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/20200722113007.gi77...@kernel.org/

Signed-off-by: Alexey Budankov <alexey.budan...@linux.intel.com>
---
 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"
-- 
2.24.1

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