RFC: Shadow Stack support in glibc

[H.J. Lu]

On Fri, Jun 9, 2017 at 4:32 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 06/09/2017 01:28 PM, H.J. Lu wrote:
>> Yes,  99% of codes just need to recompile.  If context functions
>> are used or jmpbuf is used independently of setjmp/longjmp,
>> enabling is needed.
>
> Would you please clarify if the size of the type jmp_buf changes in the
> new compilation mode?
>

jmp_buf size will be increased unconditionally in glibc whose <setjmp.h>
has

#if shadow stack is enabled
asm ("Turn on shadow stack in program property"):
#endif

The old setjmp/longjuimp only use the old jmp_buf size and the new
setjmp/longjuimp use the new jmp_buf size.  The new setjmp/longjmp
are used only if all input object files have shadow stack enabled in
program property.


-- 
H.J.