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 FPU registers change across preemption. 6 * Two things should be noted here a) The check_fpu 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 33 __thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 34 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 35 2.1}; 36 37 int threads_starting; 38 int running; 39 40 extern void preempt_fpu(double *darray, int *threads_starting, int *running); 41 42 void *preempt_fpu_c(void *p) 43 { 44 int i; 45 srand(pthread_self()); 46 for (i = 0; i < 21; i++) 47 darray[i] = rand(); 48 49 /* Test failed if it ever returns */ 50 preempt_fpu(darray, &threads_starting, &running); 51 52 return p; 53 } 54 55 int test_preempt_fpu(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_fpu_c, NULL); 68 FAIL_IF(rc); 69 } 70 71 setbuf(stdout, NULL); 72 /* Not really necessary 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_fpu '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_fpu 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 free(tids); 103 return 0; 104 } 105 106 int main(int argc, char *argv[]) 107 { 108 return test_harness(test_preempt_fpu, "fpu_preempt"); 109 } 110