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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fpu_preempt.c (2644B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright 2015, Cyril Bur, IBM Corp.
      4 *
      5 * This test attempts to see if the FPU registers change across preemption.
      6 * Two things should be noted here a) The check_fpu function in asm only checks
      7 * the non volatile registers as it is reused from the syscall test b) There is
      8 * no way to be sure preemption happened so this test just uses many threads
      9 * and a long wait. As such, a successful test doesn't mean much but a failure
     10 * is bad.
     11 */
     12
     13#include <stdio.h>
     14#include <unistd.h>
     15#include <sys/syscall.h>
     16#include <sys/time.h>
     17#include <sys/types.h>
     18#include <sys/wait.h>
     19#include <stdlib.h>
     20#include <pthread.h>
     21
     22#include "utils.h"
     23
     24/* Time to wait for workers to get preempted (seconds) */
     25#define PREEMPT_TIME 20
     26/*
     27 * Factor by which to multiply number of online CPUs for total number of
     28 * worker threads
     29 */
     30#define THREAD_FACTOR 8
     31
     32
     33__thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
     34		     1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
     35		     2.1};
     36
     37int threads_starting;
     38int running;
     39
     40extern void preempt_fpu(double *darray, int *threads_starting, int *running);
     41
     42void *preempt_fpu_c(void *p)
     43{
     44	int i;
     45	srand(pthread_self());
     46	for (i = 0; i < 21; i++)
     47		darray[i] = rand();
     48
     49	/* Test failed if it ever returns */
     50	preempt_fpu(darray, &threads_starting, &running);
     51
     52	return p;
     53}
     54
     55int test_preempt_fpu(void)
     56{
     57	int i, rc, threads;
     58	pthread_t *tids;
     59
     60	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
     61	tids = malloc((threads) * sizeof(pthread_t));
     62	FAIL_IF(!tids);
     63
     64	running = true;
     65	threads_starting = threads;
     66	for (i = 0; i < threads; i++) {
     67		rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL);
     68		FAIL_IF(rc);
     69	}
     70
     71	setbuf(stdout, NULL);
     72	/* Not really necessary but nice to wait for every thread to start */
     73	printf("\tWaiting for all workers to start...");
     74	while(threads_starting)
     75		asm volatile("": : :"memory");
     76	printf("done\n");
     77
     78	printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
     79	sleep(PREEMPT_TIME);
     80	printf("done\n");
     81
     82	printf("\tStopping workers...");
     83	/*
     84	 * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'.
     85	 * r5 will have loaded the value of running.
     86	 */
     87	running = 0;
     88	for (i = 0; i < threads; i++) {
     89		void *rc_p;
     90		pthread_join(tids[i], &rc_p);
     91
     92		/*
     93		 * Harness will say the fail was here, look at why preempt_fpu
     94		 * returned
     95		 */
     96		if ((long) rc_p)
     97			printf("oops\n");
     98		FAIL_IF((long) rc_p);
     99	}
    100	printf("done\n");
    101
    102	free(tids);
    103	return 0;
    104}
    105
    106int main(int argc, char *argv[])
    107{
    108	return test_harness(test_preempt_fpu, "fpu_preempt");
    109}