1/* $NetBSD: t_signal_and_sp.c,v 1.1 2024/04/22 07:24:22 pho Exp $ */
2
3/*
4 * Copyright (c) 2024 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <atf-c.h>
30
31#if defined(HAVE_STACK_POINTER_H)
32#  include <signal.h>
33#  include <string.h>
34#  include <sys/stdint.h>
35#  include <sys/time.h>
36#  include "stack_pointer.h"
37
38static volatile void* stack_pointer = NULL;
39static void on_alarm(int sig __attribute__((__unused__)))
40{
41	/*
42	 * Store the stack pointer into a variable so that we can test if
43	 * it's aligned.
44	 */
45	LOAD_SP(stack_pointer);
46
47	/*
48	 * Now we are going to return from a signal
49	 * handler. __sigtramp_siginfo_2 will call setcontext(2) with a
50	 * ucontext provided by the kernel. When that fails it will call
51	 * _Exit(2) with the errno, and the test will fail.
52	 */
53}
54#endif
55
56ATF_TC(misaligned_sp_and_signal);
57ATF_TC_HEAD(misaligned_sp_and_signal, tc)
58{
59	atf_tc_set_md_var(tc, "descr", "process can return from a signal"
60	    " handler even if the stack pointer is misaligned when a signal"
61	    " arrives");
62}
63ATF_TC_BODY(misaligned_sp_and_signal, tc)
64{
65#if defined(HAVE_STACK_POINTER_H)
66	/*
67	 * Set up a handler for SIGALRM.
68	 */
69	struct sigaction sa;
70	memset(&sa, 0, sizeof(sa));
71	sa.sa_handler = &on_alarm;
72	ATF_REQUIRE(sigaction(SIGALRM, &sa, NULL) == 0);
73
74	/*
75	 * Set up an interval timer so that we receive SIGALRM after 50 ms.
76	 */
77	struct itimerval itv;
78	memset(&itv, 0, sizeof(itv));
79	itv.it_value.tv_usec = 1000 * 50;
80	ATF_REQUIRE(setitimer(ITIMER_MONOTONIC, &itv, NULL) == 0);
81
82	/*
83	 * Now misalign the SP. Wait for the signal to arrive and see what
84	 * happens. This should be fine as long as we don't use it to
85	 * access memory.
86	 */
87	MISALIGN_SP;
88	while (stack_pointer == NULL) {
89		/*
90		 * Make sure the compiler does not optimize this busy loop
91		 * away.
92		 */
93		__asm__("" : : : "memory");
94	}
95	/*
96	 * We could successfully return from a signal handler. Now we
97	 * should fix the SP before calling any functions.
98	 */
99	FIX_SP;
100
101	/*
102	 * But was the stack pointer aligned when we were on the signal
103	 * handler?
104	 */
105	ATF_CHECK_MSG(is_sp_aligned((uintptr_t)stack_pointer),
106	    "signal handler was called with a misaligned sp: %p",
107	    stack_pointer);
108#else
109	atf_tc_skip("Not implemented for this platform");
110#endif
111}
112
113ATF_TP_ADD_TCS(tp)
114{
115	ATF_TP_ADD_TC(tp, misaligned_sp_and_signal);
116	return atf_no_error();
117}
118