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 
22 /* Number of times each thread should receive the signal */
23 #define ITERATIONS 10
24 /*
25  * Factor by which to multiply number of online CPUs for total number of
26  * worker threads
27  */
28 #define THREAD_FACTOR 8
29 
30 __thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
31 		     1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
32 		     2.1};
33 
34 bool bad_context;
35 int threads_starting;
36 int running;
37 
38 extern long preempt_fpu(double *darray, int *threads_starting, int *running);
39 
40 void signal_fpu_sig(int sig, siginfo_t *info, void *context)
41 {
42 	int i;
43 	ucontext_t *uc = context;
44 	mcontext_t *mc = &uc->uc_mcontext;
45 
46 	/* Only the non volatiles were loaded up */
47 	for (i = 14; i < 32; i++) {
48 		if (mc->fp_regs[i] != darray[i - 14]) {
49 			bad_context = true;
50 			break;
51 		}
52 	}
53 }
54 
55 void *signal_fpu_c(void *p)
56 {
57 	int i;
58 	long rc;
59 	struct sigaction act;
60 	act.sa_sigaction = signal_fpu_sig;
61 	act.sa_flags = SA_SIGINFO;
62 	rc = sigaction(SIGUSR1, &act, NULL);
63 	if (rc)
64 		return p;
65 
66 	srand(pthread_self());
67 	for (i = 0; i < 21; i++)
68 		darray[i] = rand();
69 
70 	rc = preempt_fpu(darray, &threads_starting, &running);
71 
72 	return (void *) rc;
73 }
74 
75 int test_signal_fpu(void)
76 {
77 	int i, j, rc, threads;
78 	void *rc_p;
79 	pthread_t *tids;
80 
81 	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
82 	tids = malloc(threads * sizeof(pthread_t));
83 	FAIL_IF(!tids);
84 
85 	running = true;
86 	threads_starting = threads;
87 	for (i = 0; i < threads; i++) {
88 		rc = pthread_create(&tids[i], NULL, signal_fpu_c, NULL);
89 		FAIL_IF(rc);
90 	}
91 
92 	setbuf(stdout, NULL);
93 	printf("\tWaiting for all workers to start...");
94 	while (threads_starting)
95 		asm volatile("": : :"memory");
96 	printf("done\n");
97 
98 	printf("\tSending signals to all threads %d times...", ITERATIONS);
99 	for (i = 0; i < ITERATIONS; i++) {
100 		for (j = 0; j < threads; j++) {
101 			pthread_kill(tids[j], SIGUSR1);
102 		}
103 		sleep(1);
104 	}
105 	printf("done\n");
106 
107 	printf("\tStopping workers...");
108 	running = 0;
109 	for (i = 0; i < threads; i++) {
110 		pthread_join(tids[i], &rc_p);
111 
112 		/*
113 		 * Harness will say the fail was here, look at why signal_fpu
114 		 * returned
115 		 */
116 		if ((long) rc_p || bad_context)
117 			printf("oops\n");
118 		if (bad_context)
119 			fprintf(stderr, "\t!! bad_context is true\n");
120 		FAIL_IF((long) rc_p || bad_context);
121 	}
122 	printf("done\n");
123 
124 	free(tids);
125 	return 0;
126 }
127 
128 int main(int argc, char *argv[])
129 {
130 	return test_harness(test_signal_fpu, "fpu_signal");
131 }
132