Messages in this thread | | | Subject | Re: [PATCHv2] arm64/cpufeature: don't use mutex in bringup path | From | Suzuki K Poulose <> | Date | Thu, 11 May 2017 16:54:27 +0100 |
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On 11/05/17 16:37, Mark Rutland wrote: > On Thu, May 11, 2017 at 04:15:38PM +0100, Suzuki K Poulose wrote: >> On 11/05/17 16:01, Mark Rutland wrote: >>> +static inline bool cpus_have_const_cap(int num) >>> +{ >>> + if (static_branch_likely(&arm64_const_caps_ready)) >>> + return __cpus_have_const_cap(num); >>> + else >>> + return cpus_have_cap(num); >> >> We use cpus_have_const_cap() from hyp code, via has_vhe() and we could potentially >> try to access unmapped kernel data from hyp if we fallback to cpus_have_cap(). >> However, it looks like we have already set arm64_const_caps_ready, so should not >> hit it in practise. May be we could add a stricter version of the helper ? >> >> static inline cpus_have_const_cap_strict(int num) >> { >> BUG_ON(!static_branch_likely(&arm64_const_caps_ready); >> return __cpus_have_const_cap(num); >> } > > Just to check, is that the only user of cpus_have_const_cap() at hyp?
Uh, no we have one more, via system_supports_fpsimd() in __actvate_traps.
Suzuki
> > If so, I can do something like the above, patching <asm/virt.h> to use > it for has_vhe(). > > We don't have a BUG handler at hyp, but that should trigger a hyp panic, > which I guess is good enough. > > Marc, thoughts? > > Thanks, > Mark. >
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