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 <stdio.h>
8 #include <unistd.h>
9 #include <stdlib.h>
10 #include <signal.h>
11 #include <linux/bpf.h>
12 #include <string.h>
13 #include <linux/perf_event.h>
14 #include <errno.h>
15 #include <assert.h>
16 #include <stdbool.h>
17 #include <sys/resource.h>
18 #include "libbpf.h"
19 #include "bpf_load.h"
20 
21 #define PRINT_RAW_ADDR 0
22 
23 static void print_ksym(__u64 addr)
24 {
25 	struct ksym *sym;
26 
27 	if (!addr)
28 		return;
29 	sym = ksym_search(addr);
30 	if (PRINT_RAW_ADDR)
31 		printf("%s/%llx;", sym->name, addr);
32 	else
33 		printf("%s;", sym->name);
34 }
35 
36 #define TASK_COMM_LEN 16
37 
38 struct key_t {
39 	char waker[TASK_COMM_LEN];
40 	char target[TASK_COMM_LEN];
41 	__u32 wret;
42 	__u32 tret;
43 };
44 
45 static void print_stack(struct key_t *key, __u64 count)
46 {
47 	__u64 ip[PERF_MAX_STACK_DEPTH] = {};
48 	static bool warned;
49 	int i;
50 
51 	printf("%s;", key->target);
52 	if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
53 		printf("---;");
54 	} else {
55 		for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
56 			print_ksym(ip[i]);
57 	}
58 	printf("-;");
59 	if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
60 		printf("---;");
61 	} else {
62 		for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
63 			print_ksym(ip[i]);
64 	}
65 	printf(";%s %lld\n", key->waker, count);
66 
67 	if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
68 		printf("stackmap collisions seen. Consider increasing size\n");
69 		warned = true;
70 	} else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
71 		printf("err stackid %d %d\n", key->tret, key->wret);
72 	}
73 }
74 
75 static void print_stacks(int fd)
76 {
77 	struct key_t key = {}, next_key;
78 	__u64 value;
79 
80 	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
81 		bpf_map_lookup_elem(fd, &next_key, &value);
82 		print_stack(&next_key, value);
83 		key = next_key;
84 	}
85 }
86 
87 static void int_exit(int sig)
88 {
89 	print_stacks(map_fd[0]);
90 	exit(0);
91 }
92 
93 int main(int argc, char **argv)
94 {
95 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
96 	char filename[256];
97 	int delay = 1;
98 
99 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
100 	setrlimit(RLIMIT_MEMLOCK, &r);
101 
102 	signal(SIGINT, int_exit);
103 	signal(SIGTERM, int_exit);
104 
105 	if (load_kallsyms()) {
106 		printf("failed to process /proc/kallsyms\n");
107 		return 2;
108 	}
109 
110 	if (load_bpf_file(filename)) {
111 		printf("%s", bpf_log_buf);
112 		return 1;
113 	}
114 
115 	if (argc > 1)
116 		delay = atoi(argv[1]);
117 	sleep(delay);
118 	print_stacks(map_fd[0]);
119 
120 	return 0;
121 }
122