LXR linux/samples/bpf/offwaketime

   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;
 152