diff options
author | David S. Miller <davem@davemloft.net> | 2016-10-30 12:42:58 -0400 |
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committer | David S. Miller <davem@davemloft.net> | 2016-10-30 12:42:58 -0400 |
commit | 27058af401e49d88a905df000dd26f443fcfa8ce (patch) | |
tree | 819f32113d3b8374b9fbf72e2202d4c4d4511a60 /tools/testing/selftests/prctl/disable-tsc-test.c | |
parent | 357f4aae859b5d74554b0ccbb18556f1df4166c3 (diff) | |
parent | 2a26d99b251b8625d27aed14e97fc10707a3a81f (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Mostly simple overlapping changes.
For example, David Ahern's adjacency list revamp in 'net-next'
conflicted with an adjacency list traversal bug fix in 'net'.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'tools/testing/selftests/prctl/disable-tsc-test.c')
-rw-r--r-- | tools/testing/selftests/prctl/disable-tsc-test.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/tools/testing/selftests/prctl/disable-tsc-test.c b/tools/testing/selftests/prctl/disable-tsc-test.c new file mode 100644 index 000000000000..8d494f7bebdb --- /dev/null +++ b/tools/testing/selftests/prctl/disable-tsc-test.c @@ -0,0 +1,95 @@ +/* + * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...) + * + * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <signal.h> +#include <inttypes.h> + + +#include <sys/prctl.h> +#include <linux/prctl.h> + +/* Get/set the process' ability to use the timestamp counter instruction */ +#ifndef PR_GET_TSC +#define PR_GET_TSC 25 +#define PR_SET_TSC 26 +# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */ +# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */ +#endif + +const char *tsc_names[] = +{ + [0] = "[not set]", + [PR_TSC_ENABLE] = "PR_TSC_ENABLE", + [PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV", +}; + +static uint64_t rdtsc(void) +{ +uint32_t lo, hi; +/* We cannot use "=A", since this would use %rax on x86_64 */ +__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi)); +return (uint64_t)hi << 32 | lo; +} + +static void sigsegv_cb(int sig) +{ + int tsc_val = 0; + + printf("[ SIG_SEGV ]\n"); + printf("prctl(PR_GET_TSC, &tsc_val); "); + fflush(stdout); + + if ( prctl(PR_GET_TSC, &tsc_val) == -1) + perror("prctl"); + + printf("tsc_val == %s\n", tsc_names[tsc_val]); + printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n"); + fflush(stdout); + if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1) + perror("prctl"); + + printf("rdtsc() == "); +} + +int main(void) +{ + int tsc_val = 0; + + signal(SIGSEGV, sigsegv_cb); + + printf("rdtsc() == %llu\n", (unsigned long long)rdtsc()); + printf("prctl(PR_GET_TSC, &tsc_val); "); + fflush(stdout); + + if ( prctl(PR_GET_TSC, &tsc_val) == -1) + perror("prctl"); + + printf("tsc_val == %s\n", tsc_names[tsc_val]); + printf("rdtsc() == %llu\n", (unsigned long long)rdtsc()); + printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n"); + fflush(stdout); + + if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1) + perror("prctl"); + + printf("rdtsc() == %llu\n", (unsigned long long)rdtsc()); + printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n"); + fflush(stdout); + + if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1) + perror("prctl"); + + printf("rdtsc() == "); + fflush(stdout); + printf("%llu\n", (unsigned long long)rdtsc()); + fflush(stdout); + + exit(EXIT_SUCCESS); +} + |