[PATCH PATCH v2 v3 3/6] perf: auxtrace: Control AUX pause and resume with BPF

[Leo Yan]

Introduce a BPF program to trigger AUX pause and resume.

Once a attached tracepoint is hit, the BPF program calls the
bpf_perf_event_aux_pause() kfunc for controlling AUX trace.

Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
---
 tools/perf/Makefile.perf                      |   1 +
 tools/perf/util/bpf_skel/auxtrace_pause.bpf.c | 156 ++++++++++++++++++++++++++
 2 files changed, 157 insertions(+)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index d4c7031b01a77f4a42326e4c9a88d8a352143178..8fdd24ba4c25ff4a69925a8e0c85bc78dd4fda47 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -1179,6 +1179,7 @@ SKELETONS += $(SKEL_OUT)/kwork_trace.skel.h $(SKEL_OUT)/sample_filter.skel.h
 SKELETONS += $(SKEL_OUT)/kwork_top.skel.h $(SKEL_OUT)/syscall_summary.skel.h
 SKELETONS += $(SKEL_OUT)/bench_uprobe.skel.h
 SKELETONS += $(SKEL_OUT)/augmented_raw_syscalls.skel.h
+SKELETONS += $(SKEL_OUT)/auxtrace_pause.skel.h
 
 $(SKEL_TMP_OUT) $(LIBAPI_OUTPUT) $(LIBBPF_OUTPUT) $(LIBPERF_OUTPUT) $(LIBSUBCMD_OUTPUT) $(LIBSYMBOL_OUTPUT):
 	$(Q)$(MKDIR) -p $@
diff --git a/tools/perf/util/bpf_skel/auxtrace_pause.bpf.c b/tools/perf/util/bpf_skel/auxtrace_pause.bpf.c
new file mode 100644
index 0000000000000000000000000000000000000000..37f8e1d096a3098415f6469014652dea948044d2
--- /dev/null
+++ b/tools/perf/util/bpf_skel/auxtrace_pause.bpf.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+// Copyright 2025 Arm Limited
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} cpu_filter SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} task_filter SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(int));
+	__uint(max_entries, 1);
+} events SEC(".maps");
+
+int enabled = 0;
+
+const volatile int has_cpu = 0;
+const volatile int has_task = 0;
+const volatile int per_thread = 0;
+
+int bpf_perf_event_aux_pause(void *map, u64 flags, bool pause) __ksym;
+
+static int event_aux_pause(void)
+{
+	__u64 flag;
+	__u32 cpu = bpf_get_smp_processor_id();
+
+	if (!enabled)
+		return 0;
+
+	if (has_cpu) {
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
+		if (!ok)
+			return 0;
+	}
+
+	if (has_task) {
+		__u32 pid = bpf_get_current_pid_tgid() & 0xffffffff;
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&task_filter, &pid);
+		if (!ok)
+			return 0;
+	}
+
+	flag = per_thread ? 0 : BPF_F_CURRENT_CPU;
+	bpf_perf_event_aux_pause(&events, flag, true);
+	return 0;
+}
+
+static int event_aux_resume(void)
+{
+	__u64 flag;
+	__u32 cpu = bpf_get_smp_processor_id();
+
+	if (!enabled)
+		return 0;
+
+	if (has_cpu) {
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
+		if (!ok)
+			return 0;
+	}
+
+	if (has_task) {
+		__u32 pid = bpf_get_current_pid_tgid() & 0xffffffff;
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&task_filter, &pid);
+		if (!ok)
+			return 0;
+	}
+
+	flag = per_thread ? 0 : BPF_F_CURRENT_CPU;
+	bpf_perf_event_aux_pause(&events, flag, false);
+	return 0;
+}
+
+SEC("kprobe/func_pause")
+int BPF_PROG(kprobe_event_pause)
+{
+	return event_aux_pause();
+}
+
+SEC("kprobe/func_resume")
+int BPF_PROG(kprobe_event_resume)
+{
+	return event_aux_resume();
+}
+
+SEC("kretprobe/func_pause")
+int BPF_PROG(kretprobe_event_pause)
+{
+	return event_aux_pause();
+}
+
+SEC("kretprobe/func_resume")
+int BPF_PROG(kretprobe_event_resume)
+{
+	return event_aux_resume();
+}
+
+SEC("uprobe/func_pause")
+int BPF_PROG(uprobe_event_pause)
+{
+	return event_aux_pause();
+}
+
+SEC("uprobe/func_resume")
+int BPF_PROG(uprobe_event_resume)
+{
+	return event_aux_resume();
+}
+
+SEC("uretprobe/func_pause")
+int BPF_PROG(uretprobe_event_pause)
+{
+	return event_aux_pause();
+}
+
+SEC("uretprobe/func_resume")
+int BPF_PROG(uretprobe_event_resume)
+{
+	return event_aux_resume();
+}
+
+SEC("tp/func_pause")
+int BPF_PROG(tp_event_pause)
+{
+	return event_aux_pause();
+}
+
+SEC("tp/func_resume")
+int BPF_PROG(tp_event_resume)
+{
+	return event_aux_resume();
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";

-- 
2.34.1