1 /*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <jni.h>
18 #include <signal.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <sys/ucontext.h>
23 #include <unistd.h>
24
25 #include "base/macros.h"
26
27 static int signal_count;
28 static const int kMaxSignal = 1;
29
30 #if defined(__i386__) || defined(__x86_64__)
31 #if defined(__APPLE__)
32 #define ucontext __darwin_ucontext
33
34 #if defined(__x86_64__)
35 // 64 bit mac build.
36 #define CTX_EIP uc_mcontext->__ss.__rip
37 #else
38 // 32 bit mac build.
39 #define CTX_EIP uc_mcontext->__ss.__eip
40 #endif
41
42 #elif defined(__x86_64__)
43 // 64 bit linux build.
44 #define CTX_EIP uc_mcontext.gregs[REG_RIP]
45 #else
46 // 32 bit linux build.
47 #define CTX_EIP uc_mcontext.gregs[REG_EIP]
48 #endif
49 #endif
50
51 #define BLOCKED_SIGNAL SIGUSR1
52 #define UNBLOCKED_SIGNAL SIGUSR2
53
blocked_signal(int sig ATTRIBUTE_UNUSED)54 static void blocked_signal(int sig ATTRIBUTE_UNUSED) {
55 printf("blocked signal received\n");
56 }
57
unblocked_signal(int sig ATTRIBUTE_UNUSED)58 static void unblocked_signal(int sig ATTRIBUTE_UNUSED) {
59 printf("unblocked signal received\n");
60 }
61
signalhandler(int sig ATTRIBUTE_UNUSED,siginfo_t * info ATTRIBUTE_UNUSED,void * context)62 static void signalhandler(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
63 void* context) {
64 printf("signal caught\n");
65 ++signal_count;
66 if (signal_count > kMaxSignal) {
67 abort();
68 }
69
70 raise(UNBLOCKED_SIGNAL);
71 raise(BLOCKED_SIGNAL);
72 printf("unblocking blocked signal\n");
73
74 sigset_t mask;
75 sigemptyset(&mask);
76 sigaddset(&mask, BLOCKED_SIGNAL);
77 sigprocmask(SIG_UNBLOCK, &mask, nullptr);
78
79 #if defined(__arm__)
80 struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
81 struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
82 sc->arm_pc += 2; // Skip instruction causing segv.
83 #elif defined(__aarch64__)
84 struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
85 struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
86 sc->pc += 4; // Skip instruction causing segv.
87 #elif defined(__i386__)
88 struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
89 uc->CTX_EIP += 3;
90 #elif defined(__x86_64__)
91 struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
92 uc->CTX_EIP += 2;
93 #else
94 UNUSED(context);
95 #endif
96
97 printf("signal handler done\n");
98 }
99
100 static struct sigaction oldaction;
101
compare_sigaction(const struct sigaction * lhs,const struct sigaction * rhs)102 bool compare_sigaction(const struct sigaction* lhs, const struct sigaction* rhs) {
103 // bionic's definition of `struct sigaction` has internal padding bytes, so we can't just do a
104 // naive memcmp of the entire struct.
105 #if defined(SA_RESTORER)
106 if (lhs->sa_restorer != rhs->sa_restorer) {
107 return false;
108 }
109 #endif
110 return memcmp(&lhs->sa_mask, &rhs->sa_mask, sizeof(lhs->sa_mask)) == 0 &&
111 lhs->sa_sigaction == rhs->sa_sigaction &&
112 lhs->sa_flags == rhs->sa_flags;
113 }
114
Java_Main_initSignalTest(JNIEnv *,jclass)115 extern "C" JNIEXPORT void JNICALL Java_Main_initSignalTest(JNIEnv*, jclass) {
116 struct sigaction action;
117 action.sa_sigaction = signalhandler;
118 sigfillset(&action.sa_mask);
119 sigdelset(&action.sa_mask, UNBLOCKED_SIGNAL);
120 action.sa_flags = SA_SIGINFO | SA_ONSTACK;
121 #if !defined(__APPLE__)
122 action.sa_restorer = nullptr;
123 #endif
124
125 sigaction(SIGSEGV, &action, &oldaction);
126 struct sigaction check;
127 sigaction(SIGSEGV, nullptr, &check);
128 if (!compare_sigaction(&check, &action)) {
129 printf("sigaction returned different value\n");
130 printf("action.sa_mask = %p, check.sa_mask = %p\n",
131 *reinterpret_cast<void**>(&action.sa_mask),
132 *reinterpret_cast<void**>(&check.sa_mask));
133 printf("action.sa_sigaction = %p, check.sa_sigaction = %p\n",
134 action.sa_sigaction, check.sa_sigaction);
135 printf("action.sa_flags = %x, check.sa_flags = %x\n",
136 action.sa_flags, check.sa_flags);
137 }
138 signal(BLOCKED_SIGNAL, blocked_signal);
139 signal(UNBLOCKED_SIGNAL, unblocked_signal);
140 }
141
Java_Main_terminateSignalTest(JNIEnv *,jclass)142 extern "C" JNIEXPORT void JNICALL Java_Main_terminateSignalTest(JNIEnv*, jclass) {
143 sigaction(SIGSEGV, &oldaction, nullptr);
144 }
145
146 // Prevent the compiler being a smart-alec and optimizing out the assignment
147 // to null.
148 char *go_away_compiler = nullptr;
149
Java_Main_testSignal(JNIEnv *,jclass)150 extern "C" JNIEXPORT jint JNICALL Java_Main_testSignal(JNIEnv*, jclass) {
151 // Unblock UNBLOCKED_SIGNAL.
152 sigset_t mask;
153 memset(&mask, 0, sizeof(mask));
154 sigaddset(&mask, UNBLOCKED_SIGNAL);
155 sigprocmask(SIG_UNBLOCK, &mask, nullptr);
156
157 #if defined(__arm__) || defined(__i386__) || defined(__aarch64__)
158 // On supported architectures we cause a real SEGV.
159 *go_away_compiler = 'a';
160 #elif defined(__x86_64__)
161 // Cause a SEGV using an instruction known to be 2 bytes long to account for hardcoded jump
162 // in the signal handler
163 asm volatile("movl $0, %%eax;" "movb %%ah, (%%rax);" : : : "%eax");
164 #else
165 // On other architectures we simulate SEGV.
166 kill(getpid(), SIGSEGV);
167 #endif
168 return 1234;
169 }
170