2459046c1d
The "Address" type is V8's general-purpose type for manipulating memory addresses. Per the C++ spec, pointer arithmetic and pointer comparisons are undefined behavior except within the same array; since we generally don't operate within a C++ array, our general-purpose type shouldn't be a pointer type. Bug: v8:3770 Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng;master.tryserver.blink:linux_trusty_blink_rel Change-Id: Ib96016c24a0f18bcdba916dabd83e3f24a1b5779 Reviewed-on: https://chromium-review.googlesource.com/988657 Commit-Queue: Jakob Kummerow <jkummerow@chromium.org> Reviewed-by: Leszek Swirski <leszeks@chromium.org> Cr-Commit-Position: refs/heads/master@{#52601}
83 lines
2.8 KiB
C++
83 lines
2.8 KiB
C++
// Copyright 2016 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_
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#define V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_
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// This file should not be included (even transitively) by files outside of
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// src/trap-handler.
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#include "src/trap-handler/trap-handler.h"
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#include <atomic>
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namespace v8 {
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namespace internal {
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namespace trap_handler {
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// This describes a chunk of code that the signal handler will be able to handle
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// faults in. {base} points to the beginning of the chunk, and {size} is the
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// number of bytes in the code chunk. The remainder of the struct is a list of
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// protected memory access instructions and an offset to a landing pad to handle
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// faults on that instruction.
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struct CodeProtectionInfo {
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Address base;
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size_t size;
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size_t num_protected_instructions;
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ProtectedInstructionData instructions[1];
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};
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class MetadataLock {
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static std::atomic_flag spinlock_;
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public:
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MetadataLock();
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~MetadataLock();
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// We'd normally use DISALLOW_COPY_AND_ASSIGN, but we're avoiding a dependency
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// on base/macros.h
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MetadataLock(const MetadataLock&) = delete;
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void operator=(const MetadataLock&) = delete;
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};
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#if V8_TRAP_HANDLER_SUPPORTED
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void HandleSignal(int signum, siginfo_t* info, void* context);
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#endif
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// To enable constant time registration of handler data, we keep a free list of
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// entries in the gCodeObjects table. Each entry contains a {next_free} field,
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// which can be used to figure out where the next entry should be inserted.
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// In order to avoid having to initialize all the links to start with, we use
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// 0 to indicate that this is a fresh, never-used list entry and that therefore
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// the next entry is known to be free. If {next_entry} is greater than zero,
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// then {next_entry - 1} is the index that we should insert into next.
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struct CodeProtectionInfoListEntry {
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CodeProtectionInfo* code_info;
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size_t next_free;
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};
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extern size_t gNumCodeObjects;
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extern CodeProtectionInfoListEntry* gCodeObjects;
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extern std::atomic_size_t gRecoveredTrapCount;
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// Searches the fault location table for an entry matching fault_addr. If found,
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// returns true and sets landing_pad to the address of a fragment of code that
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// can recover from this fault. Otherwise, returns false and leaves offset
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// unchanged.
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bool TryFindLandingPad(uintptr_t fault_addr, uintptr_t* landing_pad);
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#if V8_TRAP_HANDLER_SUPPORTED
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// When using the default signal handler, we save the old one to restore in case
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// V8 chooses not to handle the signal.
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extern struct sigaction g_old_handler;
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extern bool g_is_default_signal_handler_registered;
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#endif
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} // namespace trap_handler
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} // namespace internal
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} // namespace v8
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#endif // V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_
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