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      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 <sys/ucontext.h>
     22 #include <unistd.h>
     23 
     24 #include "base/macros.h"
     25 
     26 static int signal_count;
     27 static const int kMaxSignal = 2;
     28 
     29 #if defined(__i386__) || defined(__x86_64__)
     30 #if defined(__APPLE__)
     31 #define ucontext __darwin_ucontext
     32 
     33 #if defined(__x86_64__)
     34 // 64 bit mac build.
     35 #define CTX_EIP uc_mcontext->__ss.__rip
     36 #else
     37 // 32 bit mac build.
     38 #define CTX_EIP uc_mcontext->__ss.__eip
     39 #endif
     40 
     41 #elif defined(__x86_64__)
     42 // 64 bit linux build.
     43 #define CTX_EIP uc_mcontext.gregs[REG_RIP]
     44 #else
     45 // 32 bit linux build.
     46 #define CTX_EIP uc_mcontext.gregs[REG_EIP]
     47 #endif
     48 #endif
     49 
     50 static void signalhandler(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
     51                           void* context) {
     52   printf("signal caught\n");
     53   ++signal_count;
     54   if (signal_count > kMaxSignal) {
     55      abort();
     56   }
     57 #if defined(__arm__)
     58   struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
     59   struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
     60   sc->arm_pc += 2;          // Skip instruction causing segv.
     61 #elif defined(__aarch64__)
     62   struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
     63   struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
     64   sc->pc += 4;          // Skip instruction causing segv.
     65 #elif defined(__i386__)
     66   struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
     67   uc->CTX_EIP += 3;
     68 #elif defined(__x86_64__)
     69   struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
     70   uc->CTX_EIP += 2;
     71 #else
     72   UNUSED(context);
     73 #endif
     74 }
     75 
     76 static struct sigaction oldaction;
     77 
     78 extern "C" JNIEXPORT void JNICALL Java_Main_initSignalTest(JNIEnv*, jclass) {
     79   struct sigaction action;
     80   action.sa_sigaction = signalhandler;
     81   sigemptyset(&action.sa_mask);
     82   action.sa_flags = SA_SIGINFO | SA_ONSTACK;
     83 #if !defined(__APPLE__) && !defined(__mips__)
     84   action.sa_restorer = nullptr;
     85 #endif
     86 
     87   sigaction(SIGSEGV, &action, &oldaction);
     88 }
     89 
     90 extern "C" JNIEXPORT void JNICALL Java_Main_terminateSignalTest(JNIEnv*, jclass) {
     91   sigaction(SIGSEGV, &oldaction, nullptr);
     92 }
     93 
     94 // Prevent the compiler being a smart-alec and optimizing out the assignment
     95 // to null.
     96 char *go_away_compiler = nullptr;
     97 
     98 extern "C" JNIEXPORT jint JNICALL Java_Main_testSignal(JNIEnv*, jclass) {
     99 #if defined(__arm__) || defined(__i386__) || defined(__aarch64__)
    100   // On supported architectures we cause a real SEGV.
    101   *go_away_compiler = 'a';
    102 #elif defined(__x86_64__)
    103   // Cause a SEGV using an instruction known to be 2 bytes long to account for hardcoded jump
    104   // in the signal handler
    105   asm volatile("movl $0, %%eax;" "movb %%ah, (%%rax);" : : : "%eax");
    106 #else
    107   // On other architectures we simulate SEGV.
    108   kill(getpid(), SIGSEGV);
    109 #endif
    110   return 1234;
    111 }
    112