1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2016 Facebook
3 */
4#include <stdio.h>
5#include <unistd.h>
6#include <stdlib.h>
7#include <signal.h>
8#include <linux/perf_event.h>
9#include <errno.h>
10#include <stdbool.h>
11#include <bpf/libbpf.h>
12#include <bpf/bpf.h>
13#include "trace_helpers.h"
14
15#define PRINT_RAW_ADDR 0
16
17/* counts, stackmap */
18static int map_fd[2];
19
20static void print_ksym(__u64 addr)
21{
22 struct ksym *sym;
23
24 if (!addr)
25 return;
26 sym = ksym_search(addr);
27 if (!sym) {
28 printf("ksym not found. Is kallsyms loaded?\n");
29 return;
30 }
31
32 if (PRINT_RAW_ADDR)
33 printf("%s/%llx;", sym->name, addr);
34 else
35 printf("%s;", sym->name);
36}
37
38#define TASK_COMM_LEN 16
39
40struct key_t {
41 char waker[TASK_COMM_LEN];
42 char target[TASK_COMM_LEN];
43 __u32 wret;
44 __u32 tret;
45};
46
47static void print_stack(struct key_t *key, __u64 count)
48{
49 __u64 ip[PERF_MAX_STACK_DEPTH] = {};
50 static bool warned;
51 int i;
52
53 printf("%s;", key->target);
54 if (bpf_map_lookup_elem(map_fd[1], &key->tret, ip) != 0) {
55 printf("---;");
56 } else {
57 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
58 print_ksym(addr: ip[i]);
59 }
60 printf("-;");
61 if (bpf_map_lookup_elem(map_fd[1], &key->wret, ip) != 0) {
62 printf("---;");
63 } else {
64 for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
65 print_ksym(addr: ip[i]);
66 }
67 printf(";%s %lld\n", key->waker, count);
68
69 if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
70 printf("stackmap collisions seen. Consider increasing size\n");
71 warned = true;
72 } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
73 printf("err stackid %d %d\n", key->tret, key->wret);
74 }
75}
76
77static void print_stacks(int fd)
78{
79 struct key_t key = {}, next_key;
80 __u64 value;
81
82 while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
83 bpf_map_lookup_elem(fd, &next_key, &value);
84 print_stack(key: &next_key, count: value);
85 key = next_key;
86 }
87}
88
89static void int_exit(int sig)
90{
91 print_stacks(fd: map_fd[0]);
92 exit(0);
93}
94
95int main(int argc, char **argv)
96{
97 struct bpf_object *obj = NULL;
98 struct bpf_link *links[2];
99 struct bpf_program *prog;
100 int delay = 1, i = 0;
101 char filename[256];
102
103 if (load_kallsyms()) {
104 printf("failed to process /proc/kallsyms\n");
105 return 2;
106 }
107
108 snprintf(buf: filename, size: sizeof(filename), fmt: "%s.bpf.o", argv[0]);
109 obj = bpf_object__open_file(filename, NULL);
110 if (libbpf_get_error(obj)) {
111 fprintf(stderr, "ERROR: opening BPF object file failed\n");
112 obj = NULL;
113 goto cleanup;
114 }
115
116 /* load BPF program */
117 if (bpf_object__load(obj)) {
118 fprintf(stderr, "ERROR: loading BPF object file failed\n");
119 goto cleanup;
120 }
121
122 map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
123 map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
124 if (map_fd[0] < 0 || map_fd[1] < 0) {
125 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
126 goto cleanup;
127 }
128
129 signal(SIGINT, int_exit);
130 signal(SIGTERM, int_exit);
131
132 bpf_object__for_each_program(prog, obj) {
133 links[i] = bpf_program__attach(prog);
134 if (libbpf_get_error(links[i])) {
135 fprintf(stderr, "ERROR: bpf_program__attach failed\n");
136 links[i] = NULL;
137 goto cleanup;
138 }
139 i++;
140 }
141
142 if (argc > 1)
143 delay = atoi(argv[1]);
144 sleep(delay);
145 print_stacks(fd: map_fd[0]);
146
147cleanup:
148 for (i--; i >= 0; i--)
149 bpf_link__destroy(links[i]);
150
151 bpf_object__close(obj);
152 return 0;
153}
154

source code of linux/samples/bpf/offwaketime_user.c