Implement code patcher for x64

src/x64/assembler-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 155 matching lines @@
   ASSERT(IsSupported(CMOV));
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo
 
 // Patch the code at the current PC with a call to the target address.
 // Additional guard int3 instructions can be added if required.
 void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
-  // Call instruction takes up 13 bytes and int3 takes up one byte.
-  static const int kCallInstructionSize = 13;
-  Address patch_site = pc_;
-  Memory::uint16_at(patch_site) = 0xBA49u;  // movq r10, imm64
-  // Write "0x00, call r10" starting at last byte of address.  We overwrite
-  // the 0x00 later, and this lets us write a uint32.
-  Memory::uint32_at(patch_site + 9) = 0xD2FF4900u;  // 0x00, call r10
-  Memory::Address_at(patch_site + 2) = target;
+  // Load register with immediate 64 and call through a register instructions
+  // takes up 13 bytes and int3 takes up one byte.
+  static const int kCallCodeSize = 13;
+  int code_size = kCallCodeSize + guard_bytes;
+
+  // Create a code patcher.
+  CodePatcher patcher(pc_, code_size);
+
+  // Add a label for checking the size of the code used for returning.
+#ifdef DEBUG
+  Label check_codesize;
+  patcher.masm()->bind(&check_codesize);
+#endif
+
+  // Patch the code.
+  patcher.masm()->movq(r10, target, RelocInfo::NONE);
+  patcher.masm()->call(r10);
+
+  // Check that the size of the code generated is as expected.
+  ASSERT_EQ(kCallCodeSize,
+            patcher.masm()->SizeOfCodeGeneratedSince(&check_codesize));
 
   // Add the requested number of int3 instructions after the call.
   for (int i = 0; i < guard_bytes; i++) {
-    *(patch_site + kCallInstructionSize + i) = 0xCC;  // int3
+    patcher.masm()->int3();
   }
-
-  // Indicate that code has changed.
-  CPU::FlushICache(patch_site, kCallInstructionSize + guard_bytes);
 }
 
 
 void RelocInfo::PatchCode(byte* instructions, int instruction_count) {
   // Patch the code at the current address with the supplied instructions.
   for (int i = 0; i < instruction_count; i++) {
     *(pc_ + i) = *(instructions + i);
   }
+
+  // Indicate that code has changed.
+  CPU::FlushICache(pc_, instruction_count);
 }
 
 // -----------------------------------------------------------------------------
 // Implementation of Operand
 
 Operand::Operand(Register base, int32_t disp): rex_(0) {
   len_ = 1;
   if (base.is(rsp) || base.is(r12)) {
     // SIB byte is needed to encode (rsp + offset) or (r12 + offset).
     set_sib(times_1, rsp, base);
@@ skipping 2152 matching lines @@
     RecordRelocInfo(RelocInfo::POSITION, current_position_);
     written_position_ = current_position_;
   }
 }
 
 
 const int RelocInfo::kApplyMask = 1 << RelocInfo::INTERNAL_REFERENCE;
 
 
 } }  // namespace v8::internal