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Date: Tue, 16 Aug 2022 18:07:23 +0800
From: Qi Hu <huqi@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>
Cc: Huacai Chen <chenhuacai@...ngson.cn>,
Arnd Bergmann <arnd@...db.de>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>, loongarch@...ts.linux.dev,
linux-arch <linux-arch@...r.kernel.org>,
Xuefeng Li <lixuefeng@...ngson.cn>,
Guo Ren <guoren@...nel.org>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
linux-perf-users@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] LoongArch: Add perf events support
On 2022/8/16 16:18, Huacai Chen wrote:
> Hi, Xuerui,
>
> On Tue, Aug 16, 2022 at 1:46 PM WANG Xuerui <kernel@...0n.name> wrote:
>> On 2022/8/15 20:47, Huacai Chen wrote:
>>> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
>>> ---
>>> arch/loongarch/Kconfig | 2 +
>>> arch/loongarch/include/uapi/asm/perf_regs.h | 40 +
>>> arch/loongarch/kernel/Makefile | 2 +
>>> arch/loongarch/kernel/perf_event.c | 909 ++++++++++++++++++++
>>> arch/loongarch/kernel/perf_regs.c | 50 ++
>>> 5 files changed, 1003 insertions(+)
>>> create mode 100644 arch/loongarch/include/uapi/asm/perf_regs.h
>>> create mode 100644 arch/loongarch/kernel/perf_event.c
>>> create mode 100644 arch/loongarch/kernel/perf_regs.c
>> The code seems mostly ripped from arch/mips/kernel/perf_event_mipsxx.c.
>> I reviewed about half of the code then suddenly realized I might be
>> looking at MIPS code, given some of the English strings there seemed way
>> too "natural"...
>>
>> But unfortunately, at least for 3A5000 whose micro-architecture is
>> largely shared with the MIPS-implementing 3A4000, it seems inevitable to
>> involve some of the more MIPS-looking logic. The 1st-generation LA
>> privileged architecture is way too much MIPS-like after all, so if we
>> want any support for the 3A5000 we'd have to include this.
>>
>>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>>> index 24665808cf3d..9478f9646fa5 100644
>>> --- a/arch/loongarch/Kconfig
>>> +++ b/arch/loongarch/Kconfig
>>> @@ -93,6 +93,8 @@ config LOONGARCH
>>> select HAVE_NMI
>>> select HAVE_PCI
>>> select HAVE_PERF_EVENTS
>>> + select HAVE_PERF_REGS
>>> + select HAVE_PERF_USER_STACK_DUMP
>>> select HAVE_REGS_AND_STACK_ACCESS_API
>>> select HAVE_RSEQ
>>> select HAVE_SETUP_PER_CPU_AREA if NUMA
>>> diff --git a/arch/loongarch/include/uapi/asm/perf_regs.h b/arch/loongarch/include/uapi/asm/perf_regs.h
>>> new file mode 100644
>>> index 000000000000..9943d418e01d
>>> --- /dev/null
>>> +++ b/arch/loongarch/include/uapi/asm/perf_regs.h
>>> @@ -0,0 +1,40 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
>>> +#ifndef _ASM_LOONGARCH_PERF_REGS_H
>>> +#define _ASM_LOONGARCH_PERF_REGS_H
>>> +
>>> +enum perf_event_loongarch_regs {
>>> + PERF_REG_LOONGARCH_PC,
>>> + PERF_REG_LOONGARCH_R1,
>>> + PERF_REG_LOONGARCH_R2,
>>> + PERF_REG_LOONGARCH_R3,
>>> + PERF_REG_LOONGARCH_R4,
>>> + PERF_REG_LOONGARCH_R5,
>>> + PERF_REG_LOONGARCH_R6,
>>> + PERF_REG_LOONGARCH_R7,
>>> + PERF_REG_LOONGARCH_R8,
>>> + PERF_REG_LOONGARCH_R9,
>>> + PERF_REG_LOONGARCH_R10,
>>> + PERF_REG_LOONGARCH_R11,
>>> + PERF_REG_LOONGARCH_R12,
>>> + PERF_REG_LOONGARCH_R13,
>>> + PERF_REG_LOONGARCH_R14,
>>> + PERF_REG_LOONGARCH_R15,
>>> + PERF_REG_LOONGARCH_R16,
>>> + PERF_REG_LOONGARCH_R17,
>>> + PERF_REG_LOONGARCH_R18,
>>> + PERF_REG_LOONGARCH_R19,
>>> + PERF_REG_LOONGARCH_R20,
>>> + PERF_REG_LOONGARCH_R21,
>>> + PERF_REG_LOONGARCH_R22,
>>> + PERF_REG_LOONGARCH_R23,
>>> + PERF_REG_LOONGARCH_R24,
>>> + PERF_REG_LOONGARCH_R25,
>>> + PERF_REG_LOONGARCH_R26,
>>> + PERF_REG_LOONGARCH_R27,
>>> + PERF_REG_LOONGARCH_R28,
>>> + PERF_REG_LOONGARCH_R29,
>>> + PERF_REG_LOONGARCH_R30,
>>> + PERF_REG_LOONGARCH_R31,
>>> + PERF_REG_LOONGARCH_MAX = PERF_REG_LOONGARCH_R31 + 1,
>> No need for this "PERF_REG_LOONGARCH_R31 + 1" because it's what happens
>> without the assignment anyway?
> PERF_REG_LOONGARCH_MAX is used in perf_events.c
I think Xuerui wants to say "PERF_REG_LOONGARCH_MAX" is enough, and "=
PERF_REG_LOONGARCH_R31 + 1" can be removed.
Qi
>>> +};
>>> +#endif /* _ASM_LOONGARCH_PERF_REGS_H */
>>> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
>>> index e5be17009fe8..a213e994db68 100644
>>> --- a/arch/loongarch/kernel/Makefile
>>> +++ b/arch/loongarch/kernel/Makefile
>>> @@ -26,4 +26,6 @@ obj-$(CONFIG_NUMA) += numa.o
>>> obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>>> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>>>
>>> +obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
>>> +
>>> CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
>>> diff --git a/arch/loongarch/kernel/perf_event.c b/arch/loongarch/kernel/perf_event.c
>>> new file mode 100644
>>> index 000000000000..00cdbcebaf80
>>> --- /dev/null
>>> +++ b/arch/loongarch/kernel/perf_event.c
>>> @@ -0,0 +1,909 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Linux performance counter support for LoongArch.
>> Please indicate its MIPS origin and copyright info ;-)
> OK, thanks.
>
>>> + *
>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>>> + */
>>> +
>>> +#include <linux/cpumask.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/smp.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/perf_event.h>
>>> +#include <linux/uaccess.h>
>>> +#include <linux/sched/task_stack.h>
>>> +
>>> +#include <asm/irq.h>
>>> +#include <asm/irq_regs.h>
>>> +#include <asm/stacktrace.h>
>>> +#include <asm/unwind.h>
>>> +
>>> +/*
>>> + * Get the return address for a single stackframe and return a pointer to the
>>> + * next frame tail.
>>> + */
>>> +static unsigned long
>>> +user_backtrace(struct perf_callchain_entry_ctx *entry, unsigned long fp)
>>> +{
>>> + struct stack_frame buftail;
>>> + unsigned long err;
>>> + unsigned long __user *user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
>>> +
>>> + /* Also check accessibility of one struct frame_tail beyond */
>>> + if (!access_ok(user_frame_tail, sizeof(buftail)))
>>> + return 0;
>>> +
>>> + pagefault_disable();
>>> + err = __copy_from_user_inatomic(&buftail, user_frame_tail, sizeof(buftail));
>>> + pagefault_enable();
>>> +
>>> + if (err || (unsigned long)user_frame_tail >= buftail.fp)
>>> + return 0;
>>> +
>>> + perf_callchain_store(entry, buftail.ra);
>>> +
>>> + return buftail.fp;
>>> +}
>>> +
>>> +void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
>>> + struct pt_regs *regs)
>>> +{
>>> + unsigned long fp;
>>> +
>>> + if (perf_guest_state()) {
>>> + /* We don't support guest os callchain now */
>>> + return;
>>> + }
>>> +
>>> + perf_callchain_store(entry, regs->csr_era);
>>> +
>>> + fp = regs->regs[22];
>>> +
>>> + while (entry->nr < entry->max_stack && fp && !((unsigned long)fp & 0xf))
>>> + fp = user_backtrace(entry, fp);
>>> +}
>>> +
>>> +void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
>>> + struct pt_regs *regs)
>>> +{
>>> + struct unwind_state state;
>>> + unsigned long addr;
>>> +
>>> + for (unwind_start(&state, current, regs);
>>> + !unwind_done(&state); unwind_next_frame(&state)) {
>>> + addr = unwind_get_return_address(&state);
>>> + if (!addr || perf_callchain_store(entry, addr))
>>> + return;
>>> + }
>>> +}
>>> +
>>> +#define LOONGARCH_MAX_HWEVENTS 4
>>> +
>>> +struct cpu_hw_events {
>>> + /* Array of events on this cpu. */
>>> + struct perf_event *events[LOONGARCH_MAX_HWEVENTS];
>>> +
>>> + /*
>>> + * Set the bit (indexed by the counter number) when the counter
>>> + * is used for an event.
>>> + */
>>> + unsigned long used_mask[BITS_TO_LONGS(LOONGARCH_MAX_HWEVENTS)];
>>> +
>>> + /*
>>> + * Software copy of the control register for each performance counter.
>>> + * LoongArch CPUs vary in performance counters. They use this differently,
>>> + * and even may not use it.
>> I can't easily make sense of the paragraph. "Software copy" could mean
>> "Saved copy", but how do "use differently" and "even may not use it"
>> mean? For the latter I can't deduce if it's originally "some even may
>> not exist" in someone's head, and for the former I can't imagine what's
>> the possible cases and why we would care.
>>
>> Maybe explain a little bit more?
> I think we should remove those useless lines.
>
>>> + */
>>> + unsigned int saved_ctrl[LOONGARCH_MAX_HWEVENTS];
>>> +};
>>> +static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
>>> + .saved_ctrl = {0},
>>> +};
>>> +
>>> +/* The description of LoongArch performance events. */
>>> +struct loongarch_perf_event {
>>> + unsigned int event_id;
>>> +};
>>> +
>>> +static struct loongarch_perf_event raw_event;
>>> +static DEFINE_MUTEX(raw_event_mutex);
>>> +
>>> +#define C(x) PERF_COUNT_HW_CACHE_##x
>>> +#define HW_OP_UNSUPPORTED 0xffffffff
>>> +#define CACHE_OP_UNSUPPORTED 0xffffffff
>>> +
>>> +#define PERF_MAP_ALL_UNSUPPORTED \
>>> + [0 ... PERF_COUNT_HW_MAX - 1] = {HW_OP_UNSUPPORTED}
>>> +
>>> +#define PERF_CACHE_MAP_ALL_UNSUPPORTED \
>>> +[0 ... C(MAX) - 1] = { \
>>> + [0 ... C(OP_MAX) - 1] = { \
>>> + [0 ... C(RESULT_MAX) - 1] = {CACHE_OP_UNSUPPORTED}, \
>>> + }, \
>>> +}
>>> +
>>> +struct loongarch_pmu {
>>> + u64 max_period;
>>> + u64 valid_count;
>>> + u64 overflow;
>>> + const char *name;
>>> + u64 (*read_counter)(unsigned int idx);
>>> + void (*write_counter)(unsigned int idx, u64 val);
>>> + const struct loongarch_perf_event *(*map_raw_event)(u64 config);
>>> + const struct loongarch_perf_event (*general_event_map)[PERF_COUNT_HW_MAX];
>>> + const struct loongarch_perf_event (*cache_event_map)
>>> + [PERF_COUNT_HW_CACHE_MAX]
>>> + [PERF_COUNT_HW_CACHE_OP_MAX]
>>> + [PERF_COUNT_HW_CACHE_RESULT_MAX];
>> Apparently general_event_map and cache_event_map are not function
>> pointers? So the parens around the field name should be removed.
> They are not function pointers, but "array pointers", but we shouldn't
> change them to "array to pointers"..
>
>>> + unsigned int num_counters;
>>> +};
>>> +
>>> +static struct loongarch_pmu loongarch_pmu;
>>> +
>>> +#define M_PERFCTL_EVENT(event) (event & CSR_PERFCTRL_EVENT)
>>> +
>>> +#define M_PERFCTL_COUNT_EVENT_WHENEVER (CSR_PERFCTRL_PLV0 | \
>>> + CSR_PERFCTRL_PLV1 | \
>>> + CSR_PERFCTRL_PLV2 | \
>>> + CSR_PERFCTRL_PLV3 | \
>>> + CSR_PERFCTRL_IE)
>>> +
>>> +#define M_PERFCTL_CONFIG_MASK 0x1f0000
>>> +
>>> +#define CNTR_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
>> Isn't this just GENMASK(n - 1, 0)?
> Yes, you are right.
>
>>> +
>>> +static void resume_local_counters(void);
>>> +static void pause_local_counters(void);
>>> +
>>> +static u64 loongarch_pmu_read_counter(unsigned int idx)
>>> +{
>>> + u64 val = -1;
>>> +
>>> + switch (idx) {
>>> + case 0:
>>> + val = read_csr_perfcntr0();
>>> + break;
>>> + case 1:
>>> + val = read_csr_perfcntr1();
>>> + break;
>>> + case 2:
>>> + val = read_csr_perfcntr2();
>>> + break;
>>> + case 3:
>>> + val = read_csr_perfcntr3();
>>> + break;
>>> + default:
>>> + WARN_ONCE(1, "Invalid performance counter number (%d)\n", idx);
>>> + return 0;
>>> + }
>>> +
>>> + return val;
>>> +}
>>> +
>>> +static void loongarch_pmu_write_counter(unsigned int idx, u64 val)
>>> +{
>>> + switch (idx) {
>>> + case 0:
>>> + write_csr_perfcntr0(val);
>>> + return;
>>> + case 1:
>>> + write_csr_perfcntr1(val);
>>> + return;
>>> + case 2:
>>> + write_csr_perfcntr2(val);
>>> + return;
>>> + case 3:
>>> + write_csr_perfcntr3(val);
>>> + return;
>> Want a default branch for this function, similar to the read case?
> Yes, that is needed.
>
>>> + }
>>> +}
>>> +
>>> +static unsigned int loongarch_pmu_read_control(unsigned int idx)
>>> +{
>>> + unsigned int val = -1;
>>> +
>>> + switch (idx) {
>>> + case 0:
>>> + val = read_csr_perfctrl0();
>>> + break;
>>> + case 1:
>>> + val = read_csr_perfctrl1();
>>> + break;
>>> + case 2:
>>> + val = read_csr_perfctrl2();
>>> + break;
>>> + case 3:
>>> + val = read_csr_perfctrl3();
>>> + break;
>>> + default:
>>> + WARN_ONCE(1, "Invalid performance counter number (%d)\n", idx);
>>> + return 0;
>>> + }
>>> +
>>> + return val;
>>> +}
>>> +
>>> +static void loongarch_pmu_write_control(unsigned int idx, unsigned int val)
>>> +{
>>> + switch (idx) {
>>> + case 0:
>>> + write_csr_perfctrl0(val);
>>> + return;
>>> + case 1:
>>> + write_csr_perfctrl1(val);
>>> + return;
>>> + case 2:
>>> + write_csr_perfctrl2(val);
>>> + return;
>>> + case 3:
>>> + write_csr_perfctrl3(val);
>>> + return;
>> Similarly here.
>>
>>> + }
>>> +}
>>> +
>>> +static int loongarch_pmu_alloc_counter(struct cpu_hw_events *cpuc,
>>> + struct hw_perf_event *hwc)
>>> +{
>>> + int i;
>>> +
>>> + for (i = loongarch_pmu.num_counters - 1; i >= 0; i--) {
>>> + if (!test_and_set_bit(i, cpuc->used_mask))
>>> + return i;
>>> + }
>>> +
>>> + return -EAGAIN;
>>> +}
>>> +
>>> +static void loongarch_pmu_enable_event(struct hw_perf_event *evt, int idx)
>>> +{
>>> + struct perf_event *event = container_of(evt, struct perf_event, hw);
>>> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>>> + unsigned int cpu;
>>> +
>>> + WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
>>> +
>>> + cpuc->saved_ctrl[idx] = M_PERFCTL_EVENT(evt->event_base & 0xff) |
>>> + (evt->config_base & M_PERFCTL_CONFIG_MASK) |
>>> + /* Make sure interrupt enabled. */
>>> + CSR_PERFCTRL_IE;
>>> +
>>> + cpu = (event->cpu >= 0) ? event->cpu : smp_processor_id();
>>> +
>>> + pr_debug("Enabling perf counter for CPU%d\n", cpu);
>>> + /*
>>> + * We do not actually let the counter run. Leave it until start().
>>> + */
>>> +}
>>> +
>>> +static void loongarch_pmu_disable_event(int idx)
>>> +{
>>> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>>> + unsigned long flags;
>>> +
>>> + WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
>>> +
>>> + local_irq_save(flags);
>>> + cpuc->saved_ctrl[idx] = loongarch_pmu_read_control(idx) &
>>> + ~M_PERFCTL_COUNT_EVENT_WHENEVER;
>>> + loongarch_pmu_write_control(idx, cpuc->saved_ctrl[idx]);
>>> + local_irq_restore(flags);
>>> +}
>>> +
>>> +static int loongarch_pmu_event_set_period(struct perf_event *event,
>>> + struct hw_perf_event *hwc,
>>> + int idx)
>>> +{
>>> + u64 left = local64_read(&hwc->period_left);
>>> + u64 period = hwc->sample_period;
>>> + int ret = 0;
>>> +
>>> + if (unlikely((left + period) & (1ULL << 63))) {
>>> + /* left underflowed by more than period. */
>>> + left = period;
>>> + local64_set(&hwc->period_left, left);
>>> + hwc->last_period = period;
>>> + ret = 1;
>>> + } else if (unlikely((left + period) <= period)) {
>>> + /* left underflowed by less than period. */
>>> + left += period;
>>> + local64_set(&hwc->period_left, left);
>>> + hwc->last_period = period;
>>> + ret = 1;
>>> + }
>>> +
>>> + if (left > loongarch_pmu.max_period) {
>>> + left = loongarch_pmu.max_period;
>>> + local64_set(&hwc->period_left, left);
>>> + }
>>> +
>>> + local64_set(&hwc->prev_count, loongarch_pmu.overflow - left);
>>> +
>>> + loongarch_pmu.write_counter(idx, loongarch_pmu.overflow - left);
>>> +
>>> + perf_event_update_userpage(event);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static void loongarch_pmu_event_update(struct perf_event *event,
>>> + struct hw_perf_event *hwc,
>>> + int idx)
>>> +{
>>> + u64 delta;
>>> + u64 prev_raw_count, new_raw_count;
>>> +
>>> +again:
>>> + prev_raw_count = local64_read(&hwc->prev_count);
>>> + new_raw_count = loongarch_pmu.read_counter(idx);
>>> +
>>> + if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
>>> + new_raw_count) != prev_raw_count)
>>> + goto again;
>>> +
>>> + delta = new_raw_count - prev_raw_count;
>>> +
>>> + local64_add(delta, &event->count);
>>> + local64_sub(delta, &hwc->period_left);
>>> +}
>>> +
>>> +static void loongarch_pmu_start(struct perf_event *event, int flags)
>>> +{
>>> + struct hw_perf_event *hwc = &event->hw;
>>> +
>>> + if (flags & PERF_EF_RELOAD)
>>> + WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
>>> +
>>> + hwc->state = 0;
>>> +
>>> + /* Set the period for the event. */
>>> + loongarch_pmu_event_set_period(event, hwc, hwc->idx);
>>> +
>>> + /* Enable the event. */
>>> + loongarch_pmu_enable_event(hwc, hwc->idx);
>>> +}
>>> +
>>> +static void loongarch_pmu_stop(struct perf_event *event, int flags)
>>> +{
>>> + struct hw_perf_event *hwc = &event->hw;
>>> +
>>> + if (!(hwc->state & PERF_HES_STOPPED)) {
>>> + /* We are working on a local event. */
>>> + loongarch_pmu_disable_event(hwc->idx);
>>> + barrier();
>>> + loongarch_pmu_event_update(event, hwc, hwc->idx);
>>> + hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>> + }
>>> +}
>>> +
>>> +static int loongarch_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;
>>> + int idx;
>>> + int err = 0;
>>> +
>>> + perf_pmu_disable(event->pmu);
>>> +
>>> + /* To look for a free counter for this event. */
>>> + idx = loongarch_pmu_alloc_counter(cpuc, hwc);
>>> + if (idx < 0) {
>>> + err = idx;
>>> + goto out;
>>> + }
>>> +
>>> + /*
>>> + * If there is an event in the counter we are going to use then
>>> + * make sure it is disabled.
>>> + */
>>> + event->hw.idx = idx;
>>> + loongarch_pmu_disable_event(idx);
>>> + cpuc->events[idx] = event;
>>> +
>>> + hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>> + if (flags & PERF_EF_START)
>>> + loongarch_pmu_start(event, PERF_EF_RELOAD);
>>> +
>>> + /* Propagate our changes to the userspace mapping. */
>>> + perf_event_update_userpage(event);
>>> +
>>> +out:
>>> + perf_pmu_enable(event->pmu);
>>> + return err;
>>> +}
>>> +
>>> +static void loongarch_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;
>>> + int idx = hwc->idx;
>>> +
>>> + WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
>>> +
>>> + loongarch_pmu_stop(event, PERF_EF_UPDATE);
>>> + cpuc->events[idx] = NULL;
>>> + clear_bit(idx, cpuc->used_mask);
>>> +
>>> + perf_event_update_userpage(event);
>>> +}
>>> +
>>> +static void loongarch_pmu_read(struct perf_event *event)
>>> +{
>>> + struct hw_perf_event *hwc = &event->hw;
>>> +
>>> + /* Don't read disabled counters! */
>>> + if (hwc->idx < 0)
>>> + return;
>>> +
>>> + loongarch_pmu_event_update(event, hwc, hwc->idx);
>>> +}
>>> +
>>> +static void loongarch_pmu_enable(struct pmu *pmu)
>>> +{
>>> + resume_local_counters();
>>> +}
>>> +
>>> +static void loongarch_pmu_disable(struct pmu *pmu)
>>> +{
>>> + pause_local_counters();
>>> +}
>>> +
>>> +static atomic_t active_events = ATOMIC_INIT(0);
>>> +static DEFINE_MUTEX(pmu_reserve_mutex);
>>> +
>>> +static void reset_counters(void *arg);
>>> +static int __hw_perf_event_init(struct perf_event *event);
>>> +
>>> +static void hw_perf_event_destroy(struct perf_event *event)
>>> +{
>>> + if (atomic_dec_and_mutex_lock(&active_events,
>>> + &pmu_reserve_mutex)) {
>>> + /*
>>> + * We must not call the destroy function with interrupts
>>> + * disabled.
>>> + */
>>> + on_each_cpu(reset_counters,
>>> + (void *)(long)loongarch_pmu.num_counters, 1);
>>> + mutex_unlock(&pmu_reserve_mutex);
>>> + }
>>> +}
>>> +
>>> +/* This is needed by specific irq handlers in perf_event_*.c */
>>> +static void handle_associated_event(struct cpu_hw_events *cpuc,
>>> + int idx, struct perf_sample_data *data,
>>> + struct pt_regs *regs)
>>> +{
>>> + struct perf_event *event = cpuc->events[idx];
>>> + struct hw_perf_event *hwc = &event->hw;
>>> +
>>> + loongarch_pmu_event_update(event, hwc, idx);
>>> + data->period = event->hw.last_period;
>>> + if (!loongarch_pmu_event_set_period(event, hwc, idx))
>>> + return;
>>> +
>>> + if (perf_event_overflow(event, data, regs))
>>> + loongarch_pmu_disable_event(idx);
>>> +}
>>> +
>>> +static irqreturn_t pmu_handle_irq(int irq, void *dev)
>>> +{
>>> + int handled = IRQ_NONE;
>>> + unsigned int counters = loongarch_pmu.num_counters;
>>> + u64 counter;
>>> + struct pt_regs *regs;
>>> + struct perf_sample_data data;
>>> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>>> +
>>> + /*
>>> + * First we pause the local counters, so that when we are locked
>>> + * here, the counters are all paused. When it gets locked due to
>>> + * perf_disable(), the timer interrupt handler will be delayed.
>>> + *
>>> + * See also loongarch_pmu_start().
>>> + */
>>> + pause_local_counters();
>>> +
>>> + regs = get_irq_regs();
>>> +
>>> + perf_sample_data_init(&data, 0, 0);
>>> +
>>> + switch (counters) {
>>> +#define HANDLE_COUNTER(n) \
>>> + case n + 1: \
>>> + if (test_bit(n, cpuc->used_mask)) { \
>>> + counter = loongarch_pmu.read_counter(n); \
>>> + if (counter & loongarch_pmu.overflow) { \
>>> + handle_associated_event(cpuc, n, &data, regs); \
>>> + handled = IRQ_HANDLED; \
>>> + } \
>>> + }
>>> + HANDLE_COUNTER(3)
>>> + fallthrough;
>>> + HANDLE_COUNTER(2)
>>> + fallthrough;
>>> + HANDLE_COUNTER(1)
>>> + fallthrough;
>>> + HANDLE_COUNTER(0)
>>> + }
>>> +
>>> + resume_local_counters();
>>> +
>>> + /*
>>> + * Do all the work for the pending perf events. We can do this
>>> + * in here because the performance counter interrupt is a regular
>>> + * interrupt, not NMI.
>>> + */
>>> + if (handled == IRQ_HANDLED)
>>> + irq_work_run();
>>> +
>>> + return handled;
>>> +}
>>> +
>>> +static int get_pmc_irq(void)
>>> +{
>>> + struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
>>> +
>>> + if (d)
>>> + return irq_create_mapping(d, EXCCODE_PMC - EXCCODE_INT_START);
>>> +
>>> + return -EINVAL;
>>> +}
>>> +
>>> +static int loongarch_pmu_event_init(struct perf_event *event)
>>> +{
>>> + int r, irq;
>>> + unsigned long flags;
>>> +
>>> + /* does not support taken branch sampling */
>>> + if (has_branch_stack(event))
>>> + return -EOPNOTSUPP;
>>> +
>>> + switch (event->attr.type) {
>>> + case PERF_TYPE_RAW:
>>> + case PERF_TYPE_HARDWARE:
>>> + case PERF_TYPE_HW_CACHE:
>>> + break;
>>> +
>>> + default:
>>> + /* Init it to avoid false validate_group */
>>> + event->hw.event_base = 0xffffffff;
>>> + return -ENOENT;
>>> + }
>>> +
>>> + if (event->cpu >= 0 && !cpu_online(event->cpu))
>>> + return -ENODEV;
>>> +
>>> + irq = get_pmc_irq();
>>> + flags = IRQF_PERCPU | IRQF_NOBALANCING | IRQF_NO_THREAD | IRQF_NO_SUSPEND | IRQF_SHARED;
>>> + if (!atomic_inc_not_zero(&active_events)) {
>>> + mutex_lock(&pmu_reserve_mutex);
>>> + if (atomic_read(&active_events) == 0) {
>>> + r = request_irq(irq, pmu_handle_irq,
>>> + flags, "Perf_PMU", &loongarch_pmu);
>>> + if (r < 0) {
>>> + pr_warn("PMU IRQ request failed\n");
>>> + return -ENODEV;
>>> + }
>>> + }
>>> + atomic_inc(&active_events);
>>> + mutex_unlock(&pmu_reserve_mutex);
>>> + }
>>> +
>>> + return __hw_perf_event_init(event);
>>> +}
>>> +
>>> +static struct pmu pmu = {
>>> + .pmu_enable = loongarch_pmu_enable,
>>> + .pmu_disable = loongarch_pmu_disable,
>>> + .event_init = loongarch_pmu_event_init,
>>> + .add = loongarch_pmu_add,
>>> + .del = loongarch_pmu_del,
>>> + .start = loongarch_pmu_start,
>>> + .stop = loongarch_pmu_stop,
>>> + .read = loongarch_pmu_read,
>>> +};
>>> +
>>> +static unsigned int loongarch_pmu_perf_event_encode(const struct loongarch_perf_event *pev)
>>> +{
>>> + return (pev->event_id & 0xff);
>>> +}
>>> +
>>> +static const struct loongarch_perf_event *loongarch_pmu_map_general_event(int idx)
>>> +{
>>> + const struct loongarch_perf_event *pev;
>>> +
>>> + pev = &(*loongarch_pmu.general_event_map)[idx];
>>> +
>>> + if (pev->event_id == HW_OP_UNSUPPORTED)
>>> + return ERR_PTR(-ENOENT);
>>> +
>>> + return pev;
>>> +}
>>> +
>>> +static const struct loongarch_perf_event *loongarch_pmu_map_cache_event(u64 config)
>>> +{
>>> + unsigned int cache_type, cache_op, cache_result;
>>> + const struct loongarch_perf_event *pev;
>>> +
>>> + cache_type = (config >> 0) & 0xff;
>>> + if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + cache_op = (config >> 8) & 0xff;
>>> + if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + cache_result = (config >> 16) & 0xff;
>>> + if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + pev = &((*loongarch_pmu.cache_event_map)
>>> + [cache_type]
>>> + [cache_op]
>>> + [cache_result]);
>>> +
>>> + if (pev->event_id == CACHE_OP_UNSUPPORTED)
>>> + return ERR_PTR(-ENOENT);
>>> +
>>> + return pev;
>>> +}
>>> +
>>> +static int validate_group(struct perf_event *event)
>>> +{
>>> + struct perf_event *sibling, *leader = event->group_leader;
>>> + struct cpu_hw_events fake_cpuc;
>>> +
>>> + memset(&fake_cpuc, 0, sizeof(fake_cpuc));
>>> +
>>> + if (loongarch_pmu_alloc_counter(&fake_cpuc, &leader->hw) < 0)
>>> + return -EINVAL;
>>> +
>>> + for_each_sibling_event(sibling, leader) {
>>> + if (loongarch_pmu_alloc_counter(&fake_cpuc, &sibling->hw) < 0)
>>> + return -EINVAL;
>>> + }
>>> +
>>> + if (loongarch_pmu_alloc_counter(&fake_cpuc, &event->hw) < 0)
>>> + return -EINVAL;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static void reset_counters(void *arg)
>>> +{
>>> + int counters = (int)(long)arg;
>>> +
>>> + switch (counters) {
>>> + case 4:
>>> + loongarch_pmu_write_control(3, 0);
>>> + loongarch_pmu.write_counter(3, 0);
>>> + fallthrough;
>>> + case 3:
>>> + loongarch_pmu_write_control(2, 0);
>>> + loongarch_pmu.write_counter(2, 0);
>>> + fallthrough;
>>> + case 2:
>>> + loongarch_pmu_write_control(1, 0);
>>> + loongarch_pmu.write_counter(1, 0);
>>> + fallthrough;
>>> + case 1:
>>> + loongarch_pmu_write_control(0, 0);
>>> + loongarch_pmu.write_counter(0, 0);
>>> + }
>>> +}
>>> +
>>> +static const struct loongarch_perf_event loongson_new_event_map[PERF_COUNT_HW_MAX] = {
>>> + PERF_MAP_ALL_UNSUPPORTED,
>>> + [PERF_COUNT_HW_CPU_CYCLES] = { 0x00 },
>>> + [PERF_COUNT_HW_INSTRUCTIONS] = { 0x01 },
>>> + [PERF_COUNT_HW_CACHE_REFERENCES] = { 0x08 },
>>> + [PERF_COUNT_HW_CACHE_MISSES] = { 0x09 },
>>> + [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = { 0x02 },
>>> + [PERF_COUNT_HW_BRANCH_MISSES] = { 0x03 },
>>> +};
>>> +
>>> +static const struct loongarch_perf_event loongson_new_cache_map
>>> + [PERF_COUNT_HW_CACHE_MAX]
>>> + [PERF_COUNT_HW_CACHE_OP_MAX]
>>> + [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
>>> +PERF_CACHE_MAP_ALL_UNSUPPORTED,
>>> +[C(L1D)] = {
>>> + /*
>>> + * Like some other architectures (e.g. ARM), the performance
>>> + * counters don't differentiate between read and write
>>> + * accesses/misses, so this isn't strictly correct, but it's the
>>> + * best we can do. Writes and reads get combined.
>>> + */
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_ACCESS)] = { 0x8 },
>>> + [C(RESULT_MISS)] = { 0x9 },
>>> + },
>>> + [C(OP_WRITE)] = {
>>> + [C(RESULT_ACCESS)] = { 0x8 },
>>> + [C(RESULT_MISS)] = { 0x9 },
>>> + },
>>> + [C(OP_PREFETCH)] = {
>>> + [C(RESULT_ACCESS)] = { 0xaa },
>>> + [C(RESULT_MISS)] = { 0xa9 },
>>> + },
>>> +},
>>> +[C(L1I)] = {
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_ACCESS)] = { 0x6 },
>>> + [C(RESULT_MISS)] = { 0x7 },
>>> + },
>>> +},
>>> +[C(LL)] = {
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_ACCESS)] = { 0xc },
>>> + [C(RESULT_MISS)] = { 0xd },
>>> + },
>>> + [C(OP_WRITE)] = {
>>> + [C(RESULT_ACCESS)] = { 0xc },
>>> + [C(RESULT_MISS)] = { 0xd },
>>> + },
>>> +},
>>> +[C(ITLB)] = {
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_MISS)] = { 0x3b },
>>> + },
>>> +},
>>> +[C(DTLB)] = {
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_ACCESS)] = { 0x4 },
>>> + [C(RESULT_MISS)] = { 0x3c },
>>> + },
>>> + [C(OP_WRITE)] = {
>>> + [C(RESULT_ACCESS)] = { 0x4 },
>>> + [C(RESULT_MISS)] = { 0x3c },
>>> + },
>>> +},
>>> +[C(BPU)] = {
>>> + /* Using the same code for *HW_BRANCH* */
>>> + [C(OP_READ)] = {
>>> + [C(RESULT_ACCESS)] = { 0x02 },
>>> + [C(RESULT_MISS)] = { 0x03 },
>>> + },
>>> +},
>>> +};
>>> +
>>> +static int __hw_perf_event_init(struct perf_event *event)
>>> +{
>>> + struct perf_event_attr *attr = &event->attr;
>>> + struct hw_perf_event *hwc = &event->hw;
>>> + const struct loongarch_perf_event *pev;
>>> + int err;
>>> +
>>> + /* Returning LoongArch event descriptor for generic perf event. */
>>> + if (PERF_TYPE_HARDWARE == event->attr.type) {
>>> + if (event->attr.config >= PERF_COUNT_HW_MAX)
>>> + return -EINVAL;
>>> + pev = loongarch_pmu_map_general_event(event->attr.config);
>>> + } else if (PERF_TYPE_HW_CACHE == event->attr.type) {
>>> + pev = loongarch_pmu_map_cache_event(event->attr.config);
>>> + } else if (PERF_TYPE_RAW == event->attr.type) {
>>> + /* We are working on the global raw event. */
>>> + mutex_lock(&raw_event_mutex);
>>> + pev = loongarch_pmu.map_raw_event(event->attr.config);
>>> + } else {
>>> + /* The event type is not (yet) supported. */
>>> + return -EOPNOTSUPP;
>>> + }
>>> +
>>> + if (IS_ERR(pev)) {
>>> + if (PERF_TYPE_RAW == event->attr.type)
>>> + mutex_unlock(&raw_event_mutex);
>>> + return PTR_ERR(pev);
>>> + }
>>> +
>>> + /*
>>> + * We allow max flexibility on how each individual counter shared
>>> + * by the single CPU operates (the mode exclusion and the range).
>>> + */
>>> + hwc->config_base = CSR_PERFCTRL_IE;
>>> +
>>> + hwc->event_base = loongarch_pmu_perf_event_encode(pev);
>>> + if (PERF_TYPE_RAW == event->attr.type)
>>> + mutex_unlock(&raw_event_mutex);
>>> +
>>> + if (!attr->exclude_user) {
>>> + hwc->config_base |= CSR_PERFCTRL_PLV3;
>>> + hwc->config_base |= CSR_PERFCTRL_PLV2;
>>> + }
>>> + if (!attr->exclude_kernel) {
>>> + hwc->config_base |= CSR_PERFCTRL_PLV0;
>>> + }
>>> + if (!attr->exclude_hv) {
>>> + hwc->config_base |= CSR_PERFCTRL_PLV1;
>>> + }
>>> +
>>> + hwc->config_base &= M_PERFCTL_CONFIG_MASK;
>>> + /*
>>> + * The event can belong to another cpu. We do not assign a local
>>> + * counter for it for now.
>>> + */
>>> + hwc->idx = -1;
>>> + hwc->config = 0;
>>> +
>>> + if (!hwc->sample_period) {
>>> + hwc->sample_period = loongarch_pmu.max_period;
>>> + hwc->last_period = hwc->sample_period;
>>> + local64_set(&hwc->period_left, hwc->sample_period);
>>> + }
>>> +
>>> + err = 0;
>>> + if (event->group_leader != event)
>>> + err = validate_group(event);
>>> +
>>> + event->destroy = hw_perf_event_destroy;
>>> +
>>> + if (err)
>>> + event->destroy(event);
>>> +
>>> + return err;
>>> +}
>>> +
>>> +static void pause_local_counters(void)
>>> +{
>>> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>>> + int ctr = loongarch_pmu.num_counters;
>>> + unsigned long flags;
>>> +
>>> + local_irq_save(flags);
>>> + do {
>>> + ctr--;
>>> + cpuc->saved_ctrl[ctr] = loongarch_pmu_read_control(ctr);
>>> + loongarch_pmu_write_control(ctr, cpuc->saved_ctrl[ctr] &
>>> + ~M_PERFCTL_COUNT_EVENT_WHENEVER);
>>> + } while (ctr > 0);
>>> + local_irq_restore(flags);
>>> +}
>>> +
>>> +static void resume_local_counters(void)
>>> +{
>>> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>>> + int ctr = loongarch_pmu.num_counters;
>>> +
>>> + do {
>>> + ctr--;
>>> + loongarch_pmu_write_control(ctr, cpuc->saved_ctrl[ctr]);
>>> + } while (ctr > 0);
>>> +}
>>> +
>>> +static const struct loongarch_perf_event *loongarch_pmu_map_raw_event(u64 config)
>>> +{
>>> + raw_event.event_id = config & 0xff;
>>> +
>>> + return &raw_event;
>>> +}
>>> +
>>> +static int __init
>>> +init_hw_perf_events(void)
>>> +{
>>> + int counters = 4;
>>> +
>>> + if (!cpu_has_pmp)
>>> + return -ENODEV;
>>> +
>>> + pr_info("Performance counters: ");
>>> +
>>> + loongarch_pmu.num_counters = counters;
>>> + loongarch_pmu.max_period = (1ULL << 63) - 1;
>>> + loongarch_pmu.valid_count = (1ULL << 63) - 1;
>>> + loongarch_pmu.overflow = 1ULL << 63;
>>> + loongarch_pmu.name = "loongarch/loongson64";
>>> + loongarch_pmu.read_counter = loongarch_pmu_read_counter;
>>> + loongarch_pmu.write_counter = loongarch_pmu_write_counter;
>>> + loongarch_pmu.map_raw_event = loongarch_pmu_map_raw_event;
>>> + loongarch_pmu.general_event_map = &loongson_new_event_map;
>>> + loongarch_pmu.cache_event_map = &loongson_new_cache_map;
>>> +
>>> + on_each_cpu(reset_counters, (void *)(long)counters, 1);
>>> +
>>> + pr_cont("%s PMU enabled, %d %d-bit counters available to each "
>>> + "CPU.\n", loongarch_pmu.name, counters, 64);
>>> +
>>> + perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
>>> +
>>> + return 0;
>>> +}
>>> +early_initcall(init_hw_perf_events);
>>> diff --git a/arch/loongarch/kernel/perf_regs.c b/arch/loongarch/kernel/perf_regs.c
>>> new file mode 100644
>>> index 000000000000..a5e9768e8414
>>> --- /dev/null
>>> +++ b/arch/loongarch/kernel/perf_regs.c
>>> @@ -0,0 +1,50 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> And this file.
> OK, thanks.
>
> Huacai
>>> + */
>>> +
>>> +#include <linux/perf_event.h>
>>> +
>>> +#include <asm/ptrace.h>
>>> +
>>> +#ifdef CONFIG_32BIT
>>> +u64 perf_reg_abi(struct task_struct *tsk)
>>> +{
>>> + return PERF_SAMPLE_REGS_ABI_32;
>>> +}
>>> +#else /* Must be CONFIG_64BIT */
>>> +u64 perf_reg_abi(struct task_struct *tsk)
>>> +{
>>> + if (test_tsk_thread_flag(tsk, TIF_32BIT_REGS))
>>> + return PERF_SAMPLE_REGS_ABI_32;
>>> + else
>>> + return PERF_SAMPLE_REGS_ABI_64;
>>> +}
>>> +#endif /* CONFIG_32BIT */
>>> +
>>> +int perf_reg_validate(u64 mask)
>>> +{
>>> + if (!mask)
>>> + return -EINVAL;
>>> + if (mask & ~((1ull << PERF_REG_LOONGARCH_MAX) - 1))
>>> + return -EINVAL;
>>> + return 0;
>>> +}
>>> +
>>> +u64 perf_reg_value(struct pt_regs *regs, int idx)
>>> +{
>>> + if (WARN_ON_ONCE((u32)idx >= PERF_REG_LOONGARCH_MAX))
>>> + return 0;
>>> +
>>> + if ((u32)idx == PERF_REG_LOONGARCH_PC)
>>> + return regs->csr_era;
>>> +
>>> + return regs->regs[idx];
>>> +}
>>> +
>>> +void perf_get_regs_user(struct perf_regs *regs_user,
>>> + struct pt_regs *regs)
>>> +{
>>> + regs_user->regs = task_pt_regs(current);
>>> + regs_user->abi = perf_reg_abi(current);
>>> +}
>> --
>> WANG "xen0n" Xuerui
>>
>> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
>>
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