[PATCH] arm64: cpu_errata: Remove ARM64_MISMATCHED_CACHE_LINE_SIZE

Will Deacon will.deacon at arm.com
Wed Sep 19 03:56:15 PDT 2018


On Wed, Sep 19, 2018 at 11:53:43AM +0100, Suzuki K Poulose wrote:
> On 09/19/2018 11:41 AM, Will Deacon wrote:
> >There's no need to treat mismatched cache-line sizes reported by CTR_EL0
> >differently to any other mismatched fields that we treat as "STRICT" in
> >the cpufeature code. In both cases we need to trap and emulate EL0
> >accesses to the register, so drop ARM64_MISMATCHED_CACHE_LINE_SIZE and
> >rely on ARM64_MISMATCHED_CACHE_TYPE instead.
> 
> The only reason was to avoid trapping the kernel accesses of CTR_EL0
> for cache line sizes if there were no differences. If we are ok with
> that, I am fine with the patch.

It's not a "trap" as such though, is it? We just load the safe val and
return that. I think that makes more sense, because if somebody uses
read_ctr to try and read something like IDC or DIC, they probably want
a sanitised copy on a mismatch.

Will



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