[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 7c78b1f2320ad512b06ca0306aaa7f4ec7060e77..f084b3b1d0a21521f2c4ac537ae8ccbdf634b398 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.
   int32_t instr_offset;
@@ -19,6 +33,27 @@ struct ProtectedInstructionData {
   int32_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.
+int RegisterHandlerData(void* base, size_t size,

[Mark Seaborn, 2017/01/24 07:14:40]

Can you add a comment saying what this returns?

[Eric Holk, 2017/01/26 01:33:37]

Done.

+                        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