1 // Copyright 2017 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // PLEASE READ BEFORE CHANGING THIS FILE! 6 // 7 // This file contains code that is used both inside and outside the out of 8 // bounds trap handler. Because this code runs in a trap handler context, 9 // use extra care when modifying this file. Here are some rules to follow. 10 // 11 // 1. Do not introduce any new external dependencies. This file needs 12 // to be self contained so it is easy to audit everything that a 13 // trap handler might do. 14 // 15 // 2. Any changes must be reviewed by someone from the crash reporting 16 // or security team. See OWNERS for suggested reviewers. 17 // 18 // For more information, see https://goo.gl/yMeyUY. 19 20 #include "src/trap-handler/trap-handler-internal.h" 21 22 namespace v8 { 23 namespace internal { 24 namespace trap_handler { 25 26 // We declare this as int rather than bool as a workaround for a glibc bug, in 27 // which the dynamic loader cannot handle executables whose TLS area is only 28 // 1 byte in size; see https://sourceware.org/bugzilla/show_bug.cgi?id=14898. 29 thread_local int g_thread_in_wasm_code; 30 31 static_assert(sizeof(g_thread_in_wasm_code) > 1, 32 "sizeof(thread_local_var) must be > 1, see " 33 "https://sourceware.org/bugzilla/show_bug.cgi?id=14898"); 34 35 size_t gNumCodeObjects = 0; 36 CodeProtectionInfoListEntry* gCodeObjects = nullptr; 37 std::atomic_size_t gRecoveredTrapCount = {0}; 38 39 std::atomic_flag MetadataLock::spinlock_ = ATOMIC_FLAG_INIT; 40 MetadataLock()41MetadataLock::MetadataLock() { 42 if (g_thread_in_wasm_code) { 43 abort(); 44 } 45 46 while (spinlock_.test_and_set(std::memory_order_acquire)) { 47 } 48 } 49 ~MetadataLock()50MetadataLock::~MetadataLock() { 51 if (g_thread_in_wasm_code) { 52 abort(); 53 } 54 55 spinlock_.clear(std::memory_order_release); 56 } 57 58 } // namespace trap_handler 59 } // namespace internal 60 } // namespace v8 61