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Message-Id: <20240412015019.7060-2-khuey@kylehuey.com>
Date: Thu, 11 Apr 2024 18:50:13 -0700
From: Kyle Huey <me@...ehuey.com>
To: Kyle Huey <khuey@...ehuey.com>,
linux-kernel@...r.kernel.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Marco Elver <elver@...gle.com>,
Yonghong Song <yonghong.song@...ux.dev>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Robert O'Callahan <robert@...llahan.org>,
bpf@...r.kernel.org,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org
Subject: [PATCH v6 1/7] perf/bpf: Reorder bpf_overflow_handler() ahead of __perf_event_overflow()
This will allow __perf_event_overflow() to call bpf_overflow_handler().
Signed-off-by: Kyle Huey <khuey@...ehuey.com>
---
kernel/events/core.c | 183 ++++++++++++++++++++++---------------------
1 file changed, 92 insertions(+), 91 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 724e6d7e128f..ee025125a681 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9544,6 +9544,98 @@ static inline bool sample_is_allowed(struct perf_event *event, struct pt_regs *r
return true;
}
+#ifdef CONFIG_BPF_SYSCALL
+static void bpf_overflow_handler(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ struct bpf_perf_event_data_kern ctx = {
+ .data = data,
+ .event = event,
+ };
+ struct bpf_prog *prog;
+ int ret = 0;
+
+ ctx.regs = perf_arch_bpf_user_pt_regs(regs);
+ if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
+ goto out;
+ rcu_read_lock();
+ prog = READ_ONCE(event->prog);
+ if (prog) {
+ perf_prepare_sample(data, event, regs);
+ ret = bpf_prog_run(prog, &ctx);
+ }
+ rcu_read_unlock();
+out:
+ __this_cpu_dec(bpf_prog_active);
+ if (!ret)
+ return;
+
+ event->orig_overflow_handler(event, data, regs);
+}
+
+static int perf_event_set_bpf_handler(struct perf_event *event,
+ struct bpf_prog *prog,
+ u64 bpf_cookie)
+{
+ if (event->overflow_handler_context)
+ /* hw breakpoint or kernel counter */
+ return -EINVAL;
+
+ if (event->prog)
+ return -EEXIST;
+
+ if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
+ return -EINVAL;
+
+ if (event->attr.precise_ip &&
+ prog->call_get_stack &&
+ (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
+ event->attr.exclude_callchain_kernel ||
+ event->attr.exclude_callchain_user)) {
+ /*
+ * On perf_event with precise_ip, calling bpf_get_stack()
+ * may trigger unwinder warnings and occasional crashes.
+ * bpf_get_[stack|stackid] works around this issue by using
+ * callchain attached to perf_sample_data. If the
+ * perf_event does not full (kernel and user) callchain
+ * attached to perf_sample_data, do not allow attaching BPF
+ * program that calls bpf_get_[stack|stackid].
+ */
+ return -EPROTO;
+ }
+
+ event->prog = prog;
+ event->bpf_cookie = bpf_cookie;
+ event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
+ WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
+ return 0;
+}
+
+static void perf_event_free_bpf_handler(struct perf_event *event)
+{
+ struct bpf_prog *prog = event->prog;
+
+ if (!prog)
+ return;
+
+ WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
+ event->prog = NULL;
+ bpf_prog_put(prog);
+}
+#else
+static int perf_event_set_bpf_handler(struct perf_event *event,
+ struct bpf_prog *prog,
+ u64 bpf_cookie)
+{
+ return -EOPNOTSUPP;
+}
+
+static void perf_event_free_bpf_handler(struct perf_event *event)
+{
+}
+#endif
+
/*
* Generic event overflow handling, sampling.
*/
@@ -10422,97 +10514,6 @@ static void perf_event_free_filter(struct perf_event *event)
ftrace_profile_free_filter(event);
}
-#ifdef CONFIG_BPF_SYSCALL
-static void bpf_overflow_handler(struct perf_event *event,
- struct perf_sample_data *data,
- struct pt_regs *regs)
-{
- struct bpf_perf_event_data_kern ctx = {
- .data = data,
- .event = event,
- };
- struct bpf_prog *prog;
- int ret = 0;
-
- ctx.regs = perf_arch_bpf_user_pt_regs(regs);
- if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
- goto out;
- rcu_read_lock();
- prog = READ_ONCE(event->prog);
- if (prog) {
- perf_prepare_sample(data, event, regs);
- ret = bpf_prog_run(prog, &ctx);
- }
- rcu_read_unlock();
-out:
- __this_cpu_dec(bpf_prog_active);
- if (!ret)
- return;
-
- event->orig_overflow_handler(event, data, regs);
-}
-
-static int perf_event_set_bpf_handler(struct perf_event *event,
- struct bpf_prog *prog,
- u64 bpf_cookie)
-{
- if (event->overflow_handler_context)
- /* hw breakpoint or kernel counter */
- return -EINVAL;
-
- if (event->prog)
- return -EEXIST;
-
- if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
- return -EINVAL;
-
- if (event->attr.precise_ip &&
- prog->call_get_stack &&
- (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
- event->attr.exclude_callchain_kernel ||
- event->attr.exclude_callchain_user)) {
- /*
- * On perf_event with precise_ip, calling bpf_get_stack()
- * may trigger unwinder warnings and occasional crashes.
- * bpf_get_[stack|stackid] works around this issue by using
- * callchain attached to perf_sample_data. If the
- * perf_event does not full (kernel and user) callchain
- * attached to perf_sample_data, do not allow attaching BPF
- * program that calls bpf_get_[stack|stackid].
- */
- return -EPROTO;
- }
-
- event->prog = prog;
- event->bpf_cookie = bpf_cookie;
- event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
- WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
- return 0;
-}
-
-static void perf_event_free_bpf_handler(struct perf_event *event)
-{
- struct bpf_prog *prog = event->prog;
-
- if (!prog)
- return;
-
- WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
- event->prog = NULL;
- bpf_prog_put(prog);
-}
-#else
-static int perf_event_set_bpf_handler(struct perf_event *event,
- struct bpf_prog *prog,
- u64 bpf_cookie)
-{
- return -EOPNOTSUPP;
-}
-static void perf_event_free_bpf_handler(struct perf_event *event)
-{
-}
-#endif
-
/*
* returns true if the event is a tracepoint, or a kprobe/upprobe created
* with perf_event_open()
--
2.34.1
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