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	long key, next_key, value;
120	struct bpf_link *links[2];
121	struct bpf_program *prog;
122	struct bpf_object *obj;
123	char filename[256];
124	int i, j = 0;
125	FILE *f;
126
127	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
128	obj = bpf_object__open_file(filename, NULL);
129	if (libbpf_get_error(obj)) {
130		fprintf(stderr, "ERROR: opening BPF object file failed\n");
131		return 0;
132	}
133
134	/* load BPF program */
135	if (bpf_object__load(obj)) {
136		fprintf(stderr, "ERROR: loading BPF object file failed\n");
137		goto cleanup;
138	}
139
140	map_fd[0] = bpf_object__find_map_fd_by_name(obj, "my_map");
141	map_fd[1] = bpf_object__find_map_fd_by_name(obj, "my_hist_map");
142	if (map_fd[0] < 0 || map_fd[1] < 0) {
143		fprintf(stderr, "ERROR: finding a map in obj file failed\n");
144		goto cleanup;
145	}
146
147	signal(SIGINT, int_exit);
148	signal(SIGTERM, int_exit);
149
150	/* start 'ping' in the background to have some kfree_skb events */
151	f = popen("ping -4 -c5 localhost", "r");
152	(void) f;
153
154	/* start 'dd' in the background to have plenty of 'write' syscalls */
155	f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
156	(void) f;
157
158	bpf_object__for_each_program(prog, obj) {
159		links[j] = bpf_program__attach(prog);
160		if (libbpf_get_error(links[j])) {
161			fprintf(stderr, "ERROR: bpf_program__attach failed\n");
162			links[j] = NULL;
163			goto cleanup;
164		}
165		j++;
166	}
167
168	for (i = 0; i < 5; i++) {
169		key = 0;
170		while (bpf_map_get_next_key(map_fd[0], &key, &next_key) == 0) {
171			bpf_map_lookup_elem(map_fd[0], &next_key, &value);
172			printf("location 0x%lx count %ld\n", next_key, value);
173			key = next_key;
174		}
175		if (key)
176			printf("\n");
177		sleep(1);
178	}
179	print_hist(map_fd[1]);
180
181cleanup:
182	for (j--; j >= 0; j--)
183		bpf_link__destroy(links[j]);
184
185	bpf_object__close(obj);
186	return 0;
187}