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/* SPDX-License-Identifier: GPL-2.0 */
#include "perf-sys.h"
#include "util/cloexec.h"
#include "util/evlist.h"
#include "util/evsel.h"
#include "util/parse-events.h"
#include "util/perf_api_probe.h"
#include <perf/cpumap.h>
#include <errno.h>
typedef void (*setup_probe_fn_t)(struct evsel *evsel);
static int perf_do_probe_api(setup_probe_fn_t fn, int cpu, const char *str)
{
struct evlist *evlist;
struct evsel *evsel;
unsigned long flags = perf_event_open_cloexec_flag();
int err = -EAGAIN, fd;
static pid_t pid = -1;
evlist = evlist__new();
if (!evlist)
return -ENOMEM;
if (parse_events(evlist, str, NULL))
goto out_delete;
evsel = evlist__first(evlist);
while (1) {
fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, -1, flags);
if (fd < 0) {
if (pid == -1 && errno == EACCES) {
pid = 0;
continue;
}
goto out_delete;
}
break;
}
close(fd);
fn(evsel);
fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, -1, flags);
if (fd < 0) {
if (errno == EINVAL)
err = -EINVAL;
goto out_delete;
}
close(fd);
err = 0;
out_delete:
evlist__delete(evlist);
return err;
}
static bool perf_probe_api(setup_probe_fn_t fn)
{
const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL};
struct perf_cpu_map *cpus;
int cpu, ret, i = 0;
cpus = perf_cpu_map__new(NULL);
if (!cpus)
return false;
cpu = cpus->map[0];
perf_cpu_map__put(cpus);
do {
ret = perf_do_probe_api(fn, cpu, try[i++]);
if (!ret)
return true;
} while (ret == -EAGAIN && try[i]);
return false;
}
static void perf_probe_sample_identifier(struct evsel *evsel)
{
evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
}
static void perf_probe_comm_exec(struct evsel *evsel)
{
evsel->core.attr.comm_exec = 1;
}
static void perf_probe_context_switch(struct evsel *evsel)
{
evsel->core.attr.context_switch = 1;
}
static void perf_probe_text_poke(struct evsel *evsel)
{
evsel->core.attr.text_poke = 1;
}
static void perf_probe_build_id(struct evsel *evsel)
{
evsel->core.attr.build_id = 1;
}
bool perf_can_sample_identifier(void)
{
return perf_probe_api(perf_probe_sample_identifier);
}
bool perf_can_comm_exec(void)
{
return perf_probe_api(perf_probe_comm_exec);
}
bool perf_can_record_switch_events(void)
{
return perf_probe_api(perf_probe_context_switch);
}
bool perf_can_record_text_poke_events(void)
{
return perf_probe_api(perf_probe_text_poke);
}
bool perf_can_record_cpu_wide(void)
{
struct perf_event_attr attr = {
.type = PERF_TYPE_SOFTWARE,
.config = PERF_COUNT_SW_CPU_CLOCK,
.exclude_kernel = 1,
};
struct perf_cpu_map *cpus;
int cpu, fd;
cpus = perf_cpu_map__new(NULL);
if (!cpus)
return false;
cpu = cpus->map[0];
perf_cpu_map__put(cpus);
fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
if (fd < 0)
return false;
close(fd);
return true;
}
/*
* Architectures are expected to know if AUX area sampling is supported by the
* hardware. Here we check for kernel support.
*/
bool perf_can_aux_sample(void)
{
struct perf_event_attr attr = {
.size = sizeof(struct perf_event_attr),
.exclude_kernel = 1,
/*
* Non-zero value causes the kernel to calculate the effective
* attribute size up to that byte.
*/
.aux_sample_size = 1,
};
int fd;
fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
/*
* If the kernel attribute is big enough to contain aux_sample_size
* then we assume that it is supported. We are relying on the kernel to
* validate the attribute size before anything else that could be wrong.
*/
if (fd < 0 && errno == E2BIG)
return false;
if (fd >= 0)
close(fd);
return true;
}
bool perf_can_record_build_id(void)
{
return perf_probe_api(perf_probe_build_id);
}
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