Hi Borislav,
On Tue, Apr 19, 2022 at 8:16 PM Borislav Petkov <bp@xxxxxxxxx> wrote:
> > +static inline unsigned long random_get_entropy(void)
> > +{
> > +#ifndef CONFIG_X86_TSC
> > + if (!boot_cpu_has(X86_FEATURE_TSC))
>
> cpu_feature_enabled() pls.
This function began as a carbon copy of get_cycles(), which reads:
static inline cycles_t get_cycles(void)
{
#ifndef CONFIG_X86_TSC
if (!boot_cpu_has(X86_FEATURE_TSC))
return 0;
#endif
return rdtsc();
}
As you see, random_get_entropy() is the same function, but with that
zero replaced with the fallback. (Using the fallback in get_cycles()
wouldn't be appropriate.)
So, your options are:
a) We keep this patch as-is, using boot_cpu_has(); or
b) I make an unrelated change inside of this same patch to change
get_cycles() to use cpu_feature_enabled() (in addition to the new
random_get_entropy()).
I think I prefer doing (a), and leaving (b) for another time when you
or another x86 maintainer can do so. But I'll do whichever you say.
Which would you like?
Jason
