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-ctxt-sw-stress-test.c (1782B)

      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 * at context switches
      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
     31static uint64_t rdtsc(void)
     32{
     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
     39static void sigsegv_expect(int sig)
     40{
     41	/* */
     42}
     43
     44static void segvtask(void)
     45{
     46	if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
     47	{
     48		perror("prctl");
     49		exit(0);
     50	}
     51	signal(SIGSEGV, sigsegv_expect);
     52	alarm(10);
     53	rdtsc();
     54	fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
     55	exit(0);
     56}
     57
     58
     59static void sigsegv_fail(int sig)
     60{
     61	fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
     62	exit(0);
     63}
     64
     65static void rdtsctask(void)
     66{
     67	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
     68	{
     69		perror("prctl");
     70		exit(0);
     71	}
     72	signal(SIGSEGV, sigsegv_fail);
     73	alarm(10);
     74	for(;;) rdtsc();
     75}
     76
     77
     78int main(void)
     79{
     80	int n_tasks = 100, i;
     81
     82	fprintf(stderr, "[No further output means we're allright]\n");
     83
     84	for (i=0; i<n_tasks; i++)
     85		if (fork() == 0)
     86		{
     87			if (i & 1)
     88				segvtask();
     89			else
     90				rdtsctask();
     91		}
     92
     93	for (i=0; i<n_tasks; i++)
     94		wait(NULL);
     95
     96	exit(0);
     97}
     98