1
2
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 <sys/resource.h>
12#include <bpf/libbpf.h>
13#include <bpf/bpf.h>
14#include "trace_helpers.h"
15
16#define PRINT_RAW_ADDR 0
17
18
19static int map_fd[2];
20
21static void print_ksym(__u64 addr)
22{
23 struct ksym *sym;
24
25 if (!addr)
26 return;
27 sym = ksym_search(addr);
28 if (!sym) {
29 printf("ksym not found. Is kallsyms loaded?\n");
30 return;
31 }
32
33 if (PRINT_RAW_ADDR)
34 printf("%s/%llx;", sym->name, addr);
35 else
36 printf("%s;", sym->name);
37}
38
39#define TASK_COMM_LEN 16
40
41struct key_t {
42 char waker[TASK_COMM_LEN];
43 char target[TASK_COMM_LEN];
44 __u32 wret;
45 __u32 tret;
46};
47
48static void print_stack(struct key_t *key, __u64 count)
49{
50 __u64 ip[PERF_MAX_STACK_DEPTH] = {};
51 static bool warned;
52 int i;
53
54 printf("%s;", key->target);
55 if (bpf_map_lookup_elem(map_fd[1], &key->tret, ip) != 0) {
56 printf("---;");
57 } else {
58 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
59 print_ksym(ip[i]);
60 }
61 printf("-;");
62 if (bpf_map_lookup_elem(map_fd[1], &key->wret, ip) != 0) {
63 printf("---;");
64 } else {
65 for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
66 print_ksym(ip[i]);
67 }
68 printf(";%s %lld\n", key->waker, count);
69
70 if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
71 printf("stackmap collisions seen. Consider increasing size\n");
72 warned = true;
73 } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
74 printf("err stackid %d %d\n", key->tret, key->wret);
75 }
76}
77
78static void print_stacks(int fd)
79{
80 struct key_t key = {}, next_key;
81 __u64 value;
82
83 while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
84 bpf_map_lookup_elem(fd, &next_key, &value);
85 print_stack(&next_key, value);
86 key = next_key;
87 }
88}
89
90static void int_exit(int sig)
91{
92 print_stacks(map_fd[0]);
93 exit(0);
94}
95
96int main(int argc, char **argv)
97{
98 struct bpf_object *obj = NULL;
99 struct bpf_link *links[2];
100 struct bpf_program *prog;
101 int delay = 1, i = 0;
102 char filename[256];
103
104 if (load_kallsyms()) {
105 printf("failed to process /proc/kallsyms\n");
106 return 2;
107 }
108
109 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
110 obj = bpf_object__open_file(filename, NULL);
111 if (libbpf_get_error(obj)) {
112 fprintf(stderr, "ERROR: opening BPF object file failed\n");
113 obj = NULL;
114 goto cleanup;
115 }
116
117
118 if (bpf_object__load(obj)) {
119 fprintf(stderr, "ERROR: loading BPF object file failed\n");
120 goto cleanup;
121 }
122
123 map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
124 map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
125 if (map_fd[0] < 0 || map_fd[1] < 0) {
126 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
127 goto cleanup;
128 }
129
130 signal(SIGINT, int_exit);
131 signal(SIGTERM, int_exit);
132
133 bpf_object__for_each_program(prog, obj) {
134 links[i] = bpf_program__attach(prog);
135 if (libbpf_get_error(links[i])) {
136 fprintf(stderr, "ERROR: bpf_program__attach failed\n");
137 links[i] = NULL;
138 goto cleanup;
139 }
140 i++;
141 }
142
143 if (argc > 1)
144 delay = atoi(argv[1]);
145 sleep(delay);
146 print_stacks(map_fd[0]);
147
148cleanup:
149 for (i--; i >= 0; i--)
150 bpf_link__destroy(links[i]);
151
152 bpf_object__close(obj);
153 return 0;
154}
155
