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// Copyright 2016 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.
#ifndef V8_TRAP_HANDLER_TRAP_HANDLER_H_
#define V8_TRAP_HANDLER_TRAP_HANDLER_H_
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include "src/base/build_config.h"
#include "src/flags.h"
#include "src/globals.h"
#if V8_OS_LINUX
#include <ucontext.h>
#endif
namespace v8 {
namespace internal {
namespace trap_handler {
// TODO(eholk): Support trap handlers on other platforms.
#if V8_TARGET_ARCH_X64 && V8_OS_LINUX && !V8_OS_ANDROID
#define V8_TRAP_HANDLER_SUPPORTED 1
#else
#define V8_TRAP_HANDLER_SUPPORTED 0
#endif
struct ProtectedInstructionData {
// The offset of this instruction from the start of its code object.
// Wasm code never grows larger than 2GB, so uint32_t is sufficient.
uint32_t instr_offset;
// The offset of the landing pad from the start of its code object.
//
// TODO(eholk): Using a single landing pad and store parameters here.
uint32_t landing_offset;
};
const int kInvalidIndex = -1;
/// Adjusts the base code pointer.
void UpdateHandlerDataCodePointer(int index, void* base);
/// Adds the handler data to the place where the signal handler will find it.
///
/// This returns a number that can be used to identify the handler data to
/// UpdateHandlerDataCodePointer and ReleaseHandlerData, or -1 on failure.
int RegisterHandlerData(void* base, size_t size,
size_t num_protected_instructions,
const ProtectedInstructionData* protected_instructions);
/// Removes the data from the master list and frees any memory, if necessary.
/// TODO(mtrofin): once FLAG_wasm_jit_to_native is not needed, we can switch
/// to using size_t for index and not need kInvalidIndex.
void ReleaseHandlerData(int index);
#if V8_OS_WIN
#define THREAD_LOCAL __declspec(thread)
#elif V8_OS_ANDROID
// TODO(eholk): fix this before enabling for trap handlers for Android.
#define THREAD_LOCAL
#else
#define THREAD_LOCAL __thread
#endif
inline bool IsTrapHandlerEnabled() {
return FLAG_wasm_trap_handler && V8_TRAP_HANDLER_SUPPORTED;
}
extern THREAD_LOCAL int g_thread_in_wasm_code;
inline bool IsThreadInWasm() { return g_thread_in_wasm_code; }
inline void SetThreadInWasm() {
if (IsTrapHandlerEnabled()) {
DCHECK(!IsThreadInWasm());
g_thread_in_wasm_code = true;
}
}
inline void ClearThreadInWasm() {
if (IsTrapHandlerEnabled()) {
DCHECK(IsThreadInWasm());
g_thread_in_wasm_code = false;
}
}
bool RegisterDefaultSignalHandler();
V8_EXPORT_PRIVATE void RestoreOriginalSignalHandler();
#if V8_OS_LINUX
bool TryHandleSignal(int signum, siginfo_t* info, ucontext_t* context);
#endif // V8_OS_LINUX
size_t GetRecoveredTrapCount();
} // namespace trap_handler
} // namespace internal
} // namespace v8
#endif // V8_TRAP_HANDLER_TRAP_HANDLER_H_
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