bpf: inline bpf_get_branch_snapshot() helper

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Inline bpf_get_branch_snapshot() helper using architecture-agnostic
inline BPF code which calls directly into underlying callback of
perf_snapshot_branch_stack static call. This callback is set early
during kernel initialization and is never updated or reset, so it's ok
to fetch actual implementation using static_call_query() and call
directly into it.

This change eliminates a full function call and saves one LBR entry
in PERF_SAMPLE_BRANCH_ANY LBR mode.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240404002640.1774210-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Andrii Nakryiko 2024-04-03 17:26:40 -07:00 • committed by Alexei Starovoitov

parent 5e6a3c1ee6

commit 314a53623c

1 changed files with 55 additions and 0 deletions

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kernel/bpf/verifier.c

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