Re: [PATCH] LoongArch: Add perf events support

From: Huacai Chen
Date: Tue Aug 16 2022 - 06:58:02 EST

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On Tue, Aug 16, 2022 at 6:07 PM Qi Hu <huqi@xxxxxxxxxxx> wrote:
>
>
> On 2022/8/16 16:18, Huacai Chen wrote:
> > Hi, Xuerui,
> >
> > On Tue, Aug 16, 2022 at 1:46 PM WANG Xuerui <kernel@xxxxxxxxxx> wrote:
> >> On 2022/8/15 20:47, Huacai Chen wrote:
> >>> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> >>> ---
> >>> 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.
Yes, you are right, I'm sorry.

Huacai
>
> 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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