// Copyright 2019 The Chromium Authors // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_IMMEDIATE_CRASH_H_ #define BASE_IMMEDIATE_CRASH_H_ #include "base/fuzzing_buildflags.h" #include "build/build_config.h" #if BUILDFLAG(USE_FUZZING_ENGINE) #include <stdlib.h> #if BUILDFLAG(IS_LINUX) // The fuzzing coverage display wants to record coverage even // for failure cases. It's Linux-only. So on Linux, dump coverage // before we immediately exit. We provide a weak symbol so that // this causes no link problems on configurations that don't involve // coverage. extern "C" int __attribute__((weak)) __llvm_profile_write_file(void); #endif // BUILDFLAG(IS_LINUX) #endif // BUILDFLAG(USE_FUZZING_ENGINE) // Crashes in the fastest possible way with no attempt at logging. // There are several constraints; see http://crbug.com/664209 for more context. // // - TRAP_SEQUENCE_() must be fatal. It should not be possible to ignore the // resulting exception or simply hit 'continue' to skip over it in a debugger. // - Different instances of TRAP_SEQUENCE_() must not be folded together, to // ensure crash reports are debuggable. Unlike __builtin_trap(), asm volatile // blocks will not be folded together. // Note: TRAP_SEQUENCE_() previously required an instruction with a unique // nonce since unlike clang, GCC folds together identical asm volatile // blocks. // - TRAP_SEQUENCE_() must produce a signal that is distinct from an invalid // memory access. // - TRAP_SEQUENCE_() must be treated as a set of noreturn instructions. // __builtin_unreachable() is used to provide that hint here. clang also uses // this as a heuristic to pack the instructions in the function epilogue to // improve code density. // - base::ImmediateCrash() is used in allocation hooks. To prevent recursions, // TRAP_SEQUENCE_() must not allocate. // // Additional properties that are nice to have: // - TRAP_SEQUENCE_() should be as compact as possible. // - The first instruction of TRAP_SEQUENCE_() should not change, to avoid // shifting crash reporting clusters. As a consequence of this, explicit // assembly is preferred over intrinsics. // Note: this last bullet point may no longer be true, and may be removed in // the future. // Note: TRAP_SEQUENCE Is currently split into two macro helpers due to the fact // that clang emits an actual instruction for __builtin_unreachable() on certain // platforms (see https://crbug.com/958675). In addition, the int3/bkpt/brk will // be removed in followups, so splitting it up like this now makes it easy to // land the followups. #if defined(COMPILER_GCC) #if BUILDFLAG(IS_NACL) // Crash report accuracy is not guaranteed on NaCl. #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #elif defined(ARCH_CPU_X86_FAMILY) // TODO(crbug.com/40625592): In theory, it should be possible to use just // int3. However, there are a number of crashes with SIGILL as the exception // code, so it seems likely that there's a signal handler that allows execution // to continue after SIGTRAP. #define TRAP_SEQUENCE1_() … #if BUILDFLAG(IS_APPLE) // Intentionally empty: __builtin_unreachable() is always part of the sequence // (see IMMEDIATE_CRASH below) and already emits a ud2 on Mac. #define TRAP_SEQUENCE2_ … #else #define TRAP_SEQUENCE2_() … #endif // BUILDFLAG(IS_APPLE) #elif defined(ARCH_CPU_ARMEL) // bkpt will generate a SIGBUS when running on armv7 and a SIGTRAP when running // as a 32 bit userspace app on arm64. There doesn't seem to be any way to // cause a SIGTRAP from userspace without using a syscall (which would be a // problem for sandboxing). // TODO(crbug.com/40625592): Remove bkpt from this sequence. #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #elif defined(ARCH_CPU_ARM64) // This will always generate a SIGTRAP on arm64. // TODO(crbug.com/40625592): Remove brk from this sequence. #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #else // Crash report accuracy will not be guaranteed on other architectures, but at // least this will crash as expected. #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #endif // ARCH_CPU_* #elif defined(COMPILER_MSVC) #if !defined(__clang__) // MSVC x64 doesn't support inline asm, so use the MSVC intrinsic. #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #elif defined(ARCH_CPU_ARM64) // Windows ARM64 uses "BRK #F000" as its breakpoint instruction, and // __debugbreak() generates that in both VC++ and clang. #define TRAP_SEQUENCE1_ … // Intentionally empty: __builtin_unreachable() is always part of the sequence // (see IMMEDIATE_CRASH below) and already emits a ud2 on Win64, // https://crbug.com/958373 #define TRAP_SEQUENCE2_ … #else #define TRAP_SEQUENCE1_ … #define TRAP_SEQUENCE2_ … #endif // __clang__ #else #error No supported trap sequence! #endif // COMPILER_GCC #define TRAP_SEQUENCE_() … // This version of ALWAYS_INLINE inlines even in is_debug=true. // TODO(pbos): See if NDEBUG can be dropped from ALWAYS_INLINE as well, and if // so merge. Otherwise document why it cannot inline in debug in // base/compiler_specific.h. #if defined(COMPILER_GCC) #define IMMEDIATE_CRASH_ALWAYS_INLINE … #elif defined(COMPILER_MSVC) #define IMMEDIATE_CRASH_ALWAYS_INLINE … #else #define IMMEDIATE_CRASH_ALWAYS_INLINE … #endif namespace base { [[noreturn]] IMMEDIATE_CRASH_ALWAYS_INLINE void ImmediateCrash() { … } } // namespace base #endif // BASE_IMMEDIATE_CRASH_H_
Codebase Browser
chromium