[wasm] Initial signal handler

src/trap-handler/trap-handler.h

Index: src/trap-handler/trap-handler.h
diff --git a/src/trap-handler/trap-handler.h b/src/trap-handler/trap-handler.h
index e6dd9bdca463c456af0b4fa75972e8facbc11cee..6fa71c78ba4727e1a6a0505bb459ae8086be8f90 100644
--- a/src/trap-handler/trap-handler.h
+++ b/src/trap-handler/trap-handler.h
@@ -5,10 +5,24 @@
 #ifndef V8_TRAP_HANDLER_H_
 #define V8_TRAP_HANDLER_H_
 
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "src/base/build_config.h"
+
 namespace v8 {
 namespace internal {
 namespace trap_handler {
 
+// TODO(eholk): Support trap handlers on other platforms.
+#if V8_TARGET_ARCH_X64 && V8_OS_LINUX
+#define V8_TRAP_HANDLER_SUPPORTED 1
+const bool kTrapHandlerSupported = true;
+#else
+#define V8_TRAP_HANDLER_SUPPORTED 0
+const bool kTrapHandlerSupported = false;
+#endif
+
 struct ProtectedInstructionData {
   // The offset of this instruction from the start of its code object.
   intptr_t instr_offset;
@@ -19,6 +33,30 @@ struct ProtectedInstructionData {
   intptr_t landing_offset;
 };
 
+/// Adjusts the base code pointer.
+void UpdateCodePointer(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
+/// UpdateCodePointer and ReleaseHandlerData, or -1 on failure.
+int RegisterHandlerData(void* base, size_t size,
+                        size_t num_protected_instructions,
+                        ProtectedInstructionData* protected_instructions);
+
+/// Removes the data from the master list and frees any memory, if necessary.
+void ReleaseHandlerData(int index);
+
+void SetThreadInWasm();
+void ClearThreadInWasm();
+
+bool IsThreadInWasm();
+
+bool EnableTrapHandler();
+bool RegisterDefaultSignalHandler();
+bool TryHandleFault(void* source_instruction, void* target_data,
+                    void** return_address);
+
 }  // namespace trap_handler
 }  // namespace internal
 }  // namespace v8