fpu_signal.c

  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 are correctly reported in a
  6 * signal context. Each worker just spins checking its FPU registers, at some
  7 * point a signal will interrupt it and C code will check the signal context
  8 * ensuring it is also the same.
  9 */
 10
 11#include <stdio.h>
 12#include <unistd.h>
 13#include <sys/syscall.h>
 14#include <sys/time.h>
 15#include <sys/types.h>
 16#include <sys/wait.h>
 17#include <stdlib.h>
 18#include <pthread.h>
 19
 20#include "utils.h"
 21#include "fpu.h"
 22
 23/* Number of times each thread should receive the signal */
 24#define ITERATIONS 10
 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__thread double darray[32];
 32
 33bool bad_context;
 34int threads_starting;
 35int running;
 36
 37extern long preempt_fpu(double *darray, int *threads_starting, int *running);
 38
 39void signal_fpu_sig(int sig, siginfo_t *info, void *context)
 40{
 41	int i;
 42	ucontext_t *uc = context;
 43	mcontext_t *mc = &uc->uc_mcontext;
 44
 45	// Don't check f30/f31, they're used as scratches in check_all_fprs()
 46	for (i = 0; i < 30; i++) {
 47		if (mc->fp_regs[i] != darray[i]) {
 48			bad_context = true;
 49			break;
 50		}
 51	}
 52}
 53
 54void *signal_fpu_c(void *p)
 55{
 56	long rc;
 57	struct sigaction act;
 58	act.sa_sigaction = signal_fpu_sig;
 59	act.sa_flags = SA_SIGINFO;
 60	rc = sigaction(SIGUSR1, &act, NULL);
 61	if (rc)
 62		return p;
 63
 64	srand(pthread_self());
 65	randomise_darray(darray, ARRAY_SIZE(darray));
 66	rc = preempt_fpu(darray, &threads_starting, &running);
 67
 68	return (void *) rc;
 69}
 70
 71int test_signal_fpu(void)
 72{
 73	int i, j, rc, threads;
 74	void *rc_p;
 75	pthread_t *tids;
 76
 77	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
 78	tids = malloc(threads * sizeof(pthread_t));
 79	FAIL_IF(!tids);
 80
 81	running = true;
 82	threads_starting = threads;
 83	for (i = 0; i < threads; i++) {
 84		rc = pthread_create(&tids[i], NULL, signal_fpu_c, NULL);
 85		FAIL_IF(rc);
 86	}
 87
 88	setbuf(stdout, NULL);
 89	printf("\tWaiting for all workers to start...");
 90	while (threads_starting)
 91		asm volatile("": : :"memory");
 92	printf("done\n");
 93
 94	printf("\tSending signals to all threads %d times...", ITERATIONS);
 95	for (i = 0; i < ITERATIONS; i++) {
 96		for (j = 0; j < threads; j++) {
 97			pthread_kill(tids[j], SIGUSR1);
 98		}
 99		sleep(1);
100	}
101	printf("done\n");
102
103	printf("\tStopping workers...");
104	running = 0;
105	for (i = 0; i < threads; i++) {
106		pthread_join(tids[i], &rc_p);
107
108		/*
109		 * Harness will say the fail was here, look at why signal_fpu
110		 * returned
111		 */
112		if ((long) rc_p || bad_context)
113			printf("oops\n");
114		if (bad_context)
115			fprintf(stderr, "\t!! bad_context is true\n");
116		FAIL_IF((long) rc_p || bad_context);
117	}
118	printf("done\n");
119
120	free(tids);
121	return 0;
122}
123
124int main(int argc, char *argv[])
125{
126	return test_harness(test_signal_fpu, "fpu_signal");
127}