/* * 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", }; uint64_t rdtsc() { 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; } 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(int argc, char **argv) { 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); }