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Date: Mon, 1 Jul 2024 18:20:00 +0100
From: Mark Rutland <mark.rutland@....com>
To: "Rob Herring (Arm)" <robh@...nel.org>
Cc: Russell King <linux@...linux.org.uk>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
James Morse <james.morse@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Zenghui Yu <yuzenghui@...wei.com>,
Catalin Marinas <catalin.marinas@....com>,
James Clark <james.clark@....com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org, kvmarm@...ts.linux.dev
Subject: Re: [PATCH v2 12/12] perf: arm_pmuv3: Add support for Armv9.4 PMU
instruction counter
On Wed, Jun 26, 2024 at 04:32:36PM -0600, Rob Herring (Arm) wrote:
> Armv9.4/8.9 PMU adds optional support for a fixed instruction counter
> similar to the fixed cycle counter. Support for the feature is indicated
> in the ID_AA64DFR1_EL1 register PMICNTR field. The counter is not
> accessible in AArch32.
>
> Existing userspace using direct counter access won't know how to handle
> the fixed instruction counter, so we have to avoid using the counter
> when user access is requested.
>
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
Acked-by: Mark Rutland <mark.rutland@....com>
Mark.
> ---
> v2:
> - Use set_bit() instead of bitmap_set()
> - Check for ARMV8_PMUV3_PERFCTR_INST_RETIRED first in counter assignment
> - Check for threshold disabled in counter assignment
> ---
> arch/arm/include/asm/arm_pmuv3.h | 20 ++++++++++++++++++++
> arch/arm64/include/asm/arm_pmuv3.h | 28 ++++++++++++++++++++++++++++
> arch/arm64/kvm/pmu.c | 8 ++++++--
> arch/arm64/tools/sysreg | 25 +++++++++++++++++++++++++
> drivers/perf/arm_pmuv3.c | 25 +++++++++++++++++++++++++
> include/linux/perf/arm_pmu.h | 8 ++++++--
> include/linux/perf/arm_pmuv3.h | 6 ++++--
> 7 files changed, 114 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/include/asm/arm_pmuv3.h b/arch/arm/include/asm/arm_pmuv3.h
> index a41b503b7dcd..f63ba8986b24 100644
> --- a/arch/arm/include/asm/arm_pmuv3.h
> +++ b/arch/arm/include/asm/arm_pmuv3.h
> @@ -127,6 +127,12 @@ static inline u32 read_pmuver(void)
> return (dfr0 >> 24) & 0xf;
> }
>
> +static inline bool pmuv3_has_icntr(void)
> +{
> + /* FEAT_PMUv3_ICNTR not accessible for 32-bit */
> + return false;
> +}
> +
> static inline void write_pmcr(u32 val)
> {
> write_sysreg(val, PMCR);
> @@ -152,6 +158,13 @@ static inline u64 read_pmccntr(void)
> return read_sysreg(PMCCNTR);
> }
>
> +static inline void write_pmicntr(u64 val) {}
> +
> +static inline u64 read_pmicntr(void)
> +{
> + return 0;
> +}
> +
> static inline void write_pmcntenset(u32 val)
> {
> write_sysreg(val, PMCNTENSET);
> @@ -177,6 +190,13 @@ static inline void write_pmccfiltr(u32 val)
> write_sysreg(val, PMCCFILTR);
> }
>
> +static inline void write_pmicfiltr(u64 val) {}
> +
> +static inline u64 read_pmicfiltr(void)
> +{
> + return 0;
> +}
> +
> static inline void write_pmovsclr(u32 val)
> {
> write_sysreg(val, PMOVSR);
> diff --git a/arch/arm64/include/asm/arm_pmuv3.h b/arch/arm64/include/asm/arm_pmuv3.h
> index 36c3e82b4eec..468a049bc63b 100644
> --- a/arch/arm64/include/asm/arm_pmuv3.h
> +++ b/arch/arm64/include/asm/arm_pmuv3.h
> @@ -54,6 +54,14 @@ static inline u32 read_pmuver(void)
> ID_AA64DFR0_EL1_PMUVer_SHIFT);
> }
>
> +static inline bool pmuv3_has_icntr(void)
> +{
> + u64 dfr1 = read_sysreg(id_aa64dfr1_el1);
> +
> + return !!cpuid_feature_extract_unsigned_field(dfr1,
> + ID_AA64DFR1_EL1_PMICNTR_SHIFT);
> +}
> +
> static inline void write_pmcr(u64 val)
> {
> write_sysreg(val, pmcr_el0);
> @@ -79,6 +87,16 @@ static inline u64 read_pmccntr(void)
> return read_sysreg(pmccntr_el0);
> }
>
> +static inline void write_pmicntr(u64 val)
> +{
> + write_sysreg_s(val, SYS_PMICNTR_EL0);
> +}
> +
> +static inline u64 read_pmicntr(void)
> +{
> + return read_sysreg_s(SYS_PMICNTR_EL0);
> +}
> +
> static inline void write_pmcntenset(u64 val)
> {
> write_sysreg(val, pmcntenset_el0);
> @@ -109,6 +127,16 @@ static inline u64 read_pmccfiltr(void)
> return read_sysreg(pmccfiltr_el0);
> }
>
> +static inline void write_pmicfiltr(u64 val)
> +{
> + write_sysreg_s(val, SYS_PMICFILTR_EL0);
> +}
> +
> +static inline u64 read_pmicfiltr(void)
> +{
> + return read_sysreg_s(SYS_PMICFILTR_EL0);
> +}
> +
> static inline void write_pmovsclr(u64 val)
> {
> write_sysreg(val, pmovsclr_el0);
> diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
> index 215b74875815..0b3adf3e17b4 100644
> --- a/arch/arm64/kvm/pmu.c
> +++ b/arch/arm64/kvm/pmu.c
> @@ -66,24 +66,28 @@ void kvm_clr_pmu_events(u64 clr)
>
> /*
> * Read a value direct from PMEVTYPER<idx> where idx is 0-30
> - * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
> + * or PMxCFILTR_EL0 where idx is 31-32.
> */
> static u64 kvm_vcpu_pmu_read_evtype_direct(int idx)
> {
> if (idx == ARMV8_PMU_CYCLE_IDX)
> return read_pmccfiltr();
> + else if (idx == ARMV8_PMU_INSTR_IDX)
> + return read_pmicfiltr();
>
> return read_pmevtypern(idx);
> }
>
> /*
> * Write a value direct to PMEVTYPER<idx> where idx is 0-30
> - * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
> + * or PMxCFILTR_EL0 where idx is 31-32.
> */
> static void kvm_vcpu_pmu_write_evtype_direct(int idx, u32 val)
> {
> if (idx == ARMV8_PMU_CYCLE_IDX)
> write_pmccfiltr(val);
> + else if (idx == ARMV8_PMU_INSTR_IDX)
> + write_pmicfiltr(val);
> else
> write_pmevtypern(idx, val);
> }
> diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
> index 231817a379b5..8ab6e09871de 100644
> --- a/arch/arm64/tools/sysreg
> +++ b/arch/arm64/tools/sysreg
> @@ -2029,6 +2029,31 @@ Sysreg FAR_EL1 3 0 6 0 0
> Field 63:0 ADDR
> EndSysreg
>
> +Sysreg PMICNTR_EL0 3 3 9 4 0
> +Field 63:0 ICNT
> +EndSysreg
> +
> +Sysreg PMICFILTR_EL0 3 3 9 6 0
> +Res0 63:59
> +Field 58 SYNC
> +Field 57:56 VS
> +Res0 55:32
> +Field 31 P
> +Field 30 U
> +Field 29 NSK
> +Field 28 NSU
> +Field 27 NSH
> +Field 26 M
> +Res0 25
> +Field 24 SH
> +Field 23 T
> +Field 22 RLK
> +Field 21 RLU
> +Field 20 RLH
> +Res0 19:16
> +Field 15:0 evtCount
> +EndSysreg
> +
> Sysreg PMSCR_EL1 3 0 9 9 0
> Res0 63:8
> Field 7:6 PCT
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index f58dff49ea7d..3b3a3334cc3f 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -571,6 +571,8 @@ static u64 armv8pmu_read_counter(struct perf_event *event)
>
> if (idx == ARMV8_PMU_CYCLE_IDX)
> value = read_pmccntr();
> + else if (idx == ARMV8_PMU_INSTR_IDX)
> + value = read_pmicntr();
> else
> value = armv8pmu_read_hw_counter(event);
>
> @@ -604,6 +606,8 @@ static void armv8pmu_write_counter(struct perf_event *event, u64 value)
>
> if (idx == ARMV8_PMU_CYCLE_IDX)
> write_pmccntr(value);
> + else if (idx == ARMV8_PMU_INSTR_IDX)
> + write_pmicntr(value);
> else
> armv8pmu_write_hw_counter(event, value);
> }
> @@ -641,6 +645,8 @@ static void armv8pmu_write_event_type(struct perf_event *event)
> } else {
> if (idx == ARMV8_PMU_CYCLE_IDX)
> write_pmccfiltr(hwc->config_base);
> + else if (idx == ARMV8_PMU_INSTR_IDX)
> + write_pmicfiltr(hwc->config_base);
> else
> armv8pmu_write_evtype(idx, hwc->config_base);
> }
> @@ -769,6 +775,8 @@ static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu)
> ARMPMU_MAX_HWEVENTS) {
> if (i == ARMV8_PMU_CYCLE_IDX)
> write_pmccntr(0);
> + else if (i == ARMV8_PMU_INSTR_IDX)
> + write_pmicntr(0);
> else
> armv8pmu_write_evcntr(i, 0);
> }
> @@ -936,6 +944,19 @@ static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc,
> return -EAGAIN;
> }
>
> + /*
> + * Always prefer to place a instruction counter into the instruction counter,
> + * but don't expose the instruction counter to userspace access as userspace
> + * may not know how to handle it.
> + */
> + if ((evtype == ARMV8_PMUV3_PERFCTR_INST_RETIRED) &&
> + !armv8pmu_event_get_threshold(&event->attr) &&
> + test_bit(ARMV8_PMU_INSTR_IDX, cpu_pmu->cntr_mask) &&
> + !armv8pmu_event_want_user_access(event)) {
> + if (!test_and_set_bit(ARMV8_PMU_INSTR_IDX, cpuc->used_mask))
> + return ARMV8_PMU_INSTR_IDX;
> + }
> +
> /*
> * Otherwise use events counters
> */
> @@ -1193,6 +1214,10 @@ static void __armv8pmu_probe_pmu(void *info)
> /* Add the CPU cycles counter */
> set_bit(ARMV8_PMU_CYCLE_IDX, cpu_pmu->cntr_mask);
>
> + /* Add the CPU instructions counter */
> + if (pmuv3_has_icntr())
> + set_bit(ARMV8_PMU_INSTR_IDX, cpu_pmu->cntr_mask);
> +
> pmceid[0] = pmceid_raw[0] = read_pmceid0();
> pmceid[1] = pmceid_raw[1] = read_pmceid1();
>
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index e5d6d204beab..4b5b83677e3f 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -17,10 +17,14 @@
> #ifdef CONFIG_ARM_PMU
>
> /*
> - * The ARMv7 CPU PMU supports up to 32 event counters.
> + * The Armv7 and Armv8.8 or less CPU PMU supports up to 32 event counters.
> + * The Armv8.9/9.4 CPU PMU supports up to 33 event counters.
> */
> +#ifdef CONFIG_ARM
> #define ARMPMU_MAX_HWEVENTS 32
> -
> +#else
> +#define ARMPMU_MAX_HWEVENTS 33
> +#endif
> /*
> * ARM PMU hw_event flags
> */
> diff --git a/include/linux/perf/arm_pmuv3.h b/include/linux/perf/arm_pmuv3.h
> index 4f7a7f2222e5..3372c1b56486 100644
> --- a/include/linux/perf/arm_pmuv3.h
> +++ b/include/linux/perf/arm_pmuv3.h
> @@ -8,7 +8,7 @@
>
> #define ARMV8_PMU_MAX_GENERAL_COUNTERS 31
> #define ARMV8_PMU_CYCLE_IDX 31
> -
> +#define ARMV8_PMU_INSTR_IDX 32 /* Not accessible from AArch32 */
>
> /*
> * Common architectural and microarchitectural event numbers.
> @@ -228,8 +228,10 @@
> */
> #define ARMV8_PMU_OVSR_P GENMASK(30, 0)
> #define ARMV8_PMU_OVSR_C BIT(31)
> +#define ARMV8_PMU_OVSR_F BIT_ULL(32) /* arm64 only */
> /* Mask for writable bits is both P and C fields */
> -#define ARMV8_PMU_OVERFLOWED_MASK (ARMV8_PMU_OVSR_P | ARMV8_PMU_OVSR_C)
> +#define ARMV8_PMU_OVERFLOWED_MASK (ARMV8_PMU_OVSR_P | ARMV8_PMU_OVSR_C | \
> + ARMV8_PMU_OVSR_F)
>
> /*
> * PMXEVTYPER: Event selection reg
>
> --
> 2.43.0
>
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