On Mon, Feb 29, 2016 at 08:35:41PM +0100, Thomas Gleixner wrote:

On Sat, 27 Feb 2016, Brian Gerst wrote:

quoted

quoted

        arch_cpu_idle_prepare();
        cpu_idle_loop();
 }

Does this actually work with stack protector enabled?
boot_init_stack_canary() is inlined while arch_cpu_idle_prepare() is
not.

Stupid me. No it does of course not. I could have sworn that I tested that,
but obvioulsy not.

I drop that patch, but actually the real question is whether we can drop that
'#ifdef x86' around that boot_init_stack_canary() invocation.

AFAICT, neither arm, arm64 nor mips and sh call it on anything else than the
boot cpu. I can't see why that would be an issue on those architectures and
why it would be a problem if the boot cpu calls it again here.

CC'ed the relevant maintainers. Is there any issue with the patch below?

On arm[64], the canary is unfortunately global, so I don't think it would
be safe to update it live like this without effectively stopping the
machine and forcing everybody into idle.

Will