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39111695 AS |
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 | } |