Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2018 Facebook
3
4#include <linux/bpf.h>
5#include "bpf_helpers.h"
6
7#ifndef PERF_MAX_STACK_DEPTH
8#define PERF_MAX_STACK_DEPTH 127
9#endif
10
11struct bpf_map_def SEC("maps") control_map = {
12 .type = BPF_MAP_TYPE_ARRAY,
13 .key_size = sizeof(__u32),
14 .value_size = sizeof(__u32),
15 .max_entries = 1,
16};
17
18struct bpf_map_def SEC("maps") stackid_hmap = {
19 .type = BPF_MAP_TYPE_HASH,
20 .key_size = sizeof(__u32),
21 .value_size = sizeof(__u32),
22 .max_entries = 16384,
23};
24
25struct 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,
29 .max_entries = 16384,
30};
31
32struct 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,
36 .max_entries = 16384,
37};
38
39/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
40struct sched_switch_args {
41 unsigned long long pad;
42 char prev_comm[16];
43 int prev_pid;
44 int prev_prio;
45 long long prev_state;
46 char next_comm[16];
47 int next_pid;
48 int next_prio;
49};
50
51SEC("tracepoint/sched/sched_switch")
52int oncpu(struct sched_switch_args *ctx)
53{
54 __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
55 __u32 key = 0, val = 0, *value_p;
56 void *stack_p;
57
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 */
61
62 /* The size of stackmap and stackid_hmap should be the same */
63 key = bpf_get_stackid(ctx, &stackmap, 0);
64 if ((int)key >= 0) {
65 bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
66 stack_p = bpf_map_lookup_elem(&stack_amap, &key);
67 if (stack_p)
68 bpf_get_stack(ctx, stack_p, max_len, 0);
69 }
70
71 return 0;
72}
73
74char _license[] SEC("license") = "GPL";
75__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */