path: root/include/linux/perf_event.h
diff options
authorAndrii Nakryiko <andrii@kernel.org>2021-08-15 00:05:58 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-08-17 00:45:07 +0200
commit82e6b1eee6a8875ef4eacfd60711cce6965c6b04 (patch)
tree61a1865e08aa9917ff436d6603c6ce5f9126d971 /include/linux/perf_event.h
parentbpf: Implement minimal BPF perf link (diff)
bpf: Allow to specify user-provided bpf_cookie for BPF perf links
Add ability for users to specify custom u64 value (bpf_cookie) when creating BPF link for perf_event-backed BPF programs (kprobe/uprobe, perf_event, tracepoints). This is useful for cases when the same BPF program is used for attaching and processing invocation of different tracepoints/kprobes/uprobes in a generic fashion, but such that each invocation is distinguished from each other (e.g., BPF program can look up additional information associated with a specific kernel function without having to rely on function IP lookups). This enables new use cases to be implemented simply and efficiently that previously were possible only through code generation (and thus multiple instances of almost identical BPF program) or compilation at runtime (BCC-style) on target hosts (even more expensive resource-wise). For uprobes it is not even possible in some cases to know function IP before hand (e.g., when attaching to shared library without PID filtering, in which case base load address is not known for a library). This is done by storing u64 bpf_cookie in struct bpf_prog_array_item, corresponding to each attached and run BPF program. Given cgroup BPF programs already use two 8-byte pointers for their needs and cgroup BPF programs don't have (yet?) support for bpf_cookie, reuse that space through union of cgroup_storage and new bpf_cookie field. Make it available to kprobe/tracepoint BPF programs through bpf_trace_run_ctx. This is set by BPF_PROG_RUN_ARRAY, used by kprobe/uprobe/tracepoint BPF program execution code, which luckily is now also split from BPF_PROG_RUN_ARRAY_CG. This run context will be utilized by a new BPF helper giving access to this user-provided cookie value from inside a BPF program. Generic perf_event BPF programs will access this value from perf_event itself through passed in BPF program context. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/bpf/20210815070609.987780-6-andrii@kernel.org
Diffstat (limited to 'include/linux/perf_event.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2d510ad750ed..fe156a8170aa 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -762,6 +762,7 @@ struct perf_event {
perf_overflow_handler_t orig_overflow_handler;
struct bpf_prog *prog;
+ u64 bpf_cookie;