perf evsel: Extend message to mention CAP_SYS_PTRACE and perf security doc link

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:
https://lore.kernel.org/lkml/[email protected]/

Signed-off-by: Alexey Budankov <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: Alexey Budankov

tools/perf/util/evsel.c

@@ -2502,8 +2502,10 @@ 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"