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 FPU registers change across preemption. 10 * Two things should be noted here a) The check_fpu function in asm only checks 11 * the non volatile registers as it is reused from the syscall test b) There is 12 * no way to be sure preemption happened so this test just uses many threads 13 * and a long wait. As such, a successful test doesn't mean much but a failure 14 * is bad. 15 */ 16 17 #include <stdio.h> 18 #include <unistd.h> 19 #include <sys/syscall.h> 20 #include <sys/time.h> 21 #include <sys/types.h> 22 #include <sys/wait.h> 23 #include <stdlib.h> 24 #include <pthread.h> 25 26 #include "utils.h" 27 28 /* Time to wait for workers to get preempted (seconds) */ 29 #define PREEMPT_TIME 20 30 /* 31 * Factor by which to multiply number of online CPUs for total number of 32 * worker threads 33 */ 34 #define THREAD_FACTOR 8 35 36 37 __thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 38 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 39 2.1}; 40 41 int threads_starting; 42 int running; 43 44 extern void preempt_fpu(double *darray, int *threads_starting, int *running); 45 46 void *preempt_fpu_c(void *p) 47 { 48 int i; 49 srand(pthread_self()); 50 for (i = 0; i < 21; i++) 51 darray[i] = rand(); 52 53 /* Test failed if it ever returns */ 54 preempt_fpu(darray, &threads_starting, &running); 55 56 return p; 57 } 58 59 int test_preempt_fpu(void) 60 { 61 int i, rc, threads; 62 pthread_t *tids; 63 64 threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR; 65 tids = malloc((threads) * sizeof(pthread_t)); 66 FAIL_IF(!tids); 67 68 running = true; 69 threads_starting = threads; 70 for (i = 0; i < threads; i++) { 71 rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL); 72 FAIL_IF(rc); 73 } 74 75 setbuf(stdout, NULL); 76 /* Not really necessary but nice to wait for every thread to start */ 77 printf("\tWaiting for all workers to start..."); 78 while(threads_starting) 79 asm volatile("": : :"memory"); 80 printf("done\n"); 81 82 printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME); 83 sleep(PREEMPT_TIME); 84 printf("done\n"); 85 86 printf("\tStopping workers..."); 87 /* 88 * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'. 89 * r5 will have loaded the value of running. 90 */ 91 running = 0; 92 for (i = 0; i < threads; i++) { 93 void *rc_p; 94 pthread_join(tids[i], &rc_p); 95 96 /* 97 * Harness will say the fail was here, look at why preempt_fpu 98 * returned 99 */ 100 if ((long) rc_p) 101 printf("oops\n"); 102 FAIL_IF((long) rc_p); 103 } 104 printf("done\n"); 105 106 free(tids); 107 return 0; 108 } 109 110 int main(int argc, char *argv[]) 111 { 112 return test_harness(test_preempt_fpu, "fpu_preempt"); 113 } 114