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 "vmlinux.h" 8 #include <linux/version.h> 9 #include <bpf/bpf_helpers.h> 10 #include <bpf/bpf_tracing.h> 11 #include <bpf/bpf_core_read.h> 12 13 #ifndef PERF_MAX_STACK_DEPTH 14 #define PERF_MAX_STACK_DEPTH 127 15 #endif 16 17 #define MINBLOCK_US 1 18 #define MAX_ENTRIES 10000 19 20 struct key_t { 21 char waker[TASK_COMM_LEN]; 22 char target[TASK_COMM_LEN]; 23 u32 wret; 24 u32 tret; 25 }; 26 27 struct { 28 __uint(type, BPF_MAP_TYPE_HASH); 29 __type(key, struct key_t); 30 __type(value, u64); 31 __uint(max_entries, MAX_ENTRIES); 32 } counts SEC(".maps"); 33 34 struct { 35 __uint(type, BPF_MAP_TYPE_HASH); 36 __type(key, u32); 37 __type(value, u64); 38 __uint(max_entries, MAX_ENTRIES); 39 } start SEC(".maps"); 40 41 struct wokeby_t { 42 char name[TASK_COMM_LEN]; 43 u32 ret; 44 }; 45 46 struct { 47 __uint(type, BPF_MAP_TYPE_HASH); 48 __type(key, u32); 49 __type(value, struct wokeby_t); 50 __uint(max_entries, MAX_ENTRIES); 51 } wokeby SEC(".maps"); 52 53 struct { 54 __uint(type, BPF_MAP_TYPE_STACK_TRACE); 55 __uint(key_size, sizeof(u32)); 56 __uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64)); 57 __uint(max_entries, MAX_ENTRIES); 58 } stackmap SEC(".maps"); 59 60 #define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP) 61 62 SEC("kprobe/try_to_wake_up") 63 int waker(struct pt_regs *ctx) 64 { 65 struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx); 66 u32 pid = BPF_CORE_READ(p, pid); 67 struct wokeby_t woke; 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 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/tracing/events/sched/sched_switch/format */ 107 SEC("tracepoint/sched/sched_switch") 108 int oncpu(struct trace_event_raw_sched_switch *ctx) 109 { 110 /* record previous thread sleep time */ 111 u32 pid = ctx->prev_pid; 112 #else 113 SEC("kprobe.multi/finish_task_switch*") 114 int oncpu(struct pt_regs *ctx) 115 { 116 struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx); 117 /* record previous thread sleep time */ 118 u32 pid = BPF_CORE_READ(p, pid); 119 #endif 120 u64 delta, ts, *tsp; 121 122 ts = bpf_ktime_get_ns(); 123 bpf_map_update_elem(&start, &pid, &ts, BPF_ANY); 124 125 /* calculate current thread's delta time */ 126 pid = bpf_get_current_pid_tgid(); 127 tsp = bpf_map_lookup_elem(&start, &pid); 128 if (!tsp) 129 /* missed start or filtered */ 130 return 0; 131 132 delta = bpf_ktime_get_ns() - *tsp; 133 bpf_map_delete_elem(&start, &pid); 134 delta = delta / 1000; 135 if (delta < MINBLOCK_US) 136 return 0; 137 138 return update_counts(ctx, pid, delta); 139 } 140 char _license[] SEC("license") = "GPL"; 141 u32 _version SEC("version") = LINUX_VERSION_CODE; 142