1 /*
2  * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 // Test that values in /proc/uptime increment monotonically
17 // while shifting across CPUs.
18 #define _GNU_SOURCE
19 #undef NDEBUG
20 #include <assert.h>
21 #include <unistd.h>
22 #include <sys/syscall.h>
23 #include <stdlib.h>
24 #include <string.h>
25 
26 #include <stdint.h>
27 #include <sys/types.h>
28 #include <sys/stat.h>
29 #include <fcntl.h>
30 
31 #include "proc-uptime.h"
32 
33 static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
34 {
35 	return syscall(SYS_sched_getaffinity, pid, len, m);
36 }
37 
38 static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
39 {
40 	return syscall(SYS_sched_setaffinity, pid, len, m);
41 }
42 
43 int main(void)
44 {
45 	unsigned int len;
46 	unsigned long *m;
47 	unsigned int cpu;
48 	uint64_t u0, u1, i0, i1;
49 	int fd;
50 
51 	/* find out "nr_cpu_ids" */
52 	m = NULL;
53 	len = 0;
54 	do {
55 		len += sizeof(unsigned long);
56 		free(m);
57 		m = malloc(len);
58 	} while (sys_sched_getaffinity(0, len, m) == -EINVAL);
59 
60 	fd = open("/proc/uptime", O_RDONLY);
61 	assert(fd >= 0);
62 
63 	proc_uptime(fd, &u0, &i0);
64 	for (cpu = 0; cpu < len * 8; cpu++) {
65 		memset(m, 0, len);
66 		m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
67 
68 		/* CPU might not exist, ignore error */
69 		sys_sched_setaffinity(0, len, m);
70 
71 		proc_uptime(fd, &u1, &i1);
72 		assert(u1 >= u0);
73 		assert(i1 >= i0);
74 		u0 = u1;
75 		i0 = i1;
76 	}
77 
78 	return 0;
79 }
80