97 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)4 *5 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC6 */7 8#include <stdio.h>9#include <stdlib.h>10#include <unistd.h>11#include <signal.h>12#include <inttypes.h>13 14 15#include <sys/prctl.h>16#include <linux/prctl.h>17 18/* Get/set the process' ability to use the timestamp counter instruction */19#ifndef PR_GET_TSC20#define PR_GET_TSC 2521#define PR_SET_TSC 2622# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */23# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */24#endif25 26const char *tsc_names[] =27{28 [0] = "[not set]",29 [PR_TSC_ENABLE] = "PR_TSC_ENABLE",30 [PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",31};32 33static uint64_t rdtsc(void)34{35uint32_t lo, hi;36/* We cannot use "=A", since this would use %rax on x86_64 */37__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));38return (uint64_t)hi << 32 | lo;39}40 41static void sigsegv_cb(int sig)42{43 int tsc_val = 0;44 45 printf("[ SIG_SEGV ]\n");46 printf("prctl(PR_GET_TSC, &tsc_val); ");47 fflush(stdout);48 49 if ( prctl(PR_GET_TSC, &tsc_val) == -1)50 perror("prctl");51 52 printf("tsc_val == %s\n", tsc_names[tsc_val]);53 printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");54 fflush(stdout);55 if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)56 perror("prctl");57 58 printf("rdtsc() == ");59}60 61int main(void)62{63 int tsc_val = 0;64 65 signal(SIGSEGV, sigsegv_cb);66 67 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());68 printf("prctl(PR_GET_TSC, &tsc_val); ");69 fflush(stdout);70 71 if ( prctl(PR_GET_TSC, &tsc_val) == -1)72 perror("prctl");73 74 printf("tsc_val == %s\n", tsc_names[tsc_val]);75 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());76 printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");77 fflush(stdout);78 79 if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)80 perror("prctl");81 82 printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());83 printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");84 fflush(stdout);85 86 if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)87 perror("prctl");88 89 printf("rdtsc() == ");90 fflush(stdout);91 printf("%llu\n", (unsigned long long)rdtsc());92 fflush(stdout);93 94 exit(EXIT_SUCCESS);95}96 97