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| author | Rob Herring <robh@kernel.org> | 2021-12-08 23:11:22 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-12-14 14:30:54 +0300 |
| commit | e2012600810c9ded81f6f63a8d04781be3c300ad (patch) | |
| tree | 1193d4e24e1dc0203401af169e23d5c7b2bdd8f3 /Documentation/admin-guide/sysctl | |
| parent | 82ff0c022d19c2ad69a472692bb7ee01ac07a40b (diff) | |
| download | linux-e2012600810c9ded81f6f63a8d04781be3c300ad.tar.xz | |
arm64: perf: Add userspace counter access disable switch
Like x86, some users may want to disable userspace PMU counter
altogether. Add a sysctl 'perf_user_access' file to control userspace
counter access. The default is '0' which is disabled. Writing '1'
enables access.
Note that x86 supports globally enabling user access by writing '2' to
/sys/bus/event_source/devices/cpu/rdpmc. As there's not existing
userspace support to worry about, this shouldn't be necessary for Arm.
It could be added later if the need arises.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-perf-users@vger.kernel.org
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211208201124.310740-4-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Documentation/admin-guide/sysctl')
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 0e486f41185e..d359bcfadd39 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -905,6 +905,17 @@ enabled, otherwise writing to this file will return ``-EBUSY``. The default value is 8. +perf_user_access (arm64 only) +================================= + +Controls user space access for reading perf event counters. When set to 1, +user space can read performance monitor counter registers directly. + +The default value is 0 (access disabled). + +See Documentation/arm64/perf.rst for more information. + + pid_max ======= |