diff options
| -rw-r--r-- | tools/perf/util/probe-event.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 3a7649835ec9..0568461b06ea 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -2936,7 +2936,7 @@ static int find_probe_functions(struct map *map, char *name, bool cut_version = true; if (map__load(map) < 0) - return 0; + return -EACCES; /* Possible permission error to load symbols */ /* If user gives a version, don't cut off the version from symbols */ if (strchr(name, '@')) @@ -2975,6 +2975,17 @@ void __weak arch__fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused, struct map *map __maybe_unused, struct symbol *sym __maybe_unused) { } + +static void pr_kallsyms_access_error(void) +{ + pr_err("Please ensure you can read the /proc/kallsyms symbol addresses.\n" + "If /proc/sys/kernel/kptr_restrict is '2', you can not read\n" + "kernel symbol addresses even if you are a superuser. Please change\n" + "it to '1'. If kptr_restrict is '1', the superuser can read the\n" + "symbol addresses.\n" + "In that case, please run this command again with sudo.\n"); +} + /* * Find probe function addresses from map. * Return an error or the number of found probe_trace_event @@ -3011,8 +3022,16 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, */ num_matched_functions = find_probe_functions(map, pp->function, syms); if (num_matched_functions <= 0) { - pr_err("Failed to find symbol %s in %s\n", pp->function, - pev->target ? : "kernel"); + if (num_matched_functions == -EACCES) { + pr_err("Failed to load symbols from %s\n", + pev->target ?: "/proc/kallsyms"); + if (pev->target) + pr_err("Please ensure the file is not stripped.\n"); + else + pr_kallsyms_access_error(); + } else + pr_err("Failed to find symbol %s in %s\n", pp->function, + pev->target ? : "kernel"); ret = -ENOENT; goto out; } else if (num_matched_functions > probe_conf.max_probes) { |