// 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");
}