[PATCH] perf: fix documentation of sysctls perf_event_paranoid and perf_event_mlock_kb

From: Konstantin Khlebnikov
Date: Tue Feb 14 2017 - 07:32:38 EST


Fix misprint CAP_IOC_LOCK -> CAP_IPC_LOCK. This capability have nothing
to do with raw tracepoints. This part is about bypassing mlock limits.

Sysctl kernel.perf_event_paranoid = -1 allows raw and ftrace function
tracepoints without CAP_SYS_ADMIN.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
Documentation/sysctl/kernel.txt | 13 ++++++++++++-
tools/perf/util/evsel.c | 4 +++-
2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index a32b4b748644..f1272ff1fcb5 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -61,6 +61,7 @@ show up in /proc/sys/kernel:
- perf_cpu_time_max_percent
- perf_event_paranoid
- perf_event_max_stack
+- perf_event_mlock_kb
- perf_event_max_contexts_per_stack
- pid_max
- powersave-nap [ PPC only ]
@@ -654,7 +655,9 @@ Controls use of the performance events system by unprivileged
users (without CAP_SYS_ADMIN). The default value is 2.

-1: Allow use of (almost) all events by all users
->=0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
+ Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
+>=0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
+ Disallow raw tracepoint access by users without CAP_SYS_ADMIN
>=1: Disallow CPU event access by users without CAP_SYS_ADMIN
>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN

@@ -673,6 +676,14 @@ The default value is 127.

==============================================================

+perf_event_mlock_kb:
+
+Control size of per-cpu ring buffer not counted agains mlock limit.
+
+The default value is 512 + 1 page
+
+==============================================================
+
perf_event_max_contexts_per_stack:

Controls maximum number of stack frame context entries for
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 04e536ae4d88..9932de565aa7 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2467,7 +2467,9 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
"unprivileged users (without CAP_SYS_ADMIN).\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"
+ " Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK\n"
+ ">= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN\n"
+ " Disallow raw tracepoint access by users without CAP_SYS_ADMIN\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 " : "",