| Message ID | CA+=Sn1=TbMGsZ-YUDxVyYXV_iuLDuhssiyfzO8MjL8qnRH4T_w@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Wed, 25 Jul 2012, Andrew Pinski wrote: > Hi, > The Linux kernel already supports non-executable stack since around > February 2010. This patch has GCC emit the notes that are associated > with non-executable stack. What does the kernel do when the note isn't present? > OK? Bootstrapped and tested on mips64-linux-gnu with kernel already > supporting the non-executable stack with no regressions. > > Thanks, > Andrew Pinski > > ChangeLog: > > * config/mips/linux-common.h (TARGET_ASM_FILE_END): Define. > I can't quote your non-inline patch so I'll copy-paste it. + +/* For MIPS, the default is to assume *no* executable stack, so output + an executable-stack-note only when needed. */ +#define TARGET_ASM_FILE_END file_end_indicate_exec_stack The comment is wrong, your patch is always emitting the note. Besides IIRC, *glibc* defaults to an executable stack for MIPS, so you need to emit it if (!trampolines_created) or something like that. See the CRIS cris_file_end from which the comment seems copy-pasted, but the opposite condition. :) If the kernel and glibc are in contradiction regarding the default, you do need to use a slightly different expression, checking too whether you're creating an executable, if you really mean to emit the note only when needed. brgds, H-P
On Wed, 25 Jul 2012, Andrew Pinski wrote:
> * config/mips/linux-common.h (TARGET_ASM_FILE_END): Define.
Do you also need to change libgcc/config/mips/*.S to include the
appropriate note?
Index: config/mips/linux-common.h =================================================================== --- config/mips/linux-common.h (revision 189877) +++ config/mips/linux-common.h (working copy) @@ -56,3 +56,7 @@ along with GCC; see the file COPYING3. GNU_USER_TARGET_ENDFILE_SPEC, \ GNU_USER_TARGET_MATHFILE_SPEC " " \ ANDROID_ENDFILE_SPEC) + +/* For MIPS, the default is to assume *no* executable stack, so output + an executable-stack-note only when needed. */ +#define TARGET_ASM_FILE_END file_end_indicate_exec_stack