On 26/10/2026 05:48, Amir Ayupov wrote:

Drivers outside the PMU driver may need to know whether the local CPU's PMU implements a common event before relying on it, for example a trace unit driver checking that the PMU counts its external outputs as TRCEXTOUTn.

Add pmuv3_event_implemented() to the arm64 asm/arm_pmuv3.h, next to read_pmceid0() and read_pmceid1(). It reads PMCEID0/1 on the calling CPU: events 0x0000-0x003f are reported in bits [31:0], and the common events from ARMV8_PMUV3_EXT_COMMON_EVENT_BASE in bits [63:32] from PMUv3p1. Move ARMV8_PMUV3_EXT_COMMON_EVENT_BASE next to the event numbers in linux/perf/arm_pmuv3.h so it is available without CONFIG_ARM_PMU.

Suggested-by: James Clark james.clark@linaro.org Assisted-by: Devmate:Opus-5.5 Signed-off-by: Amir Ayupov aaupov@fb.com

---

arch/arm64/include/asm/arm_pmuv3.h | 19 +++++++++++++++++++ include/linux/perf/arm_pmu.h | 1 - include/linux/perf/arm_pmuv3.h | 3 +++ 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/arm_pmuv3.h b/arch/arm64/include/asm/arm_pmuv3.h index 8a777dec8d88a..acd62c4f16743 100644 --- a/arch/arm64/include/asm/arm_pmuv3.h +++ b/arch/arm64/include/asm/arm_pmuv3.h @@ -173,6 +173,25 @@ static inline bool pmuv3_implemented(int pmuver) pmuver == ID_AA64DFR0_EL1_PMUVer_NI); } +/*

• • Whether this CPU's PMU implements a common event, as reported by
• • PMCEID{0,1}: events 0x0000-0x003f in bits [31:0], and from PMUv3p1 events
• • 0x4000-0x403f in bits [63:32], which read as zero before PMUv3p1.
• • Must run on the CPU whose PMU is queried.
• */

+static inline bool pmuv3_event_implemented(u16 event) +{

• bool ext = event >= ARMV8_PMUV3_EXT_COMMON_EVENT_BASE;
• u16 id = ext ? event - ARMV8_PMUV3_EXT_COMMON_EVENT_BASE : event;
• u64 pmceid;
• if (id >= 64 || !pmuv3_implemented(read_pmuver()))

• return false;
  

• pmceid = id < 32 ? read_pmceid0() : read_pmceid1();
• return pmceid & BIT_ULL(id % 32 + (ext ? 32 : 0));

+}

• static inline bool is_pmuv3p4(int pmuver) { return pmuver >= ID_AA64DFR0_EL1_PMUVer_V3P4;

diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 02d2c7f45b527..792283d29d7b5 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -124,7 +124,6 @@ struct arm_pmu { u64 reg_brbidr; #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); -#define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 DECLARE_BITMAP(pmceid_ext_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); /* Only to be used by ACPI probing code */ diff --git a/include/linux/perf/arm_pmuv3.h b/include/linux/perf/arm_pmuv3.h index d698efba28a27..c21f185a283d6 100644 --- a/include/linux/perf/arm_pmuv3.h +++ b/include/linux/perf/arm_pmuv3.h @@ -78,6 +78,9 @@ #define ARMV8_PMUV3_PERFCTR_STALL_SLOT_FRONTEND 0x003E #define ARMV8_PMUV3_PERFCTR_STALL_SLOT 0x003F +/* Base of the common events reported in PMCEID{0,1}[63:32] from PMUv3p1 */ +#define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000

• /* Statistical profiling extension microarchitectural events */ #define ARMV8_SPE_PERFCTR_SAMPLE_POP 0x4000 #define ARMV8_SPE_PERFCTR_SAMPLE_FEED 0x4001

Reviewed-by: James Clark james.clark@linaro.org