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arm64: pmuv3: handle pmuv3+

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Commit f1b36dcb5c ("arm64: pmuv3: handle !PMUv3 when probing") is
a little too restrictive, and prevents the use of of backwards
compatible PMUv3 extenstions, which have a PMUver value other than 1.

For instance, ARMv8.1 PMU extensions (as implemented by ThunderX2) are
reported with PMUver value 4.

Per the usual ID register principles, at least 0x1-0x7 imply a
PMUv3-compatible PMU. It's not currently clear whether 0x8-0xe imply the
same.

For the time being, treat the value as signed, and with 0x1-0x7 treated
as meaning PMUv3 is implemented. This may be relaxed by future patches.

Reported-by: Jayachandran C <jnair@caviumnetworks.com>
Tested-by: Jayachandran C <jnair@caviumnetworks.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2017-04-25 12:08:50 +01:00 committed by Catalin Marinas
parent 9842119a23
commit faa9a08397
1 changed files with 4 additions and 3 deletions
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7
arch/arm64/kernel/perf_event.c
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@ -966,13 +966,14 @@ static void __armv8pmu_probe_pmu(void *info)
{
struct armv8pmu_probe_info *probe = info;
struct arm_pmu *cpu_pmu = probe->pmu;
u64 dfr0, pmuver;
u64 dfr0;
u32 pmceid[2];
int pmuver;
dfr0 = read_sysreg(id_aa64dfr0_el1);
pmuver = cpuid_feature_extract_unsigned_field(dfr0,
pmuver = cpuid_feature_extract_signed_field(dfr0,
ID_AA64DFR0_PMUVER_SHIFT);
if (pmuver != 1)
if (pmuver < 1)
return;
probe->present = true;