// SPDX-License-Identifier: GPL-2.0
#include <sys/mman.h>
#include <inttypes.h>
#include <asm/bug.h>
#include <errno.h>
#include <string.h>
#include <linux/ring_buffer.h>
#include <linux/perf_event.h>
#include <perf/mmap.h>
#include <perf/event.h>
#include <perf/evsel.h>
#include <internal/mmap.h>
#include <internal/lib.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/stringify.h>
#include "internal.h"
void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
bool overwrite, libperf_unmap_cb_t unmap_cb)
{
/* Assume fields were zero initialized. */
map->fd = -1;
map->overwrite = overwrite;
map->unmap_cb = unmap_cb;
refcount_set(&map->refcnt, 0);
if (prev)
prev->next = map;
}
size_t perf_mmap__mmap_len(struct perf_mmap *map)
{
return map->mask + 1 + page_size;
}
int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
int fd, struct perf_cpu cpu)
{
map->prev = 0;
map->mask = mp->mask;
map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
MAP_SHARED, fd, 0);
if (map->base == MAP_FAILED) {
map->base = NULL;
return -1;
}
map->fd = fd;
map->cpu = cpu;
return 0;
}
void perf_mmap__munmap(struct perf_mmap *map)
{
if (!map)
return;
zfree(&map->event_copy);
map->event_copy_sz = 0;
if (map->base) {
munmap(map->base, perf_mmap__mmap_len(map));
map->base = NULL;
map->fd = -1;
refcount_set(&map->refcnt, 0);
}
if (map->unmap_cb)
map->unmap_cb(map);
}
void perf_mmap__get(struct perf_mmap *map)
{
refcount_inc(&map->refcnt);
}
void perf_mmap__put(struct perf_mmap *map)
{
BUG_ON(map->base && refcount_read(&map->refcnt) == 0);
if (refcount_dec_and_test(&map->refcnt))
perf_mmap__munmap(map);
}
static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
{
ring_buffer_write_tail(md->base, tail);
}
u64 perf_mmap__read_head(struct perf_mmap *map)
{
return ring_buffer_read_head(map->base);
}
static bool perf_mmap__empty(struct perf_mmap *map)
{
struct perf_event_mmap_page *pc = map->base;
return perf_mmap__read_head(map) == map->prev && !pc->aux_size;
}
void perf_mmap__consume(struct perf_mmap *map)
{
if (!map->overwrite) {
u64 old = map->prev;
perf_mmap__write_tail(map, old);
}
if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map))
perf_mmap__put(map);
}
static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
{
struct perf_event_header *pheader;
u64 evt_head = *start;
int size = mask + 1;
pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
pheader = (struct perf_event_header *)(buf + (*start & mask));
while (true) {
if (evt_head - *start >= (unsigned int)size) {
pr_debug("Finished reading overwrite ring buffer: rewind\n");
if (evt_head - *start > (unsigned int)size)
evt_head -= pheader->size;
*end = evt_head;
return 0;
}
pheader = (struct perf_event_header *)(buf + (evt_head & mask));
if (pheader->size == 0) {
pr_debug("Finished reading overwrite ring buffer: get start\n");
*end = evt_head;
return 0;
}
evt_head += pheader->size;
pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
}
WARN_ONCE(1, "Shouldn't get here\n");
return -1;
}
/*
* Report the start and end of the available data in ringbuffer
*/
static int __perf_mmap__read_init(struct perf_mmap *md)
{
u64 head = perf_mmap__read_head(md);
u64 old = md->prev;
unsigned char *data = md->base + page_size;
unsigned long size;
md->start = md->overwrite ? head : old;
md->end = md->overwrite ? old : head;
if ((md->end - md->start) < md->flush)
return -EAGAIN;
size = md->end - md->start;
if (size > (unsigned long)(md->mask) + 1) {
if (!md->overwrite) {
WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
md->prev = head;
perf_mmap__consume(md);
return -EAGAIN;
}
/*
* Backward ring buffer is full. We still have a chance to read
* most of data from it.
*/
if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end))
return -EINVAL;
}
return 0;
}
int perf_mmap__read_init(struct perf_mmap *map)
{
/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&map->refcnt))
return -ENOENT;
return __perf_mmap__read_init(map);
}
/*
* Mandatory for overwrite mode
* The direction of overwrite mode is backward.
* The last perf_mmap__read() will set tail to map->core.prev.
* Need to correct the map->core.prev to head which is the end of next read.
*/
void perf_mmap__read_done(struct perf_mmap *map)
{
/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&map->refcnt))
return;
map->prev = perf_mmap__read_head(map);
}
/* When check_messup is true, 'end' must points to a good entry */
static union perf_event *perf_mmap__read(struct perf_mmap *map,
u64 *startp, u64 end)
{
unsigned char *data = map->base + page_size;
union perf_event *event = NULL;
int diff = end - *startp;
if (diff >= (int)sizeof(event->header)) {
size_t size;
event = (union perf_event *)&data[*startp & map->mask];
size = event->header.size;
if (size < sizeof(event->header) || diff < (int)size)
return NULL;
/*
* Event straddles the mmap boundary -- header should always
* be inside due to u64 alignment of output.
*/
if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) {
unsigned int offset = *startp;
unsigned int len = size, cpy;
void *dst = map->event_copy;
if (size > map->event_copy_sz) {
dst = realloc(map->event_copy, size);
if (!dst)
return NULL;
map->event_copy = dst;
map->event_copy_sz = size;
}
do {
cpy = min(map->mask + 1 - (offset & map->mask), len);
memcpy(dst, &data[offset & map->mask], cpy);
offset += cpy;
dst += cpy;
len -= cpy;
} while (len);
event = (union perf_event *)map->event_copy;
}
*startp += size;
}
return event;
}
/*
* Read event from ring buffer one by one.
* Return one event for each call.
*
* Usage:
* perf_mmap__read_init()
* while(event = perf_mmap__read_event()) {
* //process the event
* perf_mmap__consume()
* }
* perf_mmap__read_done()
*/
union perf_event *perf_mmap__read_event(struct perf_mmap *map)
{
union perf_event *event;
/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&map->refcnt))
return NULL;
/* non-overwrite doesn't pause the ringbuffer */
if (!map->overwrite)
map->end = perf_mmap__read_head(map);
event = perf_mmap__read(map, &map->start, map->end);
if (!map->overwrite)
map->prev = map->start;
return event;
}
#if defined(__i386__) || defined(__x86_64__)
static u64 read_perf_counter(unsigned int counter)
{
unsigned int low, high;
asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
return low | ((u64)high) << 32;
}
static u64 read_timestamp(void)
{
unsigned int low, high;
asm volatile("rdtsc" : "=a" (low), "=d" (high));
return low | ((u64)high) << 32;
}
#elif defined(__aarch64__)
#define read_sysreg(r) ({ \
u64 __val; \
asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \
__val; \
})
static u64 read_pmccntr(void)
{
return read_sysreg(pmccntr_el0);
}
#define PMEVCNTR_READ(idx) \
static u64 read_pmevcntr_##idx(void) { \
return read_sysreg(pmevcntr##idx##_el0); \
}
PMEVCNTR_READ(0);
PMEVCNTR_READ(1);
PMEVCNTR_READ(2);
PMEVCNTR_READ(3);
PMEVCNTR_READ(4);
PMEVCNTR_READ(5);
PMEVCNTR_READ(6);
PMEVCNTR_READ(7);
PMEVCNTR_READ(8);
PMEVCNTR_READ(9);
PMEVCNTR_READ(10);
PMEVCNTR_READ(11);
PMEVCNTR_READ(12);
PMEVCNTR_READ(13);
PMEVCNTR_READ(14);
PMEVCNTR_READ(15);
PMEVCNTR_READ(16);
PMEVCNTR_READ(17);
PMEVCNTR_READ(18);
PMEVCNTR_READ(19);
PMEVCNTR_READ(20);
PMEVCNTR_READ(21);
PMEVCNTR_READ(22);
PMEVCNTR_READ(23);
PMEVCNTR_READ(24);
PMEVCNTR_READ(25);
PMEVCNTR_READ(26);
PMEVCNTR_READ(27);
PMEVCNTR_READ(28);
PMEVCNTR_READ(29);
PMEVCNTR_READ(30);
/*
* Read a value direct from PMEVCNTR<idx>
*/
static u64 read_perf_counter(unsigned int counter)
{
static u64 (* const read_f[])(void) = {
read_pmevcntr_0,
read_pmevcntr_1,
read_pmevcntr_2,
read_pmevcntr_3,
read_pmevcntr_4,
read_pmevcntr_5,
read_pmevcntr_6,
read_pmevcntr_7,
read_pmevcntr_8,
read_pmevcntr_9,
read_pmevcntr_10,
read_pmevcntr_11,
read_pmevcntr_13,
read_pmevcntr_12,
read_pmevcntr_14,
read_pmevcntr_15,
read_pmevcntr_16,
read_pmevcntr_17,
read_pmevcntr_18,
read_pmevcntr_19,
read_pmevcntr_20,
read_pmevcntr_21,
read_pmevcntr_22,
read_pmevcntr_23,
read_pmevcntr_24,
read_pmevcntr_25,
read_pmevcntr_26,
read_pmevcntr_27,
read_pmevcntr_28,
read_pmevcntr_29,
read_pmevcntr_30,
read_pmccntr
};
if (counter < ARRAY_SIZE(read_f))
return (read_f[counter])();
return 0;
}
static u64 read_timestamp(void) { return read_sysreg(cntvct_el0); }
/* __riscv_xlen contains the witdh of the native base integer, here 64-bit */
#elif defined(__riscv) && __riscv_xlen == 64
/* TODO: implement rv32 support */
#define CSR_CYCLE 0xc00
#define CSR_TIME 0xc01
#define csr_read(csr) \
({ \
register unsigned long __v; \
__asm__ __volatile__ ("csrr %0, %1" \
: "=r" (__v) \
: "i" (csr) : ); \
__v; \
})
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)
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
}
static u64 read_perf_counter(unsigned int counter)
{
return csr_read_num(CSR_CYCLE + counter);
}
static u64 read_timestamp(void)
{
return csr_read_num(CSR_TIME);
}
#else
static u64 read_perf_counter(unsigned int counter __maybe_unused) { return 0; }
static u64 read_timestamp(void) { return 0; }
#endif
int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count)
{
struct perf_event_mmap_page *pc = map->base;
u32 seq, idx, time_mult = 0, time_shift = 0;
u64 cnt, cyc = 0, time_offset = 0, time_cycles = 0, time_mask = ~0ULL;
if (!pc || !pc->cap_user_rdpmc)
return -1;
do {
seq = READ_ONCE(pc->lock);
barrier();
count->ena = READ_ONCE(pc->time_enabled);
count->run = READ_ONCE(pc->time_running);
if (pc->cap_user_time && count->ena != count->run) {
cyc = read_timestamp();
time_mult = READ_ONCE(pc->time_mult);
time_shift = READ_ONCE(pc->time_shift);
time_offset = READ_ONCE(pc->time_offset);
if (pc->cap_user_time_short) {
time_cycles = READ_ONCE(pc->time_cycles);
time_mask = READ_ONCE(pc->time_mask);
}
}
idx = READ_ONCE(pc->index);
cnt = READ_ONCE(pc->offset);
if (pc->cap_user_rdpmc && idx) {
s64 evcnt = read_perf_counter(idx - 1);
u16 width = READ_ONCE(pc->pmc_width);
evcnt <<= 64 - width;
evcnt >>= 64 - width;
cnt += evcnt;
} else
return -1;
barrier();
} while (READ_ONCE(pc->lock) != seq);
if (count->ena != count->run) {
u64 delta;
/* Adjust for cap_usr_time_short, a nop if not */
cyc = time_cycles + ((cyc - time_cycles) & time_mask);
delta = time_offset + mul_u64_u32_shr(cyc, time_mult, time_shift);
count->ena += delta;
if (idx)
count->run += delta;
}
count->val = cnt;
return 0;
}
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