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

[H.J. Lu]

On Thu, Aug 27, 2020 at 6:19 AM Florian Weimer <fweimer@xxxxxxxxxx> 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.