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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_ARM
6 
7 #include "src/codegen.h"
8 #include "src/debug/debug.h"
9 
10 namespace v8 {
11 namespace internal {
12 
13 #define __ ACCESS_MASM(masm)
14 
15 
EmitDebugBreakSlot(MacroAssembler * masm)16 void EmitDebugBreakSlot(MacroAssembler* masm) {
17   Label check_size;
18   __ bind(&check_size);
19   for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
20     __ nop(MacroAssembler::DEBUG_BREAK_NOP);
21   }
22   DCHECK_EQ(Assembler::kDebugBreakSlotInstructions,
23             masm->InstructionsGeneratedSince(&check_size));
24 }
25 
26 
GenerateSlot(MacroAssembler * masm,RelocInfo::Mode mode)27 void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
28   // Generate enough nop's to make space for a call instruction. Avoid emitting
29   // the constant pool in the debug break slot code.
30   Assembler::BlockConstPoolScope block_const_pool(masm);
31   masm->RecordDebugBreakSlot(mode);
32   EmitDebugBreakSlot(masm);
33 }
34 
35 
ClearDebugBreakSlot(Isolate * isolate,Address pc)36 void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
37   CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotInstructions);
38   EmitDebugBreakSlot(patcher.masm());
39 }
40 
41 
PatchDebugBreakSlot(Isolate * isolate,Address pc,Handle<Code> code)42 void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
43                                        Handle<Code> code) {
44   DCHECK_EQ(Code::BUILTIN, code->kind());
45   CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotInstructions);
46   // Patch the code changing the debug break slot code from
47   //   mov r2, r2
48   //   mov r2, r2
49   //   mov r2, r2
50   //   mov r2, r2
51   // to a call to the debug break slot code.
52   //   ldr ip, [pc, #0]
53   //   b skip
54   //   <debug break slot code entry point address>
55   //   skip:
56   //   blx ip
57   Label skip_constant;
58   patcher.masm()->ldr(ip, MemOperand(v8::internal::pc, 0));
59   patcher.masm()->b(&skip_constant);
60   patcher.Emit(code->entry());
61   patcher.masm()->bind(&skip_constant);
62   patcher.masm()->blx(ip);
63 }
64 
65 
GenerateDebugBreakStub(MacroAssembler * masm,DebugBreakCallHelperMode mode)66 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
67                                           DebugBreakCallHelperMode mode) {
68   __ RecordComment("Debug break");
69   {
70     FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
71 
72     // Load padding words on stack.
73     __ mov(ip, Operand(Smi::FromInt(LiveEdit::kFramePaddingValue)));
74     for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) {
75       __ push(ip);
76     }
77     __ mov(ip, Operand(Smi::FromInt(LiveEdit::kFramePaddingInitialSize)));
78     __ push(ip);
79 
80     if (mode == SAVE_RESULT_REGISTER) __ push(r0);
81 
82     __ mov(r0, Operand::Zero());  // no arguments
83     __ mov(r1,
84            Operand(ExternalReference(
85                Runtime::FunctionForId(Runtime::kDebugBreak), masm->isolate())));
86 
87     CEntryStub ceb(masm->isolate(), 1);
88     __ CallStub(&ceb);
89 
90     if (FLAG_debug_code) {
91       for (int i = 0; i < kNumJSCallerSaved; i++) {
92         Register reg = {JSCallerSavedCode(i)};
93         __ mov(reg, Operand(kDebugZapValue));
94       }
95     }
96 
97     if (mode == SAVE_RESULT_REGISTER) __ pop(r0);
98 
99     // Don't bother removing padding bytes pushed on the stack
100     // as the frame is going to be restored right away.
101 
102     // Leave the internal frame.
103   }
104 
105   // Now that the break point has been handled, resume normal execution by
106   // jumping to the target address intended by the caller and that was
107   // overwritten by the address of DebugBreakXXX.
108   ExternalReference after_break_target =
109       ExternalReference::debug_after_break_target_address(masm->isolate());
110   __ mov(ip, Operand(after_break_target));
111   __ ldr(ip, MemOperand(ip));
112   __ Jump(ip);
113 }
114 
115 
GenerateFrameDropperLiveEdit(MacroAssembler * masm)116 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
117   // Load the function pointer off of our current stack frame.
118   __ ldr(r1, MemOperand(fp,
119          StandardFrameConstants::kConstantPoolOffset - kPointerSize));
120 
121   // Pop return address, frame and constant pool pointer (if
122   // FLAG_enable_embedded_constant_pool).
123   __ LeaveFrame(StackFrame::INTERNAL);
124 
125   ParameterCount dummy(0);
126   __ FloodFunctionIfStepping(r1, no_reg, dummy, dummy);
127 
128   { ConstantPoolUnavailableScope constant_pool_unavailable(masm);
129     // Load context from the function.
130     __ ldr(cp, FieldMemOperand(r1, JSFunction::kContextOffset));
131 
132     // Clear new.target as a safety measure.
133     __ LoadRoot(r3, Heap::kUndefinedValueRootIndex);
134 
135     // Get function code.
136     __ ldr(ip, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
137     __ ldr(ip, FieldMemOperand(ip, SharedFunctionInfo::kCodeOffset));
138     __ add(ip, ip, Operand(Code::kHeaderSize - kHeapObjectTag));
139 
140     // Re-run JSFunction, r1 is function, cp is context.
141     __ Jump(ip);
142   }
143 }
144 
145 
146 const bool LiveEdit::kFrameDropperSupported = true;
147 
148 #undef __
149 
150 }  // namespace internal
151 }  // namespace v8
152 
153 #endif  // V8_TARGET_ARCH_ARM
154