| // Copyright 2017 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // PLEASE READ BEFORE CHANGING THIS FILE! |
| // |
| // This file contains code that is used both inside and outside the out of |
| // bounds signal handler. Because this code runs in a signal handler context, |
| // use extra care when modifying this file. Here are some rules to follow. |
| // |
| // 1. Do not introduce any new external dependencies. This file needs |
| // to be self contained so it is easy to audit everything that a |
| // signal handler might do. |
| // |
| // 2. Any changes must be reviewed by someone from the crash reporting |
| // or security team. See OWNERS for suggested reviewers. |
| // |
| // For more information, see https://goo.gl/yMeyUY. |
| |
| #include "src/trap-handler/trap-handler-internal.h" |
| |
| namespace v8 { |
| namespace internal { |
| namespace trap_handler { |
| |
| #if !defined(STARBOARD) |
| // We declare this as int rather than bool as a workaround for a glibc bug, in |
| // which the dynamic loader cannot handle executables whose TLS area is only |
| // 1 byte in size; see https://sourceware.org/bugzilla/show_bug.cgi?id=14898. |
| THREAD_LOCAL int g_thread_in_wasm_code; |
| #endif |
| |
| #if V8_TRAP_HANDLER_SUPPORTED |
| // When using the default signal handler, we save the old one to restore in case |
| // V8 chooses not to handle the signal. |
| struct sigaction g_old_handler; |
| bool g_is_default_signal_handler_registered; |
| #endif |
| |
| V8_EXPORT_PRIVATE void RestoreOriginalSignalHandler() { |
| #if V8_TRAP_HANDLER_SUPPORTED |
| if (sigaction(SIGSEGV, &g_old_handler, nullptr) == 0) { |
| g_is_default_signal_handler_registered = false; |
| } |
| #endif |
| } |
| |
| #if !defined(STARBOARD) |
| static_assert(sizeof(g_thread_in_wasm_code) > 1, |
| "sizeof(thread_local_var) must be > 1, see " |
| "https://sourceware.org/bugzilla/show_bug.cgi?id=14898"); |
| #endif |
| |
| size_t gNumCodeObjects = 0; |
| CodeProtectionInfoListEntry* gCodeObjects = nullptr; |
| std::atomic_size_t gRecoveredTrapCount = {0}; |
| |
| std::atomic_flag MetadataLock::spinlock_ = ATOMIC_FLAG_INIT; |
| |
| #if defined(STARBOARD) |
| MetadataLock::MetadataLock() { SB_NOTREACHED(); } |
| MetadataLock::~MetadataLock() { SB_NOTREACHED(); } |
| #else |
| MetadataLock::MetadataLock() { |
| if (g_thread_in_wasm_code) { |
| abort(); |
| } |
| |
| while (spinlock_.test_and_set(std::memory_order::memory_order_acquire)) { |
| } |
| } |
| |
| MetadataLock::~MetadataLock() { |
| if (g_thread_in_wasm_code) { |
| abort(); |
| } |
| |
| spinlock_.clear(std::memory_order::memory_order_release); |
| } |
| #endif |
| |
| } // namespace trap_handler |
| } // namespace internal |
| } // namespace v8 |