[PATCH v3 11/13] perf tools: improve IBS error handling

Stephane Eranian
2021-12-01T01:03:16Z

From: Kim Phillips <kim.phillips@amd.com>

This patch improves the error message returned on failed perf_event_open() on
AMD when using IBS.

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
---
tools/perf/util/evsel.c | 42 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ac0127be0459..39e9063c0a80 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2852,12 +2852,52 @@ static bool find_process(const char *name)
return ret ? false : true;
}

+static bool is_amd;
+
+static char *fgrep(FILE *inf, const char *str)
+{
+ char line[256];
+ int slen = strlen(str);
+
+ while (!feof(inf)) {
+ if (!fgets(line, 256, inf))
+ break;
+ if (strncmp(line, str, slen))
+ continue;
+
+ return strdup(line);
+ }
+
+ return NULL;
+}
+
+static void detect_amd(void)
+{
+ FILE *inf = fopen("/proc/cpuinfo", "r");
+ char *res;
+
+ if (!inf)
+ return;
+
+ res = fgrep(inf, "vendor_id");
+
+ if (res) {
+ char *s = strchr(res, ':');
+
+ is_amd = s && !strcmp(s, ": AuthenticAMD\n");
+ free(res);
+ }
+ fclose(inf);
+}
+
int evsel__open_strerror(struct evsel *evsel, struct target *target,
int err, char *msg, size_t size)
{
char sbuf[STRERR_BUFSIZE];
int printed = 0, enforced = 0;

+ detect_amd();
+
switch (err) {
case EPERM:
case EACCES:
@@ -2950,6 +2990,8 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
return scnprintf(msg, size, "wrong clockid (%d).", clockid);
if (perf_missing_features.aux_output)
return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
+ if (is_amd && (evsel->core.attr.precise_ip || !strncmp(evsel->pmu_name, "ibs", 3)) && (evsel->core.attr.exclude_kernel))
+ return scnprintf(msg, size, "AMD IBS can't exclude kernel events. Try running at a higher privilege level.");
break;
case ENODATA:
return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "
--
2.34.0.rc2.393.gf8c9666880-goog