From: Arnaldo Carvalho de Melo <[email protected]>
We were showing a hardcoded default value for the kernel.perf_event_paranoid
sysctl, now that it became more paranoid (1 -> 2 [1]), this would need to be
updated, instead show the current value:
[acme@jouet linux]$ perf record ls
Error:
You may not have permission to collect stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid,
which controls use of the performance events system by
unprivileged users (without CAP_SYS_ADMIN).
The current value is 2:
-1: Allow use of (almost) all events by all users
>= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
>= 1: Disallow CPU event access by users without CAP_SYS_ADMIN
>= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN
[acme@jouet linux]$
[1] 0161028b7c8a ("perf/core: Change the default paranoia level to 2")
Reported-by: Ingo Molnar <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/evsel.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 738ce226002b..a5f339d447cc 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2382,12 +2382,13 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel,
struct target *target,
"Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
"which controls use of the performance events system by\n"
"unprivileged users (without CAP_SYS_ADMIN).\n\n"
- "The default value is 1:\n\n"
+ "The current value is %d:\n\n"
" -1: Allow use of (almost) all events by all users\n"
">= 0: Disallow raw tracepoint access by users without
CAP_IOC_LOCK\n"
">= 1: Disallow CPU event access by users without
CAP_SYS_ADMIN\n"
">= 2: Disallow kernel profiling by users without
CAP_SYS_ADMIN",
- target->system_wide ? "system-wide " : "");
+ target->system_wide ? "system-wide " : "",
+ perf_event_paranoid());
case ENOENT:
return scnprintf(msg, size, "The %s event is not supported.",
perf_evsel__name(evsel));
--
2.5.5
