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 #include "trace_helpers.h"
21 
22 #define PRINT_RAW_ADDR 0
23 
24 static void print_ksym(__u64 addr)
25 {
26 	struct ksym *sym;
27 
28 	if (!addr)
29 		return;
30 	sym = ksym_search(addr);
31 	if (PRINT_RAW_ADDR)
32 		printf("%s/%llx;", sym->name, addr);
33 	else
34 		printf("%s;", sym->name);
35 }
36 
37 #define TASK_COMM_LEN 16
38 
39 struct key_t {
40 	char waker[TASK_COMM_LEN];
41 	char target[TASK_COMM_LEN];
42 	__u32 wret;
43 	__u32 tret;
44 };
45 
46 static void print_stack(struct key_t *key, __u64 count)
47 {
48 	__u64 ip[PERF_MAX_STACK_DEPTH] = {};
49 	static bool warned;
50 	int i;
51 
52 	printf("%s;", key->target);
53 	if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
54 		printf("---;");
55 	} else {
56 		for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
57 			print_ksym(ip[i]);
58 	}
59 	printf("-;");
60 	if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
61 		printf("---;");
62 	} else {
63 		for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
64 			print_ksym(ip[i]);
65 	}
66 	printf(";%s %lld\n", key->waker, count);
67 
68 	if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
69 		printf("stackmap collisions seen. Consider increasing size\n");
70 		warned = true;
71 	} else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
72 		printf("err stackid %d %d\n", key->tret, key->wret);
73 	}
74 }
75 
76 static void print_stacks(int fd)
77 {
78 	struct key_t key = {}, next_key;
79 	__u64 value;
80 
81 	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
82 		bpf_map_lookup_elem(fd, &next_key, &value);
83 		print_stack(&next_key, value);
84 		key = next_key;
85 	}
86 }
87 
88 static void int_exit(int sig)
89 {
90 	print_stacks(map_fd[0]);
91 	exit(0);
92 }
93 
94 int main(int argc, char **argv)
95 {
96 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
97 	char filename[256];
98 	int delay = 1;
99 
100 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
101 	setrlimit(RLIMIT_MEMLOCK, &r);
102 
103 	signal(SIGINT, int_exit);
104 	signal(SIGTERM, int_exit);
105 
106 	if (load_kallsyms()) {
107 		printf("failed to process /proc/kallsyms\n");
108 		return 2;
109 	}
110 
111 	if (load_bpf_file(filename)) {
112 		printf("%s", bpf_log_buf);
113 		return 1;
114 	}
115 
116 	if (argc > 1)
117 		delay = atoi(argv[1]);
118 	sleep(delay);
119 	print_stacks(map_fd[0]);
120 
121 	return 0;
122 }
123