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

   1 /*
   2  * Copyright 2015, Cyril Bur, IBM Corp.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  *
   9  * This test attempts to see if the VSX registers change across preemption.
  10  * There is no way to be sure preemption happened so this test just
  11  * uses many threads and a long wait. As such, a successful test
  12  * doesn't mean much but a failure is bad.
  13  */
  14
  15 #include <stdio.h>
  16 #include <string.h>
  17 #include <unistd.h>
  18 #include <sys/syscall.h>
  19 #include <sys/time.h>
  20 #include <sys/types.h>
  21 #include <sys/wait.h>
  22 #include <stdlib.h>
  23 #include <pthread.h>
  24
  25 #include "utils.h"
  26
  27 /* Time to wait for workers to get preempted (seconds) */
  28 #define PREEMPT_TIME 20
  29 /*
  30  * Factor by which to multiply number of online CPUs for total number of
  31  * worker threads
  32  */
  33 #define THREAD_FACTOR 8
  34
  35 /*
  36  * Ensure there is twice the number of non-volatile VMX regs!
  37  * check_vmx() is going to use the other half as space to put the live
  38  * registers before calling vsx_memcmp()
  39  */
  40 __thread vector int varray[24] = {
  41         {1, 2, 3, 4 }, {5, 6, 7, 8 }, {9, 10,11,12},
  42         {13,14,15,16}, {17,18,19,20}, {21,22,23,24},
  43         {25,26,27,28}, {29,30,31,32}, {33,34,35,36},
  44         {37,38,39,40}, {41,42,43,44}, {45,46,47,48}
  45 };
  46
  47 int threads_starting;
  48 int running;
  49
  50 extern long preempt_vsx(vector int *varray, int *threads_starting, int *running);
  51
  52 long vsx_memcmp(vector int *a) {
  53         vector int zero = {0, 0, 0, 0};
  54         int i;
  55
  56         FAIL_IF(a != varray);
  57
  58         for(i = 0; i < 12; i++) {
  59                 if (memcmp(&a[i + 12], &zero, sizeof(vector int)) == 0) {
  60                         fprintf(stderr, "Detected zero from the VSX reg %d\n", i + 12);
  61                         return 2;
  62                 }
  63         }
  64
  65         if (memcmp(a, &a[12], 12 * sizeof(vector int))) {
  66                 long *p = (long *)a;
  67                 fprintf(stderr, "VSX mismatch\n");
  68                 for (i = 0; i < 24; i=i+2)
  69                         fprintf(stderr, "%d: 0x%08lx%08lx | 0x%08lx%08lx\n",
  70                                         i/2 + i%2 + 20, p[i], p[i + 1], p[i + 24], p[i + 25]);
  71                 return 1;
  72         }
  73         return 0;
  74 }
  75
  76 void *preempt_vsx_c(void *p)
  77 {
  78         int i, j;
  79         long rc;
  80         srand(pthread_self());
  81         for (i = 0; i < 12; i++)
  82                 for (j = 0; j < 4; j++) {
  83                         varray[i][j] = rand();
  84                         /* Don't want zero because it hides kernel problems */
  85                         if (varray[i][j] == 0)
  86                                 j--;
  87                 }
  88         rc = preempt_vsx(varray, &threads_starting, &running);
  89         if (rc == 2)
  90                 fprintf(stderr, "Caught zeros in VSX compares\n");
  91         return (void *)rc;
  92 }
  93
  94 int test_preempt_vsx(void)
  95 {
  96         int i, rc, threads;
  97         pthread_t *tids;
  98
  99         threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
 100         tids = malloc(threads * sizeof(pthread_t));
 101         FAIL_IF(!tids);
 102
 103         running = true;
 104         threads_starting = threads;
 105         for (i = 0; i < threads; i++) {
 106                 rc = pthread_create(&tids[i], NULL, preempt_vsx_c, NULL);
 107                 FAIL_IF(rc);
 108         }
 109
 110         setbuf(stdout, NULL);
 111         /* Not really nessesary but nice to wait for every thread to start */
 112         printf("\tWaiting for %d workers to start...", threads_starting);
 113         while(threads_starting)
 114                 asm volatile("": : :"memory");
 115         printf("done\n");
 116
 117         printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
 118         sleep(PREEMPT_TIME);
 119         printf("done\n");
 120
 121         printf("\tStopping workers...");
 122         /*
 123          * Working are checking this value every loop. In preempt_vsx 'cmpwi r5,0; bne 2b'.
 124          * r5 will have loaded the value of running.
 125          */
 126         running = 0;
 127         for (i = 0; i < threads; i++) {
 128                 void *rc_p;
 129                 pthread_join(tids[i], &rc_p);
 130
 131                 /*
 132                  * Harness will say the fail was here, look at why preempt_vsx
 133                  * returned
 134                  */
 135                 if ((long) rc_p)
 136                         printf("oops\n");
 137                 FAIL_IF((long) rc_p);
 138         }
 139         printf("done\n");
 140
 141         return 0;
 142 }
 143
 144 int main(int argc, char *argv[])
 145 {
 146         return test_harness(test_preempt_vsx, "vsx_preempt");
 147 }