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 54 static void blocked_signal(int sig ATTRIBUTE_UNUSED) { 55 printf("blocked signal received\n"); 56 } 57 58 static void unblocked_signal(int sig ATTRIBUTE_UNUSED) { 59 printf("unblocked signal received\n"); 60 } 61 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; 101 102 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 return memcmp(&lhs->sa_mask, &rhs->sa_mask, sizeof(lhs->sa_mask)) == 0 && 106 lhs->sa_sigaction == rhs->sa_sigaction && 107 lhs->sa_flags == rhs->sa_flags && 108 lhs->sa_restorer == rhs->sa_restorer; 109 } 110 111 extern "C" JNIEXPORT void JNICALL Java_Main_initSignalTest(JNIEnv*, jclass) { 112 struct sigaction action; 113 action.sa_sigaction = signalhandler; 114 sigfillset(&action.sa_mask); 115 sigdelset(&action.sa_mask, UNBLOCKED_SIGNAL); 116 action.sa_flags = SA_SIGINFO | SA_ONSTACK; 117 #if !defined(__APPLE__) && !defined(__mips__) 118 action.sa_restorer = nullptr; 119 #endif 120 121 sigaction(SIGSEGV, &action, &oldaction); 122 struct sigaction check; 123 sigaction(SIGSEGV, nullptr, &check); 124 if (!compare_sigaction(&check, &action)) { 125 printf("sigaction returned different value\n"); 126 printf("action.sa_mask = %p, check.sa_mask = %p\n", 127 *reinterpret_cast<void**>(&action.sa_mask), 128 *reinterpret_cast<void**>(&check.sa_mask)); 129 printf("action.sa_sigaction = %p, check.sa_sigaction = %p\n", 130 action.sa_sigaction, check.sa_sigaction); 131 printf("action.sa_flags = %x, check.sa_flags = %x\n", 132 action.sa_flags, check.sa_flags); 133 } 134 signal(BLOCKED_SIGNAL, blocked_signal); 135 signal(UNBLOCKED_SIGNAL, unblocked_signal); 136 } 137 138 extern "C" JNIEXPORT void JNICALL Java_Main_terminateSignalTest(JNIEnv*, jclass) { 139 sigaction(SIGSEGV, &oldaction, nullptr); 140 } 141 142 // Prevent the compiler being a smart-alec and optimizing out the assignment 143 // to null. 144 char *go_away_compiler = nullptr; 145 146 extern "C" JNIEXPORT jint JNICALL Java_Main_testSignal(JNIEnv*, jclass) { 147 // Unblock UNBLOCKED_SIGNAL. 148 sigset_t mask; 149 memset(&mask, 0, sizeof(mask)); 150 sigaddset(&mask, UNBLOCKED_SIGNAL); 151 sigprocmask(SIG_UNBLOCK, &mask, nullptr); 152 153 #if defined(__arm__) || defined(__i386__) || defined(__aarch64__) 154 // On supported architectures we cause a real SEGV. 155 *go_away_compiler = 'a'; 156 #elif defined(__x86_64__) 157 // Cause a SEGV using an instruction known to be 2 bytes long to account for hardcoded jump 158 // in the signal handler 159 asm volatile("movl $0, %%eax;" "movb %%ah, (%%rax);" : : : "%eax"); 160 #else 161 // On other architectures we simulate SEGV. 162 kill(getpid(), SIGSEGV); 163 #endif 164 return 1234; 165 } 166
