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linux/arch/x86/events
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Namhyung Kim 15ec83da43 perf/x86: Fix lockdep warning in for_each_sibling_event() on SPR 
commit 27c68c216e upstream.

On SPR, the load latency event needs an auxiliary event in the same
group to work properly.  There's a check in intel_pmu_hw_config()
for this to iterate sibling events and find a mem-loads-aux event.

The for_each_sibling_event() has a lockdep assert to make sure if it
disabled hardirq or hold leader->ctx->mutex.  This works well if the
given event has a separate leader event since perf_try_init_event()
grabs the leader->ctx->mutex to protect the sibling list.  But it can
cause a problem when the event itself is a leader since the event is
not initialized yet and there's no ctx for the event.

Actually I got a lockdep warning when I run the below command on SPR,
but I guess it could be a NULL pointer dereference.

  $ perf record -d -e cpu/mem-loads/uP true

The code path to the warning is:

  sys_perf_event_open()
    perf_event_alloc()
      perf_init_event()
        perf_try_init_event()
          x86_pmu_event_init()
            hsw_hw_config()
              intel_pmu_hw_config()
                for_each_sibling_event()
                  lockdep_assert_event_ctx()

We don't need for_each_sibling_event() when it's a standalone event.
Let's return the error code directly.

Fixes: f3c0eba287 ("perf: Add a few assertions")
Reported-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20230704181516.3293665-1-namhyung@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-07-23 13:49:45 +02:00
..
amd perf/ibs: Fix interface via core pmu events 2023-07-19 16:21:02 +02:00
intel perf/x86: Fix lockdep warning in for_each_sibling_event() on SPR 2023-07-23 13:49:45 +02:00
zhaoxin x86/perf/zhaoxin: Add stepping check for ZXC 2023-03-10 09:32:45 +01:00
core.c perf/x86: Refuse to export capabilities for hybrid PMUs 2023-02-22 12:59:55 +01:00
Kconfig perf/x86/Kconfig: Fix indentation in the Kconfig file 2022-05-25 15:54:26 +02:00
Makefile perf/x86: Move branch classifier 2022-08-27 00:05:44 +02:00
msr.c perf/x86/msr: Add Emerald Rapids 2023-02-01 08:34:30 +01:00
perf_event.h Perf events updates for v6.1: 2022-10-10 09:27:46 -07:00
perf_event_flags.h x86/perf: Assert all platform event flags are within PERF_EVENT_FLAG_ARCH 2022-09-07 21:54:01 +02:00
probe.c perf/x86/rapl: Add msr mask support 2021-02-10 14:44:54 +01:00
probe.h perf/x86/rapl: Add msr mask support 2021-02-10 14:44:54 +01:00
rapl.c perf/x86/rapl: Add support for Intel Emerald Rapids 2023-01-24 07:24:32 +01:00
utils.c perf/x86/utils: Fix uninitialized var in get_branch_type() 2022-09-29 12:20:56 +02:00