// SPDX-License-Identifier: GPL-2.0
/*
* RISC-V performance counter support.
*
* Copyright (C) 2021 Western Digital Corporation or its affiliates.
*
* This implementation is based on old RISC-V perf and ARM perf event code
* which are in turn based on sparc64 and x86 code.
*/
#include <linux/cpumask.h>
#include <linux/irq.h>
#include <linux/irqdesc.h>
#include <linux/perf/riscv_pmu.h>
#include <linux/printk.h>
#include <linux/smp.h>
#include <linux/sched_clock.h>
#include <asm/sbi.h>
static bool riscv_perf_user_access(struct perf_event *event)
{
return ((event->attr.type == PERF_TYPE_HARDWARE) ||
(event->attr.type == PERF_TYPE_HW_CACHE) ||
(event->attr.type == PERF_TYPE_RAW)) &&
!!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) &&
(event->hw.idx != -1);
}
void arch_perf_update_userpage(struct perf_event *event,
struct perf_event_mmap_page *userpg, u64 now)
{
struct clock_read_data *rd;
unsigned int seq;
u64 ns;
userpg->cap_user_time = 0;
userpg->cap_user_time_zero = 0;
userpg->cap_user_time_short = 0;
userpg->cap_user_rdpmc = riscv_perf_user_access(event);
/*
* The counters are 64-bit but the priv spec doesn't mandate all the
* bits to be implemented: that's why, counter width can vary based on
* the cpu vendor.
*/
if (userpg->cap_user_rdpmc)
userpg->pmc_width = to_riscv_pmu(event->pmu)->ctr_get_width(event->hw.idx) + 1;
do {
rd = sched_clock_read_begin(&seq);
userpg->time_mult = rd->mult;
userpg->time_shift = rd->shift;
userpg->time_zero = rd->epoch_ns;
userpg->time_cycles = rd->epoch_cyc;
userpg->time_mask = rd->sched_clock_mask;
/*
* Subtract the cycle base, such that software that
* doesn't know about cap_user_time_short still 'works'
* assuming no wraps.
*/
ns = mul_u64_u32_shr(rd->epoch_cyc, rd->mult, rd->shift);
userpg->time_zero -= ns;
} while (sched_clock_read_retry(seq));
userpg->time_offset = userpg->time_zero - now;
/*
* time_shift is not expected to be greater than 31 due to
* the original published conversion algorithm shifting a
* 32-bit value (now specifies a 64-bit value) - refer
* perf_event_mmap_page documentation in perf_event.h.
*/
if (userpg->time_shift == 32) {
userpg->time_shift = 31;
userpg->time_mult >>= 1;
}
/*
* Internal timekeeping for enabled/running/stopped times
* is always computed with the sched_clock.
*/
userpg->cap_user_time = 1;
userpg->cap_user_time_zero = 1;
userpg->cap_user_time_short = 1;
}
static unsigned long csr_read_num(int csr_num)
{
#define switchcase_csr_read(__csr_num, __val) {\
case __csr_num: \
__val = csr_read(__csr_num); \
break; }
#define switchcase_csr_read_2(__csr_num, __val) {\
switchcase_csr_read(__csr_num + 0, __val) \
switchcase_csr_read(__csr_num + 1, __val)}
#define switchcase_csr_read_4(__csr_num, __val) {\
switchcase_csr_read_2(__csr_num + 0, __val) \
switchcase_csr_read_2(__csr_num + 2, __val)}
#define switchcase_csr_read_8(__csr_num, __val) {\
switchcase_csr_read_4(__csr_num + 0, __val) \
switchcase_csr_read_4(__csr_num + 4, __val)}
#define switchcase_csr_read_16(__csr_num, __val) {\
switchcase_csr_read_8(__csr_num + 0, __val) \
switchcase_csr_read_8(__csr_num + 8, __val)}
#define switchcase_csr_read_32(__csr_num, __val) {\
switchcase_csr_read_16(__csr_num + 0, __val) \
switchcase_csr_read_16(__csr_num + 16, __val)}
unsigned long ret = 0;
switch (csr_num) {
switchcase_csr_read_32(CSR_CYCLE, ret)
switchcase_csr_read_32(CSR_CYCLEH, ret)
default :
break;
}
return ret;
#undef switchcase_csr_read_32
#undef switchcase_csr_read_16
#undef switchcase_csr_read_8
#undef switchcase_csr_read_4
#undef switchcase_csr_read_2
#undef switchcase_csr_read
}
/*
* Read the CSR of a corresponding counter.
*/
unsigned long riscv_pmu_ctr_read_csr(unsigned long csr)
{
if (csr < CSR_CYCLE || csr > CSR_HPMCOUNTER31H ||
(csr > CSR_HPMCOUNTER31 && csr < CSR_CYCLEH)) {
pr_err("Invalid performance counter csr %lx\n", csr);
return -EINVAL;
}
return csr_read_num(csr);
}
u64 riscv_pmu_ctr_get_width_mask(struct perf_event *event)
{
int cwidth;
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
if (hwc->idx == -1)
/* Handle init case where idx is not initialized yet */
cwidth = rvpmu->ctr_get_width(0);
else
cwidth = rvpmu->ctr_get_width(hwc->idx);
return GENMASK_ULL(cwidth, 0);
}
u64 riscv_pmu_event_update(struct perf_event *event)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
u64 prev_raw_count, new_raw_count;
unsigned long cmask;
u64 oldval, delta;
if (!rvpmu->ctr_read || (hwc->state & PERF_HES_UPTODATE))
return 0;
cmask = riscv_pmu_ctr_get_width_mask(event);
do {
prev_raw_count = local64_read(&hwc->prev_count);
new_raw_count = rvpmu->ctr_read(event);
oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
new_raw_count);
} while (oldval != prev_raw_count);
delta = (new_raw_count - prev_raw_count) & cmask;
local64_add(delta, &event->count);
local64_sub(delta, &hwc->period_left);
return delta;
}
void riscv_pmu_stop(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
if (!(hwc->state & PERF_HES_STOPPED)) {
if (rvpmu->ctr_stop) {
rvpmu->ctr_stop(event, 0);
hwc->state |= PERF_HES_STOPPED;
}
riscv_pmu_event_update(event);
hwc->state |= PERF_HES_UPTODATE;
}
}
int riscv_pmu_event_set_period(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
s64 left = local64_read(&hwc->period_left);
s64 period = hwc->sample_period;
int overflow = 0;
uint64_t max_period = riscv_pmu_ctr_get_width_mask(event);
if (unlikely(left <= -period)) {
left = period;
local64_set(&hwc->period_left, left);
hwc->last_period = period;
overflow = 1;
}
if (unlikely(left <= 0)) {
left += period;
local64_set(&hwc->period_left, left);
hwc->last_period = period;
overflow = 1;
}
/*
* Limit the maximum period to prevent the counter value
* from overtaking the one we are about to program. In
* effect we are reducing max_period to account for
* interrupt latency (and we are being very conservative).
*/
if (left > (max_period >> 1))
left = (max_period >> 1);
local64_set(&hwc->prev_count, (u64)-left);
perf_event_update_userpage(event);
return overflow;
}
void riscv_pmu_start(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
uint64_t max_period = riscv_pmu_ctr_get_width_mask(event);
u64 init_val;
if (flags & PERF_EF_RELOAD)
WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
hwc->state = 0;
riscv_pmu_event_set_period(event);
init_val = local64_read(&hwc->prev_count) & max_period;
rvpmu->ctr_start(event, init_val);
perf_event_update_userpage(event);
}
static int riscv_pmu_add(struct perf_event *event, int flags)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
struct hw_perf_event *hwc = &event->hw;
int idx;
idx = rvpmu->ctr_get_idx(event);
if (idx < 0)
return idx;
hwc->idx = idx;
cpuc->events[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);
/* Propagate our changes to the userspace mapping. */
perf_event_update_userpage(event);
return 0;
}
static void riscv_pmu_del(struct perf_event *event, int flags)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
struct hw_perf_event *hwc = &event->hw;
riscv_pmu_stop(event, PERF_EF_UPDATE);
cpuc->events[hwc->idx] = NULL;
/* The firmware need to reset the counter mapping */
if (rvpmu->ctr_stop)
rvpmu->ctr_stop(event, RISCV_PMU_STOP_FLAG_RESET);
cpuc->n_events--;
if (rvpmu->ctr_clear_idx)
rvpmu->ctr_clear_idx(event);
perf_event_update_userpage(event);
hwc->idx = -1;
}
static void riscv_pmu_read(struct perf_event *event)
{
riscv_pmu_event_update(event);
}
static int riscv_pmu_event_init(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
int mapped_event;
u64 event_config = 0;
uint64_t cmask;
/* driver does not support branch stack sampling */
if (has_branch_stack(event))
return -EOPNOTSUPP;
hwc->flags = 0;
mapped_event = rvpmu->event_map(event, &event_config);
if (mapped_event < 0) {
pr_debug("event %x:%llx not supported\n", event->attr.type,
event->attr.config);
return mapped_event;
}
/*
* idx is set to -1 because the index of a general event should not be
* decided until binding to some counter in pmu->add().
* config will contain the information about counter CSR
* the idx will contain the counter index
*/
hwc->config = event_config;
hwc->idx = -1;
hwc->event_base = mapped_event;
if (rvpmu->event_init)
rvpmu->event_init(event);
if (!is_sampling_event(event)) {
/*
* For non-sampling runs, limit the sample_period to half
* of the counter width. That way, the new counter value
* is far less likely to overtake the previous one unless
* you have some serious IRQ latency issues.
*/
cmask = riscv_pmu_ctr_get_width_mask(event);
hwc->sample_period = cmask >> 1;
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
}
return 0;
}
static int riscv_pmu_event_idx(struct perf_event *event)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
if (!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT))
return 0;
if (rvpmu->csr_index)
return rvpmu->csr_index(event) + 1;
return 0;
}
static void riscv_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
if (rvpmu->event_mapped) {
rvpmu->event_mapped(event, mm);
perf_event_update_userpage(event);
}
}
static void riscv_pmu_event_unmapped(struct perf_event *event, struct mm_struct *mm)
{
struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
if (rvpmu->event_unmapped) {
rvpmu->event_unmapped(event, mm);
perf_event_update_userpage(event);
}
}
struct riscv_pmu *riscv_pmu_alloc(void)
{
struct riscv_pmu *pmu;
int cpuid, i;
struct cpu_hw_events *cpuc;
pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
if (!pmu)
goto out;
pmu->hw_events = alloc_percpu_gfp(struct cpu_hw_events, GFP_KERNEL);
if (!pmu->hw_events) {
pr_info("failed to allocate per-cpu PMU data.\n");
goto out_free_pmu;
}
for_each_possible_cpu(cpuid) {
cpuc = per_cpu_ptr(pmu->hw_events, cpuid);
cpuc->n_events = 0;
for (i = 0; i < RISCV_MAX_COUNTERS; i++)
cpuc->events[i] = NULL;
cpuc->snapshot_addr = NULL;
}
pmu->pmu = (struct pmu) {
.event_init = riscv_pmu_event_init,
.event_mapped = riscv_pmu_event_mapped,
.event_unmapped = riscv_pmu_event_unmapped,
.event_idx = riscv_pmu_event_idx,
.add = riscv_pmu_add,
.del = riscv_pmu_del,
.start = riscv_pmu_start,
.stop = riscv_pmu_stop,
.read = riscv_pmu_read,
};
return pmu;
out_free_pmu:
kfree(pmu);
out:
return NULL;
}
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