1 // Copyright 2013 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_ARM64
6
7 #include "src/debug/debug.h"
8
9 #include "src/arm64/frames-arm64.h"
10 #include "src/codegen.h"
11 #include "src/debug/liveedit.h"
12
13 namespace v8 {
14 namespace internal {
15
16 #define __ ACCESS_MASM(masm)
17
18
EmitDebugBreakSlot(Assembler * masm)19 void EmitDebugBreakSlot(Assembler* masm) {
20 Label check_size;
21 __ bind(&check_size);
22 for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
23 __ nop(Assembler::DEBUG_BREAK_NOP);
24 }
25 DCHECK_EQ(Assembler::kDebugBreakSlotInstructions,
26 static_cast<int>(masm->InstructionsGeneratedSince(&check_size)));
27 }
28
29
GenerateSlot(MacroAssembler * masm,RelocInfo::Mode mode)30 void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
31 // Generate enough nop's to make space for a call instruction. Avoid emitting
32 // the constant pool in the debug break slot code.
33 InstructionAccurateScope scope(masm, Assembler::kDebugBreakSlotInstructions);
34 masm->RecordDebugBreakSlot(mode);
35 EmitDebugBreakSlot(masm);
36 }
37
38
ClearDebugBreakSlot(Isolate * isolate,Address pc)39 void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
40 PatchingAssembler patcher(isolate, reinterpret_cast<Instruction*>(pc),
41 Assembler::kDebugBreakSlotInstructions);
42 EmitDebugBreakSlot(&patcher);
43 }
44
45
PatchDebugBreakSlot(Isolate * isolate,Address pc,Handle<Code> code)46 void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
47 Handle<Code> code) {
48 DCHECK(code->is_debug_stub());
49 PatchingAssembler patcher(isolate, reinterpret_cast<Instruction*>(pc),
50 Assembler::kDebugBreakSlotInstructions);
51 // Patch the code emitted by DebugCodegen::GenerateSlots, changing the debug
52 // break slot code from
53 // mov x0, x0 @ nop DEBUG_BREAK_NOP
54 // mov x0, x0 @ nop DEBUG_BREAK_NOP
55 // mov x0, x0 @ nop DEBUG_BREAK_NOP
56 // mov x0, x0 @ nop DEBUG_BREAK_NOP
57 // mov x0, x0 @ nop DEBUG_BREAK_NOP
58 // to a call to the debug slot code.
59 // ldr ip0, [pc, #(2 * kInstructionSize)]
60 // blr ip0
61 // b skip
62 // <debug break slot code entry point address (64 bits)>
63 // skip:
64
65 Label skip_constant;
66 // The first instruction of a patched debug break slot must be a load literal
67 // loading the address of the debug break slot code.
68 patcher.ldr_pcrel(ip0, (2 * kInstructionSize) >> kLoadLiteralScaleLog2);
69 patcher.b(&skip_constant);
70 patcher.dc64(reinterpret_cast<int64_t>(code->entry()));
71 patcher.bind(&skip_constant);
72 // TODO(all): check the following is correct.
73 // The debug break slot code will push a frame and call statically compiled
74 // code. By using blr, this call site will be registered in the frame.
75 // The debugger can now iterate on the frames to find this call.
76 patcher.blr(ip0);
77 }
78
DebugBreakSlotIsPatched(Address pc)79 bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
80 Instruction* current_instr = reinterpret_cast<Instruction*>(pc);
81 return !current_instr->IsNop(Assembler::DEBUG_BREAK_NOP);
82 }
83
GenerateDebugBreakStub(MacroAssembler * masm,DebugBreakCallHelperMode mode)84 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
85 DebugBreakCallHelperMode mode) {
86 __ RecordComment("Debug break");
87 Register scratch = x10;
88 {
89 FrameScope scope(masm, StackFrame::INTERNAL);
90
91 // Load padding words on stack.
92 __ Mov(scratch, Smi::FromInt(LiveEdit::kFramePaddingValue));
93 __ PushMultipleTimes(scratch, LiveEdit::kFramePaddingInitialSize);
94 __ Mov(scratch, Smi::FromInt(LiveEdit::kFramePaddingInitialSize));
95 __ Push(scratch);
96
97 // Push arguments for DebugBreak call.
98 if (mode == SAVE_RESULT_REGISTER) {
99 // Break on return.
100 __ Push(x0);
101 } else {
102 // Non-return breaks.
103 __ Push(masm->isolate()->factory()->the_hole_value());
104 }
105 __ Mov(x0, 1);
106 __ Mov(x1, ExternalReference(Runtime::FunctionForId(Runtime::kDebugBreak),
107 masm->isolate()));
108
109 CEntryStub stub(masm->isolate(), 1);
110 __ CallStub(&stub);
111
112 if (FLAG_debug_code) {
113 for (int i = 0; i < kNumJSCallerSaved; i++) {
114 Register reg = Register::XRegFromCode(JSCallerSavedCode(i));
115 // Do not clobber x0 if mode is SAVE_RESULT_REGISTER. It will
116 // contain return value of the function.
117 if (!(reg.is(x0) && (mode == SAVE_RESULT_REGISTER))) {
118 __ Mov(reg, Operand(kDebugZapValue));
119 }
120 }
121 }
122
123 // Don't bother removing padding bytes pushed on the stack
124 // as the frame is going to be restored right away.
125
126 // Leave the internal frame.
127 }
128
129 // Now that the break point has been handled, resume normal execution by
130 // jumping to the target address intended by the caller and that was
131 // overwritten by the address of DebugBreakXXX.
132 ExternalReference after_break_target =
133 ExternalReference::debug_after_break_target_address(masm->isolate());
134 __ Mov(scratch, after_break_target);
135 __ Ldr(scratch, MemOperand(scratch));
136 __ Br(scratch);
137 }
138
139
GenerateFrameDropperLiveEdit(MacroAssembler * masm)140 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
141 // We do not know our frame height, but set sp based on fp.
142 __ Add(masm->StackPointer(), fp, FrameDropperFrameConstants::kFunctionOffset);
143 __ AssertStackConsistency();
144
145 __ Pop(x1); // Function
146 __ Mov(masm->StackPointer(), Operand(fp));
147 __ Pop(fp, lr); // Frame, Return address.
148
149 ParameterCount dummy(0);
150 __ FloodFunctionIfStepping(x1, no_reg, dummy, dummy);
151
152 UseScratchRegisterScope temps(masm);
153 Register scratch = temps.AcquireX();
154
155 // Load context from the function.
156 __ Ldr(cp, FieldMemOperand(x1, JSFunction::kContextOffset));
157
158 // Clear new.target as a safety measure.
159 __ LoadRoot(x3, Heap::kUndefinedValueRootIndex);
160
161 // Get function code.
162 __ Ldr(scratch, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
163 __ Ldr(scratch, FieldMemOperand(scratch, SharedFunctionInfo::kCodeOffset));
164 __ Add(scratch, scratch, Code::kHeaderSize - kHeapObjectTag);
165
166 // Re-run JSFunction, x1 is function, cp is context.
167 __ Br(scratch);
168 }
169
170
171 const bool LiveEdit::kFrameDropperSupported = true;
172
173 } // namespace internal
174 } // namespace v8
175
176 #endif // V8_TARGET_ARCH_ARM64
177