[v5 1/9] RISC-V: Remove the current perf implementation
Anup Patel
anup at brainfault.org
Mon Jan 17 07:58:03 PST 2022
On Sat, Dec 25, 2021 at 11:17 AM Atish Patra <atishp at atishpatra.org> wrote:
>
> From: Atish Patra <atish.patra at wdc.com>
>
> The current perf implementation in RISC-V is not very useful as it can not
> count any events other than cycle/instructions. Moreover, perf record
> can not be used or the events can not be started or stopped.
>
> Remove the implementation now for a better platform driver in future
> that will implement most of the missing functionality.
>
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> Signed-off-by: Atish Patra <atishp at rivosinc.com>
Looks good to me.
Reviewed-by: Anup Patel <anup at brainfault.org>
Regards,
Anup
> ---
> arch/riscv/Kconfig | 13 -
> arch/riscv/include/asm/perf_event.h | 72 -----
> arch/riscv/kernel/Makefile | 1 -
> arch/riscv/kernel/perf_event.c | 485 ----------------------------
> 4 files changed, 571 deletions(-)
> delete mode 100644 arch/riscv/kernel/perf_event.c
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index c79955655fa4..c4afe2c8ff03 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -360,19 +360,6 @@ config RISCV_ISA_C
>
> If you don't know what to do here, say Y.
>
> -menu "supported 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. It can run on any RISC-V machines so serves as the
> - fallback, but this option can also be disable to reduce kernel size.
> -
> -endmenu
> -
> config FPU
> bool "FPU support"
> default y
> diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
> index 062efd3a1d5d..d42c901f9a97 100644
> --- a/arch/riscv/include/asm/perf_event.h
> +++ b/arch/riscv/include/asm/perf_event.h
> @@ -9,77 +9,5 @@
> #define _ASM_RISCV_PERF_EVENT_H
>
> #include <linux/perf_event.h>
> -#include <linux/ptrace.h>
> -#include <linux/interrupt.h>
> -
> -#ifdef CONFIG_RISCV_BASE_PMU
> -#define RISCV_BASE_COUNTERS 2
> -
> -/*
> - * The RISCV_MAX_COUNTERS parameter should be specified.
> - */
> -
> -#define RISCV_MAX_COUNTERS 2
> -
> -/*
> - * 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;
> -
> - irqreturn_t (*handle_irq)(int irq_num, void *dev);
> - int irq;
> -};
> -
> -#endif
> -#ifdef CONFIG_PERF_EVENTS
> #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
> -#endif
> -
> #endif /* _ASM_RISCV_PERF_EVENT_H */
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index 3397ddac1a30..e66870a4422f 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -50,7 +50,6 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o
> obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o
> obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o
>
> -obj-$(CONFIG_RISCV_BASE_PMU) += perf_event.o
> obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o
> obj-$(CONFIG_HAVE_PERF_REGS) += perf_regs.o
> obj-$(CONFIG_RISCV_SBI) += sbi.o
> diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c
> deleted file mode 100644
> index c835f0362d94..000000000000
> --- a/arch/riscv/kernel/perf_event.c
> +++ /dev/null
> @@ -1,485 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -/*
> - * Copyright (C) 2008 Thomas Gleixner <tglx at 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 at 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/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];
> -}
> -
> -static 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(CSR_CYCLE);
> - break;
> - case RISCV_PMU_INSTRET:
> - val = csr_read(CSR_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);
> -
> -static 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;
> -}
> -
> -static 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 */ }
> -};
> -
> -static 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;
> - of_node_put(node);
> - }
> -
> - perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW);
> - return 0;
> -}
> -arch_initcall(init_hw_perf_events);
> --
> 2.33.1
>
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