[compiler-rt] r297995 - [PowerPC] Fix sanitizer frame unwind on 32-bit ABIs

[Kostya Serebryany via llvm-commits]

Hi Bill,

* Has this been code-reviewed? In general, please do pre-commit code
reviews for any code that is common between Power and other platforms.
Even if (or: especially if) there are #ifdefs involved. (I hate #ifdefs)
* Is there any chance to get rid of #ifdefs and replace them with if()? Or
maybe just a separate implementation for Power?
* do the existing tests cover the problems that this change solves?


Thanks,
--kcc

On Thu, Mar 16, 2017 at 2:14 PM, Bill Seurer via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: seurer
> Date: Thu Mar 16 16:14:13 2017
> New Revision: 297995
>
> URL: http://llvm.org/viewvc/llvm-project?rev=297995&view=rev
> Log:
> [PowerPC] Fix sanitizer frame unwind on 32-bit ABIs
>
> This fixes many sanitizer problems with -m32.  It is really intended
> for gcc but patches to the sanitizers make their way through llvm
> first.
>
> ref:  https://gcc.gnu.org/ml/gcc-patches/2017-02/msg00855.html
>
> Modified:
>     compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/
> sanitizer_common/sanitizer_stacktrace.cc?rev=297995&r1=
> 297994&r2=297995&view=diff
> ============================================================
> ==================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc
> (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc Thu
> Mar 16 16:14:13 2017
> @@ -79,15 +79,22 @@ void BufferedStackTrace::FastUnwindStack
>    while (IsValidFrame((uptr)frame, stack_top, bottom) &&
>           IsAligned((uptr)frame, sizeof(*frame)) &&
>           size < max_depth) {
> +     // PowerPC ABIs specify that the return address is saved on the
> +     // *caller's* stack frame.  Thus we must dereference the back chain
> +     // to find the caller frame before extracting it.
> +     uhwptr *caller_frame = (uhwptr*)frame[0];
> +     if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
> +         !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
> +       break;
>  #ifdef __powerpc__
> -    // PowerPC ABIs specify that the return address is saved at offset
> -    // 16 of the *caller's* stack frame.  Thus we must dereference the
> -    // back chain to find the caller frame before extracting it.
> -    uhwptr *caller_frame = (uhwptr*)frame[0];
> -    if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
> -        !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
> -      break;
> +    // For most ABIs the offset where the return address is saved is two
> +    // register sizes.  The exception is the SVR4 ABI, which uses an
> +    // offset of only one register size.
> +#ifdef _CALL_SYSV
> +    uhwptr pc1 = caller_frame[1];
> +#else
>      uhwptr pc1 = caller_frame[2];
> +#endif
>  #elif defined(__s390__)
>      uhwptr pc1 = frame[14];
>  #else
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170316/752c8fc5/attachment.html>