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authorAnshuman Khandual <anshuman.khandual@arm.com>2023-10-13 05:43:54 +0300
committerWill Deacon <will@kernel.org>2023-10-19 18:35:04 +0300
commit58f8fc57b1d314b5402c374a8c454ac7c870574c (patch)
tree21092c343eae88eabea774239b6d50e159920cc0 /drivers/perf
parent50b560783f7f71790bcf70e9e9855155fb0af8c1 (diff)
downloadlinux-58f8fc57b1d314b5402c374a8c454ac7c870574c.tar.xz
drivers: perf: arm_pmuv3: Read PMMIR_EL1 unconditionally
Currently the PMUv3 driver only reads PMMIR_EL1 if the PMU implements FEAT_PMUv3p4 and the STALL_SLOT event, but the check for STALL_SLOT event isn't necessary and can be removed. The check for STALL_SLOT event was introduced with the read of PMMIR_EL1 in commit f5be3a61fdb5dd11 ("arm64: perf: Add support caps under sysfs") When this logic was written, the ARM ARM said: | If STALL_SLOT is not implemented, it is IMPLEMENTATION DEFINED whether | the PMMIR System registers are implemented. ... and thus the driver had to check for STALL_SLOT event to verify that PMMIR_EL1 was implemented and accesses to PMMIR_EL1 would not be UNDEFINED. Subsequently, the architecture was retrospectively tightened to require that any FEAT_PMUv3p4 implementation implements PMMIR_EL1. Since the G.b release of the ARM ARM, the wording regarding STALL_SLOT event has been removed, and the description of PMMIR_EL1 says: | This register is present only when FEAT_PMUv3p4 is implemented. Drop the unnecessary check for STALL_SLOT event when reading PMMIR_EL1. Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Reviewed-by: James Clark <james.clark@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20231013024354.1289070-1-anshuman.khandual@arm.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/perf')
-rw-r--r--drivers/perf/arm_pmuv3.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 8fcaa26f0f8a..4ee0afe00527 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -1126,7 +1126,7 @@ static void __armv8pmu_probe_pmu(void *info)
pmceid, ARMV8_PMUV3_MAX_COMMON_EVENTS);
/* store PMMIR register for sysfs */
- if (is_pmuv3p4(pmuver) && (pmceid_raw[1] & BIT(31)))
+ if (is_pmuv3p4(pmuver))
cpu_pmu->reg_pmmir = read_pmmir();
else
cpu_pmu->reg_pmmir = 0;