From faa9a08397f5034efad75b06879ac0ead83bd714 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 25 Apr 2017 12:08:50 +0100 Subject: [PATCH] arm64: pmuv3: handle pmuv3+ Commit f1b36dcb5c316c27 ("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 Tested-by: Jayachandran C Acked-by: Will Deacon Signed-off-by: Mark Rutland Signed-off-by: Catalin Marinas --- arch/arm64/kernel/perf_event.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 98c749394c4b..5f64d19a3411 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -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; -- GitLab