On Thu, Jul 09, 2015 at 11:05:34AM +0100, Marc Zyngier wrote:
> On 09/07/15 10:42, Mark Rutland wrote:
> > Hi,
> >
> >> +static inline bool is_kernel_in_hyp_mode(void)
> >> +{
> >> + u64 el;
> >> +
> >> + asm("mrs %0, CurrentEL" : "=r" (el));
> >> + return el == CurrentEL_EL2;
> >> +}
> >
> > If you can include cputype.h, I think this can be:
> >
> > static inline bool is_kernel_in_hyp_mode(void)
> > {
> > return read_cpuid(CurrentEL) == CurrentEL_EL2;
> > }
>
> This would indeed work, but CurrentEL is hardly an ID register. I feel
> slightly uncomfortable using read_cpuid (which might return a cached
> version at some point) for random system registers.
>
> Thoughts?
I have no strong feelings either way, but I agree with the general
uneasiness w.r.t. what read_cpuid can be expected to do.
Elsewhere we just use inline asm to read non CPUID system registers, so
let's leave your patch as it was.
Thanks,
Mark.
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