1 /* Copyright (c) 2016 Facebook
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7 #include <uapi/linux/bpf.h>
8 #include "bpf_helpers.h"
9 #include <uapi/linux/ptrace.h>
10 #include <uapi/linux/perf_event.h>
11 #include <linux/version.h>
12 #include <linux/sched.h>
13
14 #define _(P) ({typeof(P) val; bpf_probe_read(&val, sizeof(val), &P); val;})
15
16 #define MINBLOCK_US 1
17
18 struct key_t {
19 char waker[TASK_COMM_LEN];
20 char target[TASK_COMM_LEN];
21 u32 wret;
22 u32 tret;
23 };
24
25 struct bpf_map_def SEC("maps") counts = {
26 .type = BPF_MAP_TYPE_HASH,
27 .key_size = sizeof(struct key_t),
28 .value_size = sizeof(u64),
29 .max_entries = 10000,
30 };
31
32 struct bpf_map_def SEC("maps") start = {
33 .type = BPF_MAP_TYPE_HASH,
34 .key_size = sizeof(u32),
35 .value_size = sizeof(u64),
36 .max_entries = 10000,
37 };
38
39 struct wokeby_t {
40 char name[TASK_COMM_LEN];
41 u32 ret;
42 };
43
44 struct bpf_map_def SEC("maps") wokeby = {
45 .type = BPF_MAP_TYPE_HASH,
46 .key_size = sizeof(u32),
47 .value_size = sizeof(struct wokeby_t),
48 .max_entries = 10000,
49 };
50
51 struct bpf_map_def SEC("maps") stackmap = {
52 .type = BPF_MAP_TYPE_STACK_TRACE,
53 .key_size = sizeof(u32),
54 .value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
55 .max_entries = 10000,
56 };
57
58 #define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
59
60 SEC("kprobe/try_to_wake_up")
waker(struct pt_regs * ctx)61 int waker(struct pt_regs *ctx)
62 {
63 struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
64 struct wokeby_t woke;
65 u32 pid;
66
67 pid = _(p->pid);
68
69 bpf_get_current_comm(&woke.name, sizeof(woke.name));
70 woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
71
72 bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
73 return 0;
74 }
75
update_counts(void * ctx,u32 pid,u64 delta)76 static inline int update_counts(void *ctx, u32 pid, u64 delta)
77 {
78 struct wokeby_t *woke;
79 u64 zero = 0, *val;
80 struct key_t key;
81
82 __builtin_memset(&key.waker, 0, sizeof(key.waker));
83 bpf_get_current_comm(&key.target, sizeof(key.target));
84 key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
85 key.wret = 0;
86
87 woke = bpf_map_lookup_elem(&wokeby, &pid);
88 if (woke) {
89 key.wret = woke->ret;
90 __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));
91 bpf_map_delete_elem(&wokeby, &pid);
92 }
93
94 val = bpf_map_lookup_elem(&counts, &key);
95 if (!val) {
96 bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
97 val = bpf_map_lookup_elem(&counts, &key);
98 if (!val)
99 return 0;
100 }
101 (*val) += delta;
102 return 0;
103 }
104
105 #if 1
106 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
107 struct sched_switch_args {
108 unsigned long long pad;
109 char prev_comm[16];
110 int prev_pid;
111 int prev_prio;
112 long long prev_state;
113 char next_comm[16];
114 int next_pid;
115 int next_prio;
116 };
117 SEC("tracepoint/sched/sched_switch")
oncpu(struct sched_switch_args * ctx)118 int oncpu(struct sched_switch_args *ctx)
119 {
120 /* record previous thread sleep time */
121 u32 pid = ctx->prev_pid;
122 #else
123 SEC("kprobe/finish_task_switch")
124 int oncpu(struct pt_regs *ctx)
125 {
126 struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
127 /* record previous thread sleep time */
128 u32 pid = _(p->pid);
129 #endif
130 u64 delta, ts, *tsp;
131
132 ts = bpf_ktime_get_ns();
133 bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
134
135 /* calculate current thread's delta time */
136 pid = bpf_get_current_pid_tgid();
137 tsp = bpf_map_lookup_elem(&start, &pid);
138 if (!tsp)
139 /* missed start or filtered */
140 return 0;
141
142 delta = bpf_ktime_get_ns() - *tsp;
143 bpf_map_delete_elem(&start, &pid);
144 delta = delta / 1000;
145 if (delta < MINBLOCK_US)
146 return 0;
147
148 return update_counts(ctx, pid, delta);
149 }
150 char _license[] SEC("license") = "GPL";
151 u32 _version SEC("version") = LINUX_VERSION_CODE;
152
