diff options
Diffstat (limited to 'drivers/perf')
| -rw-r--r-- | drivers/perf/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/perf/Makefile | 1 | ||||
| -rw-r--r-- | drivers/perf/riscv_pmu.c | 322 |
3 files changed, 333 insertions, 0 deletions
diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig index e1a0c44bc686..dbc0e3f98be9 100644 --- a/drivers/perf/Kconfig +++ b/drivers/perf/Kconfig @@ -56,6 +56,16 @@ config ARM_PMU Say y if you want to use CPU performance monitors on ARM-based systems. +config RISCV_PMU + depends on RISCV + bool "RISC-V PMU framework" + default y + help + Say y if you want to use CPU performance monitors on RISCV-based + systems. This provides the core PMU framework that abstracts common + PMU functionalities in a core library so that different PMU drivers + can reuse it. + config ARM_PMU_ACPI depends on ARM_PMU && ACPI def_bool y diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile index 2db5418d5b0a..09082dea154b 100644 --- a/drivers/perf/Makefile +++ b/drivers/perf/Makefile @@ -10,6 +10,7 @@ obj-$(CONFIG_FSL_IMX8_DDR_PMU) += fsl_imx8_ddr_perf.o obj-$(CONFIG_HISI_PMU) += hisilicon/ obj-$(CONFIG_QCOM_L2_PMU) += qcom_l2_pmu.o obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o +obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c new file mode 100644 index 000000000000..590a5789c128 --- /dev/null +++ b/drivers/perf/riscv_pmu.c @@ -0,0 +1,322 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RISC-V performance counter support. + * + * Copyright (C) 2021 Western Digital Corporation or its affiliates. + * + * This implementation is based on old RISC-V perf and ARM perf event code + * which are in turn based on sparc64 and x86 code. + */ + +#include <linux/cpumask.h> +#include <linux/irq.h> +#include <linux/irqdesc.h> +#include <linux/perf/riscv_pmu.h> +#include <linux/printk.h> +#include <linux/smp.h> + +static unsigned long csr_read_num(int csr_num) +{ +#define switchcase_csr_read(__csr_num, __val) {\ + case __csr_num: \ + __val = csr_read(__csr_num); \ + break; } +#define switchcase_csr_read_2(__csr_num, __val) {\ + switchcase_csr_read(__csr_num + 0, __val) \ + switchcase_csr_read(__csr_num + 1, __val)} +#define switchcase_csr_read_4(__csr_num, __val) {\ + switchcase_csr_read_2(__csr_num + 0, __val) \ + switchcase_csr_read_2(__csr_num + 2, __val)} +#define switchcase_csr_read_8(__csr_num, __val) {\ + switchcase_csr_read_4(__csr_num + 0, __val) \ + switchcase_csr_read_4(__csr_num + 4, __val)} +#define switchcase_csr_read_16(__csr_num, __val) {\ + switchcase_csr_read_8(__csr_num + 0, __val) \ + switchcase_csr_read_8(__csr_num + 8, __val)} +#define switchcase_csr_read_32(__csr_num, __val) {\ + switchcase_csr_read_16(__csr_num + 0, __val) \ + switchcase_csr_read_16(__csr_num + 16, __val)} + + unsigned long ret = 0; + + switch (csr_num) { + switchcase_csr_read_32(CSR_CYCLE, ret) + switchcase_csr_read_32(CSR_CYCLEH, ret) + default : + break; + } + + return ret; +#undef switchcase_csr_read_32 +#undef switchcase_csr_read_16 +#undef switchcase_csr_read_8 +#undef switchcase_csr_read_4 +#undef switchcase_csr_read_2 +#undef switchcase_csr_read +} + +/* + * Read the CSR of a corresponding counter. + */ +unsigned long riscv_pmu_ctr_read_csr(unsigned long csr) +{ + if (csr < CSR_CYCLE || csr > CSR_HPMCOUNTER31H || + (csr > CSR_HPMCOUNTER31 && csr < CSR_CYCLEH)) { + pr_err("Invalid performance counter csr %lx\n", csr); + return -EINVAL; + } + + return csr_read_num(csr); +} + +u64 riscv_pmu_ctr_get_width_mask(struct perf_event *event) +{ + int cwidth; + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + struct hw_perf_event *hwc = &event->hw; + + if (!rvpmu->ctr_get_width) + /** + * If the pmu driver doesn't support counter width, set it to default + * maximum allowed by the specification. + */ + cwidth = 63; + else { + if (hwc->idx == -1) + /* Handle init case where idx is not initialized yet */ + cwidth = rvpmu->ctr_get_width(0); + else + cwidth = rvpmu->ctr_get_width(hwc->idx); + } + + return GENMASK_ULL(cwidth, 0); +} + +u64 riscv_pmu_event_update(struct perf_event *event) +{ + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + struct hw_perf_event *hwc = &event->hw; + u64 prev_raw_count, new_raw_count; + unsigned long cmask; + u64 oldval, delta; + + if (!rvpmu->ctr_read) + return 0; + + cmask = riscv_pmu_ctr_get_width_mask(event); + + do { + prev_raw_count = local64_read(&hwc->prev_count); + new_raw_count = rvpmu->ctr_read(event); + oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count, + new_raw_count); + } while (oldval != prev_raw_count); + + delta = (new_raw_count - prev_raw_count) & cmask; + local64_add(delta, &event->count); + local64_sub(delta, &hwc->period_left); + + return delta; +} + +static void riscv_pmu_stop(struct perf_event *event, int flags) +{ + struct hw_perf_event *hwc = &event->hw; + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + + WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED); + + if (!(hwc->state & PERF_HES_STOPPED)) { + if (rvpmu->ctr_stop) { + rvpmu->ctr_stop(event, 0); + hwc->state |= PERF_HES_STOPPED; + } + riscv_pmu_event_update(event); + hwc->state |= PERF_HES_UPTODATE; + } +} + +int riscv_pmu_event_set_period(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + s64 left = local64_read(&hwc->period_left); + s64 period = hwc->sample_period; + int overflow = 0; + uint64_t max_period = riscv_pmu_ctr_get_width_mask(event); + + if (unlikely(left <= -period)) { + left = period; + local64_set(&hwc->period_left, left); + hwc->last_period = period; + overflow = 1; + } + + if (unlikely(left <= 0)) { + left += period; + local64_set(&hwc->period_left, left); + hwc->last_period = period; + overflow = 1; + } + + /* + * Limit the maximum period to prevent the counter value + * from overtaking the one we are about to program. In + * effect we are reducing max_period to account for + * interrupt latency (and we are being very conservative). + */ + if (left > (max_period >> 1)) + left = (max_period >> 1); + + local64_set(&hwc->prev_count, (u64)-left); + perf_event_update_userpage(event); + + return overflow; +} + +static void riscv_pmu_start(struct perf_event *event, int flags) +{ + struct hw_perf_event *hwc = &event->hw; + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + uint64_t max_period = riscv_pmu_ctr_get_width_mask(event); + u64 init_val; + + if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED))) + return; + + if (flags & PERF_EF_RELOAD) + WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE)); + + hwc->state = 0; + riscv_pmu_event_set_period(event); + init_val = local64_read(&hwc->prev_count) & max_period; + rvpmu->ctr_start(event, init_val); + perf_event_update_userpage(event); +} + +static int riscv_pmu_add(struct perf_event *event, int flags) +{ + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events); + struct hw_perf_event *hwc = &event->hw; + int idx; + + idx = rvpmu->ctr_get_idx(event); + if (idx < 0) + return idx; + + hwc->idx = idx; + cpuc->events[idx] = event; + cpuc->n_events++; + hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED; + if (flags & PERF_EF_START) + riscv_pmu_start(event, PERF_EF_RELOAD); + + /* Propagate our changes to the userspace mapping. */ + perf_event_update_userpage(event); + + return 0; +} + +static void riscv_pmu_del(struct perf_event *event, int flags) +{ + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events); + struct hw_perf_event *hwc = &event->hw; + + riscv_pmu_stop(event, PERF_EF_UPDATE); + cpuc->events[hwc->idx] = NULL; + /* The firmware need to reset the counter mapping */ + if (rvpmu->ctr_stop) + rvpmu->ctr_stop(event, RISCV_PMU_STOP_FLAG_RESET); + cpuc->n_events--; + if (rvpmu->ctr_clear_idx) + rvpmu->ctr_clear_idx(event); + perf_event_update_userpage(event); + hwc->idx = -1; +} + +static void riscv_pmu_read(struct perf_event *event) +{ + riscv_pmu_event_update(event); +} + +static int riscv_pmu_event_init(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); + int mapped_event; + u64 event_config = 0; + uint64_t cmask; + + hwc->flags = 0; + mapped_event = rvpmu->event_map(event, &event_config); + if (mapped_event < 0) { + pr_debug("event %x:%llx not supported\n", event->attr.type, + event->attr.config); + return mapped_event; + } + + /* + * idx is set to -1 because the index of a general event should not be + * decided until binding to some counter in pmu->add(). + * config will contain the information about counter CSR + * the idx will contain the counter index + */ + hwc->config = event_config; + hwc->idx = -1; + hwc->event_base = mapped_event; + + if (!is_sampling_event(event)) { + /* + * For non-sampling runs, limit the sample_period to half + * of the counter width. That way, the new counter value + * is far less likely to overtake the previous one unless + * you have some serious IRQ latency issues. + */ + cmask = riscv_pmu_ctr_get_width_mask(event); + hwc->sample_period = cmask >> 1; + hwc->last_period = hwc->sample_period; + local64_set(&hwc->period_left, hwc->sample_period); + } + + return 0; +} + +struct riscv_pmu *riscv_pmu_alloc(void) +{ + struct riscv_pmu *pmu; + int cpuid, i; + struct cpu_hw_events *cpuc; + + pmu = kzalloc(sizeof(*pmu), GFP_KERNEL); + if (!pmu) + goto out; + + pmu->hw_events = alloc_percpu_gfp(struct cpu_hw_events, GFP_KERNEL); + if (!pmu->hw_events) { + pr_info("failed to allocate per-cpu PMU data.\n"); + goto out_free_pmu; + } + + for_each_possible_cpu(cpuid) { + cpuc = per_cpu_ptr(pmu->hw_events, cpuid); + cpuc->n_events = 0; + for (i = 0; i < RISCV_MAX_COUNTERS; i++) + cpuc->events[i] = NULL; + } + pmu->pmu = (struct pmu) { + .event_init = riscv_pmu_event_init, + .add = riscv_pmu_add, + .del = riscv_pmu_del, + .start = riscv_pmu_start, + .stop = riscv_pmu_stop, + .read = riscv_pmu_read, + }; + + return pmu; + +out_free_pmu: + kfree(pmu); +out: + return NULL; +} |