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