diff options
Diffstat (limited to 'arch/riscv/kernel/perf_event.c')
| -rw-r--r-- | arch/riscv/kernel/perf_event.c | 485 |
1 files changed, 485 insertions, 0 deletions
diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c new file mode 100644 index 0000000..b0e10c4 --- /dev/null +++ b/arch/riscv/kernel/perf_event.c @@ -0,0 +1,485 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de> + * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar + * Copyright (C) 2009 Jaswinder Singh Rajput + * Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter + * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra + * Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com> + * Copyright (C) 2009 Google, Inc., Stephane Eranian + * Copyright 2014 Tilera Corporation. All Rights Reserved. + * Copyright (C) 2018 Andes Technology Corporation + * + * Perf_events support for RISC-V platforms. + * + * Since the spec. (as of now, Priv-Spec 1.10) does not provide enough + * functionality for perf event to fully work, this file provides + * the very basic framework only. + * + * For platform portings, please check Documentations/riscv/pmu.txt. + * + * The Copyright line includes x86 and tile ones. + */ + +#include <linux/kprobes.h> +#include <linux/kernel.h> +#include <linux/kdebug.h> +#include <linux/mutex.h> +#include <linux/bitmap.h> +#include <linux/irq.h> +#include <linux/interrupt.h> +#include <linux/perf_event.h> +#include <linux/atomic.h> +#include <linux/of.h> +#include <asm/perf_event.h> + +static const struct riscv_pmu *riscv_pmu __read_mostly; +static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events); + +/* + * Hardware & cache maps and their methods + */ + +static const int riscv_hw_event_map[] = { + [PERF_COUNT_HW_CPU_CYCLES] = RISCV_PMU_CYCLE, + [PERF_COUNT_HW_INSTRUCTIONS] = RISCV_PMU_INSTRET, + [PERF_COUNT_HW_CACHE_REFERENCES] = RISCV_OP_UNSUPP, + [PERF_COUNT_HW_CACHE_MISSES] = RISCV_OP_UNSUPP, + [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = RISCV_OP_UNSUPP, + [PERF_COUNT_HW_BRANCH_MISSES] = RISCV_OP_UNSUPP, + [PERF_COUNT_HW_BUS_CYCLES] = RISCV_OP_UNSUPP, +}; + +#define C(x) PERF_COUNT_HW_CACHE_##x +static const int riscv_cache_event_map[PERF_COUNT_HW_CACHE_MAX] +[PERF_COUNT_HW_CACHE_OP_MAX] +[PERF_COUNT_HW_CACHE_RESULT_MAX] = { + [C(L1D)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, + [C(L1I)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, + [C(LL)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, + [C(DTLB)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, + [C(ITLB)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, + [C(BPU)] = { + [C(OP_READ)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_WRITE)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + [C(OP_PREFETCH)] = { + [C(RESULT_ACCESS)] = RISCV_OP_UNSUPP, + [C(RESULT_MISS)] = RISCV_OP_UNSUPP, + }, + }, +}; + +static int riscv_map_hw_event(u64 config) +{ + if (config >= riscv_pmu->max_events) + return -EINVAL; + + return riscv_pmu->hw_events[config]; +} + +int riscv_map_cache_decode(u64 config, unsigned int *type, + unsigned int *op, unsigned int *result) +{ + return -ENOENT; +} + +static int riscv_map_cache_event(u64 config) +{ + unsigned int type, op, result; + int err = -ENOENT; + int code; + + err = riscv_map_cache_decode(config, &type, &op, &result); + if (!riscv_pmu->cache_events || err) + return err; + + if (type >= PERF_COUNT_HW_CACHE_MAX || + op >= PERF_COUNT_HW_CACHE_OP_MAX || + result >= PERF_COUNT_HW_CACHE_RESULT_MAX) + return -EINVAL; + + code = (*riscv_pmu->cache_events)[type][op][result]; + if (code == RISCV_OP_UNSUPP) + return -EINVAL; + + return code; +} + +/* + * Low-level functions: reading/writing counters + */ + +static inline u64 read_counter(int idx) +{ + u64 val = 0; + + switch (idx) { + case RISCV_PMU_CYCLE: + val = csr_read(cycle); + break; + case RISCV_PMU_INSTRET: + val = csr_read(instret); + break; + default: + WARN_ON_ONCE(idx < 0 || idx > RISCV_MAX_COUNTERS); + return -EINVAL; + } + + return val; +} + +static inline void write_counter(int idx, u64 value) +{ + /* currently not supported */ + WARN_ON_ONCE(1); +} + +/* + * pmu->read: read and update the counter + * + * Other architectures' implementation often have a xxx_perf_event_update + * routine, which can return counter values when called in the IRQ, but + * return void when being called by the pmu->read method. + */ +static void riscv_pmu_read(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + u64 prev_raw_count, new_raw_count; + u64 oldval; + int idx = hwc->idx; + u64 delta; + + do { + prev_raw_count = local64_read(&hwc->prev_count); + new_raw_count = read_counter(idx); + + oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count, + new_raw_count); + } while (oldval != prev_raw_count); + + /* + * delta is the value to update the counter we maintain in the kernel. + */ + delta = (new_raw_count - prev_raw_count) & + ((1ULL << riscv_pmu->counter_width) - 1); + local64_add(delta, &event->count); + /* + * Something like local64_sub(delta, &hwc->period_left) here is + * needed if there is an interrupt for perf. + */ +} + +/* + * State transition functions: + * + * stop()/start() & add()/del() + */ + +/* + * pmu->stop: stop the counter + */ +static void riscv_pmu_stop(struct perf_event *event, int flags) +{ + struct hw_perf_event *hwc = &event->hw; + + WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED); + hwc->state |= PERF_HES_STOPPED; + + if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) { + riscv_pmu->pmu->read(event); + hwc->state |= PERF_HES_UPTODATE; + } +} + +/* + * pmu->start: start the event. + */ +static void riscv_pmu_start(struct perf_event *event, int flags) +{ + struct hw_perf_event *hwc = &event->hw; + + 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)); + + /* + * Set the counter to the period to the next interrupt here, + * if you have any. + */ + } + + hwc->state = 0; + perf_event_update_userpage(event); + + /* + * Since we cannot write to counters, this serves as an initialization + * to the delta-mechanism in pmu->read(); otherwise, the delta would be + * wrong when pmu->read is called for the first time. + */ + local64_set(&hwc->prev_count, read_counter(hwc->idx)); +} + +/* + * pmu->add: add the event to PMU. + */ +static int riscv_pmu_add(struct perf_event *event, int flags) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + struct hw_perf_event *hwc = &event->hw; + + if (cpuc->n_events == riscv_pmu->num_counters) + return -ENOSPC; + + /* + * We don't have general conunters, so no binding-event-to-counter + * process here. + * + * Indexing using hwc->config generally not works, since config may + * contain extra information, but here the only info we have in + * hwc->config is the event index. + */ + hwc->idx = hwc->config; + cpuc->events[hwc->idx] = event; + cpuc->n_events++; + + hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED; + + if (flags & PERF_EF_START) + riscv_pmu->pmu->start(event, PERF_EF_RELOAD); + + return 0; +} + +/* + * pmu->del: delete the event from PMU. + */ +static void riscv_pmu_del(struct perf_event *event, int flags) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + struct hw_perf_event *hwc = &event->hw; + + cpuc->events[hwc->idx] = NULL; + cpuc->n_events--; + riscv_pmu->pmu->stop(event, PERF_EF_UPDATE); + perf_event_update_userpage(event); +} + +/* + * Interrupt: a skeletion for reference. + */ + +static DEFINE_MUTEX(pmc_reserve_mutex); + +irqreturn_t riscv_base_pmu_handle_irq(int irq_num, void *dev) +{ + return IRQ_NONE; +} + +static int reserve_pmc_hardware(void) +{ + int err = 0; + + mutex_lock(&pmc_reserve_mutex); + if (riscv_pmu->irq >= 0 && riscv_pmu->handle_irq) { + err = request_irq(riscv_pmu->irq, riscv_pmu->handle_irq, + IRQF_PERCPU, "riscv-base-perf", NULL); + } + mutex_unlock(&pmc_reserve_mutex); + + return err; +} + +void release_pmc_hardware(void) +{ + mutex_lock(&pmc_reserve_mutex); + if (riscv_pmu->irq >= 0) + free_irq(riscv_pmu->irq, NULL); + mutex_unlock(&pmc_reserve_mutex); +} + +/* + * Event Initialization/Finalization + */ + +static atomic_t riscv_active_events = ATOMIC_INIT(0); + +static void riscv_event_destroy(struct perf_event *event) +{ + if (atomic_dec_return(&riscv_active_events) == 0) + release_pmc_hardware(); +} + +static int riscv_event_init(struct perf_event *event) +{ + struct perf_event_attr *attr = &event->attr; + struct hw_perf_event *hwc = &event->hw; + int err; + int code; + + if (atomic_inc_return(&riscv_active_events) == 1) { + err = reserve_pmc_hardware(); + + if (err) { + pr_warn("PMC hardware not available\n"); + atomic_dec(&riscv_active_events); + return -EBUSY; + } + } + + switch (event->attr.type) { + case PERF_TYPE_HARDWARE: + code = riscv_pmu->map_hw_event(attr->config); + break; + case PERF_TYPE_HW_CACHE: + code = riscv_pmu->map_cache_event(attr->config); + break; + case PERF_TYPE_RAW: + return -EOPNOTSUPP; + default: + return -ENOENT; + } + + event->destroy = riscv_event_destroy; + if (code < 0) { + event->destroy(event); + return code; + } + + /* + * idx is set to -1 because the index of a general event should not be + * decided until binding to some counter in pmu->add(). + * + * But since we don't have such support, later in pmu->add(), we just + * use hwc->config as the index instead. + */ + hwc->config = code; + hwc->idx = -1; + + return 0; +} + +/* + * Initialization + */ + +static struct pmu min_pmu = { + .name = "riscv-base", + .event_init = riscv_event_init, + .add = riscv_pmu_add, + .del = riscv_pmu_del, + .start = riscv_pmu_start, + .stop = riscv_pmu_stop, + .read = riscv_pmu_read, +}; + +static const struct riscv_pmu riscv_base_pmu = { + .pmu = &min_pmu, + .max_events = ARRAY_SIZE(riscv_hw_event_map), + .map_hw_event = riscv_map_hw_event, + .hw_events = riscv_hw_event_map, + .map_cache_event = riscv_map_cache_event, + .cache_events = &riscv_cache_event_map, + .counter_width = 63, + .num_counters = RISCV_BASE_COUNTERS + 0, + .handle_irq = &riscv_base_pmu_handle_irq, + + /* This means this PMU has no IRQ. */ + .irq = -1, +}; + +static const struct of_device_id riscv_pmu_of_ids[] = { + {.compatible = "riscv,base-pmu", .data = &riscv_base_pmu}, + { /* sentinel value */ } +}; + +int __init init_hw_perf_events(void) +{ + struct device_node *node = of_find_node_by_type(NULL, "pmu"); + const struct of_device_id *of_id; + + riscv_pmu = &riscv_base_pmu; + + if (node) { + of_id = of_match_node(riscv_pmu_of_ids, node); + + if (of_id) + riscv_pmu = of_id->data; + } + + perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW); + return 0; +} +arch_initcall(init_hw_perf_events); |
