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
38 static volatile void* stack_pointer = NULL;
on_alarm(int sig)39 static 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
56 ATF_TC(misaligned_sp_and_signal);
ATF_TC_HEAD(misaligned_sp_and_signal,tc)57 ATF_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 }
ATF_TC_BODY(misaligned_sp_and_signal,tc)63 ATF_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
ATF_TP_ADD_TCS(tp)113 ATF_TP_ADD_TCS(tp)
114 {
115 ATF_TP_ADD_TC(tp, misaligned_sp_and_signal);
116 return atf_no_error();
117 }
118