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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2015, Cyril Bur, IBM Corp.
* Copyright 2023, Michael Ellerman, IBM Corp.
*
* This test attempts to see if the FPU registers change across preemption.
* 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"
#include "fpu.h"
/* Time to wait for workers to get preempted (seconds) */
#define PREEMPT_TIME 60
/*
* Factor by which to multiply number of online CPUs for total number of
* worker threads
*/
#define THREAD_FACTOR 8
__thread double darray[32];
int threads_starting;
int running;
extern int preempt_fpu(double *darray, int *threads_starting, int *running);
void *preempt_fpu_c(void *p)
{
long rc;
srand(pthread_self());
randomise_darray(darray, ARRAY_SIZE(darray));
rc = preempt_fpu(darray, &threads_starting, &running);
return (void *)rc;
}
int test_preempt_fpu(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_fpu_c, NULL);
FAIL_IF(rc);
}
setbuf(stdout, NULL);
/* Not really necessary 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_fpu '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_fpu
* returned
*/
if ((long) rc_p)
printf("oops\n");
FAIL_IF((long) rc_p);
}
printf("done\n");
free(tids);
return 0;
}
int main(int argc, char *argv[])
{
return test_harness(test_preempt_fpu, "fpu_preempt");
}
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