Re: [PATCH v2 33/35] arm64/mm: attempt speculative mm faults first

[Mike Rapoport]

On Mon, Jan 31, 2022 at 12:07:29AM -0800, Michel Lespinasse wrote:
> On Sun, Jan 30, 2022 at 11:13:26AM +0200, Mike Rapoport wrote:
> > The speculative page fault implementation here (and for PowerPC as well)
> > looks very similar to x86. Can we factor it our rather than copy 3 (or
> > more) times?
> 
> In each arch, the speculative code was written along the lines of the
> existing non-speculative code, so that behavior would be unchanged
> when speculation succeeds.
> 
> Now each arch's existing, non-speculative code paths are quite similar,
> but they do have small differences as to how they implement various
> permission checks, protection keys and the like. The same small
> differences end up being reflected in the new speculative code paths.
> 
> I agree it would be nice if this code could be unified between archs,
> but IMO this should start with the existing non-speculative code -
> I don't think it would make sense to try unifying the new speculative
> code while trying to follow the behavior of the non-unified old
> non-speculative code paths...

Then maybe this unification can be done as the ground work for the
speculative page fault handling?

-- 
Sincerely yours,
Mike.