tools/perf/util/perf_api_probe.c

Source file repositories/reference/linux-study-clean/tools/perf/util/perf_api_probe.c

File Facts

System
Linux kernel
Corpus path
tools/perf/util/perf_api_probe.c
Extension
.c
Size
4210 bytes
Lines
209
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

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;
}

static void perf_probe_cgroup(struct evsel *evsel)
{
	evsel->core.attr.cgroup = 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;
	struct perf_cpu cpu;
	int fd;

	cpus = perf_cpu_map__new_online_cpus();
	if (!cpus)
		return false;

	cpu = perf_cpu_map__cpu(cpus, 0);
	perf_cpu_map__put(cpus);

	fd = sys_perf_event_open(&attr, -1, cpu.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)

Annotation

Implementation Notes