1 /* This program is free software; you can redistribute it and/or
2  * modify it under the terms of version 2 of the GNU General Public
3  * License as published by the Free Software Foundation.
4  */
5 #include <stdio.h>
6 #include <unistd.h>
7 #include <stdlib.h>
8 #include <stdbool.h>
9 #include <string.h>
10 #include <fcntl.h>
11 #include <poll.h>
12 #include <sys/ioctl.h>
13 #include <linux/perf_event.h>
14 #include <linux/bpf.h>
15 #include <errno.h>
16 #include <assert.h>
17 #include <sys/syscall.h>
18 #include <sys/ioctl.h>
19 #include <sys/mman.h>
20 #include <time.h>
21 #include <signal.h>
22 #include "libbpf.h"
23 #include "bpf_load.h"
24 
25 static int pmu_fd;
26 
27 int page_size;
28 int page_cnt = 8;
29 volatile struct perf_event_mmap_page *header;
30 
31 typedef void (*print_fn)(void *data, int size);
32 
33 static int perf_event_mmap(int fd)
34 {
35 	void *base;
36 	int mmap_size;
37 
38 	page_size = getpagesize();
39 	mmap_size = page_size * (page_cnt + 1);
40 
41 	base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
42 	if (base == MAP_FAILED) {
43 		printf("mmap err\n");
44 		return -1;
45 	}
46 
47 	header = base;
48 	return 0;
49 }
50 
51 static int perf_event_poll(int fd)
52 {
53 	struct pollfd pfd = { .fd = fd, .events = POLLIN };
54 
55 	return poll(&pfd, 1, 1000);
56 }
57 
58 struct perf_event_sample {
59 	struct perf_event_header header;
60 	__u32 size;
61 	char data[];
62 };
63 
64 void perf_event_read(print_fn fn)
65 {
66 	__u64 data_tail = header->data_tail;
67 	__u64 data_head = header->data_head;
68 	__u64 buffer_size = page_cnt * page_size;
69 	void *base, *begin, *end;
70 	char buf[256];
71 
72 	asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
73 	if (data_head == data_tail)
74 		return;
75 
76 	base = ((char *)header) + page_size;
77 
78 	begin = base + data_tail % buffer_size;
79 	end = base + data_head % buffer_size;
80 
81 	while (begin != end) {
82 		struct perf_event_sample *e;
83 
84 		e = begin;
85 		if (begin + e->header.size > base + buffer_size) {
86 			long len = base + buffer_size - begin;
87 
88 			assert(len < e->header.size);
89 			memcpy(buf, begin, len);
90 			memcpy(buf + len, base, e->header.size - len);
91 			e = (void *) buf;
92 			begin = base + e->header.size - len;
93 		} else if (begin + e->header.size == base + buffer_size) {
94 			begin = base;
95 		} else {
96 			begin += e->header.size;
97 		}
98 
99 		if (e->header.type == PERF_RECORD_SAMPLE) {
100 			fn(e->data, e->size);
101 		} else if (e->header.type == PERF_RECORD_LOST) {
102 			struct {
103 				struct perf_event_header header;
104 				__u64 id;
105 				__u64 lost;
106 			} *lost = (void *) e;
107 			printf("lost %lld events\n", lost->lost);
108 		} else {
109 			printf("unknown event type=%d size=%d\n",
110 			       e->header.type, e->header.size);
111 		}
112 	}
113 
114 	__sync_synchronize(); /* smp_mb() */
115 	header->data_tail = data_head;
116 }
117 
118 static __u64 time_get_ns(void)
119 {
120 	struct timespec ts;
121 
122 	clock_gettime(CLOCK_MONOTONIC, &ts);
123 	return ts.tv_sec * 1000000000ull + ts.tv_nsec;
124 }
125 
126 static __u64 start_time;
127 
128 #define MAX_CNT 100000ll
129 
130 static void print_bpf_output(void *data, int size)
131 {
132 	static __u64 cnt;
133 	struct {
134 		__u64 pid;
135 		__u64 cookie;
136 	} *e = data;
137 
138 	if (e->cookie != 0x12345678) {
139 		printf("BUG pid %llx cookie %llx sized %d\n",
140 		       e->pid, e->cookie, size);
141 		kill(0, SIGINT);
142 	}
143 
144 	cnt++;
145 
146 	if (cnt == MAX_CNT) {
147 		printf("recv %lld events per sec\n",
148 		       MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
149 		kill(0, SIGINT);
150 	}
151 }
152 
153 static void test_bpf_perf_event(void)
154 {
155 	struct perf_event_attr attr = {
156 		.sample_type = PERF_SAMPLE_RAW,
157 		.type = PERF_TYPE_SOFTWARE,
158 		.config = PERF_COUNT_SW_BPF_OUTPUT,
159 	};
160 	int key = 0;
161 
162 	pmu_fd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
163 
164 	assert(pmu_fd >= 0);
165 	assert(bpf_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
166 	ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
167 }
168 
169 int main(int argc, char **argv)
170 {
171 	char filename[256];
172 	FILE *f;
173 
174 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
175 
176 	if (load_bpf_file(filename)) {
177 		printf("%s", bpf_log_buf);
178 		return 1;
179 	}
180 
181 	test_bpf_perf_event();
182 
183 	if (perf_event_mmap(pmu_fd) < 0)
184 		return 1;
185 
186 	f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
187 	(void) f;
188 
189 	start_time = time_get_ns();
190 	for (;;) {
191 		perf_event_poll(pmu_fd);
192 		perf_event_read(print_bpf_output);
193 	}
194 
195 	return 0;
196 }
197