000004009cf <+63>: mov %rsp,%rdi 0x00000000004009d2 <+66>: callq 0x4007b0 <__pthread_unwind_next@plt> End of assembler dump. (gdb) break *0x00000000004009c2 Breakpoint 7 at 0x4009c2: file simple-cancel.c, line 37. (gdb) up #5 0x00000000004009ff in threadfunc (closure=<optimized out>) at simple-cancel.c:45 45 handlerfunc (); (gdb) disas Dump of assembler code for function threadfunc: 0x00000000004009e0 <+0>: sub $0x78,%rsp 0x00000000004009e4 <+4>: xor %esi,%esi 0x00000000004009e6 <+6>: mov %rsp,%rdi 0x00000000004009e9 <+9>: callq 0x4007c0 <__sigsetjmp@plt> 0x00000000004009ee <+14>: test %eax,%eax 0x00000000004009f0 <+16>: jne 0x400a10 <threadfunc+48> 0x00000000004009f2 <+18>: mov %rsp,%rdi 0x00000000004009f5 <+21>: callq 0x400750 <__pthread_register_cancel@plt> 0x00000000004009fa <+26>: callq 0x400990 <handlerfunc> => 0x00000000004009ff <+31>: mov %rsp,%rdi 0x0000000000400a02 <+34>: callq 0x400770 <__pthread_unregister_cancel@plt> 0x0000000000400a07 <+39>: xor %eax,%eax 0x0000000000400a09 <+41>: add $0x78,%rsp 0x0000000000400a0d <+45>: retq 0x0000000000400a0e <+46>: xchg %ax,%ax 0x0000000000400a10 <+48>: xor %edi,%edi 0x0000000000400a12 <+50>: callq 0x400960 <handler1> 0x0000000000400a17 <+55>: mov %rsp,%rdi 0x0000000000400a1a <+58>: callq 0x4007b0 <__pthread_unwind_next@plt> End of assembler dump. (gdb) break *0x0000000000400a0d Breakpoint 8 at 0x400a0d: file simple-cancel.c, line 48. (gdb) up #6 0x00007ffff7bbe36d in start_thread (arg=0x7ffff77e1700) at pthread_create.c:456 456 THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd)); (gdb) disas Dump of assembler code for function start_thread: 0x00007ffff7bbe290 <+0>: push %rbx 0x00007ffff7bbe291 <+1>: mov %rdi,%rbx 0x00007ffff7bbe294 <+4>: sub $0xa0,%rsp 0x00007ffff7bbe29b <+11>: mov %rdi,0x8(%rsp) 0x00007ffff7bbe2a0 <+16>: mov %fs:0x28,%rax 0x00007ffff7bbe2a9 <+25>: mov %rax,0x98(%rsp) 0x00007ffff7bbe2b1 <+33>: xor %eax,%eax 0x00007ffff7bbe2b3 <+35>: rdtsc 0x00007ffff7bbe2b5 <+37>: shl $0x20,%rdx 0x00007ffff7bbe2b9 <+41>: mov %eax,%eax 0x00007ffff7bbe2bb <+43>: or %rax,%rdx 0x00007ffff7bbe2be <+46>: mov %rdx,%fs:0x620 0x00007ffff7bbe2c7 <+55>: mov 0x212ada(%rip),%rax # 0x7ffff7dd0da8 0x00007ffff7bbe2ce <+62>: lea 0x6b8(%rdi),%rdx 0x00007ffff7bbe2d5 <+69>: mov %rdx,%fs:(%rax) 0x00007ffff7bbe2d9 <+73>: callq 0x7ffff7bbc780 0x00007ffff7bbe2de <+78>: xor %eax,%eax 0x00007ffff7bbe2e0 <+80>: xchg %eax,0x61c(%rbx) 0x00007ffff7bbe2e6 <+86>: cmp $0xfffffffe,%eax 0x00007ffff7bbe2e9 <+89>: je 0x7ffff7bbe46b <start_thread+475> 0x00007ffff7bbe2ef <+95>: mov 0x8(%rsp),%rbx 0x00007ffff7bbe2f4 <+100>: mov $0x18,%esi 0x00007ffff7bbe2f9 <+105>: mov $0x111,%eax 0x00007ffff7bbe2fe <+110>: lea 0x2e0(%rbx),%rdi 0x00007ffff7bbe305 <+117>: syscall 0x00007ffff7bbe307 <+119>: testb $0x4,0x614(%rbx) 0x00007ffff7bbe30e <+126>: jne 0x7ffff7bbe432 <start_thread+418> 0x00007ffff7bbe314 <+132>: lea 0x10(%rsp),%rdi 0x00007ffff7bbe319 <+137>: movq $0x0,0x58(%rsp) 0x00007ffff7bbe322 <+146>: movq $0x0,0x60(%rsp) 0x00007ffff7bbe32b <+155>: callq 0x7ffff7bbc6e0 0x00007ffff7bbe330 <+160>: test %eax,%eax 0x00007ffff7bbe332 <+162>: mov %eax,%ebx 0x00007ffff7bbe334 <+164>: jne 0x7ffff7bbe376 <start_thread+230> 0x00007ffff7bbe336 <+166>: lea 0x10(%rsp),%rax 0x00007ffff7bbe33b <+171>: mov %rax,%fs:0x300 0x00007ffff7bbe344 <+180>: mov 0x8(%rsp),%rax 0x00007ffff7bbe349 <+185>: cmpb $0x0,0x613(%rax) 0x00007ffff7bbe350 <+192>: jne 0x7ffff7bbe4d4 <start_thread+580> 0x00007ffff7bbe356 <+198>: mov 0x8(%rsp),%rax 0x00007ffff7bbe35b <+203>: nop 0x00007ffff7bbe35c <+204>: mov %fs:0x648,%rdi 0x00007ffff7bbe365 <+213>: callq *%fs:0x640 => 0x00007ffff7bbe36d <+221>: mov %rax,%fs:0x630 0x00007ffff7bbe376 <+230>: callq 0x7ffff7bbc6d0 0x00007ffff7bbe37b <+235>: xor %eax,%eax 0x00007ffff7bbe37d <+237>: mov %fs:0x610,%al 0x00007ffff7bbe385 <+245>: test %al,%al 0x00007ffff7bbe387 <+247>: jne 0x7ffff7bbe428 <start_thread+408> 0x00007ffff7bbe38d <+253>: callq 0x7ffff7bbc710 0x00007ffff7bbe392 <+258>: lock decl 0x212c87(%rip) # 0x7ffff7dd1020 <__nptl_nthreads> 0x00007ffff7bbe399 <+265>: sete %al 0x00007ffff7bbe39c <+268>: test %al,%al 0x00007ffff7bbe39e <+270>: jne 0x7ffff7bbe5cd <start_thread+829> 0x00007ffff7bbe3a4 <+276>: mov 0x8(%rsp),%rax 0x00007ffff7bbe3a9 <+281>: cmpb $0x0,0x611(%rax) 0x00007ffff7bbe3b0 <+288>: jne 0x7ffff7bbe59f <start_thread+783> 0x00007ffff7bbe3b6 <+294>: mov 0x8(%rsp),%rbx 0x00007ffff7bbe3bb <+299>: lock orl $0x10,0x308(%rbx) 0x00007ffff7bbe3c3 <+307>: callq 0x7ffff7bbc758 0x00007ffff7bbe3c8 <+312>: mov 0x690(%rbx),%rdi 0x00007ffff7bbe3cf <+319>: neg %eax 0x00007ffff7bbe3d1 <+321>: mov %rsp,%rdx 0x00007ffff7bbe3d4 <+324>: cltq 0x00007ffff7bbe3d6 <+326>: sub %rdi,%rdx 0x00007ffff7bbe3d9 <+329>: and %rdx,%rax 0x00007ffff7bbe3dc <+332>: cmp %rax,0x698(%rbx) 0x00007ffff7bbe3e3 <+339>: jbe 0x7ffff7bbe4b5 <start_thread+549> 0x00007ffff7bbe3e9 <+345>: cmp $0x4000,%rax 0x00007ffff7bbe3ef <+351>: ja 0x7ffff7bbe617 <start_thread+903> 0x00007ffff7bbe3f5 <+357>: mov 0x8(%rsp),%rax 0x00007ffff7bbe3fa <+362>: cmp %rax,0x628(%rax) 0x00007ffff7bbe401 <+369>: je 0x7ffff7bbe608 <start_thread+888> 0x00007ffff7bbe407 <+375>: mov 0x8(%rsp),%rax 0x00007ffff7bbe40c <+380>: testb $0x40,0x308(%rax) 0x00007ffff7bbe413 <+387>: jne 0x7ffff7bbe53a <start_thread+682> 0x00007ffff7bbe419 <+393>: mov $0x3c,%edx 0x00007ffff7bbe41e <+398>: xchg %ax,%ax 0x00007ffff7bbe420 <+400>: xor %edi,%edi 0x00007ffff7bbe422 <+402>: mov %edx,%eax 0x00007ffff7bbe424 <+404>: syscall 0x00007ffff7bbe426 <+406>: jmp 0x7ffff7bbe420 <start_thread+400> 0x00007ffff7bbe428 <+408>: callq 0x7ffff7bbd020 <__nptl_deallocate_tsd> 0x00007ffff7bbe42d <+413>: jmpq 0x7ffff7bbe38d <start_thread+253> 0x00007ffff7bbe432 <+418>: lea 0x18(%rsp),%rdx 0x00007ffff7bbe437 <+423>: xor %eax,%eax 0x00007ffff7bbe439 <+425>: mov $0x1e,%ecx 0x00007ffff7bbe43e <+430>: lea 0x10(%rsp),%rsi 0x00007ffff7bbe443 <+435>: mov $0x8,%r10d 0x00007ffff7bbe449 <+441>: mov %rdx,%rdi 0x00007ffff7bbe44c <+444>: xor %edx,%edx 0x00007ffff7bbe44e <+446>: rep stos %eax,%es:(%rdi) 0x00007ffff7bbe450 <+448>: mov $0x80000000,%eax 0x00007ffff7bbe455 <+453>: mov $0x1,%edi 0x00007ffff7bbe45a <+458>: mov %rax,0x10(%rsp) 0x00007ffff7bbe45f <+463>: mov $0xe,%eax 0x00007ffff7bbe464 <+468>: syscall 0x00007ffff7bbe466 <+470>: jmpq 0x7ffff7bbe314 <start_thread+132> 0x00007ffff7bbe46b <+475>: mov 0x8(%rsp),%rax 0x00007ffff7bbe470 <+480>: xor %r10d,%r10d 0x00007ffff7bbe473 <+483>: mov $0x1,%edx 0x00007ffff7bbe478 <+488>: mov $0x81,%esi 0x00007ffff7bbe47d <+493>: lea 0x61c(%rax),%rdi 0x00007ffff7bbe484 <+500>: mov $0xca,%eax 0x00007ffff7bbe489 <+505>: syscall 0x00007ffff7bbe48b <+507>: cmp $0xfffffffffffff000,%rax 0x00007ffff7bbe491 <+513>: jbe 0x7ffff7bbe2ef <start_thread+95> 0x00007ffff7bbe497 <+519>: cmp $0xffffffea,%eax 0x00007ffff7bbe49a <+522>: je 0x7ffff7bbe2ef <start_thread+95> 0x00007ffff7bbe4a0 <+528>: cmp $0xfffffff2,%eax 0x00007ffff7bbe4a3 <+531>: je 0x7ffff7bbe2ef <start_thread+95> 0x00007ffff7bbe4a9 <+537>: lea 0xc770(%rip),%rdi # 0x7ffff7bcac20 0x00007ffff7bbe4b0 <+544>: callq 0x7ffff7bbc638 0x00007ffff7bbe4b5 <+549>: lea 0xc914(%rip),%rcx # 0x7ffff7bcadd0 <__PRETTY_FUNCTION__.11908> 0x00007ffff7bbe4bc <+556>: lea 0xc962(%rip),%rsi # 0x7ffff7bcae25 0x00007ffff7bbe4c3 <+563>: lea 0xc8b6(%rip),%rdi # 0x7ffff7bcad80 0x00007ffff7bbe4ca <+570>: mov $0x22a,%edx 0x00007ffff7bbe4cf <+575>: callq 0x7ffff7bbc6a0 0x00007ffff7bbe4d4 <+580>: callq 0x7ffff7bc7f90 <__pthread_enable_asynccancel> 0x00007ffff7bbe4d9 <+585>: mov $0x1,%esi 0x00007ffff7bbe4de <+590>: mov %eax,%edx 0x00007ffff7bbe4e0 <+592>: mov %ebx,%eax 0x00007ffff7bbe4e2 <+594>: mov 0x8(%rsp),%rbx 0x00007ffff7bbe4e7 <+599>: lock cmpxchg %esi,0x618(%rbx) 0x00007ffff7bbe4ef <+607>: je 0x7ffff7bbe50b <start_thread+635> 0x00007ffff7bbe4f1 <+609>: lea 0x618(%rbx),%rdi 0x00007ffff7bbe4f8 <+616>: sub $0x80,%rsp 0x00007ffff7bbe4ff <+623>: callq 0x7ffff7bc8050 <__lll_lock_wait_private> 0x00007ffff7bbe504 <+628>: add $0x80,%rsp 0x00007ffff7bbe50b <+635>: lock decl 0x618(%rbx) 0x00007ffff7bbe512 <+642>: je 0x7ffff7bbe52e <start_thread+670> 0x00007ffff7bbe514 <+644>: lea 0x618(%rbx),%rdi 0x00007ffff7bbe51b <+651>: sub $0x80,%rsp 0x00007ffff7bbe522 <+658>: callq 0x7ffff7bc8100 <__lll_unlock_wake_private> 0x00007ffff7bbe527 <+663>: add $0x80,%rsp 0x00007ffff7bbe52e <+670>: mov %edx,%edi 0x00007ffff7bbe530 <+672>: callq 0x7ffff7bc7ff0 <__pthread_disable_asynccancel> 0x00007ffff7bbe535 <+677>: jmpq 0x7ffff7bbe356 <start_thread+198> 0x00007ffff7bbe53a <+682>: lea 0x61c(%rax),%rbx 0x00007ffff7bbe541 <+689>: mov $0xca,%r9d 0x00007ffff7bbe547 <+695>: mov $0x1,%r8d 0x00007ffff7bbe54d <+701>: jmp 0x7ffff7bbe561 <start_thread+721> 0x00007ffff7bbe54f <+703>: mov 0x8(%rsp),%rax 0x00007ffff7bbe554 <+708>: testb $0x40,0x308(%rax) 0x00007ffff7bbe55b <+715>: je 0x7ffff7bbe62d <start_thread+925> 0x00007ffff7bbe561 <+721>: xor %r10d,%r10d 0x00007ffff7bbe564 <+724>: xor %edx,%edx 0x00007ffff7bbe566 <+726>: mov $0x80,%esi 0x00007ffff7bbe56b <+731>: mov %rbx,%rdi 0x00007ffff7bbe56e <+734>: mov %r9d,%eax 0x00007ffff7bbe571 <+737>: syscall 0x00007ffff7bbe573 <+739>: cmp $0xfffffffffffff000,%rax 0x00007ffff7bbe579 <+745>: jbe 0x7ffff7bbe54f <start_thread+703> 0x00007ffff7bbe57b <+747>: add $0xb,%eax 0x00007ffff7bbe57e <+750>: cmp $0xb,%eax 0x00007ffff7bbe581 <+753>: ja 0x7ffff7bbe4a9 <start_thread+537> 0x00007ffff7bbe587 <+759>: mov %eax,%ecx 0x00007ffff7bbe589 <+761>: mov %r8,%rsi 0x00007ffff7bbe58c <+764>: shl %cl,%rsi 0x00007ffff7bbe58f <+767>: mov %rsi,%rax 0x00007ffff7bbe592 <+770>: test $0x881,%eax 0x00007ffff7bbe597 <+775>: je 0x7ffff7bbe4a9 <start_thread+537> 0x00007ffff7bbe59d <+781>: jmp 0x7ffff7bbe54f <start_thread+703> 0x00007ffff7bbe59f <+783>: mov 0x8(%rsp),%rcx 0x00007ffff7bbe5a4 <+788>: mov 0x216b36(%rip),%eax # 0x7ffff7dd50e0 <__nptl_threads_events> 0x00007ffff7bbe5aa <+794>: or 0x650(%rcx),%eax 0x00007ffff7bbe5b0 <+800>: test $0x1,%ah 0x00007ffff7bbe5b3 <+803>: je 0x7ffff7bbe3b6 <start_thread+294> 0x00007ffff7bbe5b9 <+809>: cmpq $0x0,0x668(%rcx) 0x00007ffff7bbe5c1 <+817>: je 0x7ffff7bbe5d4 <start_thread+836> 0x00007ffff7bbe5c3 <+819>: callq 0x7ffff7bbced0 <__nptl_death_event> 0x00007ffff7bbe5c8 <+824>: jmpq 0x7ffff7bbe3b6 <start_thread+294> 0x00007ffff7bbe5cd <+829>: xor %edi,%edi 0x00007ffff7bbe5cf <+831>: callq 0x7ffff7bbc810 0x00007ffff7bbe5d4 <+836>: mov %rcx,%rax 0x00007ffff7bbe5d7 <+839>: movl $0x9,0x658(%rcx) 0x00007ffff7bbe5e1 <+849>: mov %rcx,0x660(%rax) 0x00007ffff7bbe5e8 <+856>: mov 0x216ae9(%rip),%rax # 0x7ffff7dd50d8 <__nptl_last_event> 0x00007ffff7bbe5ef <+863>: mov 0x8(%rsp),%rsi 0x00007ffff7bbe5f4 <+868>: mov %rax,0x668(%rsi) 0x00007ffff7bbe5fb <+875>: lock cmpxchg %rsi,0x216ad4(%rip) # 0x7ffff7dd50d8 <__nptl_last_event> 0x00007ffff7bbe604 <+884>: je 0x7ffff7bbe5c3 <start_thread+819> 0x00007ffff7bbe606 <+886>: jmp 0x7ffff7bbe5e8 <start_thread+856> 0x00007ffff7bbe608 <+888>: mov 0x8(%rsp),%rdi 0x00007ffff7bbe60d <+893>: callq 0x7ffff7bbe0a0 <__free_tcb> 0x00007ffff7bbe612 <+898>: jmpq 0x7ffff7bbe419 <start_thread+393> 0x00007ffff7bbe617 <+903>: lea -0x4000(%rax),%rsi 0x00007ffff7bbe61e <+910>: mov $0x4,%edx 0x00007ffff7bbe623 <+915>: callq 0x7ffff7bbc7b8 0x00007ffff7bbe628 <+920>: jmpq 0x7ffff7bbe3f5 <start_thread+357> 0x00007ffff7bbe62d <+925>: movl $0x0,0x61c(%rax) 0x00007ffff7bbe637 <+935>: jmpq 0x7ffff7bbe419 <start_thread+393> End of assembler dump. (gdb) up #7 0x00007ffff78f2e1f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 97 call *%rax (gdb) disas Dump of assembler code for function clone: 0x00007ffff78f2de0 <+0>: mov $0xffffffffffffffea,%rax 0x00007ffff78f2de7 <+7>: test %rdi,%rdi 0x00007ffff78f2dea <+10>: je 0x7ffff78f2e27 <clone+71> 0x00007ffff78f2dec <+12>: test %rsi,%rsi 0x00007ffff78f2def <+15>: je 0x7ffff78f2e27 <clone+71> 0x00007ffff78f2df1 <+17>: sub $0x10,%rsi 0x00007ffff78f2df5 <+21>: mov %rcx,0x8(%rsi) 0x00007ffff78f2df9 <+25>: mov %rdi,(%rsi) 0x00007ffff78f2dfc <+28>: mov %rdx,%rdi 0x00007ffff78f2dff <+31>: mov %r8,%rdx 0x00007ffff78f2e02 <+34>: mov %r9,%r8 0x00007ffff78f2e05 <+37>: mov 0x8(%rsp),%r10 0x00007ffff78f2e0a <+42>: mov $0x38,%eax 0x00007ffff78f2e0f <+47>: syscall 0x00007ffff78f2e11 <+49>: test %rax,%rax 0x00007ffff78f2e14 <+52>: jl 0x7ffff78f2e27 <clone+71> 0x00007ffff78f2e16 <+54>: je 0x7ffff78f2e19 <clone+57> 0x00007ffff78f2e18 <+56>: retq 0x00007ffff78f2e19 <+57>: xor %ebp,%ebp 0x00007ffff78f2e1b <+59>: pop %rax 0x00007ffff78f2e1c <+60>: pop %rdi 0x00007ffff78f2e1d <+61>: callq *%rax => 0x00007ffff78f2e1f <+63>: mov %rax,%rdi 0x00007ffff78f2e22 <+66>: callq 0x7ffff78b6fc0 <__GI__exit> 0x00007ffff78f2e27 <+71>: mov 0x2be03a(%rip),%rcx # 0x7ffff7bb0e68 0x00007ffff78f2e2e <+78>: neg %eax 0x00007ffff78f2e30 <+80>: mov %eax,%fs:(%rcx) 0x00007ffff78f2e33 <+83>: or $0xffffffffffffffff,%rax 0x00007ffff78f2e37 <+87>: retq End of assembler dump. (gdb) break *0x00007ffff78f2e37 Breakpoint 9 at 0x7ffff78f2e37: file ../sysdeps/unix/sysv/linux/x86_64/clone.S, line 104. (gdb) up Initial frame selected; you cannot go up. (gdb) c Continuing. handler2 called handler1 called [Thread 0x7ffff77e1700 (LWP 12258) exited] [Inferior 1 (process 12257) exited normally] (gdb)
On Mon, Dec 18, 2017 at 2:25 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/08/2017 03:25 AM, H.J. Lu wrote: >> >> Here is call stack during stack unwind: >> >> (gdb) bt > > > (snip) > >> To unwind shadow stack, we need to save shadow stack pointer in >> __cancel_buf. This updated patch adds bits/types/__cancel_jmp_buf_tag.h >> to define struct __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask >> to __cancel_jmp_buf. We will check if shadow stack is enabled before >> saving >> and restoring shadow stack pointer so that it works with the old smaller >> cancel_jmp_buf which doesn't have space for shadow stack pointer. > > > I still don't understand why you think you have to reset the shadow stack. > > I used this test program: > > #include <err.h> > #include <errno.h> > #include <pthread.h> > #include <stdbool.h> > #include <stdio.h> > #include <unistd.h> > > __attribute__ ((noinline, noclone, weak)) > void > handler1 (void *closure) > { > printf ("handler1 called\n"); > } > > __attribute__ ((noinline, noclone, weak)) > void > handler2 (void *closure) > { > printf ("handler2 called\n"); > } > > __attribute__ ((noinline, noclone, weak)) > void > pausefunc (void) > { > while (true) > pause (); > } > > __attribute__ ((noinline, noclone, weak)) > void > handlerfunc (void) > { > pthread_cleanup_push (handler2, NULL); > pausefunc (); > pthread_cleanup_pop (1); > } > > > __attribute__ ((noinline, noclone, weak)) > void * > threadfunc (void *closure) > { > pthread_cleanup_push (handler1, NULL); > handlerfunc (); > pthread_cleanup_pop (0); > return NULL; > } > > int > main (void) > { > pthread_t thr; > int ret = pthread_create (&thr, NULL, threadfunc, NULL); > if (ret != 0) > { > errno = ret; > err (1, "pthread_create"); > } > > ret = pthread_cancel (thr); > if (ret != 0) > { > errno = ret; > err (1, "pthread_cancel"); > } > > void *result; > ret = pthread_join (thr, &result); > if (ret != 0) > { > errno = ret; > err (1, "pthread_join"); > } > if (result != PTHREAD_CANCELED) > errx (1, "pthread_join did not return PTHREAD_CANCEL, but %p", result); > > return 0; > } > > See the attached GDB log. As you can see, I set breakpoints on all > pre-existing RET instructions on the call stack (which would be protected by > the shadow stack with CET). None of the RET instructions actually execute, > ergo we do not have to restore the shadow stack. > Shadow stack is invisible to programs. Shadow stack instructions are used to maintain shadow stack, like what my patch does. Any times there is a "call" instruction, the return address is pushed onto shadow stack. In your case, gdb) r The program being debugged has been started already. Start it from the beginning? (y or n) y Starting program: /tmp/a.out [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". Breakpoint 1, main () at x.c:52 52 { (gdb) ena 2 (gdb) c Continuing. [New Thread 0x7ffff77d2700 (LWP 12779)] Thread 1 "a.out" hit Breakpoint 2, 0x00007ffff780a320 in __sigsetjmp () from /lib64/libc.so.6 (gdb) bt #0 0x00007ffff780a320 in __sigsetjmp () from /lib64/libc.so.6 We need to save stack stack pointer here in __sigsetjmp, #1 0x00007ffff7bbd5c0 in start_thread () from /lib64/libpthread.so.0 #2 0x00007ffff78ea88f in clone () from /lib64/libc.so.6 (gdb) dis 2 (gdb) ena 3 (gdb) c Continuing. [Switching to Thread 0x7ffff77d2700 (LWP 12779)] Thread 2 "a.out" hit Breakpoint 3, 0x00007ffff780a410 in __longjmp () from /lib64/libc.so.6 Missing separate debuginfos, use: dnf debuginfo-install libgcc-7.2.1-4.0.fc27.x86_64 (gdb) bt #0 0x00007ffff780a410 in __longjmp () from /lib64/libc.so.6 We need to restore shadow stack pointer here so that we can jump back to the function where __sigsetjmp is called. #1 0x00007ffff780a3fb in siglongjmp () from /lib64/libc.so.6 #2 0x00007ffff7bc707d in unwind_stop () from /lib64/libpthread.so.0 #3 0x00007ffff6dcaf2e in ?? () from /lib64/libgcc_s.so.1 #4 0x00007ffff6dcb515 in _Unwind_ForcedUnwind () from /lib64/libgcc_s.so.1 #5 0x00007ffff7bc7180 in __pthread_unwind () from /lib64/libpthread.so.0 #6 0x00007ffff7bbbc82 in sigcancel_handler () from /lib64/libpthread.so.0 #7 <signal handler called> #8 0x00007ffff7bc8052 in pause () from /lib64/libpthread.so.0 #9 0x000000000040098d in pausefunc () at x.c:27 #10 0x00000000004009af in handlerfunc () at x.c:35 #11 0x00000000004009ff in threadfunc (closure=<optimized out>) at x.c:45 #12 0x00007ffff7bbd5f9 in start_thread () from /lib64/libpthread.so.0 #13 0x00007ffff78ea88f in clone () from /lib64/libc.so.6 (gdb) As long as there is a call stack, there is a shadow stack if shadow stack is enabled. Does it answer your question?
On 12/18/2017 12:42 PM, H.J. Lu wrote: > We need to restore shadow stack pointer here so that we can jump back > to the function where __sigsetjmp is called. But neither __sigsetjmp (when called the second time) nor the function that calls it return normally during cancellation, so it is still completely unclear to me what issue you are observing. Could you post a backtrace from the CET verification failure, please? Thanks, Florian
On Mon, Dec 18, 2017 at 3:49 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/18/2017 12:42 PM, H.J. Lu wrote: >> >> We need to restore shadow stack pointer here so that we can jump back >> to the function where __sigsetjmp is called. > > > But neither __sigsetjmp (when called the second time) nor the function that > calls it return normally during cancellation, so it is still completely > unclear to me what issue you are observing. > > Could you post a backtrace from the CET verification failure, please? > Here is your testcase with full debug info: (gdb) r The program being debugged has been started already. Start it from the beginning? (y or n) y Starting program: /export/build/gnu/glibc-cet/build-x86_64-linux/nptl/tst-foo warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available. Breakpoint 1, main () at tst-foo.c:52 52 { (gdb) ena 2 (gdb) c Continuing. [Switching to LWP 18711] Thread 2 "tst-foo" hit Breakpoint 2, __sigsetjmp () at ../sysdeps/unix/sysv/linux/x86_64/setjmp.S:26 26 ENTRY (__sigsetjmp) (gdb) bt #0 __sigsetjmp () at ../sysdeps/unix/sysv/linux/x86_64/setjmp.S:26 #1 0x0000000000400e15 in threadfunc (closure=<optimized out>) at tst-foo.c:44 #2 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) at pthread_create.c:463 #3 0x00007ffff78f5f73 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) f 1 #1 0x0000000000400e15 in threadfunc (closure=<optimized out>) at tst-foo.c:44 44 pthread_cleanup_push (handler1, NULL); Here we call __sigsetjmp with cancel_jmp_buf. There is a shadow stack for the normal call stack. We need to save shadow stack pointer so that we can lonjmp back here later. (gdb) dis 2 (gdb) ena 3 (gdb) c Continuing. Thread 2 "tst-foo" hit Breakpoint 3, __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 30 ENTRY(__longjmp) (gdb) bt #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 If we don't restore shadow stack pointer, when we jump back to tst-foo.c:45, shadow stack won't match call stack when threadfunc () returns. #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800ca0, val=val@entry=1) at longjmp.c:39 #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, actions=<optimized out>, exc_class=<optimized out>, exc_obj=<optimized out>, context=<optimized out>, stop_parameter=0x7ffff7800ca0) at unwind.c:94 #3 0x00007ffff6df9b1e in _Unwind_ForcedUnwind_Phase2 (exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff7800550, frames_p=frames_p@entry=0x7ffff7800458) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 #4 0x00007ffff6dfa170 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, stop_argument=<optimized out>) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) at unwind.c:121 #6 0x00007ffff7bbe46a in __do_cancel () at ./pthreadP.h:297 #7 sigcancel_handler (sig=<optimized out>, si=0x7ffff78007f0, ctx=<optimized out>) at nptl-init.c:216 #8 <signal handler called> #9 0x00007ffff7bc99b2 in __libc_pause () at ../sysdeps/unix/sysv/linux/pause.c:30 #10 0x0000000000400d95 in pausefunc () at tst-foo.c:27 #11 0x0000000000400dca in handlerfunc () at tst-foo.c:35 #12 0x0000000000400e2a in threadfunc (closure=<optimized out>) at tst-foo.c:45 #13 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) at pthread_create.c:463 #14 0x00007ffff78f5f73 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) f 6 #6 0x00007ffff7bbe46a in __do_cancel () at ./pthreadP.h:297 297 __pthread_unwind ((__pthread_unwind_buf_t *) (gdb) list 292 struct pthread *self = THREAD_SELF; 293 294 /* Make sure we get no more cancellations. */ 295 THREAD_ATOMIC_BIT_SET (self, cancelhandling, EXITING_BIT); 296 297 __pthread_unwind ((__pthread_unwind_buf_t *) 298 THREAD_GETMEM (self, cleanup_jmp_buf)); 299 } 300 301 (gdb) Does it answer your question?
On 12/18/2017 01:25 PM, H.J. Lu wrote: > If we don't restore shadow stack pointer, when we jump back to tst-foo.c:45, > shadow stack won't match call stack when threadfunc () returns. But threadfunc never returns if the thread is canceled, so I'm still as puzzled as before. Sorry. Florian
On Mon, Dec 18, 2017 at 4:52 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/18/2017 01:25 PM, H.J. Lu wrote: >> >> If we don't restore shadow stack pointer, when we jump back to >> tst-foo.c:45, >> shadow stack won't match call stack when threadfunc () returns. > > > But threadfunc never returns if the thread is canceled, so I'm still as > puzzled as before. Sorry. True, threadfunc never returns. Instead, it lonjmps back to start_thread: Thread 2 "tst-foo" hit Breakpoint 2, __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 30 ENTRY(__longjmp) (gdb) bt #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800eb0, val=val@entry=1) at longjmp.c:39 #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, actions=<optimized out>, exc_class=<optimized out>, exc_obj=<optimized out>, context=<optimized out>, stop_parameter=0x7ffff7800eb0) at unwind.c:94 #3 0x00007ffff6df9b1e in _Unwind_ForcedUnwind_Phase2 ( exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff7800c40, frames_p=frames_p@entry=0x7ffff7800b48) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 #4 0x00007ffff6dfa170 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, stop_argument=<optimized out>) at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) at unwind.c:121 #6 0x00007ffff7bc8aa4 in __GI___pthread_unwind_next ( buf=buf@entry=0x7ffff7800da0) at unwind.c:136 #7 0x0000000000400e4f in threadfunc (closure=<optimized out>) at tst-foo.c:44 #8 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) at pthread_create.c:463 #9 0x00007ffff78f5f73 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) 104 jmpq *%rdx (gdb) next start_thread (arg=<optimized out>) at pthread_create.c:436 436 if (__glibc_likely (! not_first_call)) (gdb) bt #0 start_thread (arg=<optimized out>) at pthread_create.c:436 #1 0x00007ffff78f5f73 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) list 431 unwind_buf.priv.data.prev = NULL; 432 unwind_buf.priv.data.cleanup = NULL; 433 434 int not_first_call; 435 not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This has to save and restore shadow stack pointer. Since we only have one __sigsetjmp and one __longjmp, when shadow stack is enabled, they have to save and restore shadow stack pointer. It means cancel_jmp_buf has to match __jmp_buf_tag. 436 if (__glibc_likely (! not_first_call)) 437 { 438 /* Store the new cleanup handler info. */ 439 THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf); 440 (gdb) Does it answer your question?
On Mon, Dec 18, 2017 at 5:19 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Mon, Dec 18, 2017 at 4:52 AM, Florian Weimer <fweimer@redhat.com> wrote: >> On 12/18/2017 01:25 PM, H.J. Lu wrote: >>> >>> If we don't restore shadow stack pointer, when we jump back to >>> tst-foo.c:45, >>> shadow stack won't match call stack when threadfunc () returns. >> >> >> But threadfunc never returns if the thread is canceled, so I'm still as >> puzzled as before. Sorry. > > True, threadfunc never returns. Instead, it lonjmps back to > start_thread: > > Thread 2 "tst-foo" hit Breakpoint 2, __longjmp () > at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 > 30 ENTRY(__longjmp) > (gdb) bt > #0 __longjmp () at ../sysdeps/unix/sysv/linux/x86_64/__longjmp.S:30 > #1 0x00007ffff7837f5f in __libc_siglongjmp (env=env@entry=0x7ffff7800eb0, > val=val@entry=1) at longjmp.c:39 > #2 0x00007ffff7bc899d in unwind_stop (version=<optimized out>, > actions=<optimized out>, exc_class=<optimized out>, > exc_obj=<optimized out>, context=<optimized out>, > stop_parameter=0x7ffff7800eb0) at unwind.c:94 > #3 0x00007ffff6df9b1e in _Unwind_ForcedUnwind_Phase2 ( > exc=exc@entry=0x7ffff7801d70, context=context@entry=0x7ffff7800c40, > frames_p=frames_p@entry=0x7ffff7800b48) > at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:170 > #4 0x00007ffff6dfa170 in _Unwind_ForcedUnwind (exc=0x7ffff7801d70, > stop=stop@entry=0x7ffff7bc88e0 <unwind_stop>, > stop_argument=<optimized out>) > at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:217 > #5 0x00007ffff7bc8a84 in __GI___pthread_unwind (buf=<optimized out>) > at unwind.c:121 > #6 0x00007ffff7bc8aa4 in __GI___pthread_unwind_next ( > buf=buf@entry=0x7ffff7800da0) at unwind.c:136 > #7 0x0000000000400e4f in threadfunc (closure=<optimized out>) at tst-foo.c:44 > #8 0x00007ffff7bbfcde in start_thread (arg=<optimized out>) > at pthread_create.c:463 > #9 0x00007ffff78f5f73 in clone () > at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 > (gdb) > 104 jmpq *%rdx > (gdb) next > start_thread (arg=<optimized out>) at pthread_create.c:436 > 436 if (__glibc_likely (! not_first_call)) > (gdb) bt > #0 start_thread (arg=<optimized out>) at pthread_create.c:436 > #1 0x00007ffff78f5f73 in clone () > at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 > (gdb) list > 431 unwind_buf.priv.data.prev = NULL; > 432 unwind_buf.priv.data.cleanup = NULL; > 433 > 434 int not_first_call; > 435 not_first_call = setjmp ((struct __jmp_buf_tag *) > unwind_buf.cancel_jmp_buf); > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > This has to save and restore shadow stack pointer. Since we only have > one __sigsetjmp and one __longjmp, when shadow stack is enabled, they > have to save and restore shadow stack pointer. It means cancel_jmp_buf > has to match __jmp_buf_tag. > > 436 if (__glibc_likely (! not_first_call)) > 437 { > 438 /* Store the new cleanup handler info. */ > 439 THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf); > 440 > (gdb) > > Does it answer your question? > Here is the updated patch with commit message: On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer to support shadow stack in Intel Control-flow Enforcemen Technology. Since the cancel_jmp_buf array is passed to setjmp and longjmp by casting it to pointer to struct __jmp_buf_tag, it should be as large as struct __jmp_buf_tag. Otherwise when shadow stack is enabled, setjmp and longjmp will write and read beyond cancel_jmp_buf when saving and restoring shadow stack pointer. Does it look OK? Thanks.
On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: > This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct > __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to > cancel_jmp_buf. Isn't that an ABI change? Andreas.
On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: > On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: > >> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >> cancel_jmp_buf. > > Isn't that an ABI change? > Yes, this change is exposed to application via <phread.h>. The backward binary compatibility is provided by https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html
On Mon, Dec 18, 2017 at 6:48 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: >> On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: >> >>> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >>> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >>> cancel_jmp_buf. >> >> Isn't that an ABI change? >> > > Yes, this change is exposed to application via <phread.h>. The backward > binary compatibility is provided by > > https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html > Here is the patch of shadow stack enabled setjmp/longjmp: https://sourceware.org/ml/libc-alpha/2017-12/msg00559.html which is backward binary compatible with existing binaries.
I think any change applied to sysdeps/nptl/pthread.h should also be applied to sysdeps/unix/sysv/linux/hppa/pthread.h to avoid divergence between those header versions.
On Mon, Dec 18, 2017 at 9:37 AM, Joseph Myers <joseph@codesourcery.com> wrote: > I think any change applied to sysdeps/nptl/pthread.h should also be > applied to sysdeps/unix/sysv/linux/hppa/pthread.h to avoid divergence > between those header versions. > Here is the updated patch with sysdeps/unix/sysv/linux/hppa/pthread.h change. Tested natively on i386, x86_64 and x32. Tested hppa-linux-gnu with build-many-glibcs.py. I am checking it in tomorrow.
On 12/18/2017 03:48 PM, H.J. Lu wrote: > On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: >> On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: >> >>> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >>> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >>> cancel_jmp_buf. >> >> Isn't that an ABI change? >> > > Yes, this change is exposed to application via <phread.h>. The backward > binary compatibility is provided by > > https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html This doesn't seem to work: <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> I have no idea what is going on, but if we can't find the root cause, I think we should revert all the setjmp changes. Thanks, Florian
On Tue, Jan 9, 2018 at 2:47 AM, Florian Weimer <fweimer@redhat.com> wrote: > On 12/18/2017 03:48 PM, H.J. Lu wrote: >> >> On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: >>> >>> On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: >>> >>>> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >>>> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >>>> cancel_jmp_buf. >>> >>> >>> Isn't that an ABI change? >>> >> >> Yes, this change is exposed to application via <phread.h>. The backward >> binary compatibility is provided by >> >> https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html > > > This doesn't seem to work: > > <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> > > I have no idea what is going on, but if we can't find the root cause, I > think we should revert all the setjmp changes. Hi Andrew, Igor, Please investigate to find out what happened. Thanks.
> -----Original Message----- > From: H.J. Lu [mailto:hjl.tools@gmail.com] > Sent: Tuesday, January 9, 2018 13:18 > To: Florian Weimer <fweimer@redhat.com>; Tsimbalist, Igor V > <igor.v.tsimbalist@intel.com>; Senkevich, Andrew > <andrew.senkevich@intel.com> > Cc: Andreas Schwab <schwab@suse.de>; GNU C Library <libc- > alpha@sourceware.org> > Subject: Re: [PATCH 1/2] Linux/x86: Update cancel_jmp_buf to match > __jmp_buf_tag [BZ #22563] > > On Tue, Jan 9, 2018 at 2:47 AM, Florian Weimer <fweimer@redhat.com> > wrote: > > On 12/18/2017 03:48 PM, H.J. Lu wrote: > >> > >> On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> > wrote: > >>> > >>> On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: > >>> > >>>> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct > >>>> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to > >>>> cancel_jmp_buf. > >>> > >>> > >>> Isn't that an ABI change? > >>> > >> > >> Yes, this change is exposed to application via <phread.h>. The > >> backward binary compatibility is provided by > >> > >> https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html > > > > > > This doesn't seem to work: > > > > <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> > > > > I have no idea what is going on, but if we can't find the root cause, > > I think we should revert all the setjmp changes. > > Hi Andrew, Igor, > > Please investigate to find out what happened. > > Thanks. We have connected with Tom Englund who reported issue and we will work on this issue. -- Andrew
On 2018-01-09 11:47, Florian Weimer wrote: > On 12/18/2017 03:48 PM, H.J. Lu wrote: > > On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: > > > On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: > > > > > > > This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct > > > > __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to > > > > cancel_jmp_buf. > > > > > > Isn't that an ABI change? > > > > > > > Yes, this change is exposed to application via <phread.h>. The backward > > binary compatibility is provided by > > > > https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html > > This doesn't seem to work: > > <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> > > I have no idea what is going on, but if we can't find the root cause, I > think we should revert all the setjmp changes. Commit f81ddabffd also breaks software like vlc or amarok, they crash with a segmentation fault during startup. Reverting the commit f81ddabffd fixes the issue. See debian bugs #887078 and #887886.
On Sun, Jan 21, 2018 at 8:15 AM, Aurelien Jarno <aurelien@aurel32.net> wrote: > On 2018-01-09 11:47, Florian Weimer wrote: >> On 12/18/2017 03:48 PM, H.J. Lu wrote: >> > On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: >> > > On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: >> > > >> > > > This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >> > > > __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >> > > > cancel_jmp_buf. >> > > >> > > Isn't that an ABI change? >> > > >> > >> > Yes, this change is exposed to application via <phread.h>. The backward >> > binary compatibility is provided by >> > >> > https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html >> >> This doesn't seem to work: >> >> <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> >> >> I have no idea what is going on, but if we can't find the root cause, I >> think we should revert all the setjmp changes. > > Commit f81ddabffd also breaks software like vlc or amarok, they crash > with a segmentation fault during startup. Reverting the commit > f81ddabffd fixes the issue. > > See debian bugs #887078 and #887886. > Hi Andrew, This may be easier to track. Please investigate.
On 01/21/2018 08:27 AM, H.J. Lu wrote: > On Sun, Jan 21, 2018 at 8:15 AM, Aurelien Jarno <aurelien@aurel32.net> wrote: >> On 2018-01-09 11:47, Florian Weimer wrote: >>> On 12/18/2017 03:48 PM, H.J. Lu wrote: >>>> On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> wrote: >>>>> On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: >>>>> >>>>>> This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct >>>>>> __cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to >>>>>> cancel_jmp_buf. >>>>> >>>>> Isn't that an ABI change? >>>>> >>>> >>>> Yes, this change is exposed to application via <phread.h>. The backward >>>> binary compatibility is provided by >>>> >>>> https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html >>> >>> This doesn't seem to work: >>> >>> <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> >>> >>> I have no idea what is going on, but if we can't find the root cause, I >>> think we should revert all the setjmp changes. >> >> Commit f81ddabffd also breaks software like vlc or amarok, they crash >> with a segmentation fault during startup. Reverting the commit >> f81ddabffd fixes the issue. >> >> See debian bugs #887078 and #887886. >> > > Hi Andrew, > > This may be easier to track. Please investigate. This is now the last remaining release blocker IMO. I'm going to start investigating this on Monday.
> -----Original Message----- > From: H.J. Lu [mailto:hjl.tools@gmail.com] > Sent: Sunday, January 21, 2018 17:27 > To: Florian Weimer <fweimer@redhat.com>; Andreas Schwab > <schwab@suse.de>; GNU C Library <libc-alpha@sourceware.org>; > Senkevich, Andrew <andrew.senkevich@intel.com> > Subject: Re: [PATCH 1/2] Linux/x86: Update cancel_jmp_buf to match > __jmp_buf_tag [BZ #22563] > > On Sun, Jan 21, 2018 at 8:15 AM, Aurelien Jarno <aurelien@aurel32.net> > wrote: > > On 2018-01-09 11:47, Florian Weimer wrote: > >> On 12/18/2017 03:48 PM, H.J. Lu wrote: > >> > On Mon, Dec 18, 2017 at 6:44 AM, Andreas Schwab <schwab@suse.de> > wrote: > >> > > On Dez 18 2017, "H.J. Lu" <hjl.tools@gmail.com> wrote: > >> > > > >> > > > This patch adds bits/types/__cancel_jmp_buf_tag.h to define > >> > > > struct __cancel_jmp_buf_tag so that Linux/x86 can add > >> > > > saved_mask to cancel_jmp_buf. > >> > > > >> > > Isn't that an ABI change? > >> > > > >> > > >> > Yes, this change is exposed to application via <phread.h>. The > >> > backward binary compatibility is provided by > >> > > >> > https://sourceware.org/ml/libc-alpha/2017-12/msg00208.html > >> > >> This doesn't seem to work: > >> > >> <https://sourceware.org/ml/libc-alpha/2018-01/msg00178.html> > >> > >> I have no idea what is going on, but if we can't find the root cause, > >> I think we should revert all the setjmp changes. > > > > Commit f81ddabffd also breaks software like vlc or amarok, they crash > > with a segmentation fault during startup. Reverting the commit > > f81ddabffd fixes the issue. > > > > See debian bugs #887078 and #887886. > > > > Hi Andrew, > > This may be easier to track. Please investigate. Looks like that. I will have ability to investigate it during tomorrow. -- Andrew
On 01/22/2018 06:44 AM, Senkevich, Andrew wrote: > Looks like that. > I will have ability to investigate it during tomorrow. Any idea what's going wrong?
> -----Original Message----- > From: Carlos O'Donell [mailto:carlos@redhat.com] > Sent: Tuesday, January 23, 2018 20:35 > To: Senkevich, Andrew <andrew.senkevich@intel.com>; H.J. Lu > <hjl.tools@gmail.com>; Florian Weimer <fweimer@redhat.com>; Andreas > Schwab <schwab@suse.de> > Cc: GNU C Library <libc-alpha@sourceware.org> > Subject: Re: [PATCH 1/2] Linux/x86: Update cancel_jmp_buf to match > __jmp_buf_tag [BZ #22563] > > On 01/22/2018 06:44 AM, Senkevich, Andrew wrote: > > Looks like that. > > I will have ability to investigate it during tomorrow. > > Any idea what's going wrong? Currently not clear why but I see return from var_AddCallback () (from /usr/lib/x86_64-linux-gnu/libvlccore.so.9) to wrong address. And setjmp/longjmp doesn't break. Will continue tomorrow. -- Andrew
On Tue, Jan 23, 2018 at 1:13 PM, Senkevich, Andrew <andrew.senkevich@intel.com> wrote: >> -----Original Message----- >> From: Carlos O'Donell [mailto:carlos@redhat.com] >> Sent: Tuesday, January 23, 2018 20:35 >> To: Senkevich, Andrew <andrew.senkevich@intel.com>; H.J. Lu >> <hjl.tools@gmail.com>; Florian Weimer <fweimer@redhat.com>; Andreas >> Schwab <schwab@suse.de> >> Cc: GNU C Library <libc-alpha@sourceware.org> >> Subject: Re: [PATCH 1/2] Linux/x86: Update cancel_jmp_buf to match >> __jmp_buf_tag [BZ #22563] >> >> On 01/22/2018 06:44 AM, Senkevich, Andrew wrote: >> > Looks like that. >> > I will have ability to investigate it during tomorrow. >> >> Any idea what's going wrong? > > Currently not clear why but I see return from var_AddCallback () (from /usr/lib/x86_64-linux-gnu/libvlccore.so.9) to wrong address. > And setjmp/longjmp doesn't break. Will continue tomorrow. > We opened a bug: https://sourceware.org/bugzilla/show_bug.cgi?id=22743 Any help to track down the root cause is appreciated.
On 01/24/2018 07:08 PM, H.J. Lu wrote: > On Tue, Jan 23, 2018 at 1:13 PM, Senkevich, Andrew > <andrew.senkevich@intel.com> wrote: >>> -----Original Message----- >>> From: Carlos O'Donell [mailto:carlos@redhat.com] >>> Sent: Tuesday, January 23, 2018 20:35 >>> To: Senkevich, Andrew <andrew.senkevich@intel.com>; H.J. Lu >>> <hjl.tools@gmail.com>; Florian Weimer <fweimer@redhat.com>; Andreas >>> Schwab <schwab@suse.de> >>> Cc: GNU C Library <libc-alpha@sourceware.org> >>> Subject: Re: [PATCH 1/2] Linux/x86: Update cancel_jmp_buf to match >>> __jmp_buf_tag [BZ #22563] >>> >>> On 01/22/2018 06:44 AM, Senkevich, Andrew wrote: >>>> Looks like that. >>>> I will have ability to investigate it during tomorrow. >>> >>> Any idea what's going wrong? >> >> Currently not clear why but I see return from var_AddCallback () (from /usr/lib/x86_64-linux-gnu/libvlccore.so.9) to wrong address. >> And setjmp/longjmp doesn't break. Will continue tomorrow. >> > > We opened a bug: > > https://sourceware.org/bugzilla/show_bug.cgi?id=22743 > > Any help to track down the root cause is appreciated. Doesn't the bug report clearly show the root cause? The offset of priv.data.cleanup changed, and old binaries have an insufficiently large stack allocation for the new offset. (Congratulations for tracking it down, by the way. I know that such bugs are hard.) You need to add a symbol version for pthread_register_cancel. It's too late for that now, so I recommend reverting the faulty commit. Thanks, Florian
On 01/24/2018 10:23 AM, Florian Weimer wrote: > On 01/24/2018 07:08 PM, H.J. Lu wrote: >> We opened a bug: >> >> https://sourceware.org/bugzilla/show_bug.cgi?id=22743 >> >> Any help to track down the root cause is appreciated. > > Doesn't the bug report clearly show the root cause? The offset of > priv.data.cleanup changed, and old binaries have an insufficiently > large stack allocation for the new offset. > > (Congratulations for tracking it down, by the way. I know that such > bugs are hard.) > > You need to add a symbol version for pthread_register_cancel. It's > too late for that now, so I recommend reverting the faulty commit. I have finished analyzing this and debugging the root cause myself, and I agree with Florian, we need to revert: commit f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec commit cba595c350e52194e10c0006732e1991e3d0803b At a minimum. I am testing with them reverted locally. To be honest I'm surprised that this passed review and was checked in, because the __pthread_unwind_buf_t has only at most 4-bytes of space left before it is an ABI change. In the future please ping me if you have any doubts and I'll review. The addition of __sigset_t saved_mask moves pthread_unwind_buf's priv.data.cleanup forward by 124-bytes. The on-stack allocation of the pthread_cleanup_push's __pthread_unwind_buf_t is not that big and so __pthread_register_cancel writes to other structures which are allocated on the stack. You cannot expand struct pthread_unwind_buf because the on-stack allocated __pthread_unwind_buf_t is not large enough in existing applications. You *might* have used feature_1 to change between two different layouts of struct pthread_unwind_buf, but that will have to wait for 2.28. As Florian suggests though it is cleaner to version __pthread_register_cancel for x86 and the older version expects the smaller non-CET-enabled structure.
On Wed, 24 Jan 2018, Carlos O'Donell wrote: > I have finished analyzing this and debugging the root cause myself, > and I agree with Florian, we need to revert: > > commit f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec > commit cba595c350e52194e10c0006732e1991e3d0803b > > At a minimum. I am testing with them reverted locally. > > To be honest I'm surprised that this passed review and was checked > in, because the __pthread_unwind_buf_t has only at most 4-bytes of It didn't pass review. It was checked in with no evidence of consensus (and even with ABI concerns raised in the original discussion).
On Wed, Jan 24, 2018 at 4:32 PM, Carlos O'Donell <carlos@redhat.com> wrote: > On 01/24/2018 10:23 AM, Florian Weimer wrote: >> On 01/24/2018 07:08 PM, H.J. Lu wrote: >>> We opened a bug: >>> >>> https://sourceware.org/bugzilla/show_bug.cgi?id=22743 >>> >>> Any help to track down the root cause is appreciated. >> >> Doesn't the bug report clearly show the root cause? The offset of >> priv.data.cleanup changed, and old binaries have an insufficiently >> large stack allocation for the new offset. >> >> (Congratulations for tracking it down, by the way. I know that such >> bugs are hard.) >> >> You need to add a symbol version for pthread_register_cancel. It's >> too late for that now, so I recommend reverting the faulty commit. > > I have finished analyzing this and debugging the root cause myself, > and I agree with Florian, we need to revert: > > commit f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec > commit cba595c350e52194e10c0006732e1991e3d0803b > > At a minimum. I am testing with them reverted locally. > > To be honest I'm surprised that this passed review and was checked > in, because the __pthread_unwind_buf_t has only at most 4-bytes of > space left before it is an ABI change. In the future please ping > me if you have any doubts and I'll review. > > The addition of __sigset_t saved_mask moves pthread_unwind_buf's > priv.data.cleanup forward by 124-bytes. The on-stack allocation of > the pthread_cleanup_push's __pthread_unwind_buf_t is not that big > and so __pthread_register_cancel writes to other structures which > are allocated on the stack. > > You cannot expand struct pthread_unwind_buf because the on-stack > allocated __pthread_unwind_buf_t is not large enough in existing > applications. > > You *might* have used feature_1 to change between two different > layouts of struct pthread_unwind_buf, but that will have to wait > for 2.28. As Florian suggests though it is cleaner to version > __pthread_register_cancel for x86 and the older version expects > the smaller non-CET-enabled structure. > I will try to fix it by next Monday.
On 01/24/2018 05:09 PM, H.J. Lu wrote: > On Wed, Jan 24, 2018 at 4:32 PM, Carlos O'Donell <carlos@redhat.com> wrote: >> On 01/24/2018 10:23 AM, Florian Weimer wrote: >>> On 01/24/2018 07:08 PM, H.J. Lu wrote: >>>> We opened a bug: >>>> >>>> https://sourceware.org/bugzilla/show_bug.cgi?id=22743 >>>> >>>> Any help to track down the root cause is appreciated. >>> >>> Doesn't the bug report clearly show the root cause? The offset of >>> priv.data.cleanup changed, and old binaries have an insufficiently >>> large stack allocation for the new offset. >>> >>> (Congratulations for tracking it down, by the way. I know that such >>> bugs are hard.) >>> >>> You need to add a symbol version for pthread_register_cancel. It's >>> too late for that now, so I recommend reverting the faulty commit. >> >> I have finished analyzing this and debugging the root cause myself, >> and I agree with Florian, we need to revert: >> >> commit f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec >> commit cba595c350e52194e10c0006732e1991e3d0803b >> >> At a minimum. I am testing with them reverted locally. >> >> To be honest I'm surprised that this passed review and was checked >> in, because the __pthread_unwind_buf_t has only at most 4-bytes of >> space left before it is an ABI change. In the future please ping >> me if you have any doubts and I'll review. >> >> The addition of __sigset_t saved_mask moves pthread_unwind_buf's >> priv.data.cleanup forward by 124-bytes. The on-stack allocation of >> the pthread_cleanup_push's __pthread_unwind_buf_t is not that big >> and so __pthread_register_cancel writes to other structures which >> are allocated on the stack. >> >> You cannot expand struct pthread_unwind_buf because the on-stack >> allocated __pthread_unwind_buf_t is not large enough in existing >> applications. >> >> You *might* have used feature_1 to change between two different >> layouts of struct pthread_unwind_buf, but that will have to wait >> for 2.28. As Florian suggests though it is cleaner to version >> __pthread_register_cancel for x86 and the older version expects >> the smaller non-CET-enabled structure. >> > > I will try to fix it by next Monday. I will be reverting these changes in the next 24 hours. They have a directly proven negative ABI consequences and will be removed as soon as I finish validation that the reverted patches are functional and pass the expected tests. On Monday when you have a full fix ready we can discuss this with Dmitry Levin and the other developers to see if everyone agrees that the solution is acceptable risk for 2.27.
On Wed, Jan 24, 2018 at 05:09:39PM -0800, H.J. Lu wrote: > On Wed, Jan 24, 2018 at 4:32 PM, Carlos O'Donell <carlos@redhat.com> wrote: > > On 01/24/2018 10:23 AM, Florian Weimer wrote: > >> On 01/24/2018 07:08 PM, H.J. Lu wrote: > >>> We opened a bug: > >>> > >>> https://sourceware.org/bugzilla/show_bug.cgi?id=22743 > >>> > >>> Any help to track down the root cause is appreciated. > >> > >> Doesn't the bug report clearly show the root cause? The offset of > >> priv.data.cleanup changed, and old binaries have an insufficiently > >> large stack allocation for the new offset. > >> > >> (Congratulations for tracking it down, by the way. I know that such > >> bugs are hard.) > >> > >> You need to add a symbol version for pthread_register_cancel. It's > >> too late for that now, so I recommend reverting the faulty commit. > > > > I have finished analyzing this and debugging the root cause myself, > > and I agree with Florian, we need to revert: > > > > commit f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec > > commit cba595c350e52194e10c0006732e1991e3d0803b > > > > At a minimum. I am testing with them reverted locally. > > > > To be honest I'm surprised that this passed review and was checked > > in, because the __pthread_unwind_buf_t has only at most 4-bytes of > > space left before it is an ABI change. In the future please ping > > me if you have any doubts and I'll review. > > > > The addition of __sigset_t saved_mask moves pthread_unwind_buf's > > priv.data.cleanup forward by 124-bytes. The on-stack allocation of > > the pthread_cleanup_push's __pthread_unwind_buf_t is not that big > > and so __pthread_register_cancel writes to other structures which > > are allocated on the stack. > > > > You cannot expand struct pthread_unwind_buf because the on-stack > > allocated __pthread_unwind_buf_t is not large enough in existing > > applications. > > > > You *might* have used feature_1 to change between two different > > layouts of struct pthread_unwind_buf, but that will have to wait > > for 2.28. As Florian suggests though it is cleaner to version > > __pthread_register_cancel for x86 and the older version expects > > the smaller non-CET-enabled structure. > > I will try to fix it by next Monday. I'm afraid by Monday it will be too late for 2.27 as we will get very little testing before the release.
diff --git a/nptl/descr.h b/nptl/descr.h index c83b17b674..fdeb397eab 100644 --- a/nptl/descr.h +++ b/nptl/descr.h @@ -65,6 +65,9 @@ struct pthread_unwind_buf { __jmp_buf jmp_buf; int mask_was_saved; +#ifdef NEED_SAVED_MASK_IN_CANCEL_JMP_BUF + __sigset_t saved_mask; +#endif } cancel_jmp_buf[1]; union diff --git a/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h b/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h new file mode 100644 index 0000000000..8c36ba3a5d --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h @@ -0,0 +1,36 @@ +/* Internal pthread header. Linux/x86 version. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include_next <nptl/pthreadP.h> + +#ifndef _PTHREADP_H_X86 +#define _PTHREADP_H_X86 1 + +extern struct pthread_unwind_buf ____pthread_unwind_buf_private; + +_Static_assert (sizeof (____pthread_unwind_buf_private.cancel_jmp_buf) + >= sizeof (struct __jmp_buf_tag), + "size of cancel_jmp_buf < sizeof __jmp_buf_tag"); + +extern __pthread_unwind_buf_t ____pthread_unwind_buf; + +_Static_assert (sizeof (____pthread_unwind_buf.__cancel_jmp_buf) + >= sizeof (struct __jmp_buf_tag), + "size of __cancel_jmp_buf < sizeof __jmp_buf_tag"); + +#endif diff --git a/sysdeps/unix/sysv/linux/x86/pthread.h b/sysdeps/unix/sysv/linux/x86/pthread.h new file mode 100644 index 0000000000..f8991777c1 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/pthread.h @@ -0,0 +1,1165 @@ +/* Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _PTHREAD_H +#define _PTHREAD_H 1 + +#include <features.h> +#include <endian.h> +#include <sched.h> +#include <time.h> + +#include <bits/pthreadtypes.h> +#include <bits/setjmp.h> +#include <bits/wordsize.h> +#include <bits/types/struct_timespec.h> +#include <bits/types/__sigset_t.h> + + +/* Detach state. */ +enum +{ + PTHREAD_CREATE_JOINABLE, +#define PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_JOINABLE + PTHREAD_CREATE_DETACHED +#define PTHREAD_CREATE_DETACHED PTHREAD_CREATE_DETACHED +}; + + +/* Mutex types. */ +enum +{ + PTHREAD_MUTEX_TIMED_NP, + PTHREAD_MUTEX_RECURSIVE_NP, + PTHREAD_MUTEX_ERRORCHECK_NP, + PTHREAD_MUTEX_ADAPTIVE_NP +#if defined __USE_UNIX98 || defined __USE_XOPEN2K8 + , + PTHREAD_MUTEX_NORMAL = PTHREAD_MUTEX_TIMED_NP, + PTHREAD_MUTEX_RECURSIVE = PTHREAD_MUTEX_RECURSIVE_NP, + PTHREAD_MUTEX_ERRORCHECK = PTHREAD_MUTEX_ERRORCHECK_NP, + PTHREAD_MUTEX_DEFAULT = PTHREAD_MUTEX_NORMAL +#endif +#ifdef __USE_GNU + /* For compatibility. */ + , PTHREAD_MUTEX_FAST_NP = PTHREAD_MUTEX_TIMED_NP +#endif +}; + + +#ifdef __USE_XOPEN2K +/* Robust mutex or not flags. */ +enum +{ + PTHREAD_MUTEX_STALLED, + PTHREAD_MUTEX_STALLED_NP = PTHREAD_MUTEX_STALLED, + PTHREAD_MUTEX_ROBUST, + PTHREAD_MUTEX_ROBUST_NP = PTHREAD_MUTEX_ROBUST +}; +#endif + + +#if defined __USE_POSIX199506 || defined __USE_UNIX98 +/* Mutex protocols. */ +enum +{ + PTHREAD_PRIO_NONE, + PTHREAD_PRIO_INHERIT, + PTHREAD_PRIO_PROTECT +}; +#endif + + +#if __PTHREAD_MUTEX_HAVE_PREV +# define PTHREAD_MUTEX_INITIALIZER \ + { { 0, 0, 0, 0, 0, __PTHREAD_SPINS, { 0, 0 } } } +# ifdef __USE_GNU +# define PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, 0, PTHREAD_MUTEX_RECURSIVE_NP, __PTHREAD_SPINS, { 0, 0 } } } +# define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, __PTHREAD_SPINS, { 0, 0 } } } +# define PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, 0, PTHREAD_MUTEX_ADAPTIVE_NP, __PTHREAD_SPINS, { 0, 0 } } } + +# endif +#else +# define PTHREAD_MUTEX_INITIALIZER \ + { { 0, 0, 0, 0, 0, { __PTHREAD_SPINS } } } +# ifdef __USE_GNU +# define PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, PTHREAD_MUTEX_RECURSIVE_NP, 0, { __PTHREAD_SPINS } } } +# define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, 0, { __PTHREAD_SPINS } } } +# define PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP \ + { { 0, 0, 0, PTHREAD_MUTEX_ADAPTIVE_NP, 0, { __PTHREAD_SPINS } } } + +# endif +#endif + + +/* Read-write lock types. */ +#if defined __USE_UNIX98 || defined __USE_XOPEN2K +enum +{ + PTHREAD_RWLOCK_PREFER_READER_NP, + PTHREAD_RWLOCK_PREFER_WRITER_NP, + PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP, + PTHREAD_RWLOCK_DEFAULT_NP = PTHREAD_RWLOCK_PREFER_READER_NP +}; + +/* Define __PTHREAD_RWLOCK_INT_FLAGS_SHARED to 1 if pthread_rwlock_t + has the shared field. All 64-bit architectures have the shared field + in pthread_rwlock_t. */ +#ifndef __PTHREAD_RWLOCK_INT_FLAGS_SHARED +# if __WORDSIZE == 64 +# define __PTHREAD_RWLOCK_INT_FLAGS_SHARED 1 +# endif +#endif + +/* Read-write lock initializers. */ +# define PTHREAD_RWLOCK_INITIALIZER \ + { { 0, 0, 0, 0, 0, 0, 0, 0, __PTHREAD_RWLOCK_ELISION_EXTRA, 0, 0 } } +# ifdef __USE_GNU +# ifdef __PTHREAD_RWLOCK_INT_FLAGS_SHARED +# define PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP \ + { { 0, 0, 0, 0, 0, 0, 0, 0, __PTHREAD_RWLOCK_ELISION_EXTRA, 0, \ + PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP } } +# else +# if __BYTE_ORDER == __LITTLE_ENDIAN +# define PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP \ + { { 0, 0, 0, 0, 0, 0, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP, \ + 0, __PTHREAD_RWLOCK_ELISION_EXTRA, 0, 0 } } +# else +# define PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP \ + { { 0, 0, 0, 0, 0, 0, 0, 0, 0, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP,\ + 0 } } +# endif +# endif +# endif +#endif /* Unix98 or XOpen2K */ + + +/* Scheduler inheritance. */ +enum +{ + PTHREAD_INHERIT_SCHED, +#define PTHREAD_INHERIT_SCHED PTHREAD_INHERIT_SCHED + PTHREAD_EXPLICIT_SCHED +#define PTHREAD_EXPLICIT_SCHED PTHREAD_EXPLICIT_SCHED +}; + + +/* Scope handling. */ +enum +{ + PTHREAD_SCOPE_SYSTEM, +#define PTHREAD_SCOPE_SYSTEM PTHREAD_SCOPE_SYSTEM + PTHREAD_SCOPE_PROCESS +#define PTHREAD_SCOPE_PROCESS PTHREAD_SCOPE_PROCESS +}; + + +/* Process shared or private flag. */ +enum +{ + PTHREAD_PROCESS_PRIVATE, +#define PTHREAD_PROCESS_PRIVATE PTHREAD_PROCESS_PRIVATE + PTHREAD_PROCESS_SHARED +#define PTHREAD_PROCESS_SHARED PTHREAD_PROCESS_SHARED +}; + + + +/* Conditional variable handling. */ +#define PTHREAD_COND_INITIALIZER { { {0}, {0}, {0, 0}, {0, 0}, 0, 0, {0, 0} } } + + +/* Cleanup buffers */ +struct _pthread_cleanup_buffer +{ + void (*__routine) (void *); /* Function to call. */ + void *__arg; /* Its argument. */ + int __canceltype; /* Saved cancellation type. */ + struct _pthread_cleanup_buffer *__prev; /* Chaining of cleanup functions. */ +}; + +/* Cancellation */ +enum +{ + PTHREAD_CANCEL_ENABLE, +#define PTHREAD_CANCEL_ENABLE PTHREAD_CANCEL_ENABLE + PTHREAD_CANCEL_DISABLE +#define PTHREAD_CANCEL_DISABLE PTHREAD_CANCEL_DISABLE +}; +enum +{ + PTHREAD_CANCEL_DEFERRED, +#define PTHREAD_CANCEL_DEFERRED PTHREAD_CANCEL_DEFERRED + PTHREAD_CANCEL_ASYNCHRONOUS +#define PTHREAD_CANCEL_ASYNCHRONOUS PTHREAD_CANCEL_ASYNCHRONOUS +}; +#define PTHREAD_CANCELED ((void *) -1) + + +/* Single execution handling. */ +#define PTHREAD_ONCE_INIT 0 + + +#ifdef __USE_XOPEN2K +/* Value returned by 'pthread_barrier_wait' for one of the threads after + the required number of threads have called this function. + -1 is distinct from 0 and all errno constants */ +# define PTHREAD_BARRIER_SERIAL_THREAD -1 +#endif + + +__BEGIN_DECLS + +/* Create a new thread, starting with execution of START-ROUTINE + getting passed ARG. Creation attributed come from ATTR. The new + handle is stored in *NEWTHREAD. */ +extern int pthread_create (pthread_t *__restrict __newthread, + const pthread_attr_t *__restrict __attr, + void *(*__start_routine) (void *), + void *__restrict __arg) __THROWNL __nonnull ((1, 3)); + +/* Terminate calling thread. + + The registered cleanup handlers are called via exception handling + so we cannot mark this function with __THROW.*/ +extern void pthread_exit (void *__retval) __attribute__ ((__noreturn__)); + +/* Make calling thread wait for termination of the thread TH. The + exit status of the thread is stored in *THREAD_RETURN, if THREAD_RETURN + is not NULL. + + This function is a cancellation point and therefore not marked with + __THROW. */ +extern int pthread_join (pthread_t __th, void **__thread_return); + +#ifdef __USE_GNU +/* Check whether thread TH has terminated. If yes return the status of + the thread in *THREAD_RETURN, if THREAD_RETURN is not NULL. */ +extern int pthread_tryjoin_np (pthread_t __th, void **__thread_return) __THROW; + +/* Make calling thread wait for termination of the thread TH, but only + until TIMEOUT. The exit status of the thread is stored in + *THREAD_RETURN, if THREAD_RETURN is not NULL. + + This function is a cancellation point and therefore not marked with + __THROW. */ +extern int pthread_timedjoin_np (pthread_t __th, void **__thread_return, + const struct timespec *__abstime); +#endif + +/* Indicate that the thread TH is never to be joined with PTHREAD_JOIN. + The resources of TH will therefore be freed immediately when it + terminates, instead of waiting for another thread to perform PTHREAD_JOIN + on it. */ +extern int pthread_detach (pthread_t __th) __THROW; + + +/* Obtain the identifier of the current thread. */ +extern pthread_t pthread_self (void) __THROW __attribute__ ((__const__)); + +/* Compare two thread identifiers. */ +extern int pthread_equal (pthread_t __thread1, pthread_t __thread2) + __THROW __attribute__ ((__const__)); + + +/* Thread attribute handling. */ + +/* Initialize thread attribute *ATTR with default attributes + (detachstate is PTHREAD_JOINABLE, scheduling policy is SCHED_OTHER, + no user-provided stack). */ +extern int pthread_attr_init (pthread_attr_t *__attr) __THROW __nonnull ((1)); + +/* Destroy thread attribute *ATTR. */ +extern int pthread_attr_destroy (pthread_attr_t *__attr) + __THROW __nonnull ((1)); + +/* Get detach state attribute. */ +extern int pthread_attr_getdetachstate (const pthread_attr_t *__attr, + int *__detachstate) + __THROW __nonnull ((1, 2)); + +/* Set detach state attribute. */ +extern int pthread_attr_setdetachstate (pthread_attr_t *__attr, + int __detachstate) + __THROW __nonnull ((1)); + + +/* Get the size of the guard area created for stack overflow protection. */ +extern int pthread_attr_getguardsize (const pthread_attr_t *__attr, + size_t *__guardsize) + __THROW __nonnull ((1, 2)); + +/* Set the size of the guard area created for stack overflow protection. */ +extern int pthread_attr_setguardsize (pthread_attr_t *__attr, + size_t __guardsize) + __THROW __nonnull ((1)); + + +/* Return in *PARAM the scheduling parameters of *ATTR. */ +extern int pthread_attr_getschedparam (const pthread_attr_t *__restrict __attr, + struct sched_param *__restrict __param) + __THROW __nonnull ((1, 2)); + +/* Set scheduling parameters (priority, etc) in *ATTR according to PARAM. */ +extern int pthread_attr_setschedparam (pthread_attr_t *__restrict __attr, + const struct sched_param *__restrict + __param) __THROW __nonnull ((1, 2)); + +/* Return in *POLICY the scheduling policy of *ATTR. */ +extern int pthread_attr_getschedpolicy (const pthread_attr_t *__restrict + __attr, int *__restrict __policy) + __THROW __nonnull ((1, 2)); + +/* Set scheduling policy in *ATTR according to POLICY. */ +extern int pthread_attr_setschedpolicy (pthread_attr_t *__attr, int __policy) + __THROW __nonnull ((1)); + +/* Return in *INHERIT the scheduling inheritance mode of *ATTR. */ +extern int pthread_attr_getinheritsched (const pthread_attr_t *__restrict + __attr, int *__restrict __inherit) + __THROW __nonnull ((1, 2)); + +/* Set scheduling inheritance mode in *ATTR according to INHERIT. */ +extern int pthread_attr_setinheritsched (pthread_attr_t *__attr, + int __inherit) + __THROW __nonnull ((1)); + + +/* Return in *SCOPE the scheduling contention scope of *ATTR. */ +extern int pthread_attr_getscope (const pthread_attr_t *__restrict __attr, + int *__restrict __scope) + __THROW __nonnull ((1, 2)); + +/* Set scheduling contention scope in *ATTR according to SCOPE. */ +extern int pthread_attr_setscope (pthread_attr_t *__attr, int __scope) + __THROW __nonnull ((1)); + +/* Return the previously set address for the stack. */ +extern int pthread_attr_getstackaddr (const pthread_attr_t *__restrict + __attr, void **__restrict __stackaddr) + __THROW __nonnull ((1, 2)) __attribute_deprecated__; + +/* Set the starting address of the stack of the thread to be created. + Depending on whether the stack grows up or down the value must either + be higher or lower than all the address in the memory block. The + minimal size of the block must be PTHREAD_STACK_MIN. */ +extern int pthread_attr_setstackaddr (pthread_attr_t *__attr, + void *__stackaddr) + __THROW __nonnull ((1)) __attribute_deprecated__; + +/* Return the currently used minimal stack size. */ +extern int pthread_attr_getstacksize (const pthread_attr_t *__restrict + __attr, size_t *__restrict __stacksize) + __THROW __nonnull ((1, 2)); + +/* Add information about the minimum stack size needed for the thread + to be started. This size must never be less than PTHREAD_STACK_MIN + and must also not exceed the system limits. */ +extern int pthread_attr_setstacksize (pthread_attr_t *__attr, + size_t __stacksize) + __THROW __nonnull ((1)); + +#ifdef __USE_XOPEN2K +/* Return the previously set address for the stack. */ +extern int pthread_attr_getstack (const pthread_attr_t *__restrict __attr, + void **__restrict __stackaddr, + size_t *__restrict __stacksize) + __THROW __nonnull ((1, 2, 3)); + +/* The following two interfaces are intended to replace the last two. They + require setting the address as well as the size since only setting the + address will make the implementation on some architectures impossible. */ +extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr, + size_t __stacksize) __THROW __nonnull ((1)); +#endif + +#ifdef __USE_GNU +/* Thread created with attribute ATTR will be limited to run only on + the processors represented in CPUSET. */ +extern int pthread_attr_setaffinity_np (pthread_attr_t *__attr, + size_t __cpusetsize, + const cpu_set_t *__cpuset) + __THROW __nonnull ((1, 3)); + +/* Get bit set in CPUSET representing the processors threads created with + ATTR can run on. */ +extern int pthread_attr_getaffinity_np (const pthread_attr_t *__attr, + size_t __cpusetsize, + cpu_set_t *__cpuset) + __THROW __nonnull ((1, 3)); + +/* Get the default attributes used by pthread_create in this process. */ +extern int pthread_getattr_default_np (pthread_attr_t *__attr) + __THROW __nonnull ((1)); + +/* Set the default attributes to be used by pthread_create in this + process. */ +extern int pthread_setattr_default_np (const pthread_attr_t *__attr) + __THROW __nonnull ((1)); + +/* Initialize thread attribute *ATTR with attributes corresponding to the + already running thread TH. It shall be called on uninitialized ATTR + and destroyed with pthread_attr_destroy when no longer needed. */ +extern int pthread_getattr_np (pthread_t __th, pthread_attr_t *__attr) + __THROW __nonnull ((2)); +#endif + + +/* Functions for scheduling control. */ + +/* Set the scheduling parameters for TARGET_THREAD according to POLICY + and *PARAM. */ +extern int pthread_setschedparam (pthread_t __target_thread, int __policy, + const struct sched_param *__param) + __THROW __nonnull ((3)); + +/* Return in *POLICY and *PARAM the scheduling parameters for TARGET_THREAD. */ +extern int pthread_getschedparam (pthread_t __target_thread, + int *__restrict __policy, + struct sched_param *__restrict __param) + __THROW __nonnull ((2, 3)); + +/* Set the scheduling priority for TARGET_THREAD. */ +extern int pthread_setschedprio (pthread_t __target_thread, int __prio) + __THROW; + + +#ifdef __USE_GNU +/* Get thread name visible in the kernel and its interfaces. */ +extern int pthread_getname_np (pthread_t __target_thread, char *__buf, + size_t __buflen) + __THROW __nonnull ((2)); + +/* Set thread name visible in the kernel and its interfaces. */ +extern int pthread_setname_np (pthread_t __target_thread, const char *__name) + __THROW __nonnull ((2)); +#endif + + +#ifdef __USE_UNIX98 +/* Determine level of concurrency. */ +extern int pthread_getconcurrency (void) __THROW; + +/* Set new concurrency level to LEVEL. */ +extern int pthread_setconcurrency (int __level) __THROW; +#endif + +#ifdef __USE_GNU +/* Yield the processor to another thread or process. + This function is similar to the POSIX `sched_yield' function but + might be differently implemented in the case of a m-on-n thread + implementation. */ +extern int pthread_yield (void) __THROW; + + +/* Limit specified thread TH to run only on the processors represented + in CPUSET. */ +extern int pthread_setaffinity_np (pthread_t __th, size_t __cpusetsize, + const cpu_set_t *__cpuset) + __THROW __nonnull ((3)); + +/* Get bit set in CPUSET representing the processors TH can run on. */ +extern int pthread_getaffinity_np (pthread_t __th, size_t __cpusetsize, + cpu_set_t *__cpuset) + __THROW __nonnull ((3)); +#endif + + +/* Functions for handling initialization. */ + +/* Guarantee that the initialization function INIT_ROUTINE will be called + only once, even if pthread_once is executed several times with the + same ONCE_CONTROL argument. ONCE_CONTROL must point to a static or + extern variable initialized to PTHREAD_ONCE_INIT. + + The initialization functions might throw exception which is why + this function is not marked with __THROW. */ +extern int pthread_once (pthread_once_t *__once_control, + void (*__init_routine) (void)) __nonnull ((1, 2)); + + +/* Functions for handling cancellation. + + Note that these functions are explicitly not marked to not throw an + exception in C++ code. If cancellation is implemented by unwinding + this is necessary to have the compiler generate the unwind information. */ + +/* Set cancelability state of current thread to STATE, returning old + state in *OLDSTATE if OLDSTATE is not NULL. */ +extern int pthread_setcancelstate (int __state, int *__oldstate); + +/* Set cancellation state of current thread to TYPE, returning the old + type in *OLDTYPE if OLDTYPE is not NULL. */ +extern int pthread_setcanceltype (int __type, int *__oldtype); + +/* Cancel THREAD immediately or at the next possibility. */ +extern int pthread_cancel (pthread_t __th); + +/* Test for pending cancellation for the current thread and terminate + the thread as per pthread_exit(PTHREAD_CANCELED) if it has been + cancelled. */ +extern void pthread_testcancel (void); + + +/* Cancellation handling with integration into exception handling. */ + +typedef struct +{ + /* This must match struct __jmp_buf_tag in <setjmp.h>. */ + struct + { + __jmp_buf __cancel_jmp_buf; + int __mask_was_saved; + __sigset_t __saved_mask; + } __cancel_jmp_buf[1]; + void *__pad[4]; +} __pthread_unwind_buf_t __attribute__ ((__aligned__)); + +/* No special attributes by default. */ +#ifndef __cleanup_fct_attribute +# define __cleanup_fct_attribute +#endif + + +/* Structure to hold the cleanup handler information. */ +struct __pthread_cleanup_frame +{ + void (*__cancel_routine) (void *); + void *__cancel_arg; + int __do_it; + int __cancel_type; +}; + +#if defined __GNUC__ && defined __EXCEPTIONS +# ifdef __cplusplus +/* Class to handle cancellation handler invocation. */ +class __pthread_cleanup_class +{ + void (*__cancel_routine) (void *); + void *__cancel_arg; + int __do_it; + int __cancel_type; + + public: + __pthread_cleanup_class (void (*__fct) (void *), void *__arg) + : __cancel_routine (__fct), __cancel_arg (__arg), __do_it (1) { } + ~__pthread_cleanup_class () { if (__do_it) __cancel_routine (__cancel_arg); } + void __setdoit (int __newval) { __do_it = __newval; } + void __defer () { pthread_setcanceltype (PTHREAD_CANCEL_DEFERRED, + &__cancel_type); } + void __restore () const { pthread_setcanceltype (__cancel_type, 0); } +}; + +/* Install a cleanup handler: ROUTINE will be called with arguments ARG + when the thread is canceled or calls pthread_exit. ROUTINE will also + be called with arguments ARG when the matching pthread_cleanup_pop + is executed with non-zero EXECUTE argument. + + pthread_cleanup_push and pthread_cleanup_pop are macros and must always + be used in matching pairs at the same nesting level of braces. */ +# define pthread_cleanup_push(routine, arg) \ + do { \ + __pthread_cleanup_class __clframe (routine, arg) + +/* Remove a cleanup handler installed by the matching pthread_cleanup_push. + If EXECUTE is non-zero, the handler function is called. */ +# define pthread_cleanup_pop(execute) \ + __clframe.__setdoit (execute); \ + } while (0) + +# ifdef __USE_GNU +/* Install a cleanup handler as pthread_cleanup_push does, but also + saves the current cancellation type and sets it to deferred + cancellation. */ +# define pthread_cleanup_push_defer_np(routine, arg) \ + do { \ + __pthread_cleanup_class __clframe (routine, arg); \ + __clframe.__defer () + +/* Remove a cleanup handler as pthread_cleanup_pop does, but also + restores the cancellation type that was in effect when the matching + pthread_cleanup_push_defer was called. */ +# define pthread_cleanup_pop_restore_np(execute) \ + __clframe.__restore (); \ + __clframe.__setdoit (execute); \ + } while (0) +# endif +# else +/* Function called to call the cleanup handler. As an extern inline + function the compiler is free to decide inlining the change when + needed or fall back on the copy which must exist somewhere + else. */ +__extern_inline void +__pthread_cleanup_routine (struct __pthread_cleanup_frame *__frame) +{ + if (__frame->__do_it) + __frame->__cancel_routine (__frame->__cancel_arg); +} + +/* Install a cleanup handler: ROUTINE will be called with arguments ARG + when the thread is canceled or calls pthread_exit. ROUTINE will also + be called with arguments ARG when the matching pthread_cleanup_pop + is executed with non-zero EXECUTE argument. + + pthread_cleanup_push and pthread_cleanup_pop are macros and must always + be used in matching pairs at the same nesting level of braces. */ +# define pthread_cleanup_push(routine, arg) \ + do { \ + struct __pthread_cleanup_frame __clframe \ + __attribute__ ((__cleanup__ (__pthread_cleanup_routine))) \ + = { .__cancel_routine = (routine), .__cancel_arg = (arg), \ + .__do_it = 1 }; + +/* Remove a cleanup handler installed by the matching pthread_cleanup_push. + If EXECUTE is non-zero, the handler function is called. */ +# define pthread_cleanup_pop(execute) \ + __clframe.__do_it = (execute); \ + } while (0) + +# ifdef __USE_GNU +/* Install a cleanup handler as pthread_cleanup_push does, but also + saves the current cancellation type and sets it to deferred + cancellation. */ +# define pthread_cleanup_push_defer_np(routine, arg) \ + do { \ + struct __pthread_cleanup_frame __clframe \ + __attribute__ ((__cleanup__ (__pthread_cleanup_routine))) \ + = { .__cancel_routine = (routine), .__cancel_arg = (arg), \ + .__do_it = 1 }; \ + (void) pthread_setcanceltype (PTHREAD_CANCEL_DEFERRED, \ + &__clframe.__cancel_type) + +/* Remove a cleanup handler as pthread_cleanup_pop does, but also + restores the cancellation type that was in effect when the matching + pthread_cleanup_push_defer was called. */ +# define pthread_cleanup_pop_restore_np(execute) \ + (void) pthread_setcanceltype (__clframe.__cancel_type, NULL); \ + __clframe.__do_it = (execute); \ + } while (0) +# endif +# endif +#else +/* Install a cleanup handler: ROUTINE will be called with arguments ARG + when the thread is canceled or calls pthread_exit. ROUTINE will also + be called with arguments ARG when the matching pthread_cleanup_pop + is executed with non-zero EXECUTE argument. + + pthread_cleanup_push and pthread_cleanup_pop are macros and must always + be used in matching pairs at the same nesting level of braces. */ +# define pthread_cleanup_push(routine, arg) \ + do { \ + __pthread_unwind_buf_t __cancel_buf; \ + void (*__cancel_routine) (void *) = (routine); \ + void *__cancel_arg = (arg); \ + int __not_first_call = __sigsetjmp ((struct __jmp_buf_tag *) (void *) \ + __cancel_buf.__cancel_jmp_buf, 0); \ + if (__glibc_unlikely (__not_first_call)) \ + { \ + __cancel_routine (__cancel_arg); \ + __pthread_unwind_next (&__cancel_buf); \ + /* NOTREACHED */ \ + } \ + \ + __pthread_register_cancel (&__cancel_buf); \ + do { +extern void __pthread_register_cancel (__pthread_unwind_buf_t *__buf) + __cleanup_fct_attribute; + +/* Remove a cleanup handler installed by the matching pthread_cleanup_push. + If EXECUTE is non-zero, the handler function is called. */ +# define pthread_cleanup_pop(execute) \ + do { } while (0);/* Empty to allow label before pthread_cleanup_pop. */\ + } while (0); \ + __pthread_unregister_cancel (&__cancel_buf); \ + if (execute) \ + __cancel_routine (__cancel_arg); \ + } while (0) +extern void __pthread_unregister_cancel (__pthread_unwind_buf_t *__buf) + __cleanup_fct_attribute; + +# ifdef __USE_GNU +/* Install a cleanup handler as pthread_cleanup_push does, but also + saves the current cancellation type and sets it to deferred + cancellation. */ +# define pthread_cleanup_push_defer_np(routine, arg) \ + do { \ + __pthread_unwind_buf_t __cancel_buf; \ + void (*__cancel_routine) (void *) = (routine); \ + void *__cancel_arg = (arg); \ + int __not_first_call = __sigsetjmp ((struct __jmp_buf_tag *) (void *) \ + __cancel_buf.__cancel_jmp_buf, 0); \ + if (__glibc_unlikely (__not_first_call)) \ + { \ + __cancel_routine (__cancel_arg); \ + __pthread_unwind_next (&__cancel_buf); \ + /* NOTREACHED */ \ + } \ + \ + __pthread_register_cancel_defer (&__cancel_buf); \ + do { +extern void __pthread_register_cancel_defer (__pthread_unwind_buf_t *__buf) + __cleanup_fct_attribute; + +/* Remove a cleanup handler as pthread_cleanup_pop does, but also + restores the cancellation type that was in effect when the matching + pthread_cleanup_push_defer was called. */ +# define pthread_cleanup_pop_restore_np(execute) \ + do { } while (0);/* Empty to allow label before pthread_cleanup_pop. */\ + } while (0); \ + __pthread_unregister_cancel_restore (&__cancel_buf); \ + if (execute) \ + __cancel_routine (__cancel_arg); \ + } while (0) +extern void __pthread_unregister_cancel_restore (__pthread_unwind_buf_t *__buf) + __cleanup_fct_attribute; +# endif + +/* Internal interface to initiate cleanup. */ +extern void __pthread_unwind_next (__pthread_unwind_buf_t *__buf) + __cleanup_fct_attribute __attribute__ ((__noreturn__)) +# ifndef SHARED + __attribute__ ((__weak__)) +# endif + ; +#endif + +/* Function used in the macros. */ +struct __jmp_buf_tag; +extern int __sigsetjmp (struct __jmp_buf_tag *__env, int __savemask) __THROWNL; + + +/* Mutex handling. */ + +/* Initialize a mutex. */ +extern int pthread_mutex_init (pthread_mutex_t *__mutex, + const pthread_mutexattr_t *__mutexattr) + __THROW __nonnull ((1)); + +/* Destroy a mutex. */ +extern int pthread_mutex_destroy (pthread_mutex_t *__mutex) + __THROW __nonnull ((1)); + +/* Try locking a mutex. */ +extern int pthread_mutex_trylock (pthread_mutex_t *__mutex) + __THROWNL __nonnull ((1)); + +/* Lock a mutex. */ +extern int pthread_mutex_lock (pthread_mutex_t *__mutex) + __THROWNL __nonnull ((1)); + +#ifdef __USE_XOPEN2K +/* Wait until lock becomes available, or specified time passes. */ +extern int pthread_mutex_timedlock (pthread_mutex_t *__restrict __mutex, + const struct timespec *__restrict + __abstime) __THROWNL __nonnull ((1, 2)); +#endif + +/* Unlock a mutex. */ +extern int pthread_mutex_unlock (pthread_mutex_t *__mutex) + __THROWNL __nonnull ((1)); + + +/* Get the priority ceiling of MUTEX. */ +extern int pthread_mutex_getprioceiling (const pthread_mutex_t * + __restrict __mutex, + int *__restrict __prioceiling) + __THROW __nonnull ((1, 2)); + +/* Set the priority ceiling of MUTEX to PRIOCEILING, return old + priority ceiling value in *OLD_CEILING. */ +extern int pthread_mutex_setprioceiling (pthread_mutex_t *__restrict __mutex, + int __prioceiling, + int *__restrict __old_ceiling) + __THROW __nonnull ((1, 3)); + + +#ifdef __USE_XOPEN2K8 +/* Declare the state protected by MUTEX as consistent. */ +extern int pthread_mutex_consistent (pthread_mutex_t *__mutex) + __THROW __nonnull ((1)); +# ifdef __USE_GNU +extern int pthread_mutex_consistent_np (pthread_mutex_t *__mutex) + __THROW __nonnull ((1)); +# endif +#endif + + +/* Functions for handling mutex attributes. */ + +/* Initialize mutex attribute object ATTR with default attributes + (kind is PTHREAD_MUTEX_TIMED_NP). */ +extern int pthread_mutexattr_init (pthread_mutexattr_t *__attr) + __THROW __nonnull ((1)); + +/* Destroy mutex attribute object ATTR. */ +extern int pthread_mutexattr_destroy (pthread_mutexattr_t *__attr) + __THROW __nonnull ((1)); + +/* Get the process-shared flag of the mutex attribute ATTR. */ +extern int pthread_mutexattr_getpshared (const pthread_mutexattr_t * + __restrict __attr, + int *__restrict __pshared) + __THROW __nonnull ((1, 2)); + +/* Set the process-shared flag of the mutex attribute ATTR. */ +extern int pthread_mutexattr_setpshared (pthread_mutexattr_t *__attr, + int __pshared) + __THROW __nonnull ((1)); + +#if defined __USE_UNIX98 || defined __USE_XOPEN2K8 +/* Return in *KIND the mutex kind attribute in *ATTR. */ +extern int pthread_mutexattr_gettype (const pthread_mutexattr_t *__restrict + __attr, int *__restrict __kind) + __THROW __nonnull ((1, 2)); + +/* Set the mutex kind attribute in *ATTR to KIND (either PTHREAD_MUTEX_NORMAL, + PTHREAD_MUTEX_RECURSIVE, PTHREAD_MUTEX_ERRORCHECK, or + PTHREAD_MUTEX_DEFAULT). */ +extern int pthread_mutexattr_settype (pthread_mutexattr_t *__attr, int __kind) + __THROW __nonnull ((1)); +#endif + +/* Return in *PROTOCOL the mutex protocol attribute in *ATTR. */ +extern int pthread_mutexattr_getprotocol (const pthread_mutexattr_t * + __restrict __attr, + int *__restrict __protocol) + __THROW __nonnull ((1, 2)); + +/* Set the mutex protocol attribute in *ATTR to PROTOCOL (either + PTHREAD_PRIO_NONE, PTHREAD_PRIO_INHERIT, or PTHREAD_PRIO_PROTECT). */ +extern int pthread_mutexattr_setprotocol (pthread_mutexattr_t *__attr, + int __protocol) + __THROW __nonnull ((1)); + +/* Return in *PRIOCEILING the mutex prioceiling attribute in *ATTR. */ +extern int pthread_mutexattr_getprioceiling (const pthread_mutexattr_t * + __restrict __attr, + int *__restrict __prioceiling) + __THROW __nonnull ((1, 2)); + +/* Set the mutex prioceiling attribute in *ATTR to PRIOCEILING. */ +extern int pthread_mutexattr_setprioceiling (pthread_mutexattr_t *__attr, + int __prioceiling) + __THROW __nonnull ((1)); + +#ifdef __USE_XOPEN2K +/* Get the robustness flag of the mutex attribute ATTR. */ +extern int pthread_mutexattr_getrobust (const pthread_mutexattr_t *__attr, + int *__robustness) + __THROW __nonnull ((1, 2)); +# ifdef __USE_GNU +extern int pthread_mutexattr_getrobust_np (const pthread_mutexattr_t *__attr, + int *__robustness) + __THROW __nonnull ((1, 2)); +# endif + +/* Set the robustness flag of the mutex attribute ATTR. */ +extern int pthread_mutexattr_setrobust (pthread_mutexattr_t *__attr, + int __robustness) + __THROW __nonnull ((1)); +# ifdef __USE_GNU +extern int pthread_mutexattr_setrobust_np (pthread_mutexattr_t *__attr, + int __robustness) + __THROW __nonnull ((1)); +# endif +#endif + + +#if defined __USE_UNIX98 || defined __USE_XOPEN2K +/* Functions for handling read-write locks. */ + +/* Initialize read-write lock RWLOCK using attributes ATTR, or use + the default values if later is NULL. */ +extern int pthread_rwlock_init (pthread_rwlock_t *__restrict __rwlock, + const pthread_rwlockattr_t *__restrict + __attr) __THROW __nonnull ((1)); + +/* Destroy read-write lock RWLOCK. */ +extern int pthread_rwlock_destroy (pthread_rwlock_t *__rwlock) + __THROW __nonnull ((1)); + +/* Acquire read lock for RWLOCK. */ +extern int pthread_rwlock_rdlock (pthread_rwlock_t *__rwlock) + __THROWNL __nonnull ((1)); + +/* Try to acquire read lock for RWLOCK. */ +extern int pthread_rwlock_tryrdlock (pthread_rwlock_t *__rwlock) + __THROWNL __nonnull ((1)); + +# ifdef __USE_XOPEN2K +/* Try to acquire read lock for RWLOCK or return after specfied time. */ +extern int pthread_rwlock_timedrdlock (pthread_rwlock_t *__restrict __rwlock, + const struct timespec *__restrict + __abstime) __THROWNL __nonnull ((1, 2)); +# endif + +/* Acquire write lock for RWLOCK. */ +extern int pthread_rwlock_wrlock (pthread_rwlock_t *__rwlock) + __THROWNL __nonnull ((1)); + +/* Try to acquire write lock for RWLOCK. */ +extern int pthread_rwlock_trywrlock (pthread_rwlock_t *__rwlock) + __THROWNL __nonnull ((1)); + +# ifdef __USE_XOPEN2K +/* Try to acquire write lock for RWLOCK or return after specfied time. */ +extern int pthread_rwlock_timedwrlock (pthread_rwlock_t *__restrict __rwlock, + const struct timespec *__restrict + __abstime) __THROWNL __nonnull ((1, 2)); +# endif + +/* Unlock RWLOCK. */ +extern int pthread_rwlock_unlock (pthread_rwlock_t *__rwlock) + __THROWNL __nonnull ((1)); + + +/* Functions for handling read-write lock attributes. */ + +/* Initialize attribute object ATTR with default values. */ +extern int pthread_rwlockattr_init (pthread_rwlockattr_t *__attr) + __THROW __nonnull ((1)); + +/* Destroy attribute object ATTR. */ +extern int pthread_rwlockattr_destroy (pthread_rwlockattr_t *__attr) + __THROW __nonnull ((1)); + +/* Return current setting of process-shared attribute of ATTR in PSHARED. */ +extern int pthread_rwlockattr_getpshared (const pthread_rwlockattr_t * + __restrict __attr, + int *__restrict __pshared) + __THROW __nonnull ((1, 2)); + +/* Set process-shared attribute of ATTR to PSHARED. */ +extern int pthread_rwlockattr_setpshared (pthread_rwlockattr_t *__attr, + int __pshared) + __THROW __nonnull ((1)); + +/* Return current setting of reader/writer preference. */ +extern int pthread_rwlockattr_getkind_np (const pthread_rwlockattr_t * + __restrict __attr, + int *__restrict __pref) + __THROW __nonnull ((1, 2)); + +/* Set reader/write preference. */ +extern int pthread_rwlockattr_setkind_np (pthread_rwlockattr_t *__attr, + int __pref) __THROW __nonnull ((1)); +#endif + + +/* Functions for handling conditional variables. */ + +/* Initialize condition variable COND using attributes ATTR, or use + the default values if later is NULL. */ +extern int pthread_cond_init (pthread_cond_t *__restrict __cond, + const pthread_condattr_t *__restrict __cond_attr) + __THROW __nonnull ((1)); + +/* Destroy condition variable COND. */ +extern int pthread_cond_destroy (pthread_cond_t *__cond) + __THROW __nonnull ((1)); + +/* Wake up one thread waiting for condition variable COND. */ +extern int pthread_cond_signal (pthread_cond_t *__cond) + __THROWNL __nonnull ((1)); + +/* Wake up all threads waiting for condition variables COND. */ +extern int pthread_cond_broadcast (pthread_cond_t *__cond) + __THROWNL __nonnull ((1)); + +/* Wait for condition variable COND to be signaled or broadcast. + MUTEX is assumed to be locked before. + + This function is a cancellation point and therefore not marked with + __THROW. */ +extern int pthread_cond_wait (pthread_cond_t *__restrict __cond, + pthread_mutex_t *__restrict __mutex) + __nonnull ((1, 2)); + +/* Wait for condition variable COND to be signaled or broadcast until + ABSTIME. MUTEX is assumed to be locked before. ABSTIME is an + absolute time specification; zero is the beginning of the epoch + (00:00:00 GMT, January 1, 1970). + + This function is a cancellation point and therefore not marked with + __THROW. */ +extern int pthread_cond_timedwait (pthread_cond_t *__restrict __cond, + pthread_mutex_t *__restrict __mutex, + const struct timespec *__restrict __abstime) + __nonnull ((1, 2, 3)); + +/* Functions for handling condition variable attributes. */ + +/* Initialize condition variable attribute ATTR. */ +extern int pthread_condattr_init (pthread_condattr_t *__attr) + __THROW __nonnull ((1)); + +/* Destroy condition variable attribute ATTR. */ +extern int pthread_condattr_destroy (pthread_condattr_t *__attr) + __THROW __nonnull ((1)); + +/* Get the process-shared flag of the condition variable attribute ATTR. */ +extern int pthread_condattr_getpshared (const pthread_condattr_t * + __restrict __attr, + int *__restrict __pshared) + __THROW __nonnull ((1, 2)); + +/* Set the process-shared flag of the condition variable attribute ATTR. */ +extern int pthread_condattr_setpshared (pthread_condattr_t *__attr, + int __pshared) __THROW __nonnull ((1)); + +#ifdef __USE_XOPEN2K +/* Get the clock selected for the condition variable attribute ATTR. */ +extern int pthread_condattr_getclock (const pthread_condattr_t * + __restrict __attr, + __clockid_t *__restrict __clock_id) + __THROW __nonnull ((1, 2)); + +/* Set the clock selected for the condition variable attribute ATTR. */ +extern int pthread_condattr_setclock (pthread_condattr_t *__attr, + __clockid_t __clock_id) + __THROW __nonnull ((1)); +#endif + + +#ifdef __USE_XOPEN2K +/* Functions to handle spinlocks. */ + +/* Initialize the spinlock LOCK. If PSHARED is nonzero the spinlock can + be shared between different processes. */ +extern int pthread_spin_init (pthread_spinlock_t *__lock, int __pshared) + __THROW __nonnull ((1)); + +/* Destroy the spinlock LOCK. */ +extern int pthread_spin_destroy (pthread_spinlock_t *__lock) + __THROW __nonnull ((1)); + +/* Wait until spinlock LOCK is retrieved. */ +extern int pthread_spin_lock (pthread_spinlock_t *__lock) + __THROWNL __nonnull ((1)); + +/* Try to lock spinlock LOCK. */ +extern int pthread_spin_trylock (pthread_spinlock_t *__lock) + __THROWNL __nonnull ((1)); + +/* Release spinlock LOCK. */ +extern int pthread_spin_unlock (pthread_spinlock_t *__lock) + __THROWNL __nonnull ((1)); + + +/* Functions to handle barriers. */ + +/* Initialize BARRIER with the attributes in ATTR. The barrier is + opened when COUNT waiters arrived. */ +extern int pthread_barrier_init (pthread_barrier_t *__restrict __barrier, + const pthread_barrierattr_t *__restrict + __attr, unsigned int __count) + __THROW __nonnull ((1)); + +/* Destroy a previously dynamically initialized barrier BARRIER. */ +extern int pthread_barrier_destroy (pthread_barrier_t *__barrier) + __THROW __nonnull ((1)); + +/* Wait on barrier BARRIER. */ +extern int pthread_barrier_wait (pthread_barrier_t *__barrier) + __THROWNL __nonnull ((1)); + + +/* Initialize barrier attribute ATTR. */ +extern int pthread_barrierattr_init (pthread_barrierattr_t *__attr) + __THROW __nonnull ((1)); + +/* Destroy previously dynamically initialized barrier attribute ATTR. */ +extern int pthread_barrierattr_destroy (pthread_barrierattr_t *__attr) + __THROW __nonnull ((1)); + +/* Get the process-shared flag of the barrier attribute ATTR. */ +extern int pthread_barrierattr_getpshared (const pthread_barrierattr_t * + __restrict __attr, + int *__restrict __pshared) + __THROW __nonnull ((1, 2)); + +/* Set the process-shared flag of the barrier attribute ATTR. */ +extern int pthread_barrierattr_setpshared (pthread_barrierattr_t *__attr, + int __pshared) + __THROW __nonnull ((1)); +#endif + + +/* Functions for handling thread-specific data. */ + +/* Create a key value identifying a location in the thread-specific + data area. Each thread maintains a distinct thread-specific data + area. DESTR_FUNCTION, if non-NULL, is called with the value + associated to that key when the key is destroyed. + DESTR_FUNCTION is not called if the value associated is NULL when + the key is destroyed. */ +extern int pthread_key_create (pthread_key_t *__key, + void (*__destr_function) (void *)) + __THROW __nonnull ((1)); + +/* Destroy KEY. */ +extern int pthread_key_delete (pthread_key_t __key) __THROW; + +/* Return current value of the thread-specific data slot identified by KEY. */ +extern void *pthread_getspecific (pthread_key_t __key) __THROW; + +/* Store POINTER in the thread-specific data slot identified by KEY. */ +extern int pthread_setspecific (pthread_key_t __key, + const void *__pointer) __THROW ; + + +#ifdef __USE_XOPEN2K +/* Get ID of CPU-time clock for thread THREAD_ID. */ +extern int pthread_getcpuclockid (pthread_t __thread_id, + __clockid_t *__clock_id) + __THROW __nonnull ((2)); +#endif + + +/* Install handlers to be called when a new process is created with FORK. + The PREPARE handler is called in the parent process just before performing + FORK. The PARENT handler is called in the parent process just after FORK. + The CHILD handler is called in the child process. Each of the three + handlers can be NULL, meaning that no handler needs to be called at that + point. + PTHREAD_ATFORK can be called several times, in which case the PREPARE + handlers are called in LIFO order (last added with PTHREAD_ATFORK, + first called before FORK), and the PARENT and CHILD handlers are called + in FIFO (first added, first called). */ + +extern int pthread_atfork (void (*__prepare) (void), + void (*__parent) (void), + void (*__child) (void)) __THROW; + + +#ifdef __USE_EXTERN_INLINES +/* Optimizations. */ +__extern_inline int +__NTH (pthread_equal (pthread_t __thread1, pthread_t __thread2)) +{ + return __thread1 == __thread2; +} +#endif + +__END_DECLS + +#endif /* pthread.h */ diff --git a/sysdeps/unix/sysv/linux/x86/pthreaddef.h b/sysdeps/unix/sysv/linux/x86/pthreaddef.h new file mode 100644 index 0000000000..89d19d60a1 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/pthreaddef.h @@ -0,0 +1,22 @@ +/* Pthread macros. Linux/x86 version. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include_next <pthreaddef.h> + +/* Need saved_mask in cancel_jmp_buf. */ +#define NEED_SAVED_MASK_IN_CANCEL_JMP_BUF 1