Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack

H.J. Lu
2020-08-27T13:42:58Z

On Thu, Aug 27, 2020 at 6:19 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Dave Martin:
>
> > You're right that this has implications: for i386, libc probably pulls
> > more arguments off the stack than are really there in some situations.
> > This isn't a new problem though. There are already generic prctls with
> > fewer than 4 args that are used on x86.
>
> As originally posted, glibc prctl would have to know that it has to pull
> an u64 argument off the argument list for ARCH_X86_CET_DISABLE. But
> then the u64 argument is a problem for arch_prctl as well.
>

Argument of ARCH_X86_CET_DISABLE is int and passed in register.

--
H.J.