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

   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 VMX registers change across preemption.
   6  * Two things should be noted here a) The check_vmx 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 __thread vector int varray[] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10,11,12},
  33         {13,14,15,16},{17,18,19,20},{21,22,23,24},
  34         {25,26,27,28},{29,30,31,32},{33,34,35,36},
  35         {37,38,39,40},{41,42,43,44},{45,46,47,48}};
  36
  37 int threads_starting;
  38 int running;
  39
  40 extern void preempt_vmx(vector int *varray, int *threads_starting, int *running);
  41
  42 void *preempt_vmx_c(void *p)
  43 {
  44         int i, j;
  45         srand(pthread_self());
  46         for (i = 0; i < 12; i++)
  47                 for (j = 0; j < 4; j++)
  48                         varray[i][j] = rand();
  49
  50         /* Test fails if it ever returns */
  51         preempt_vmx(varray, &threads_starting, &running);
  52         return p;
  53 }
  54
  55 int test_preempt_vmx(void)
  56 {
  57         int i, rc, threads;
  58         pthread_t *tids;
  59
  60         // vcmpequd used in vmx_asm.S is v2.07
  61         SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_2_07));
  62
  63         threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
  64         tids = malloc(threads * sizeof(pthread_t));
  65         FAIL_IF(!tids);
  66
  67         running = true;
  68         threads_starting = threads;
  69         for (i = 0; i < threads; i++) {
  70                 rc = pthread_create(&tids[i], NULL, preempt_vmx_c, NULL);
  71                 FAIL_IF(rc);
  72         }
  73
  74         setbuf(stdout, NULL);
  75         /* Not really nessesary but nice to wait for every thread to start */
  76         printf("\tWaiting for all workers to start...");
  77         while(threads_starting)
  78                 asm volatile("": : :"memory");
  79         printf("done\n");
  80
  81         printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
  82         sleep(PREEMPT_TIME);
  83         printf("done\n");
  84
  85         printf("\tStopping workers...");
  86         /*
  87          * Working are checking this value every loop. In preempt_vmx 'cmpwi r5,0; bne 2b'.
  88          * r5 will have loaded the value of running.
  89          */
  90         running = 0;
  91         for (i = 0; i < threads; i++) {
  92                 void *rc_p;
  93                 pthread_join(tids[i], &rc_p);
  94
  95                 /*
  96                  * Harness will say the fail was here, look at why preempt_vmx
  97                  * returned
  98                  */
  99                 if ((long) rc_p)
 100                         printf("oops\n");
 101                 FAIL_IF((long) rc_p);
 102         }
 103         printf("done\n");
 104
 105         return 0;
 106 }
 107
 108 int main(int argc, char *argv[])
 109 {
 110         return test_harness(test_preempt_vmx, "vmx_preempt");
 111 }