1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2018 Facebook
5 #include "bpf_helpers.h"
7 #ifndef PERF_MAX_STACK_DEPTH
8 #define PERF_MAX_STACK_DEPTH 127
11 struct bpf_map_def SEC("maps") control_map = {
12 .type = BPF_MAP_TYPE_ARRAY,
13 .key_size = sizeof(__u32),
14 .value_size = sizeof(__u32),
18 struct bpf_map_def SEC("maps") stackid_hmap = {
19 .type = BPF_MAP_TYPE_HASH,
20 .key_size = sizeof(__u32),
21 .value_size = sizeof(__u32),
25 struct bpf_map_def SEC("maps") stackmap = {
26 .type = BPF_MAP_TYPE_STACK_TRACE,
27 .key_size = sizeof(__u32),
28 .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
32 struct bpf_map_def SEC("maps") stack_amap = {
33 .type = BPF_MAP_TYPE_ARRAY,
34 .key_size = sizeof(__u32),
35 .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
39 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
40 struct sched_switch_args {
41 unsigned long long pad;
51 SEC("tracepoint/sched/sched_switch")
52 int oncpu(struct sched_switch_args *ctx)
54 __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
55 __u32 key = 0, val = 0, *value_p;
58 value_p = bpf_map_lookup_elem(&control_map, &key);
59 if (value_p && *value_p)
60 return 0; /* skip if non-zero *value_p */
62 /* The size of stackmap and stackid_hmap should be the same */
63 key = bpf_get_stackid(ctx, &stackmap, 0);
65 bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
66 stack_p = bpf_map_lookup_elem(&stack_amap, &key);
68 bpf_get_stack(ctx, stack_p, max_len, 0);
74 char _license[] SEC("license") = "GPL";
75 __u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */