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 <uapi/linux/ptrace.h>
9 #include <uapi/linux/perf_event.h>
10 #include <linux/version.h>
11 #include <linux/sched.h>
12 #include <bpf/bpf_helpers.h>
13 #include <bpf/bpf_tracing.h>
14
15 #define _(P) \
16 ({ \
17 typeof(P) val; \
18 bpf_probe_read_kernel(&val, sizeof(val), &(P)); \
19 val; \
20 })
21
22 #define MINBLOCK_US 1
23 #define MAX_ENTRIES 10000
24
25 struct key_t {
26 char waker[TASK_COMM_LEN];
27 char target[TASK_COMM_LEN];
28 u32 wret;
29 u32 tret;
30 };
31
32 struct {
33 __uint(type, BPF_MAP_TYPE_HASH);
34 __type(key, struct key_t);
35 __type(value, u64);
36 __uint(max_entries, MAX_ENTRIES);
37 } counts SEC(".maps");
38
39 struct {
40 __uint(type, BPF_MAP_TYPE_HASH);
41 __type(key, u32);
42 __type(value, u64);
43 __uint(max_entries, MAX_ENTRIES);
44 } start SEC(".maps");
45
46 struct wokeby_t {
47 char name[TASK_COMM_LEN];
48 u32 ret;
49 };
50
51 struct {
52 __uint(type, BPF_MAP_TYPE_HASH);
53 __type(key, u32);
54 __type(value, struct wokeby_t);
55 __uint(max_entries, MAX_ENTRIES);
56 } wokeby SEC(".maps");
57
58 struct {
59 __uint(type, BPF_MAP_TYPE_STACK_TRACE);
60 __uint(key_size, sizeof(u32));
61 __uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
62 __uint(max_entries, MAX_ENTRIES);
63 } stackmap SEC(".maps");
64
65 #define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
66
67 SEC("kprobe/try_to_wake_up")
waker(struct pt_regs * ctx)68 int waker(struct pt_regs *ctx)
69 {
70 struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
71 struct wokeby_t woke;
72 u32 pid;
73
74 pid = _(p->pid);
75
76 bpf_get_current_comm(&woke.name, sizeof(woke.name));
77 woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
78
79 bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
80 return 0;
81 }
82
update_counts(void * ctx,u32 pid,u64 delta)83 static inline int update_counts(void *ctx, u32 pid, u64 delta)
84 {
85 struct wokeby_t *woke;
86 u64 zero = 0, *val;
87 struct key_t key;
88
89 __builtin_memset(&key.waker, 0, sizeof(key.waker));
90 bpf_get_current_comm(&key.target, sizeof(key.target));
91 key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
92 key.wret = 0;
93
94 woke = bpf_map_lookup_elem(&wokeby, &pid);
95 if (woke) {
96 key.wret = woke->ret;
97 __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));
98 bpf_map_delete_elem(&wokeby, &pid);
99 }
100
101 val = bpf_map_lookup_elem(&counts, &key);
102 if (!val) {
103 bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
104 val = bpf_map_lookup_elem(&counts, &key);
105 if (!val)
106 return 0;
107 }
108 (*val) += delta;
109 return 0;
110 }
111
112 #if 1
113 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
114 struct sched_switch_args {
115 unsigned long long pad;
116 char prev_comm[16];
117 int prev_pid;
118 int prev_prio;
119 long long prev_state;
120 char next_comm[16];
121 int next_pid;
122 int next_prio;
123 };
124 SEC("tracepoint/sched/sched_switch")
oncpu(struct sched_switch_args * ctx)125 int oncpu(struct sched_switch_args *ctx)
126 {
127 /* record previous thread sleep time */
128 u32 pid = ctx->prev_pid;
129 #else
130 SEC("kprobe/finish_task_switch")
131 int oncpu(struct pt_regs *ctx)
132 {
133 struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
134 /* record previous thread sleep time */
135 u32 pid = _(p->pid);
136 #endif
137 u64 delta, ts, *tsp;
138
139 ts = bpf_ktime_get_ns();
140 bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
141
142 /* calculate current thread's delta time */
143 pid = bpf_get_current_pid_tgid();
144 tsp = bpf_map_lookup_elem(&start, &pid);
145 if (!tsp)
146 /* missed start or filtered */
147 return 0;
148
149 delta = bpf_ktime_get_ns() - *tsp;
150 bpf_map_delete_elem(&start, &pid);
151 delta = delta / 1000;
152 if (delta < MINBLOCK_US)
153 return 0;
154
155 return update_counts(ctx, pid, delta);
156 }
157 char _license[] SEC("license") = "GPL";
158 u32 _version SEC("version") = LINUX_VERSION_CODE;
159