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

DEFINITIONS

1. vsx_memcmp
2. preempt_vsx_c
3. test_preempt_vsx
4. 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 VSX registers change across preemption.
   6  * There is no way to be sure preemption happened so this test just
   7  * uses many threads and a long wait. As such, a successful test
   8  * doesn't mean much but a failure is bad.
   9  */
  10 
  11 #include <stdio.h>
  12 #include <string.h>
  13 #include <unistd.h>
  14 #include <sys/syscall.h>
  15 #include <sys/time.h>
  16 #include <sys/types.h>
  17 #include <sys/wait.h>
  18 #include <stdlib.h>
  19 #include <pthread.h>
  20 
  21 #include "utils.h"
  22 
  23 /* Time to wait for workers to get preempted (seconds) */
  24 #define PREEMPT_TIME 20
  25 /*
  26  * Factor by which to multiply number of online CPUs for total number of
  27  * worker threads
  28  */
  29 #define THREAD_FACTOR 8
  30 
  31 /*
  32  * Ensure there is twice the number of non-volatile VMX regs!
  33  * check_vmx() is going to use the other half as space to put the live
  34  * registers before calling vsx_memcmp()
  35  */
  36 __thread vector int varray[24] = {
  37         {1, 2, 3, 4 }, {5, 6, 7, 8 }, {9, 10,11,12},
  38         {13,14,15,16}, {17,18,19,20}, {21,22,23,24},
  39         {25,26,27,28}, {29,30,31,32}, {33,34,35,36},
  40         {37,38,39,40}, {41,42,43,44}, {45,46,47,48}
  41 };
  42 
  43 int threads_starting;
  44 int running;
  45 
  46 extern long preempt_vsx(vector int *varray, int *threads_starting, int *running);
  47 
  48 long vsx_memcmp(vector int *a) {
  49         vector int zero = {0, 0, 0, 0};
  50         int i;
  51 
  52         FAIL_IF(a != varray);
  53 
  54         for(i = 0; i < 12; i++) {
  55                 if (memcmp(&a[i + 12], &zero, sizeof(vector int)) == 0) {
  56                         fprintf(stderr, "Detected zero from the VSX reg %d\n", i + 12);
  57                         return 2;
  58                 }
  59         }
  60 
  61         if (memcmp(a, &a[12], 12 * sizeof(vector int))) {
  62                 long *p = (long *)a;
  63                 fprintf(stderr, "VSX mismatch\n");
  64                 for (i = 0; i < 24; i=i+2)
  65                         fprintf(stderr, "%d: 0x%08lx%08lx | 0x%08lx%08lx\n",
  66                                         i/2 + i%2 + 20, p[i], p[i + 1], p[i + 24], p[i + 25]);
  67                 return 1;
  68         }
  69         return 0;
  70 }
  71 
  72 void *preempt_vsx_c(void *p)
  73 {
  74         int i, j;
  75         long rc;
  76         srand(pthread_self());
  77         for (i = 0; i < 12; i++)
  78                 for (j = 0; j < 4; j++) {
  79                         varray[i][j] = rand();
  80                         /* Don't want zero because it hides kernel problems */
  81                         if (varray[i][j] == 0)
  82                                 j--;
  83                 }
  84         rc = preempt_vsx(varray, &threads_starting, &running);
  85         if (rc == 2)
  86                 fprintf(stderr, "Caught zeros in VSX compares\n");
  87         return (void *)rc;
  88 }
  89 
  90 int test_preempt_vsx(void)
  91 {
  92         int i, rc, threads;
  93         pthread_t *tids;
  94 
  95         threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
  96         tids = malloc(threads * sizeof(pthread_t));
  97         FAIL_IF(!tids);
  98 
  99         running = true;
 100         threads_starting = threads;
 101         for (i = 0; i < threads; i++) {
 102                 rc = pthread_create(&tids[i], NULL, preempt_vsx_c, NULL);
 103                 FAIL_IF(rc);
 104         }
 105 
 106         setbuf(stdout, NULL);
 107         /* Not really nessesary but nice to wait for every thread to start */
 108         printf("\tWaiting for %d workers to start...", threads_starting);
 109         while(threads_starting)
 110                 asm volatile("": : :"memory");
 111         printf("done\n");
 112 
 113         printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
 114         sleep(PREEMPT_TIME);
 115         printf("done\n");
 116 
 117         printf("\tStopping workers...");
 118         /*
 119          * Working are checking this value every loop. In preempt_vsx 'cmpwi r5,0; bne 2b'.
 120          * r5 will have loaded the value of running.
 121          */
 122         running = 0;
 123         for (i = 0; i < threads; i++) {
 124                 void *rc_p;
 125                 pthread_join(tids[i], &rc_p);
 126 
 127                 /*
 128                  * Harness will say the fail was here, look at why preempt_vsx
 129                  * returned
 130                  */
 131                 if ((long) rc_p)
 132                         printf("oops\n");
 133                 FAIL_IF((long) rc_p);
 134         }
 135         printf("done\n");
 136 
 137         return 0;
 138 }
 139 
 140 int main(int argc, char *argv[])
 141 {
 142         return test_harness(test_preempt_vsx, "vsx_preempt");
 143 }