cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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disable-tsc-on-off-stress-test.c (1761B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
      4 *
      5 * Tests if the control register is updated correctly
      6 * when set with prctl()
      7 *
      8 * Warning: this test will cause a very high load for a few seconds
      9 *
     10 */
     11
     12#include <stdio.h>
     13#include <stdlib.h>
     14#include <unistd.h>
     15#include <signal.h>
     16#include <inttypes.h>
     17#include <wait.h>
     18
     19
     20#include <sys/prctl.h>
     21#include <linux/prctl.h>
     22
     23/* Get/set the process' ability to use the timestamp counter instruction */
     24#ifndef PR_GET_TSC
     25#define PR_GET_TSC 25
     26#define PR_SET_TSC 26
     27# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
     28# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
     29#endif
     30
     31/* snippet from wikipedia :-) */
     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
     41int should_segv = 0;
     42
     43static void sigsegv_cb(int sig)
     44{
     45	if (!should_segv)
     46	{
     47		fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
     48		exit(0);
     49	}
     50	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
     51	{
     52		perror("prctl");
     53		exit(0);
     54	}
     55	should_segv = 0;
     56
     57	rdtsc();
     58}
     59
     60static void task(void)
     61{
     62	signal(SIGSEGV, sigsegv_cb);
     63	alarm(10);
     64	for(;;)
     65	{
     66		rdtsc();
     67		if (should_segv)
     68		{
     69			fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
     70			exit(0);
     71		}
     72		if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
     73		{
     74			perror("prctl");
     75			exit(0);
     76		}
     77		should_segv = 1;
     78	}
     79}
     80
     81
     82int main(void)
     83{
     84	int n_tasks = 100, i;
     85
     86	fprintf(stderr, "[No further output means we're allright]\n");
     87
     88	for (i=0; i<n_tasks; i++)
     89		if (fork() == 0)
     90			task();
     91
     92	for (i=0; i<n_tasks; i++)
     93		wait(NULL);
     94
     95	exit(0);
     96}
     97