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 <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 /* counts, stackmap */
19 static int map_fd[2];
20 
21 static 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 
41 struct key_t {
42 	char waker[TASK_COMM_LEN];
43 	char target[TASK_COMM_LEN];
44 	__u32 wret;
45 	__u32 tret;
46 };
47 
48 static 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 
78 static 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 
90 static void int_exit(int sig)
91 {
92 	print_stacks(map_fd[0]);
93 	exit(0);
94 }
95 
96 int 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 	/* load BPF program */
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 
148 cleanup:
149 	for (i--; i >= 0; i--)
150 		bpf_link__destroy(links[i]);
151 
152 	bpf_object__close(obj);
153 	return 0;
154 }
155