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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - Documentation/prctl/disable-tsc-test.c
2 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
4 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
14 #include <sys/prctl.h>
15 #include <linux/prctl.h>
17 /* Get/set the process' ability to use the timestamp counter instruction */
21 # define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
22 # define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
25 const char *tsc_names
[] =
28 [PR_TSC_ENABLE
] = "PR_TSC_ENABLE",
29 [PR_TSC_SIGSEGV
] = "PR_TSC_SIGSEGV",
34 /* We cannot use "=A", since this would use %rax on x86_64 */
35 __asm__
__volatile__ ("rdtsc" : "=a" (lo
), "=d" (hi
));
36 return (uint64_t)hi
<< 32 | lo
;
39 void sigsegv_cb(int sig
)
43 printf("[ SIG_SEGV ]\n");
44 printf("prctl(PR_GET_TSC, &tsc_val); ");
47 if ( prctl(PR_GET_TSC
, &tsc_val
) == -1)
50 printf("tsc_val == %s\n", tsc_names
[tsc_val
]);
51 printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
53 if ( prctl(PR_SET_TSC
, PR_TSC_ENABLE
) == -1)
56 printf("rdtsc() == ");
59 int main(int argc
, char **argv
)
63 signal(SIGSEGV
, sigsegv_cb
);
65 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
66 printf("prctl(PR_GET_TSC, &tsc_val); ");
69 if ( prctl(PR_GET_TSC
, &tsc_val
) == -1)
72 printf("tsc_val == %s\n", tsc_names
[tsc_val
]);
73 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
74 printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
77 if ( prctl(PR_SET_TSC
, PR_TSC_ENABLE
) == -1)
80 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
81 printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
84 if ( prctl(PR_SET_TSC
, PR_TSC_SIGSEGV
) == -1)
87 printf("rdtsc() == ");
89 printf("%llu\n", (unsigned long long)rdtsc());