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author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2019-07-01 14:07:55 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-28 08:29:28 +0200 |
commit | 75100ec5f079c5c3c65b28a6b8d360acfe00b983 (patch) | |
tree | b07645eac334a0ce28e44a3bf59daf09f7aa184f /include | |
parent | 0e6ef184315d43ec26ae6c3acaadd88466621e5d (diff) | |
download | linux-stable-75100ec5f079c5c3c65b28a6b8d360acfe00b983.tar.gz linux-stable-75100ec5f079c5c3c65b28a6b8d360acfe00b983.tar.bz2 linux-stable-75100ec5f079c5c3c65b28a6b8d360acfe00b983.zip |
perf/core: Fix exclusive events' grouping
commit 8a58ddae23796c733c5dfbd717538d89d036c5bd upstream.
So far, we tried to disallow grouping exclusive events for the fear of
complications they would cause with moving between contexts. Specifically,
moving a software group to a hardware context would violate the exclusivity
rules if both groups contain matching exclusive events.
This attempt was, however, unsuccessful: the check that we have in the
perf_event_open() syscall is both wrong (looks at wrong PMU) and
insufficient (group leader may still be exclusive), as can be illustrated
by running:
$ perf record -e '{intel_pt//,cycles}' uname
$ perf record -e '{cycles,intel_pt//}' uname
ultimately successfully.
Furthermore, we are completely free to trigger the exclusivity violation
by:
perf -e '{cycles,intel_pt//}' -e '{intel_pt//,instructions}'
even though the helpful perf record will not allow that, the ABI will.
The warning later in the perf_event_open() path will also not trigger, because
it's also wrong.
Fix all this by validating the original group before moving, getting rid
of broken safeguards and placing a useful one to perf_install_in_context().
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: mathieu.poirier@linaro.org
Cc: will.deacon@arm.com
Fixes: bed5b25ad9c8a ("perf: Add a pmu capability for "exclusive" events")
Link: https://lkml.kernel.org/r/20190701110755.24646-1-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/perf_event.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 42fc852bf512..b22bc81f3669 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1030,6 +1030,11 @@ static inline int in_software_context(struct perf_event *event) return event->ctx->pmu->task_ctx_nr == perf_sw_context; } +static inline int is_exclusive_pmu(struct pmu *pmu) +{ + return pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE; +} + extern struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX]; extern void ___perf_sw_event(u32, u64, struct pt_regs *, u64); |