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-rw-r--r--tools/perf/util/perf_api_probe.c174
1 files changed, 174 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 000000000..3840d02f0
--- /dev/null
+++ b/tools/perf/util/perf_api_probe.c
@@ -0,0 +1,174 @@
+/* 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;
+}
+
+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;
+}