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 */
18 static int map_fd[2];
19 
20 static 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 
40 struct key_t {
41 	char waker[TASK_COMM_LEN];
42 	char target[TASK_COMM_LEN];
43 	__u32 wret;
44 	__u32 tret;
45 };
46 
47 static 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(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(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 
77 static 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(&next_key, value);
85 		key = next_key;
86 	}
87 }
88 
89 static void int_exit(int sig)
90 {
91 	print_stacks(map_fd[0]);
92 	exit(0);
93 }
94 
95 int 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(filename, sizeof(filename), "%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(map_fd[0]);
146 
147 cleanup:
148 	for (i--; i >= 0; i--)
149 		bpf_link__destroy(links[i]);
150 
151 	bpf_object__close(obj);
152 	return 0;
153 }
154