From: Namhyung Kim <namhyung@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Song Liu <songliubraving@fb.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
Stanislav Fomichev <sdf@google.com>,
LKML <linux-kernel@vger.kernel.org>,
bpf@vger.kernel.org, Jiri Olsa <jolsa@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: [PATCH bpf-next 1/3] perf/core: Prepare sample data before calling BPF
Date: Mon, 31 Oct 2022 22:23:38 -0700 [thread overview]
Message-ID: <20221101052340.1210239-2-namhyung@kernel.org> (raw)
In-Reply-To: <20221101052340.1210239-1-namhyung@kernel.org>
To allow bpf overflow handler to access the perf sample data, it needs to
prepare missing but requested data before calling the handler.
I'm taking a conservative approach to allow a list of sample formats only
instead of allowing them all. For now, IP and ADDR data are allowed and
I think it's good enough to build and verify general BPF-based sample
filters for perf events.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
kernel/events/core.c | 40 +++++++++++++++++++++++++++++++---------
1 file changed, 31 insertions(+), 9 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index aefc1e08e015..519f30c33a24 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7329,8 +7329,10 @@ void perf_prepare_sample(struct perf_event_header *header,
filtered_sample_type = sample_type & ~data->sample_flags;
__perf_event_header__init_id(header, data, event, filtered_sample_type);
- if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE))
- data->ip = perf_instruction_pointer(regs);
+ if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE)) {
+ if (filtered_sample_type & PERF_SAMPLE_IP)
+ data->ip = perf_instruction_pointer(regs);
+ }
if (sample_type & PERF_SAMPLE_CALLCHAIN) {
int size = 1;
@@ -10006,6 +10008,32 @@ static void perf_event_free_filter(struct perf_event *event)
}
#ifdef CONFIG_BPF_SYSCALL
+static void bpf_prepare_sample(struct bpf_prog *prog,
+ struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ u64 filtered_sample_type;
+
+ filtered_sample_type = event->attr.sample_type & ~data->sample_flags;
+
+ if (prog->call_get_stack &&
+ (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)) {
+ data->callchain = perf_callchain(event, regs);
+ data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
+ }
+
+ if (filtered_sample_type & PERF_SAMPLE_IP) {
+ data->ip = perf_instruction_pointer(regs);
+ data->sample_flags |= PERF_SAMPLE_IP;
+ }
+
+ if (filtered_sample_type & PERF_SAMPLE_ADDR) {
+ data->addr = 0;
+ data->sample_flags |= PERF_SAMPLE_ADDR;
+ }
+}
+
static void bpf_overflow_handler(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs)
@@ -10023,13 +10051,7 @@ static void bpf_overflow_handler(struct perf_event *event,
rcu_read_lock();
prog = READ_ONCE(event->prog);
if (prog) {
- if (prog->call_get_stack &&
- (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
- !(data->sample_flags & PERF_SAMPLE_CALLCHAIN)) {
- data->callchain = perf_callchain(event, regs);
- data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
- }
-
+ bpf_prepare_sample(prog, event, data, regs);
ret = bpf_prog_run(prog, &ctx);
}
rcu_read_unlock();
--
2.38.1.273.g43a17bfeac-goog
next prev parent reply other threads:[~2022-11-01 5:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-01 5:23 [PATCH bpf-next 0/3] bpf: Add bpf_perf_event_read_sample() helper (v1) Namhyung Kim
2022-11-01 5:23 ` Namhyung Kim [this message]
2022-11-01 10:03 ` [PATCH bpf-next 1/3] perf/core: Prepare sample data before calling BPF Jiri Olsa
2022-11-04 6:03 ` Namhyung Kim
2022-11-01 5:23 ` [PATCH bpf-next 2/3] bpf: Add bpf_perf_event_read_sample() helper Namhyung Kim
2022-11-01 10:02 ` Jiri Olsa
2022-11-01 18:26 ` Alexei Starovoitov
2022-11-01 18:46 ` Song Liu
2022-11-01 18:52 ` Alexei Starovoitov
2022-11-01 20:04 ` Song Liu
2022-11-01 22:16 ` Namhyung Kim
2022-11-02 0:13 ` Song Liu
2022-11-02 22:18 ` Namhyung Kim
2022-11-03 18:41 ` Song Liu
2022-11-03 19:45 ` Yonghong Song
2022-11-03 20:55 ` Song Liu
2022-11-03 21:21 ` Yonghong Song
2022-11-04 6:18 ` Namhyung Kim
2022-11-01 5:23 ` [PATCH bpf-next 3/3] bpf: Add perf_event_read_sample test cases Namhyung Kim
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