Hi Mark,
On Fri, Apr 08, 2022 at 07:33:53PM +0100, Mark Rutland wrote:
On Fri, Apr 08, 2022 at 08:21:42PM +0200, Jason A. Donenfeld wrote:
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling sched_clock() would be preferable, because
that always needs to return _something_, even falling back to jiffies
eventually. It's not as though sched_clock() is super high precision or
guaranteed to be entropic, but basically anything that's not zero all
the time is better than returning zero all the time.
If CONFIG_ARM_ARCH_TIMER=n, then get_cycles() will return 0, so we only
need the fallback code for that case.
In arch/arm64/Kconfig we unconditionally select CONFIG_ARM_ARCH_TIMER,
so that configuration shouldn't be possible, and I don't think this
patch is necessary.
On arm64 we depend on the architected timer in a bunch of places, so
anyone hacking that out has bigger problems.
Thanks for the tip. I'll drop this patch from the series.
Jason
