1 files changed, 164 insertions, 0 deletions
diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
new file mode 100644
index 000000000000..1337965673d7
--- /dev/null
+++ b/tools/perf/util/perf_api_probe.c
@@ -0,0 +1,164 @@
+/* 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;
+}
+
+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_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;
+}