BACKPORT: perf tools: Document the perf sysctls
perf_event_paranoid was only documented in source code and a perf error
message. Copy the documentation from the error message to
Documentation/sysctl/kernel.txt.
perf_cpu_time_max_percent was already documented but missing from the
list at the top, so add it there.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20160119213515.GG2637@decadent.org.uk
[ Remove reference to external Documentation file, provide info inline, as before ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Bug: 29054680
Patchset: perf-lockdown
(backported from 3379e0c3effa87d7734fc06277a7023292aadb0c)
Signed-off-by: Mattias Nissler <mnissler@google.com>
Change-Id: I0373a15cfa0aae9123570af7095994b5cf8cd9ef
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index af70d15..88a2c8e 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -58,6 +58,8 @@
- panic_on_stackoverflow
- panic_on_unrecovered_nmi
- panic_on_warn
+- perf_cpu_time_max_percent
+- perf_event_paranoid
- pid_max
- powersave-nap [ PPC only ]
- printk
@@ -624,6 +626,17 @@
==============================================================
+perf_event_paranoid:
+
+Controls use of the performance events system by unprivileged
+users (without CAP_SYS_ADMIN). The default value is 1.
+
+ -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
+
+==============================================================
pid_max:
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 397fb4e..d4913a4 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2313,12 +2313,15 @@
case EPERM:
case EACCES:
return scnprintf(msg, size,
- "You may not have permission to collect %sstats.\n"
- "Consider tweaking /proc/sys/kernel/perf_event_paranoid:\n"
- " -1 - Not paranoid at all\n"
- " 0 - Disallow raw tracepoint access for unpriv\n"
- " 1 - Disallow cpu events for unpriv\n"
- " 2 - Disallow kernel profiling for unpriv",
+ "You may not have permission to collect %sstats.\n\n"
+ "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"
+ " -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 " : "");
case ENOENT:
return scnprintf(msg, size, "The %s event is not supported.",
