1/* 2 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...) 3 * 4 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC 5 */ 6 7#include <stdio.h> 8#include <stdlib.h> 9#include <unistd.h> 10#include <signal.h> 11#include <inttypes.h> 12 13 14#include <sys/prctl.h> 15#include <linux/prctl.h> 16 17/* Get/set the process' ability to use the timestamp counter instruction */ 18#ifndef PR_GET_TSC 19#define PR_GET_TSC 25 20#define PR_SET_TSC 26 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 */ 23#endif 24 25const char *tsc_names[] = 26{ 27 [0] = "[not set]", 28 [PR_TSC_ENABLE] = "PR_TSC_ENABLE", 29 [PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV", 30}; 31 32uint64_t rdtsc() { 33uint32_t lo, hi; 34/* We cannot use "=A", since this would use %rax on x86_64 */ 35__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi)); 36return (uint64_t)hi << 32 | lo; 37} 38 39void sigsegv_cb(int sig) 40{ 41 int tsc_val = 0; 42 43 printf("[ SIG_SEGV ]\n"); 44 printf("prctl(PR_GET_TSC, &tsc_val); "); 45 fflush(stdout); 46 47 if ( prctl(PR_GET_TSC, &tsc_val) == -1) 48 perror("prctl"); 49 50 printf("tsc_val == %s\n", tsc_names[tsc_val]); 51 printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n"); 52 fflush(stdout); 53 if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1) 54 perror("prctl"); 55 56 printf("rdtsc() == "); 57} 58 59int main(int argc, char **argv) 60{ 61 int tsc_val = 0; 62 63 signal(SIGSEGV, sigsegv_cb); 64 65 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc()); 66 printf("prctl(PR_GET_TSC, &tsc_val); "); 67 fflush(stdout); 68 69 if ( prctl(PR_GET_TSC, &tsc_val) == -1) 70 perror("prctl"); 71 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"); 75 fflush(stdout); 76 77 if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1) 78 perror("prctl"); 79 80 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc()); 81 printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n"); 82 fflush(stdout); 83 84 if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1) 85 perror("prctl"); 86 87 printf("rdtsc() == "); 88 fflush(stdout); 89 printf("%llu\n", (unsigned long long)rdtsc()); 90 fflush(stdout); 91 92 exit(EXIT_SUCCESS); 93} 94