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....@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
