From e65cc8f9c46c6b8119826fbc22ffeb4e96e80e8a Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Tue, 19 Jan 2016 21:35:15 +0000 Subject: 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. Conflicts: Documentation/sysctl/kernel.txt tools/perf/util/evsel.c Signed-off-by: Ben Hutchings Cc: Peter Zijlstra 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 Bug: 29054680 Bug: 29119870 Signed-off-by: Dennis Cagle Change-Id: I13e73cfb2ad761c94762d0c8196df7725abdf5c5 (cherry picked from commit 746938f9d97d74f6c2833a0ede49506bdfcd89e4) --- Documentation/sysctl/kernel.txt | 41 ++++++++++++++++++++++++++--------------- tools/perf/util/evsel.c | 15 +++++++++------ 2 files changed, 35 insertions(+), 21 deletions(-) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 550ece7..942d769 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. @@ -459,7 +447,6 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled. 0: try to continue operation. -1: panic immediately. ============================================================== @@ -489,6 +476,30 @@ allowed to execute. ============================================================== +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 63b6f8c..54494df 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1515,12 +1515,15 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, 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.", -- cgit v1.1