projects/linux·blob master · refs

99 lines · 2.2 KiB

1#include <stdbool.h>
2#include <stdio.h>
3#include <unistd.h>
4#include <errno.h>
5#include <sys/types.h>
6#include <sys/stat.h>
7#include <fcntl.h>
8#include <stdlib.h>
9#include <signal.h>
10
11#define _SDT_HAS_SEMAPHORES 1
12#include "sdt.h"
13
14#define SHARED 1
15#include "bpf/libbpf_internal.h"
16
17#define SEC(name) __attribute__((section(name), used))
18
19#define BUF_SIZE 256
20
21/* defined in urandom_read_aux.c */
22void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
23/* these are coming from urandom_read_lib{1,2}.c */
24void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
25void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
26
27int urandlib_api(void);
28COMPAT_VERSION(urandlib_api_old, urandlib_api, LIBURANDOM_READ_1.0.0)
29int urandlib_api_old(void);
30int urandlib_api_sameoffset(void);
31
32unsigned short urand_read_with_sema_semaphore SEC(".probes");
33
34static noinline void urandom_read(int fd, int count)
35{
36 char buf[BUF_SIZE];
37 int i;
38
39 for (i = 0; i < count; ++i) {
40 read(fd, buf, BUF_SIZE);
41
42 /* trigger USDTs defined in executable itself */
43 urand_read_without_sema(i, count, BUF_SIZE);
44 STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);
45
46 /* trigger USDTs defined in shared lib */
47 urandlib_read_without_sema(i, count, BUF_SIZE);
48 urandlib_read_with_sema(i, count, BUF_SIZE);
49 }
50}
51
52static volatile bool parent_ready;
53
54static void handle_sigpipe(int sig)
55{
56 parent_ready = true;
57}
58
59int main(int argc, char *argv[])
60{
61 int fd = open("/dev/urandom", O_RDONLY);
62 int count = 4;
63 bool report_pid = false;
64
65 if (fd < 0)
66 return 1;
67
68 if (argc >= 2)
69 count = atoi(argv[1]);
70 if (argc >= 3) {
71 report_pid = true;
72 /* install SIGPIPE handler to catch when parent closes their
73 * end of the pipe (on the other side of our stdout)
74 */
75 signal(SIGPIPE, handle_sigpipe);
76 }
77
78 /* report PID and wait for parent process to send us "signal" by
79 * closing stdout
80 */
81 if (report_pid) {
82 while (!parent_ready) {
83 fprintf(stdout, "%d\n", getpid());
84 fflush(stdout);
85 }
86 /* at this point stdout is closed, parent process knows our
87 * PID and is ready to trace us
88 */
89 }
90
91 urandom_read(fd, count);
92
93 urandlib_api();
94 urandlib_api_old();
95 urandlib_api_sameoffset();
96
97 close(fd);
98 return 0;
99}