1// Copyright 2012 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#if V8_TARGET_ARCH_X64
6
7#include "src/debug/debug.h"
8
9#include "src/assembler.h"
10#include "src/codegen.h"
11#include "src/debug/liveedit.h"
12
13namespace v8 {
14namespace internal {
15
16#define __ ACCESS_MASM(masm)
17
18
19void EmitDebugBreakSlot(MacroAssembler* masm) {
20  Label check_codesize;
21  __ bind(&check_codesize);
22  __ Nop(Assembler::kDebugBreakSlotLength);
23  DCHECK_EQ(Assembler::kDebugBreakSlotLength,
24            masm->SizeOfCodeGeneratedSince(&check_codesize));
25}
26
27
28void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
29  // Generate enough nop's to make space for a call instruction.
30  masm->RecordDebugBreakSlot(mode);
31  EmitDebugBreakSlot(masm);
32}
33
34
35void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
36  CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotLength);
37  EmitDebugBreakSlot(patcher.masm());
38}
39
40
41void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
42                                       Handle<Code> code) {
43  DCHECK(code->is_debug_stub());
44  static const int kSize = Assembler::kDebugBreakSlotLength;
45  CodePatcher patcher(isolate, pc, kSize);
46  Label check_codesize;
47  patcher.masm()->bind(&check_codesize);
48  patcher.masm()->movp(kScratchRegister, reinterpret_cast<void*>(code->entry()),
49                       Assembler::RelocInfoNone());
50  patcher.masm()->call(kScratchRegister);
51  // Check that the size of the code generated is as expected.
52  DCHECK_EQ(kSize, patcher.masm()->SizeOfCodeGeneratedSince(&check_codesize));
53}
54
55bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
56  return !Assembler::IsNop(pc);
57}
58
59void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
60                                          DebugBreakCallHelperMode mode) {
61  __ RecordComment("Debug break");
62
63  // Enter an internal frame.
64  {
65    FrameScope scope(masm, StackFrame::INTERNAL);
66
67    // Load padding words on stack.
68    for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) {
69      __ Push(Smi::FromInt(LiveEdit::kFramePaddingValue));
70    }
71    __ Push(Smi::FromInt(LiveEdit::kFramePaddingInitialSize));
72
73    // Push arguments for DebugBreak call.
74    if (mode == SAVE_RESULT_REGISTER) {
75      // Break on return.
76      __ Push(rax);
77    } else {
78      // Non-return breaks.
79      __ Push(masm->isolate()->factory()->the_hole_value());
80    }
81    __ Set(rax, 1);
82    __ Move(rbx, ExternalReference(Runtime::FunctionForId(Runtime::kDebugBreak),
83                                   masm->isolate()));
84
85    CEntryStub ceb(masm->isolate(), 1);
86    __ CallStub(&ceb);
87
88    if (FLAG_debug_code) {
89      for (int i = 0; i < kNumJSCallerSaved; ++i) {
90        Register reg = {JSCallerSavedCode(i)};
91        // Do not clobber rax if mode is SAVE_RESULT_REGISTER. It will
92        // contain return value of the function.
93        if (!(reg.is(rax) && (mode == SAVE_RESULT_REGISTER))) {
94          __ Set(reg, kDebugZapValue);
95        }
96      }
97    }
98
99    // Read current padding counter and skip corresponding number of words.
100    __ Pop(kScratchRegister);
101    __ SmiToInteger32(kScratchRegister, kScratchRegister);
102    __ leap(rsp, Operand(rsp, kScratchRegister, times_pointer_size, 0));
103
104    // Get rid of the internal frame.
105  }
106
107  // This call did not replace a call , so there will be an unwanted
108  // return address left on the stack. Here we get rid of that.
109  __ addp(rsp, Immediate(kPCOnStackSize));
110
111  // Now that the break point has been handled, resume normal execution by
112  // jumping to the target address intended by the caller and that was
113  // overwritten by the address of DebugBreakXXX.
114  ExternalReference after_break_target =
115      ExternalReference::debug_after_break_target_address(masm->isolate());
116  __ Move(kScratchRegister, after_break_target);
117  __ Jump(Operand(kScratchRegister, 0));
118}
119
120
121void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
122  // We do not know our frame height, but set rsp based on rbp.
123  __ leap(rsp, Operand(rbp, FrameDropperFrameConstants::kFunctionOffset));
124  __ Pop(rdi);  // Function.
125  __ addp(rsp,
126          Immediate(-FrameDropperFrameConstants::kCodeOffset));  // INTERNAL
127                                                                 // frame marker
128                                                                 // and code
129  __ popq(rbp);
130
131  ParameterCount dummy(0);
132  __ FloodFunctionIfStepping(rdi, no_reg, dummy, dummy);
133
134  // Load context from the function.
135  __ movp(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
136
137  // Clear new.target as a safety measure.
138  __ LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
139
140  // Get function code.
141  __ movp(rbx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
142  __ movp(rbx, FieldOperand(rbx, SharedFunctionInfo::kCodeOffset));
143  __ leap(rbx, FieldOperand(rbx, Code::kHeaderSize));
144
145  // Re-run JSFunction, rdi is function, rsi is context.
146  __ jmp(rbx);
147}
148
149const bool LiveEdit::kFrameDropperSupported = true;
150
151#undef __
152
153}  // namespace internal
154}  // namespace v8
155
156#endif  // V8_TARGET_ARCH_X64
157