runtime/runtime_common.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2017 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "runtime_common.h"

 #include <signal.h>

 #include <cinttypes>
 #include <iostream>
 #include <sstream>
 #include <string>

 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>

 #include "base/aborting.h"
 #include "base/file_utils.h"
 #include "base/logging.h"  // For LogHelper, GetCmdLine.
 #include "base/macros.h"
 #include "base/mutex.h"
 #include "native_stack_dump.h"
 #include "runtime.h"
 #include "thread-current-inl.h"
 #include "thread_list.h"

 namespace art {

 using android::base::StringPrintf;

 static constexpr bool kUseSigRTTimeout = true;
 static constexpr bool kDumpNativeStackOnTimeout = true;

 const char* GetSignalName(int signal_number) {
   switch (signal_number) {
     case SIGABRT: return "SIGABRT";
     case SIGBUS: return "SIGBUS";
     case SIGFPE: return "SIGFPE";
     case SIGILL: return "SIGILL";
     case SIGPIPE: return "SIGPIPE";
     case SIGSEGV: return "SIGSEGV";
 #if defined(SIGSTKFLT)
     case SIGSTKFLT: return "SIGSTKFLT";
 #endif
     case SIGTRAP: return "SIGTRAP";
   }
   return "??";
 }

 const char* GetSignalCodeName(int signal_number, int signal_code) {
   // Try the signal-specific codes...
   switch (signal_number) {
     case SIGILL:
       switch (signal_code) {
         case ILL_ILLOPC: return "ILL_ILLOPC";
         case ILL_ILLOPN: return "ILL_ILLOPN";
         case ILL_ILLADR: return "ILL_ILLADR";
         case ILL_ILLTRP: return "ILL_ILLTRP";
         case ILL_PRVOPC: return "ILL_PRVOPC";
         case ILL_PRVREG: return "ILL_PRVREG";
         case ILL_COPROC: return "ILL_COPROC";
         case ILL_BADSTK: return "ILL_BADSTK";
       }
       break;
     case SIGBUS:
       switch (signal_code) {
         case BUS_ADRALN: return "BUS_ADRALN";
         case BUS_ADRERR: return "BUS_ADRERR";
         case BUS_OBJERR: return "BUS_OBJERR";
       }
       break;
     case SIGFPE:
       switch (signal_code) {
         case FPE_INTDIV: return "FPE_INTDIV";
         case FPE_INTOVF: return "FPE_INTOVF";
         case FPE_FLTDIV: return "FPE_FLTDIV";
         case FPE_FLTOVF: return "FPE_FLTOVF";
         case FPE_FLTUND: return "FPE_FLTUND";
         case FPE_FLTRES: return "FPE_FLTRES";
         case FPE_FLTINV: return "FPE_FLTINV";
         case FPE_FLTSUB: return "FPE_FLTSUB";
       }
       break;
     case SIGSEGV:
       switch (signal_code) {
         case SEGV_MAPERR: return "SEGV_MAPERR";
         case SEGV_ACCERR: return "SEGV_ACCERR";
 #if defined(SEGV_BNDERR)
         case SEGV_BNDERR: return "SEGV_BNDERR";
 #endif
       }
       break;
     case SIGTRAP:
       switch (signal_code) {
         case TRAP_BRKPT: return "TRAP_BRKPT";
         case TRAP_TRACE: return "TRAP_TRACE";
       }
       break;
   }
   // Then the other codes...
   switch (signal_code) {
     case SI_USER:     return "SI_USER";
 #if defined(SI_KERNEL)
     case SI_KERNEL:   return "SI_KERNEL";
 #endif
     case SI_QUEUE:    return "SI_QUEUE";
     case SI_TIMER:    return "SI_TIMER";
     case SI_MESGQ:    return "SI_MESGQ";
     case SI_ASYNCIO:  return "SI_ASYNCIO";
 #if defined(SI_SIGIO)
     case SI_SIGIO:    return "SI_SIGIO";
 #endif
 #if defined(SI_TKILL)
     case SI_TKILL:    return "SI_TKILL";
 #endif
   }
   // Then give up...
   return "?";
 }

 struct UContext {
   explicit UContext(void* raw_context)
       : context(reinterpret_cast<ucontext_t*>(raw_context)->uc_mcontext) {}

   void Dump(std::ostream& os) const;

   void DumpRegister32(std::ostream& os, const char* name, uint32_t value) const;
   void DumpRegister64(std::ostream& os, const char* name, uint64_t value) const;

   void DumpX86Flags(std::ostream& os, uint32_t flags) const;
   // Print some of the information from the status register (CPSR on ARMv7, PSTATE on ARMv8).
   template <typename RegisterType>
   void DumpArmStatusRegister(std::ostream& os, RegisterType status_register) const;

   mcontext_t& context;
 };

 void UContext::Dump(std::ostream& os) const {
 #if defined(__APPLE__) && defined(__i386__)
   DumpRegister32(os, "eax", context->__ss.__eax);
   DumpRegister32(os, "ebx", context->__ss.__ebx);
   DumpRegister32(os, "ecx", context->__ss.__ecx);
   DumpRegister32(os, "edx", context->__ss.__edx);
   os << '\n';

   DumpRegister32(os, "edi", context->__ss.__edi);
   DumpRegister32(os, "esi", context->__ss.__esi);
   DumpRegister32(os, "ebp", context->__ss.__ebp);
   DumpRegister32(os, "esp", context->__ss.__esp);
   os << '\n';

   DumpRegister32(os, "eip", context->__ss.__eip);
   os << "                   ";
   DumpRegister32(os, "eflags", context->__ss.__eflags);
   DumpX86Flags(os, context->__ss.__eflags);
   os << '\n';

   DumpRegister32(os, "cs",  context->__ss.__cs);
   DumpRegister32(os, "ds",  context->__ss.__ds);
   DumpRegister32(os, "es",  context->__ss.__es);
   DumpRegister32(os, "fs",  context->__ss.__fs);
   os << '\n';
   DumpRegister32(os, "gs",  context->__ss.__gs);
   DumpRegister32(os, "ss",  context->__ss.__ss);
 #elif defined(__linux__) && defined(__i386__)
   DumpRegister32(os, "eax", context.gregs[REG_EAX]);
   DumpRegister32(os, "ebx", context.gregs[REG_EBX]);
   DumpRegister32(os, "ecx", context.gregs[REG_ECX]);
   DumpRegister32(os, "edx", context.gregs[REG_EDX]);
   os << '\n';

   DumpRegister32(os, "edi", context.gregs[REG_EDI]);
   DumpRegister32(os, "esi", context.gregs[REG_ESI]);
   DumpRegister32(os, "ebp", context.gregs[REG_EBP]);
   DumpRegister32(os, "esp", context.gregs[REG_ESP]);
   os << '\n';

   DumpRegister32(os, "eip", context.gregs[REG_EIP]);
   os << "                   ";
   DumpRegister32(os, "eflags", context.gregs[REG_EFL]);
   DumpX86Flags(os, context.gregs[REG_EFL]);
   os << '\n';

   DumpRegister32(os, "cs",  context.gregs[REG_CS]);
   DumpRegister32(os, "ds",  context.gregs[REG_DS]);
   DumpRegister32(os, "es",  context.gregs[REG_ES]);
   DumpRegister32(os, "fs",  context.gregs[REG_FS]);
   os << '\n';
   DumpRegister32(os, "gs",  context.gregs[REG_GS]);
   DumpRegister32(os, "ss",  context.gregs[REG_SS]);
 #elif defined(__linux__) && defined(__x86_64__)
   DumpRegister64(os, "rax", context.gregs[REG_RAX]);
   DumpRegister64(os, "rbx", context.gregs[REG_RBX]);
   DumpRegister64(os, "rcx", context.gregs[REG_RCX]);
   DumpRegister64(os, "rdx", context.gregs[REG_RDX]);
   os << '\n';

   DumpRegister64(os, "rdi", context.gregs[REG_RDI]);
   DumpRegister64(os, "rsi", context.gregs[REG_RSI]);
   DumpRegister64(os, "rbp", context.gregs[REG_RBP]);
   DumpRegister64(os, "rsp", context.gregs[REG_RSP]);
   os << '\n';

   DumpRegister64(os, "r8 ", context.gregs[REG_R8]);
   DumpRegister64(os, "r9 ", context.gregs[REG_R9]);
   DumpRegister64(os, "r10", context.gregs[REG_R10]);
   DumpRegister64(os, "r11", context.gregs[REG_R11]);
   os << '\n';

   DumpRegister64(os, "r12", context.gregs[REG_R12]);
   DumpRegister64(os, "r13", context.gregs[REG_R13]);
   DumpRegister64(os, "r14", context.gregs[REG_R14]);
   DumpRegister64(os, "r15", context.gregs[REG_R15]);
   os << '\n';

   DumpRegister64(os, "rip", context.gregs[REG_RIP]);
   os << "   ";
   DumpRegister32(os, "eflags", context.gregs[REG_EFL]);
   DumpX86Flags(os, context.gregs[REG_EFL]);
   os << '\n';

   DumpRegister32(os, "cs",  (context.gregs[REG_CSGSFS]) & 0x0FFFF);
   DumpRegister32(os, "gs",  (context.gregs[REG_CSGSFS] >> 16) & 0x0FFFF);
   DumpRegister32(os, "fs",  (context.gregs[REG_CSGSFS] >> 32) & 0x0FFFF);
   os << '\n';
 #elif defined(__linux__) && defined(__arm__)
   DumpRegister32(os, "r0", context.arm_r0);
   DumpRegister32(os, "r1", context.arm_r1);
   DumpRegister32(os, "r2", context.arm_r2);
   DumpRegister32(os, "r3", context.arm_r3);
   os << '\n';

   DumpRegister32(os, "r4", context.arm_r4);
   DumpRegister32(os, "r5", context.arm_r5);
   DumpRegister32(os, "r6", context.arm_r6);
   DumpRegister32(os, "r7", context.arm_r7);
   os << '\n';

   DumpRegister32(os, "r8", context.arm_r8);
   DumpRegister32(os, "r9", context.arm_r9);
   DumpRegister32(os, "r10", context.arm_r10);
   DumpRegister32(os, "fp", context.arm_fp);
   os << '\n';

   DumpRegister32(os, "ip", context.arm_ip);
   DumpRegister32(os, "sp", context.arm_sp);
   DumpRegister32(os, "lr", context.arm_lr);
   DumpRegister32(os, "pc", context.arm_pc);
   os << '\n';

   DumpRegister32(os, "cpsr", context.arm_cpsr);
   DumpArmStatusRegister(os, context.arm_cpsr);
   os << '\n';
 #elif defined(__linux__) && defined(__aarch64__)
   for (size_t i = 0; i <= 30; ++i) {
     std::string reg_name = "x" + std::to_string(i);
     DumpRegister64(os, reg_name.c_str(), context.regs[i]);
     if (i % 4 == 3) {
       os << '\n';
     }
   }
   os << '\n';

   DumpRegister64(os, "sp", context.sp);
   DumpRegister64(os, "pc", context.pc);
   os << '\n';

   DumpRegister64(os, "pstate", context.pstate);
   DumpArmStatusRegister(os, context.pstate);
   os << '\n';
 #else
   os << "Unknown architecture/word size/OS in ucontext dump";
 #endif
 }

 void UContext::DumpRegister32(std::ostream& os, const char* name, uint32_t value) const {
   os << StringPrintf(" %6s: 0x%08x", name, value);
 }

 void UContext::DumpRegister64(std::ostream& os, const char* name, uint64_t value) const {
   os << StringPrintf(" %6s: 0x%016" PRIx64, name, value);
 }

 void UContext::DumpX86Flags(std::ostream& os, uint32_t flags) const {
   os << " [";
   if ((flags & (1 << 0)) != 0) {
     os << " CF";
   }
   if ((flags & (1 << 2)) != 0) {
     os << " PF";
   }
   if ((flags & (1 << 4)) != 0) {
     os << " AF";
   }
   if ((flags & (1 << 6)) != 0) {
     os << " ZF";
   }
   if ((flags & (1 << 7)) != 0) {
     os << " SF";
   }
   if ((flags & (1 << 8)) != 0) {
     os << " TF";
   }
   if ((flags & (1 << 9)) != 0) {
     os << " IF";
   }
   if ((flags & (1 << 10)) != 0) {
     os << " DF";
   }
   if ((flags & (1 << 11)) != 0) {
     os << " OF";
   }
   os << " ]";
 }

 template <typename RegisterType>
 void UContext::DumpArmStatusRegister(std::ostream& os, RegisterType status_register) const {
   // Condition flags.
   constexpr RegisterType kFlagV = 1U << 28;
   constexpr RegisterType kFlagC = 1U << 29;
   constexpr RegisterType kFlagZ = 1U << 30;
   constexpr RegisterType kFlagN = 1U << 31;

   os << " [";
   if ((status_register & kFlagN) != 0) {
     os << " N";
   }
   if ((status_register & kFlagZ) != 0) {
     os << " Z";
   }
   if ((status_register & kFlagC) != 0) {
     os << " C";
   }
   if ((status_register & kFlagV) != 0) {
     os << " V";
   }
   os << " ]";
 }

 int GetTimeoutSignal() {
 #if defined(__APPLE__)
   // Mac does not support realtime signals.
   UNUSED(kUseSigRTTimeout);
   return -1;
 #else
   return kUseSigRTTimeout ? (SIGRTMIN + 2) : -1;
 #endif
 }

 static bool IsTimeoutSignal(int signal_number) {
   return signal_number == GetTimeoutSignal();
 }

 #if defined(__APPLE__)
 // On macOS, clang complains about art::HandleUnexpectedSignalCommon's
 // stack frame size being too large; disable that warning locally.
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wframe-larger-than="
 #endif

 std::string GetFaultMessageForAbortLogging() {
   Runtime* runtime = Runtime::Current();
   return  (runtime != nullptr) ? runtime->GetFaultMessage() : "";
 }

 static std::atomic<bool> gIsRuntimeAbort = false;

 void FlagRuntimeAbort() {
   gIsRuntimeAbort = true;
 }

 static void HandleUnexpectedSignalCommonDump(int signal_number,
                                              siginfo_t* info,
                                              void* raw_context,
                                              bool handle_timeout_signal,
                                              bool dump_on_stderr) {
   auto logger = [&](auto& stream) {
     bool has_address = (signal_number == SIGILL || signal_number == SIGBUS ||
                         signal_number == SIGFPE || signal_number == SIGSEGV);
     OsInfo os_info;
     const char* cmd_line = GetCmdLine();
     if (cmd_line == nullptr) {
       cmd_line = "<unset>";  // Because no-one called InitLogging.
     }
     pid_t tid = GetTid();
     std::string thread_name(GetThreadName(tid));
     UContext thread_context(raw_context);
     Backtrace thread_backtrace(raw_context);

     stream << "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***" << std::endl
            << StringPrintf("Fatal signal %d (%s), code %d (%s)",
                              signal_number,
                              GetSignalName(signal_number),
                              info->si_code,
                              GetSignalCodeName(signal_number, info->si_code))
            << (has_address ? StringPrintf(" fault addr %p", info->si_addr) : "") << std::endl
            << "OS: " << Dumpable<OsInfo>(os_info) << std::endl
            << "Cmdline: " << cmd_line << std::endl
            << "Thread: " << tid << " \"" << thread_name << "\"" << std::endl
            << "Registers:\n" << Dumpable<UContext>(thread_context) << std::endl
            << "Backtrace:\n" << Dumpable<Backtrace>(thread_backtrace) << std::endl;
     stream << std::flush;
   };

   if (dump_on_stderr) {
     // Note: We are using cerr directly instead of LOG macros to ensure even just partial output
     //       makes it out. That means we lose the "dalvikvm..." prefix, but that is acceptable
     //       considering this is an abort situation.
     logger(std::cerr);
   } else {
     logger(LOG_STREAM(FATAL_WITHOUT_ABORT));
   }
   if (kIsDebugBuild && signal_number == SIGSEGV) {
     PrintFileToLog("/proc/self/maps", android::base::LogSeverity::FATAL_WITHOUT_ABORT);
   }

   Runtime* runtime = Runtime::Current();
   if (runtime != nullptr) {
     if (handle_timeout_signal && IsTimeoutSignal(signal_number)) {
       // Special timeout signal. Try to dump all threads.
       // Note: Do not use DumpForSigQuit, as that might disable native unwind, but the native parts
       //       are of value here.
       runtime->GetThreadList()->Dump(std::cerr, kDumpNativeStackOnTimeout);
       std::cerr << std::endl;
     }

     if (dump_on_stderr) {
       std::cerr << "Fault message: " << GetFaultMessageForAbortLogging() << std::endl;
     } else {
       LOG(FATAL_WITHOUT_ABORT) << "Fault message: " << GetFaultMessageForAbortLogging();
     }
   }
 }

 void HandleUnexpectedSignalCommon(int signal_number,
                                   siginfo_t* info,
                                   void* raw_context,
                                   bool handle_timeout_signal,
                                   bool dump_on_stderr) {
   bool runtime_abort = gIsRuntimeAbort.exchange(false);
   if (runtime_abort) {
     return;
   }

   // Local _static_ storing the currently handled signal (or -1).
   static int handling_unexpected_signal = -1;

   // Whether the dump code should be run under the unexpected-signal lock. For diagnostics we
   // allow recursive unexpected-signals in certain cases - avoid a deadlock.
   bool grab_lock = true;

   if (handling_unexpected_signal != -1) {
     LogHelper::LogLineLowStack(__FILE__,
                                __LINE__,
                                ::android::base::FATAL_WITHOUT_ABORT,
                                "HandleUnexpectedSignal reentered\n");
     // Print the signal number. Don't use any standard functions, just some arithmetic. Just best
     // effort, with a minimal buffer.
     if (0 < signal_number && signal_number < 100) {
       char buf[] = { ' ',
                      'S',
                      static_cast<char>('0' + (signal_number / 10)),
                      static_cast<char>('0' + (signal_number % 10)),
                      '\n',
                      0 };
       LogHelper::LogLineLowStack(__FILE__,
                                  __LINE__,
                                  ::android::base::FATAL_WITHOUT_ABORT,
                                  buf);
     }
     if (handle_timeout_signal) {
       if (IsTimeoutSignal(signal_number)) {
         // Ignore a recursive timeout.
         return;
       }
     }
     // If we were handling a timeout signal, try to go on. Otherwise hard-exit.
     // This relies on the expectation that we'll only ever get one timeout signal.
     if (!handle_timeout_signal || handling_unexpected_signal != GetTimeoutSignal()) {
       _exit(1);
     }
     grab_lock = false;  // The "outer" handling instance already holds the lock.
   }
   handling_unexpected_signal = signal_number;

   gAborting++;  // set before taking any locks

   if (grab_lock) {
     MutexLock mu(Thread::Current(), *Locks::unexpected_signal_lock_);

     HandleUnexpectedSignalCommonDump(signal_number,
                                      info,
                                      raw_context,
                                      handle_timeout_signal,
                                      dump_on_stderr);
   } else {
     HandleUnexpectedSignalCommonDump(signal_number,
                                      info,
                                      raw_context,
                                      handle_timeout_signal,
                                      dump_on_stderr);
   }
 }

 #if defined(__APPLE__)
 #pragma GCC diagnostic pop
 #endif

 void InitPlatformSignalHandlersCommon(void (*newact)(int, siginfo_t*, void*),
                                       struct sigaction* oldact,
                                       bool handle_timeout_signal) {
   struct sigaction action;
   memset(&action, 0, sizeof(action));
   sigemptyset(&action.sa_mask);
   action.sa_sigaction = newact;
   // Use the three-argument sa_sigaction handler.
   action.sa_flags |= SA_SIGINFO;
   // Use the alternate signal stack so we can catch stack overflows.
   action.sa_flags |= SA_ONSTACK;

   int rc = 0;
   rc += sigaction(SIGABRT, &action, oldact);
   rc += sigaction(SIGBUS, &action, oldact);
   rc += sigaction(SIGFPE, &action, oldact);
   rc += sigaction(SIGILL, &action, oldact);
   rc += sigaction(SIGPIPE, &action, oldact);
   rc += sigaction(SIGSEGV, &action, oldact);
 #if defined(SIGSTKFLT)
   rc += sigaction(SIGSTKFLT, &action, oldact);
 #endif
   rc += sigaction(SIGTRAP, &action, oldact);
   // Special dump-all timeout.
   if (handle_timeout_signal && GetTimeoutSignal() != -1) {
     rc += sigaction(GetTimeoutSignal(), &action, oldact);
   }
   CHECK_EQ(rc, 0);
 }

 }  // namespace art
	/*
	* Copyright (C) 2017 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "runtime_common.h"

	#include <signal.h>

	#include <cinttypes>
	#include <iostream>
	#include <sstream>
	#include <string>

	#include <android-base/logging.h>
	#include <android-base/stringprintf.h>

	#include "base/aborting.h"
	#include "base/file_utils.h"
	#include "base/logging.h" // For LogHelper, GetCmdLine.
	#include "base/macros.h"
	#include "base/mutex.h"
	#include "native_stack_dump.h"
	#include "runtime.h"
	#include "thread-current-inl.h"
	#include "thread_list.h"

	namespace art {

	using android::base::StringPrintf;

	static constexpr bool kUseSigRTTimeout = true;
	static constexpr bool kDumpNativeStackOnTimeout = true;

	const char* GetSignalName(int signal_number) {
	switch (signal_number) {
	case SIGABRT: return "SIGABRT";
	case SIGBUS: return "SIGBUS";
	case SIGFPE: return "SIGFPE";
	case SIGILL: return "SIGILL";
	case SIGPIPE: return "SIGPIPE";
	case SIGSEGV: return "SIGSEGV";
	#if defined(SIGSTKFLT)
	case SIGSTKFLT: return "SIGSTKFLT";
	#endif
	case SIGTRAP: return "SIGTRAP";
	}
	return "??";
	}

	const char* GetSignalCodeName(int signal_number, int signal_code) {
	// Try the signal-specific codes...
	switch (signal_number) {
	case SIGILL:
	switch (signal_code) {
	case ILL_ILLOPC: return "ILL_ILLOPC";
	case ILL_ILLOPN: return "ILL_ILLOPN";
	case ILL_ILLADR: return "ILL_ILLADR";
	case ILL_ILLTRP: return "ILL_ILLTRP";
	case ILL_PRVOPC: return "ILL_PRVOPC";
	case ILL_PRVREG: return "ILL_PRVREG";
	case ILL_COPROC: return "ILL_COPROC";
	case ILL_BADSTK: return "ILL_BADSTK";
	}
	break;
	case SIGBUS:
	switch (signal_code) {
	case BUS_ADRALN: return "BUS_ADRALN";
	case BUS_ADRERR: return "BUS_ADRERR";
	case BUS_OBJERR: return "BUS_OBJERR";
	}
	break;
	case SIGFPE:
	switch (signal_code) {
	case FPE_INTDIV: return "FPE_INTDIV";
	case FPE_INTOVF: return "FPE_INTOVF";
	case FPE_FLTDIV: return "FPE_FLTDIV";
	case FPE_FLTOVF: return "FPE_FLTOVF";
	case FPE_FLTUND: return "FPE_FLTUND";
	case FPE_FLTRES: return "FPE_FLTRES";
	case FPE_FLTINV: return "FPE_FLTINV";
	case FPE_FLTSUB: return "FPE_FLTSUB";
	}
	break;
	case SIGSEGV:
	switch (signal_code) {
	case SEGV_MAPERR: return "SEGV_MAPERR";
	case SEGV_ACCERR: return "SEGV_ACCERR";
	#if defined(SEGV_BNDERR)
	case SEGV_BNDERR: return "SEGV_BNDERR";
	#endif
	}
	break;
	case SIGTRAP:
	switch (signal_code) {
	case TRAP_BRKPT: return "TRAP_BRKPT";
	case TRAP_TRACE: return "TRAP_TRACE";
	}
	break;
	}
	// Then the other codes...
	switch (signal_code) {
	case SI_USER: return "SI_USER";
	#if defined(SI_KERNEL)
	case SI_KERNEL: return "SI_KERNEL";
	#endif
	case SI_QUEUE: return "SI_QUEUE";
	case SI_TIMER: return "SI_TIMER";
	case SI_MESGQ: return "SI_MESGQ";
	case SI_ASYNCIO: return "SI_ASYNCIO";
	#if defined(SI_SIGIO)
	case SI_SIGIO: return "SI_SIGIO";
	#endif
	#if defined(SI_TKILL)
	case SI_TKILL: return "SI_TKILL";
	#endif
	}
	// Then give up...
	return "?";
	}

	struct UContext {
	explicit UContext(void* raw_context)
	: context(reinterpret_cast<ucontext_t*>(raw_context)->uc_mcontext) {}

	void Dump(std::ostream& os) const;

	void DumpRegister32(std::ostream& os, const char* name, uint32_t value) const;
	void DumpRegister64(std::ostream& os, const char* name, uint64_t value) const;

	void DumpX86Flags(std::ostream& os, uint32_t flags) const;
	// Print some of the information from the status register (CPSR on ARMv7, PSTATE on ARMv8).
	template <typename RegisterType>
	void DumpArmStatusRegister(std::ostream& os, RegisterType status_register) const;

	mcontext_t& context;
	};

	void UContext::Dump(std::ostream& os) const {
	#if defined(__APPLE__) && defined(__i386__)
	DumpRegister32(os, "eax", context->__ss.__eax);
	DumpRegister32(os, "ebx", context->__ss.__ebx);
	DumpRegister32(os, "ecx", context->__ss.__ecx);
	DumpRegister32(os, "edx", context->__ss.__edx);
	os << '\n';

	DumpRegister32(os, "edi", context->__ss.__edi);
	DumpRegister32(os, "esi", context->__ss.__esi);
	DumpRegister32(os, "ebp", context->__ss.__ebp);
	DumpRegister32(os, "esp", context->__ss.__esp);
	os << '\n';

	DumpRegister32(os, "eip", context->__ss.__eip);
	os << " ";
	DumpRegister32(os, "eflags", context->__ss.__eflags);
	DumpX86Flags(os, context->__ss.__eflags);
	os << '\n';

	DumpRegister32(os, "cs", context->__ss.__cs);
	DumpRegister32(os, "ds", context->__ss.__ds);
	DumpRegister32(os, "es", context->__ss.__es);
	DumpRegister32(os, "fs", context->__ss.__fs);
	os << '\n';
	DumpRegister32(os, "gs", context->__ss.__gs);
	DumpRegister32(os, "ss", context->__ss.__ss);
	#elif defined(__linux__) && defined(__i386__)
	DumpRegister32(os, "eax", context.gregs[REG_EAX]);
	DumpRegister32(os, "ebx", context.gregs[REG_EBX]);
	DumpRegister32(os, "ecx", context.gregs[REG_ECX]);
	DumpRegister32(os, "edx", context.gregs[REG_EDX]);
	os << '\n';

	DumpRegister32(os, "edi", context.gregs[REG_EDI]);
	DumpRegister32(os, "esi", context.gregs[REG_ESI]);
	DumpRegister32(os, "ebp", context.gregs[REG_EBP]);
	DumpRegister32(os, "esp", context.gregs[REG_ESP]);
	os << '\n';

	DumpRegister32(os, "eip", context.gregs[REG_EIP]);
	os << " ";
	DumpRegister32(os, "eflags", context.gregs[REG_EFL]);
	DumpX86Flags(os, context.gregs[REG_EFL]);
	os << '\n';

	DumpRegister32(os, "cs", context.gregs[REG_CS]);
	DumpRegister32(os, "ds", context.gregs[REG_DS]);
	DumpRegister32(os, "es", context.gregs[REG_ES]);
	DumpRegister32(os, "fs", context.gregs[REG_FS]);
	os << '\n';
	DumpRegister32(os, "gs", context.gregs[REG_GS]);
	DumpRegister32(os, "ss", context.gregs[REG_SS]);
	#elif defined(__linux__) && defined(__x86_64__)
	DumpRegister64(os, "rax", context.gregs[REG_RAX]);
	DumpRegister64(os, "rbx", context.gregs[REG_RBX]);
	DumpRegister64(os, "rcx", context.gregs[REG_RCX]);
	DumpRegister64(os, "rdx", context.gregs[REG_RDX]);
	os << '\n';

	DumpRegister64(os, "rdi", context.gregs[REG_RDI]);
	DumpRegister64(os, "rsi", context.gregs[REG_RSI]);
	DumpRegister64(os, "rbp", context.gregs[REG_RBP]);
	DumpRegister64(os, "rsp", context.gregs[REG_RSP]);
	os << '\n';

	DumpRegister64(os, "r8 ", context.gregs[REG_R8]);
	DumpRegister64(os, "r9 ", context.gregs[REG_R9]);
	DumpRegister64(os, "r10", context.gregs[REG_R10]);
	DumpRegister64(os, "r11", context.gregs[REG_R11]);
	os << '\n';

	DumpRegister64(os, "r12", context.gregs[REG_R12]);
	DumpRegister64(os, "r13", context.gregs[REG_R13]);
	DumpRegister64(os, "r14", context.gregs[REG_R14]);
	DumpRegister64(os, "r15", context.gregs[REG_R15]);
	os << '\n';

	DumpRegister64(os, "rip", context.gregs[REG_RIP]);
	os << " ";
	DumpRegister32(os, "eflags", context.gregs[REG_EFL]);
	DumpX86Flags(os, context.gregs[REG_EFL]);
	os << '\n';

	DumpRegister32(os, "cs", (context.gregs[REG_CSGSFS]) & 0x0FFFF);
	DumpRegister32(os, "gs", (context.gregs[REG_CSGSFS] >> 16) & 0x0FFFF);
	DumpRegister32(os, "fs", (context.gregs[REG_CSGSFS] >> 32) & 0x0FFFF);
	os << '\n';
	#elif defined(__linux__) && defined(__arm__)
	DumpRegister32(os, "r0", context.arm_r0);
	DumpRegister32(os, "r1", context.arm_r1);
	DumpRegister32(os, "r2", context.arm_r2);
	DumpRegister32(os, "r3", context.arm_r3);
	os << '\n';

	DumpRegister32(os, "r4", context.arm_r4);
	DumpRegister32(os, "r5", context.arm_r5);
	DumpRegister32(os, "r6", context.arm_r6);
	DumpRegister32(os, "r7", context.arm_r7);
	os << '\n';

	DumpRegister32(os, "r8", context.arm_r8);
	DumpRegister32(os, "r9", context.arm_r9);
	DumpRegister32(os, "r10", context.arm_r10);
	DumpRegister32(os, "fp", context.arm_fp);
	os << '\n';

	DumpRegister32(os, "ip", context.arm_ip);
	DumpRegister32(os, "sp", context.arm_sp);
	DumpRegister32(os, "lr", context.arm_lr);
	DumpRegister32(os, "pc", context.arm_pc);
	os << '\n';

	DumpRegister32(os, "cpsr", context.arm_cpsr);
	DumpArmStatusRegister(os, context.arm_cpsr);
	os << '\n';
	#elif defined(__linux__) && defined(__aarch64__)
	for (size_t i = 0; i <= 30; ++i) {
	std::string reg_name = "x" + std::to_string(i);
	DumpRegister64(os, reg_name.c_str(), context.regs[i]);
	if (i % 4 == 3) {
	os << '\n';
	}
	}
	os << '\n';

	DumpRegister64(os, "sp", context.sp);
	DumpRegister64(os, "pc", context.pc);
	os << '\n';

	DumpRegister64(os, "pstate", context.pstate);
	DumpArmStatusRegister(os, context.pstate);
	os << '\n';
	#else
	os << "Unknown architecture/word size/OS in ucontext dump";
	#endif
	}

	void UContext::DumpRegister32(std::ostream& os, const char* name, uint32_t value) const {
	os << StringPrintf(" %6s: 0x%08x", name, value);
	}

	void UContext::DumpRegister64(std::ostream& os, const char* name, uint64_t value) const {
	os << StringPrintf(" %6s: 0x%016" PRIx64, name, value);
	}

	void UContext::DumpX86Flags(std::ostream& os, uint32_t flags) const {
	os << " [";
	if ((flags & (1 << 0)) != 0) {
	os << " CF";
	}
	if ((flags & (1 << 2)) != 0) {
	os << " PF";
	}
	if ((flags & (1 << 4)) != 0) {
	os << " AF";
	}
	if ((flags & (1 << 6)) != 0) {
	os << " ZF";
	}
	if ((flags & (1 << 7)) != 0) {
	os << " SF";
	}
	if ((flags & (1 << 8)) != 0) {
	os << " TF";
	}
	if ((flags & (1 << 9)) != 0) {
	os << " IF";
	}
	if ((flags & (1 << 10)) != 0) {
	os << " DF";
	}
	if ((flags & (1 << 11)) != 0) {
	os << " OF";
	}
	os << " ]";
	}

	template <typename RegisterType>
	void UContext::DumpArmStatusRegister(std::ostream& os, RegisterType status_register) const {
	// Condition flags.
	constexpr RegisterType kFlagV = 1U << 28;
	constexpr RegisterType kFlagC = 1U << 29;
	constexpr RegisterType kFlagZ = 1U << 30;
	constexpr RegisterType kFlagN = 1U << 31;

	os << " [";
	if ((status_register & kFlagN) != 0) {
	os << " N";
	}
	if ((status_register & kFlagZ) != 0) {
	os << " Z";
	}
	if ((status_register & kFlagC) != 0) {
	os << " C";
	}
	if ((status_register & kFlagV) != 0) {
	os << " V";
	}
	os << " ]";
	}

	int GetTimeoutSignal() {
	#if defined(__APPLE__)
	// Mac does not support realtime signals.
	UNUSED(kUseSigRTTimeout);
	return -1;
	#else
	return kUseSigRTTimeout ? (SIGRTMIN + 2) : -1;
	#endif
	}

	static bool IsTimeoutSignal(int signal_number) {
	return signal_number == GetTimeoutSignal();
	}

	#if defined(__APPLE__)
	// On macOS, clang complains about art::HandleUnexpectedSignalCommon's
	// stack frame size being too large; disable that warning locally.
	#pragma GCC diagnostic push
	#pragma GCC diagnostic ignored "-Wframe-larger-than="
	#endif

	std::string GetFaultMessageForAbortLogging() {
	Runtime* runtime = Runtime::Current();
	return (runtime != nullptr) ? runtime->GetFaultMessage() : "";
	}

	static std::atomic<bool> gIsRuntimeAbort = false;

	void FlagRuntimeAbort() {
	gIsRuntimeAbort = true;
	}

	static void HandleUnexpectedSignalCommonDump(int signal_number,
	siginfo_t* info,
	void* raw_context,
	bool handle_timeout_signal,
	bool dump_on_stderr) {
	auto logger = [&](auto& stream) {
	bool has_address = (signal_number == SIGILL \|\| signal_number == SIGBUS \|\|
	signal_number == SIGFPE \|\| signal_number == SIGSEGV);
	OsInfo os_info;
	const char* cmd_line = GetCmdLine();
	if (cmd_line == nullptr) {
	cmd_line = "<unset>"; // Because no-one called InitLogging.
	}
	pid_t tid = GetTid();
	std::string thread_name(GetThreadName(tid));
	UContext thread_context(raw_context);
	Backtrace thread_backtrace(raw_context);

	stream << "* * * * * * * * * * * * * * * *" << std::endl
	<< StringPrintf("Fatal signal %d (%s), code %d (%s)",
	signal_number,
	GetSignalName(signal_number),
	info->si_code,
	GetSignalCodeName(signal_number, info->si_code))
	<< (has_address ? StringPrintf(" fault addr %p", info->si_addr) : "") << std::endl
	<< "OS: " << Dumpable<OsInfo>(os_info) << std::endl
	<< "Cmdline: " << cmd_line << std::endl
	<< "Thread: " << tid << " \"" << thread_name << "\"" << std::endl
	<< "Registers:\n" << Dumpable<UContext>(thread_context) << std::endl
	<< "Backtrace:\n" << Dumpable<Backtrace>(thread_backtrace) << std::endl;
	stream << std::flush;
	};

	if (dump_on_stderr) {
	// Note: We are using cerr directly instead of LOG macros to ensure even just partial output
	// makes it out. That means we lose the "dalvikvm..." prefix, but that is acceptable
	// considering this is an abort situation.
	logger(std::cerr);
	} else {
	logger(LOG_STREAM(FATAL_WITHOUT_ABORT));
	}
	if (kIsDebugBuild && signal_number == SIGSEGV) {
	PrintFileToLog("/proc/self/maps", android::base::LogSeverity::FATAL_WITHOUT_ABORT);
	}

	Runtime* runtime = Runtime::Current();
	if (runtime != nullptr) {
	if (handle_timeout_signal && IsTimeoutSignal(signal_number)) {
	// Special timeout signal. Try to dump all threads.
	// Note: Do not use DumpForSigQuit, as that might disable native unwind, but the native parts
	// are of value here.
	runtime->GetThreadList()->Dump(std::cerr, kDumpNativeStackOnTimeout);
	std::cerr << std::endl;
	}

	if (dump_on_stderr) {
	std::cerr << "Fault message: " << GetFaultMessageForAbortLogging() << std::endl;
	} else {
	LOG(FATAL_WITHOUT_ABORT) << "Fault message: " << GetFaultMessageForAbortLogging();
	}
	}
	}

	void HandleUnexpectedSignalCommon(int signal_number,
	siginfo_t* info,
	void* raw_context,
	bool handle_timeout_signal,
	bool dump_on_stderr) {
	bool runtime_abort = gIsRuntimeAbort.exchange(false);
	if (runtime_abort) {
	return;
	}

	// Local _static_ storing the currently handled signal (or -1).
	static int handling_unexpected_signal = -1;

	// Whether the dump code should be run under the unexpected-signal lock. For diagnostics we
	// allow recursive unexpected-signals in certain cases - avoid a deadlock.
	bool grab_lock = true;

	if (handling_unexpected_signal != -1) {
	LogHelper::LogLineLowStack(__FILE__,
	__LINE__,
	::android::base::FATAL_WITHOUT_ABORT,
	"HandleUnexpectedSignal reentered\n");
	// Print the signal number. Don't use any standard functions, just some arithmetic. Just best
	// effort, with a minimal buffer.
	if (0 < signal_number && signal_number < 100) {
	char buf[] = { ' ',
	'S',
	static_cast<char>('0' + (signal_number / 10)),
	static_cast<char>('0' + (signal_number % 10)),
	'\n',
	0 };
	LogHelper::LogLineLowStack(__FILE__,
	__LINE__,
	::android::base::FATAL_WITHOUT_ABORT,
	buf);
	}
	if (handle_timeout_signal) {
	if (IsTimeoutSignal(signal_number)) {
	// Ignore a recursive timeout.
	return;
	}
	}
	// If we were handling a timeout signal, try to go on. Otherwise hard-exit.
	// This relies on the expectation that we'll only ever get one timeout signal.
	if (!handle_timeout_signal \|\| handling_unexpected_signal != GetTimeoutSignal()) {
	_exit(1);
	}
	grab_lock = false; // The "outer" handling instance already holds the lock.
	}
	handling_unexpected_signal = signal_number;

	gAborting++; // set before taking any locks

	if (grab_lock) {
	MutexLock mu(Thread::Current(), *Locks::unexpected_signal_lock_);

	HandleUnexpectedSignalCommonDump(signal_number,
	info,
	raw_context,
	handle_timeout_signal,
	dump_on_stderr);
	} else {
	HandleUnexpectedSignalCommonDump(signal_number,
	info,
	raw_context,
	handle_timeout_signal,
	dump_on_stderr);
	}
	}

	#if defined(__APPLE__)
	#pragma GCC diagnostic pop
	#endif

	void InitPlatformSignalHandlersCommon(void (newact)(int, siginfo_t, void*),
	struct sigaction* oldact,
	bool handle_timeout_signal) {
	struct sigaction action;
	memset(&action, 0, sizeof(action));
	sigemptyset(&action.sa_mask);
	action.sa_sigaction = newact;
	// Use the three-argument sa_sigaction handler.
	action.sa_flags \|= SA_SIGINFO;
	// Use the alternate signal stack so we can catch stack overflows.
	action.sa_flags \|= SA_ONSTACK;

	int rc = 0;
	rc += sigaction(SIGABRT, &action, oldact);
	rc += sigaction(SIGBUS, &action, oldact);
	rc += sigaction(SIGFPE, &action, oldact);
	rc += sigaction(SIGILL, &action, oldact);
	rc += sigaction(SIGPIPE, &action, oldact);
	rc += sigaction(SIGSEGV, &action, oldact);
	#if defined(SIGSTKFLT)
	rc += sigaction(SIGSTKFLT, &action, oldact);
	#endif
	rc += sigaction(SIGTRAP, &action, oldact);
	// Special dump-all timeout.
	if (handle_timeout_signal && GetTimeoutSignal() != -1) {
	rc += sigaction(GetTimeoutSignal(), &action, oldact);
	}
	CHECK_EQ(rc, 0);
	}

	} // namespace art