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
 18struct key_t {
 19	char waker[TASK_COMM_LEN];
 20	char target[TASK_COMM_LEN];
 21	u32 wret;
 22	u32 tret;
 23};
 24
 25struct 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
 32struct 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
 39struct wokeby_t {
 40	char name[TASK_COMM_LEN];
 41	u32 ret;
 42};
 43
 44struct 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
 51struct 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
 60SEC("kprobe/try_to_wake_up")
 61int 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
 76static 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 */
107struct 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};
117SEC("tracepoint/sched/sched_switch")
118int oncpu(struct sched_switch_args *ctx)
119{
120	/* record previous thread sleep time */
121	u32 pid = ctx->prev_pid;
122#else
123SEC("kprobe/finish_task_switch")
124int 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}
150char _license[] SEC("license") = "GPL";
151u32 _version SEC("version") = LINUX_VERSION_CODE;