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 */
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	/* 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
148cleanup:
149	for (i--; i >= 0; i--)
150		bpf_link__destroy(links[i]);
151
152	bpf_object__close(obj);
153	return 0;
154}
155