1// SPDX-License-Identifier: GPL-2.0
2#include <stdio.h>
3#include <unistd.h>
4#include <stdlib.h>
5#include <signal.h>
6#include <string.h>
7#include <sys/resource.h>
8
9#include <bpf/bpf.h>
10#include <bpf/libbpf.h>
11#include "bpf_util.h"
12
13#define MAX_INDEX	64
14#define MAX_STARS	38
15
16/* my_map, my_hist_map */
17static int map_fd[2];
18
19static void stars(char *str, long val, long max, int width)
20{
21	int i;
22
23	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
24		str[i] = '*';
25	if (val > max)
26		str[i - 1] = '+';
27	str[i] = '\0';
28}
29
30struct task {
31	char comm[16];
32	__u64 pid_tgid;
33	__u64 uid_gid;
34};
35
36struct hist_key {
37	struct task t;
38	__u32 index;
39};
40
41#define SIZE sizeof(struct task)
42
43static void print_hist_for_pid(int fd, void *task)
44{
45	unsigned int nr_cpus = bpf_num_possible_cpus();
46	struct hist_key key = {}, next_key;
47	long values[nr_cpus];
48	char starstr[MAX_STARS];
49	long value;
50	long data[MAX_INDEX] = {};
51	int max_ind = -1;
52	long max_value = 0;
53	int i, ind;
54
55	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
56		if (memcmp(&next_key, task, SIZE)) {
57			key = next_key;
58			continue;
59		}
60		bpf_map_lookup_elem(fd, &next_key, values);
61		value = 0;
62		for (i = 0; i < nr_cpus; i++)
63			value += values[i];
64		ind = next_key.index;
65		data[ind] = value;
66		if (value && ind > max_ind)
67			max_ind = ind;
68		if (value > max_value)
69			max_value = value;
70		key = next_key;
71	}
72
73	printf("           syscall write() stats\n");
74	printf("     byte_size       : count     distribution\n");
75	for (i = 1; i <= max_ind + 1; i++) {
76		stars(starstr, data[i - 1], max_value, MAX_STARS);
77		printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
78		       (1l << i) >> 1, (1l << i) - 1, data[i - 1],
79		       MAX_STARS, starstr);
80	}
81}
82
83static void print_hist(int fd)
84{
85	struct hist_key key = {}, next_key;
86	static struct task tasks[1024];
87	int task_cnt = 0;
88	int i;
89
90	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
91		int found = 0;
92
93		for (i = 0; i < task_cnt; i++)
94			if (memcmp(&tasks[i], &next_key, SIZE) == 0)
95				found = 1;
96		if (!found)
97			memcpy(&tasks[task_cnt++], &next_key, SIZE);
98		key = next_key;
99	}
100
101	for (i = 0; i < task_cnt; i++) {
102		printf("\npid %d cmd %s uid %d\n",
103		       (__u32) tasks[i].pid_tgid,
104		       tasks[i].comm,
105		       (__u32) tasks[i].uid_gid);
106		print_hist_for_pid(fd, &tasks[i]);
107	}
108
109}
110
111static void int_exit(int sig)
112{
113	print_hist(map_fd[1]);
114	exit(0);
115}
116
117int main(int ac, char **argv)
118{
119	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
120	long key, next_key, value;
121	struct bpf_link *links[2];
122	struct bpf_program *prog;
123	struct bpf_object *obj;
124	char filename[256];
125	int i, j = 0;
126	FILE *f;
127
128	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
129		perror("setrlimit(RLIMIT_MEMLOCK)");
130		return 1;
131	}
132
133	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
134	obj = bpf_object__open_file(filename, NULL);
135	if (libbpf_get_error(obj)) {
136		fprintf(stderr, "ERROR: opening BPF object file failed\n");
137		return 0;
138	}
139
140	/* load BPF program */
141	if (bpf_object__load(obj)) {
142		fprintf(stderr, "ERROR: loading BPF object file failed\n");
143		goto cleanup;
144	}
145
146	map_fd[0] = bpf_object__find_map_fd_by_name(obj, "my_map");
147	map_fd[1] = bpf_object__find_map_fd_by_name(obj, "my_hist_map");
148	if (map_fd[0] < 0 || map_fd[1] < 0) {
149		fprintf(stderr, "ERROR: finding a map in obj file failed\n");
150		goto cleanup;
151	}
152
153	signal(SIGINT, int_exit);
154	signal(SIGTERM, int_exit);
155
156	/* start 'ping' in the background to have some kfree_skb events */
157	f = popen("ping -4 -c5 localhost", "r");
158	(void) f;
159
160	/* start 'dd' in the background to have plenty of 'write' syscalls */
161	f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
162	(void) f;
163
164	bpf_object__for_each_program(prog, obj) {
165		links[j] = bpf_program__attach(prog);
166		if (libbpf_get_error(links[j])) {
167			fprintf(stderr, "ERROR: bpf_program__attach failed\n");
168			links[j] = NULL;
169			goto cleanup;
170		}
171		j++;
172	}
173
174	for (i = 0; i < 5; i++) {
175		key = 0;
176		while (bpf_map_get_next_key(map_fd[0], &key, &next_key) == 0) {
177			bpf_map_lookup_elem(map_fd[0], &next_key, &value);
178			printf("location 0x%lx count %ld\n", next_key, value);
179			key = next_key;
180		}
181		if (key)
182			printf("\n");
183		sleep(1);
184	}
185	print_hist(map_fd[1]);
186
187cleanup:
188	for (j--; j >= 0; j--)
189		bpf_link__destroy(links[j]);
190
191	bpf_object__close(obj);
192	return 0;
193}
194