This patch provide a basic PMU, riscv_base_pmu, which supports two general hardware event, instructions and cycles. Furthermore, this PMU serves as a reference implementation to ease the portings in the future. riscv_base_pmu should be able to run on any RISC-V machine that conforms to the Priv-Spec. Note that the latest qemu model hasn't fully support a proper behavior of Priv-Spec 1.10 yet, but work around should be easy with very small fixes. Please check https://github.com/riscv/riscv-qemu/pull/115 for future updates. Cc: Nick Hu <nickhu@xxxxxxxxxxxxx> Cc: Greentime Hu <greentime@xxxxxxxxxxxxx> Signed-off-by: Alan Kao <alankao@xxxxxxxxxxxxx> --- arch/riscv/Kconfig | 12 + arch/riscv/include/asm/perf_event.h | 76 +++++- arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/perf_event.c | 468 ++++++++++++++++++++++++++++++++++++ 4 files changed, 553 insertions(+), 4 deletions(-) create mode 100644 arch/riscv/kernel/perf_event.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index c22ebe08e902..3fbf19456c9a 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -203,6 +203,18 @@ config RISCV_ISA_C config RISCV_ISA_A def_bool y +menu "PMU type" + depends on PERF_EVENTS + +config RISCV_BASE_PMU + bool "Base Performance Monitoring Unit" + def_bool y + help + A base PMU that serves as a reference implementation and has limited + feature of perf. + +endmenu + endmenu menu "Kernel type" diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h index e13d2ff29e83..98e2efb02d25 100644 --- a/arch/riscv/include/asm/perf_event.h +++ b/arch/riscv/include/asm/perf_event.h @@ -1,13 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0 */ /* * Copyright (C) 2018 SiFive + * Copyright (C) 2018 Andes Technology Corporation * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public Licence - * as published by the Free Software Foundation; either version - * 2 of the Licence, or (at your option) any later version. */ #ifndef _ASM_RISCV_PERF_EVENT_H #define _ASM_RISCV_PERF_EVENT_H +#include <linux/perf_event.h> +#include <linux/ptrace.h> + +#define RISCV_BASE_COUNTERS 2 + +/* + * The RISCV_MAX_COUNTERS parameter should be specified. + */ + +#ifdef CONFIG_RISCV_BASE_PMU +#define RISCV_MAX_COUNTERS 2 +#endif + +#ifndef RISCV_MAX_COUNTERS +#error "Please provide a valid RISCV_MAX_COUNTERS for the PMU." +#endif + +/* + * These are the indexes of bits in counteren register *minus* 1, + * except for cycle. It would be coherent if it can directly mapped + * to counteren bit definition, but there is a *time* register at + * counteren[1]. Per-cpu structure is scarce resource here. + * + * According to the spec, an implementation can support counter up to + * mhpmcounter31, but many high-end processors has at most 6 general + * PMCs, we give the definition to MHPMCOUNTER8 here. + */ +#define RISCV_PMU_CYCLE 0 +#define RISCV_PMU_INSTRET 1 +#define RISCV_PMU_MHPMCOUNTER3 2 +#define RISCV_PMU_MHPMCOUNTER4 3 +#define RISCV_PMU_MHPMCOUNTER5 4 +#define RISCV_PMU_MHPMCOUNTER6 5 +#define RISCV_PMU_MHPMCOUNTER7 6 +#define RISCV_PMU_MHPMCOUNTER8 7 + +#define RISCV_OP_UNSUPP (-EOPNOTSUPP) + +struct cpu_hw_events { + /* # currently enabled events*/ + int n_events; + /* currently enabled events */ + struct perf_event *events[RISCV_MAX_COUNTERS]; + /* vendor-defined PMU data */ + void *platform; +}; + +struct riscv_pmu { + struct pmu *pmu; + + /* generic hw/cache events table */ + const int *hw_events; + const int (*cache_events)[PERF_COUNT_HW_CACHE_MAX] + [PERF_COUNT_HW_CACHE_OP_MAX] + [PERF_COUNT_HW_CACHE_RESULT_MAX]; + /* method used to map hw/cache events */ + int (*map_hw_event)(u64 config); + int (*map_cache_event)(u64 config); + + /* max generic hw events in map */ + int max_events; + /* number total counters, 2(base) + x(general) */ + int num_counters; + /* the width of the counter */ + int counter_width; + + /* vendor-defined PMU features */ + void *platform; +}; + #endif /* _ASM_RISCV_PERF_EVENT_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index ffa439d4a364..f50d19816757 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -39,5 +39,6 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o +obj-$(CONFIG_PERF_EVENTS) += perf_event.o clean: diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c new file mode 100644 index 000000000000..cac4abd0a884 --- /dev/null +++ b/arch/riscv/kernel/perf_event.c @@ -0,0 +1,468 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2008 Thomas Gleixner <tglx@xxxxxxxxxxxxx> + * 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@xxxxxxxxx> + * 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 <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 */ +} + +/* + * 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_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_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_stop(event, PERF_EF_UPDATE); + perf_event_update_userpage(event); +} + +/* + * Interrupt + */ + +static DEFINE_MUTEX(pmc_reserve_mutex); +typedef void (*perf_irq_t)(void *riscv_perf_irq); +perf_irq_t perf_irq; + +void riscv_pmu_handle_irq(void *riscv_perf_irq) +{ +} + +static perf_irq_t reserve_pmc_hardware(void) +{ + perf_irq_t old; + + mutex_lock(&pmc_reserve_mutex); + old = perf_irq; + perf_irq = &riscv_pmu_handle_irq; + mutex_unlock(&pmc_reserve_mutex); + + return old; +} + +void release_pmc_hardware(void) +{ + mutex_lock(&pmc_reserve_mutex); + perf_irq = NULL; + mutex_unlock(&pmc_reserve_mutex); +} + +/* + * Event Initialization + */ + +static atomic_t riscv_active_events; + +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; + perf_irq_t old_irq_handler = NULL; + int code; + + if (atomic_inc_return(&riscv_active_events) == 1) + old_irq_handler = reserve_pmc_hardware(); + + if (old_irq_handler) { + pr_warn("PMC hardware busy (reserved by oprofile)\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, +}; + +struct pmu * __weak __init riscv_init_platform_pmu(void) +{ + riscv_pmu = &riscv_base_pmu; + return riscv_pmu->pmu; +} + +int __init init_hw_perf_events(void) +{ + struct pmu *pmu = riscv_init_platform_pmu(); + + perf_irq = NULL; + perf_pmu_register(pmu, "cpu", PERF_TYPE_RAW); + return 0; +} +arch_initcall(init_hw_perf_events); -- 2.16.2 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
