[PATCH v1] perf: extend message to mention CAP_SYS_PTRACE and perf security doc link

From: Alexey Budankov
Date: Wed Aug 05 2020 - 03:31:28 EST

Adjust limited access message to mention CAP_SYS_PTRACE capability
for processes of unprivileged users. Add link to perf security
document in the end of the section about capabilities.
The change has been inspired by this discussion:

Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
tools/perf/util/evsel.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 9aa51a65593d..e241ee773ccb 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2500,8 +2500,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,

return scnprintf(msg + printed, size - printed,
"Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open\n"
- "access to performance monitoring and observability operations for users\n"
- "without CAP_PERFMON or CAP_SYS_ADMIN Linux capability.\n"
+ "access to performance monitoring and observability operations for processes\n"
+ "without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.\n"
+ "More information can be found at 'Perf events and tool security' document:\n"
+ "https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html\n";
"perf_event_paranoid setting is %d:\n"
" -1: Allow use of (almost) all events by all users\n"
" Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK\n"