Re: [RFC PATCH v3 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11`

Ammar Faizi
2023-01-25T03:30:39Z

On Tue, Jan 24, 2023 at 12:59:23PM -0800, H. Peter Anvin wrote:
>
>
> On 1/24/23 02:09, Ammar Faizi wrote:
> > From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
> >
> > Test that:
> >
> > - "syscall" in a FRED system doesn't clobber %rcx and %r11.
> > - "syscall" in a non-FRED system sets %rcx=%rip and %r11=%rflags.
> >
> > Test them out with a trivial system call like __NR_getppid and friends
> > which are extremely likely to return with SYSRET on an IDT system.
> >
> > Link: https://lore.kernel.org/lkml/25b96960-a07e-a952-5c23-786b55054126@zytor.com
> > Co-developed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>
> Add to the description that the purpose of this is to ensure that various
> system calls are *consistent*, as per the comment immediately below your
> code.

Added in v4.

--
Ammar Faizi