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
 23static 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
 38struct key_t {
 39	char waker[TASK_COMM_LEN];
 40	char target[TASK_COMM_LEN];
 41	__u32 wret;
 42	__u32 tret;
 43};
 44
 45static 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_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_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
 75static void print_stacks(int fd)
 76{
 77	struct key_t key = {}, next_key;
 78	__u64 value;
 79
 80	while (bpf_get_next_key(fd, &key, &next_key) == 0) {
 81		bpf_lookup_elem(fd, &next_key, &value);
 82		print_stack(&next_key, value);
 83		key = next_key;
 84	}
 85}
 86
 87static void int_exit(int sig)
 88{
 89	print_stacks(map_fd[0]);
 90	exit(0);
 91}
 92
 93int 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
104	if (load_kallsyms()) {
105		printf("failed to process /proc/kallsyms\n");
106		return 2;
107	}
108
109	if (load_bpf_file(filename)) {
110		printf("%s", bpf_log_buf);
111		return 1;
112	}
113
114	if (argc > 1)
115		delay = atoi(argv[1]);
116	sleep(delay);
117	print_stacks(map_fd[0]);
118
119	return 0;
120}