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

DEFINITIONS

1. preempt_vmx_c
2. test_preempt_vmx
3. main

   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         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_vmx_c, NULL);
  68                 FAIL_IF(rc);
  69         }
  70 
  71         setbuf(stdout, NULL);
  72         /* Not really nessesary 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_vmx '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_vmx
  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         return 0;
 103 }
 104 
 105 int main(int argc, char *argv[])
 106 {
 107         return test_harness(test_preempt_vmx, "vmx_preempt");
 108 }