RFC: Shadow Stack support in glibc

[Szabolcs Nagy]

On 09/06/17 12:13, H.J. Lu wrote:
> On Fri, Jun 9, 2017 at 2:05 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
>>
>> fixing setjmp/longjmp is non-trivial since jmpbuf size is abi,
>> it may be possible to do without saving ssp into jmpbuf though.
>>
> 
> Shadow stack is enabled at run-time only if all sources are compiled
> with shadow stack enabled compiler against shadow stack enabled
> glibc.  setjmp/longjmp are implemented with IFUNC, which uses
> the old setjmp/longjmp if shadow stack is off and uses the new
> setjmp/longjmp if shadow stack is on.
> 

that is not enough.

jmpbuf may be used in user code independently of setjmp/longjmp.