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| author | Song Liu <songliubraving@fb.com> | 2021-09-10 20:33:50 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-09-13 19:53:50 +0200 |
| commit | c22ac2a3d4bd83411ebf0b1726e9e5fc4f5e7ebf (patch) | |
| tree | 5a4286065571c6433ae43c49182fd8bbb9406c32 /kernel/events | |
| parent | selftests/bpf: Test new __sk_buff field hwtstamp (diff) | |
| download | linux-c22ac2a3d4bd83411ebf0b1726e9e5fc4f5e7ebf.tar.xz linux-c22ac2a3d4bd83411ebf0b1726e9e5fc4f5e7ebf.zip | |
perf: Enable branch record for software events
The typical way to access branch record (e.g. Intel LBR) is via hardware
perf_event. For CPUs with FREEZE_LBRS_ON_PMI support, PMI could capture
reliable LBR. On the other hand, LBR could also be useful in non-PMI
scenario. For example, in kretprobe or bpf fexit program, LBR could
provide a lot of information on what happened with the function. Add API
to use branch record for software use.
Note that, when the software event triggers, it is necessary to stop the
branch record hardware asap. Therefore, static_call is used to remove some
branch instructions in this process.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210910183352.3151445-2-songliubraving@fb.com
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 744e8726c5b2..349f80aa9e7d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -13435,3 +13435,5 @@ struct cgroup_subsys perf_event_cgrp_subsys = { .threaded = true, }; #endif /* CONFIG_CGROUP_PERF */ + +DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t); |