cregit-Linux how code gets into the kernel

Release 4.11 tools/testing/selftests/powerpc/math/vmx_preempt.c

/*
 * Copyright 2015, Cyril Bur, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * This test attempts to see if the VMX registers change across preemption.
 * Two things should be noted here a) The check_vmx function in asm only checks
 * the non volatile registers as it is reused from the syscall test b) There is
 * no way to be sure preemption happened so this test just uses many threads
 * and a long wait. As such, a successful test doesn't mean much but a failure
 * is bad.
 */

#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <pthread.h>

#include "utils.h"

/* Time to wait for workers to get preempted (seconds) */

#define PREEMPT_TIME 20
/*
 * Factor by which to multiply number of online CPUs for total number of
 * worker threads
 */

#define THREAD_FACTOR 8


__thread vector int varray[] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10,11,12},
	{13,14,15,16},{17,18,19,20},{21,22,23,24},
	{25,26,27,28},{29,30,31,32},{33,34,35,36},
	{37,38,39,40},{41,42,43,44},{45,46,47,48}};


int threads_starting;

int running;

extern void preempt_vmx(vector int *varray, int *threads_starting, int *running);


void *preempt_vmx_c(void *p) { int i, j; srand(pthread_self()); for (i = 0; i < 12; i++) for (j = 0; j < 4; j++) varray[i][j] = rand(); /* Test fails if it ever returns */ preempt_vmx(varray, &threads_starting, &running); return p; }

Contributors

PersonTokensPropCommitsCommitProp
Cyril Bur73100.00%1100.00%
Total73100.00%1100.00%


int test_preempt_vmx(void) { int i, rc, threads; pthread_t *tids; threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR; tids = malloc(threads * sizeof(pthread_t)); FAIL_IF(!tids); running = true; threads_starting = threads; for (i = 0; i < threads; i++) { rc = pthread_create(&tids[i], NULL, preempt_vmx_c, NULL); FAIL_IF(rc); } setbuf(stdout, NULL); /* Not really nessesary but nice to wait for every thread to start */ printf("\tWaiting for all workers to start..."); while(threads_starting) asm volatile("": : :"memory"); printf("done\n"); printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME); sleep(PREEMPT_TIME); printf("done\n"); printf("\tStopping workers..."); /* * Working are checking this value every loop. In preempt_vmx 'cmpwi r5,0; bne 2b'. * r5 will have loaded the value of running. */ running = 0; for (i = 0; i < threads; i++) { void *rc_p; pthread_join(tids[i], &rc_p); /* * Harness will say the fail was here, look at why preempt_vmx * returned */ if ((long) rc_p) printf("oops\n"); FAIL_IF((long) rc_p); } printf("done\n"); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Cyril Bur201100.00%1100.00%
Total201100.00%1100.00%


int main(int argc, char *argv[]) { return test_harness(test_preempt_vmx, "vmx_preempt"); }

Contributors

PersonTokensPropCommitsCommitProp
Cyril Bur21100.00%1100.00%
Total21100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Cyril Bur485100.00%1100.00%
Total485100.00%1100.00%
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