Re: [PATCH v3 13/17] arm64: preserve x18 when CPU is suspended

Nick Desaulniers
2019-10-31T17:35:17Z

On Thu, Oct 31, 2019 at 10:27 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> On Thu, Oct 31, 2019 at 10:18 AM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> > > +#ifdef CONFIG_SHADOW_CALL_STACK
> > > + ldr x18, [x0, #96]
> > > + str xzr, [x0, #96]
> >
> > How come we zero out x0+#96, but not for other offsets? Is this str necessary?
>
> It clears the shadow stack pointer from the sleep state buffer, which
> is not strictly speaking necessary, but leaves one fewer place to find
> it.

That sounds like a good idea. Consider adding comments or to the
commit message so that the str doesn't get removed accidentally in the
future.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
--
Thanks,
~Nick Desaulniers