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c57eb478 BB |
1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* | |
3 | * Copyright (c) 2021, Microsoft Corporation. | |
4 | * | |
5 | * Authors: | |
6 | * Beau Belgrave <beaub@linux.microsoft.com> | |
7 | */ | |
8 | ||
9 | #include <errno.h> | |
10 | #include <sys/ioctl.h> | |
11 | #include <sys/mman.h> | |
9211ddaa | 12 | #include <sys/uio.h> |
c57eb478 BB |
13 | #include <fcntl.h> |
14 | #include <stdio.h> | |
15 | #include <unistd.h> | |
16 | #include <linux/user_events.h> | |
17 | ||
2455f0e1 | 18 | const char *data_file = "/sys/kernel/tracing/user_events_data"; |
9211ddaa | 19 | int enabled = 0; |
c57eb478 | 20 | |
9211ddaa | 21 | static int event_reg(int fd, const char *command, int *write, int *enabled) |
c57eb478 BB |
22 | { |
23 | struct user_reg reg = {0}; | |
24 | ||
25 | reg.size = sizeof(reg); | |
9211ddaa BB |
26 | reg.enable_bit = 31; |
27 | reg.enable_size = sizeof(*enabled); | |
28 | reg.enable_addr = (__u64)enabled; | |
c57eb478 BB |
29 | reg.name_args = (__u64)command; |
30 | ||
31 | if (ioctl(fd, DIAG_IOCSREG, ®) == -1) | |
32 | return -1; | |
33 | ||
c57eb478 BB |
34 | *write = reg.write_index; |
35 | ||
36 | return 0; | |
37 | } | |
38 | ||
39 | int main(int argc, char **argv) | |
40 | { | |
39d6d08b | 41 | int data_fd, write; |
c57eb478 BB |
42 | struct iovec io[2]; |
43 | __u32 count = 0; | |
44 | ||
c57eb478 BB |
45 | data_fd = open(data_file, O_RDWR); |
46 | ||
9211ddaa | 47 | if (event_reg(data_fd, "test u32 count", &write, &enabled) == -1) |
c57eb478 BB |
48 | return errno; |
49 | ||
50 | /* Setup iovec */ | |
51 | io[0].iov_base = &write; | |
52 | io[0].iov_len = sizeof(write); | |
53 | io[1].iov_base = &count; | |
54 | io[1].iov_len = sizeof(count); | |
c57eb478 BB |
55 | ask: |
56 | printf("Press enter to check status...\n"); | |
57 | getchar(); | |
58 | ||
59 | /* Check if anyone is listening */ | |
9211ddaa | 60 | if (enabled) { |
c57eb478 BB |
61 | /* Yep, trace out our data */ |
62 | writev(data_fd, (const struct iovec *)io, 2); | |
63 | ||
64 | /* Increase the count */ | |
65 | count++; | |
66 | ||
67 | printf("Something was attached, wrote data\n"); | |
68 | } | |
69 | ||
70 | goto ask; | |
71 | ||
72 | return 0; | |
73 | } |