From 7ecf6dab846a5e1b9529a10941f9105b52839e53 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Tue, 19 Jan 2016 21:35:15 +0000
Subject: [PATCH] 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.
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
Change-Id: I13e73cfb2ad761c94762d0c8196df7725abdf5c5
---
Documentation/sysctl/kernel.txt | 40 +++++++++++++++++++++------------
tools/perf/util/evsel.c | 17 ++++++++------
2 files changed, 36 insertions(+), 21 deletions(-)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index a7b1d7643839..924cc64ff8f9 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -51,8 +51,9 @@ show up in /proc/sys/kernel:
- overflowuid
- panic
- panic_on_oops
-- panic_on_unrecovered_nmi
- panic_on_stackoverflow
+- panic_on_unrecovered_nmi
+- perf_event_paranoid
- pid_max
- powersave-nap [ PPC only ]
- printk
@@ -427,19 +428,6 @@ the recommended setting is 60.
==============================================================
-panic_on_unrecovered_nmi:
-
-The default Linux behaviour on an NMI of either memory or unknown is
-to continue operation. For many environments such as scientific
-computing it is preferable that the box is taken out and the error
-dealt with than an uncorrected parity/ECC error get propagated.
-
-A small number of systems do generate NMI's for bizarre random reasons
-such as power management so the default is off. That sysctl works like
-the existing panic controls already in that directory.
-
-==============================================================
-
panic_on_oops:
Controls the kernel's behaviour when an oops or BUG is encountered.
@@ -463,6 +451,30 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled.
==============================================================
+panic_on_unrecovered_nmi:
+
+The default Linux behaviour on an NMI of either memory or unknown is
+to continue operation. For many environments such as scientific
+computing it is preferable that the box is taken out and the error
+dealt with than an uncorrected parity/ECC error get propagated.
+
+A small number of systems do generate NMI's for bizarre random reasons
+such as power management so the default is off. That sysctl works like
+the existing panic controls already in that directory.
+
+==============================================================
+
+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 07b1a3ad3e24..54494df33dd2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1514,13 +1514,16 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel,
switch (err) {
case EPERM:
case EACCES:
- return scnprintf(msg, size, "%s",
- "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",
+ return scnprintf(msg, size,
+ "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.",
--
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