projects/linux·blob master · refs

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1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2018 Facebook
3
4#include <vmlinux.h>
5#include <bpf/bpf_helpers.h>
6
7#ifndef PERF_MAX_STACK_DEPTH
8#define PERF_MAX_STACK_DEPTH 127
9#endif
10
11struct {
12 __uint(type, BPF_MAP_TYPE_ARRAY);
13 __uint(max_entries, 1);
14 __type(key, __u32);
15 __type(value, __u32);
16} control_map SEC(".maps");
17
18struct {
19 __uint(type, BPF_MAP_TYPE_HASH);
20 __uint(max_entries, 16384);
21 __type(key, __u32);
22 __type(value, __u32);
23} stackid_hmap SEC(".maps");
24
25typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];
26
27struct {
28 __uint(type, BPF_MAP_TYPE_STACK_TRACE);
29 __uint(max_entries, 16384);
30 __type(key, __u32);
31 __type(value, stack_trace_t);
32} stackmap SEC(".maps");
33
34struct {
35 __uint(type, BPF_MAP_TYPE_ARRAY);
36 __uint(max_entries, 16384);
37 __type(key, __u32);
38 __type(value, stack_trace_t);
39} stack_amap SEC(".maps");
40
41/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
42struct sched_switch_args {
43 unsigned long long pad;
44 char prev_comm[TASK_COMM_LEN];
45 int prev_pid;
46 int prev_prio;
47 long long prev_state;
48 char next_comm[TASK_COMM_LEN];
49 int next_pid;
50 int next_prio;
51};
52
53__u32 stack_id;
54SEC("tracepoint/sched/sched_switch")
55int oncpu(struct sched_switch_args *ctx)
56{
57 __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
58 __u32 key = 0, val = 0, *value_p;
59 void *stack_p;
60
61 value_p = bpf_map_lookup_elem(&control_map, &key);
62 if (value_p && *value_p)
63 return 0; /* skip if non-zero *value_p */
64
65 /* The size of stackmap and stackid_hmap should be the same */
66 key = bpf_get_stackid(ctx, &stackmap, 0);
67 if ((int)key >= 0) {
68 stack_id = key;
69 bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
70 stack_p = bpf_map_lookup_elem(&stack_amap, &key);
71 if (stack_p)
72 bpf_get_stack(ctx, stack_p, max_len, 0);
73 }
74
75 return 0;
76}
77
78char _license[] SEC("license") = "GPL";