Make sure the stack pointer is properly aligned when invoking a
signal on amd64-linux systems.

The amd64 ABI describes the required alignment on function entry
as follows:

  "In other words, the value (%rsp − 8) is always a multiple
   of 16 when control is transferred to the function entry point. 

So we need to 16 byte align and then subtract an extra 8 bytes
to achieve the correct alignment.

Patch from fjgmacc@gmail.com to fix BZ#280114.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13182 a5019735-40e9-0310-863c-91ae7b9d1cf9
1 file changed