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Message-ID: <20160111152159.GR28542@decadent.org.uk>
Date: Mon, 11 Jan 2016 15:21:59 +0000
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 1/2] Documentation,perf: Document the perf sysctls
perf_event_paranoid was only documented in source code and a perf
error message. Move 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@...adent.org.uk>
---
Documentation/sysctl/kernel.txt | 13 +++++++++++++
tools/perf/util/evsel.c | 7 ++-----
2 files changed, 15 insertions(+), 5 deletions(-)
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 @@ show up in /proc/sys/kernel:
- 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 @@ allowed to execute.
==============================================================
+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..9b4df11 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2314,11 +2314,8 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
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",
+ "Consider tweaking /proc/sys/kernel/perf_event_paranoid -\n"
+ "see Documentation/sysctl/kernel.txt",
target->system_wide ? "system-wide " : "");
case ENOENT:
return scnprintf(msg, size, "The %s event is not supported.",
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