The bpf_perf_event_aux_pause kfunc is introduced for pause and resume
the Perf AUX trace used by eBPF programs.

An attached tracepoint (e.g., ftrace tracepoint or a dynamic tracepoint
using uprobe or kprobe) can invoke bpf_perf_event_aux_pause() to pause
or resume AUX trace. This is useful for fine-grained tracing.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 kernel/trace/bpf_trace.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3ae52978cae61a5d60b43c764d3e267bd32e1085..fbed1f9a92cce666e2a61d6bfceaabfd5efade1c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -704,6 +704,61 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
+__bpf_kfunc_start_defs();
+
+__bpf_kfunc int bpf_perf_event_aux_pause(void *p__map, u64 flags, bool pause)
+{
+	struct bpf_map *map = p__map;
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	unsigned int cpu = smp_processor_id();
+	u64 index = flags & BPF_F_INDEX_MASK;
+	struct bpf_event_entry *ee;
+
+	if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
+		return -EINVAL;
+
+	/* Disabling IRQ avoids race condition with perf event flows. */
+	guard(irqsave)();
+
+	if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+		return -EINVAL;
+
+	if (index == BPF_F_CURRENT_CPU)
+		index = cpu;
+
+	if (unlikely(index >= array->map.max_entries))
+		return -E2BIG;
+
+	ee = READ_ONCE(array->ptrs[index]);
+	if (!ee)
+		return -ENOENT;
+
+	if (!has_aux(ee->event))
+		return -EINVAL;
+
+	perf_event_aux_pause(ee->event, pause);
+	return 0;
+}
+
+__bpf_kfunc_end_defs();
+
+BTF_KFUNCS_START(perf_event_kfunc_set_ids)
+BTF_ID_FLAGS(func, bpf_perf_event_aux_pause, KF_TRUSTED_ARGS)
+BTF_KFUNCS_END(perf_event_kfunc_set_ids)
+
+static const struct btf_kfunc_id_set bpf_perf_event_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set = &perf_event_kfunc_set_ids,
+};
+
+static int __init bpf_perf_event_kfuncs_init(void)
+{
+	return register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC,
+					 &bpf_perf_event_kfunc_set);
+}
+
+late_initcall(bpf_perf_event_kfuncs_init);
+
 static DEFINE_PER_CPU(int, bpf_event_output_nest_level);
 struct bpf_nested_pt_regs {
 	struct pt_regs regs[3];

-- 
2.34.1