linux-kernel - [PATCH] arm64/perf: Replace PMU version number '0' with ID_AA64DFR0_EL1_PMUVer

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Date:   Mon, 28 Nov 2022 08:24:49 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org, will@...nel.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] arm64/perf: Replace PMU version number '0' with ID_AA64DFR0_EL1_PMUVer_NI

__armv8pmu_probe_pmu() returns if detected PMU is either not implemented or
implementation defined. Extracted ID_AA64DFR0_EL1_PMUVer value, when PMU is
not implemented is '0' which can be replaced with ID_AA64DFR0_EL1_PMUVer_NI
defined as '0b0000'.

Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: linux-perf-users@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
This applies on v6.1-rc6

 arch/arm64/kernel/perf_event.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 85a3aaefc0fb..b638f584b4dd 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1188,7 +1188,8 @@ static void __armv8pmu_probe_pmu(void *info)
 	dfr0 = read_sysreg(id_aa64dfr0_el1);
 	pmuver = cpuid_feature_extract_unsigned_field(dfr0,
 			ID_AA64DFR0_EL1_PMUVer_SHIFT);
-	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF || pmuver == 0)
+	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF ||
+	    pmuver == ID_AA64DFR0_EL1_PMUVer_NI)
 		return;
 
 	cpu_pmu->pmuver = pmuver;
-- 
2.25.1