1//===- AArch64ExternalSymbolizer.cpp - Symbolizer for AArch64 ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "AArch64ExternalSymbolizer.h"
11#include "AArch64Subtarget.h"
12#include "MCTargetDesc/AArch64AddressingModes.h"
13#include "Utils/AArch64BaseInfo.h"
14#include "llvm/MC/MCContext.h"
15#include "llvm/MC/MCExpr.h"
16#include "llvm/MC/MCInst.h"
17#include "llvm/Support/Format.h"
18#include "llvm/Support/raw_ostream.h"
19
20using namespace llvm;
21
22#define DEBUG_TYPE "aarch64-disassembler"
23
24static MCSymbolRefExpr::VariantKind
25getVariant(uint64_t LLVMDisassembler_VariantKind) {
26  switch (LLVMDisassembler_VariantKind) {
27  case LLVMDisassembler_VariantKind_None:
28    return MCSymbolRefExpr::VK_None;
29  case LLVMDisassembler_VariantKind_ARM64_PAGE:
30    return MCSymbolRefExpr::VK_PAGE;
31  case LLVMDisassembler_VariantKind_ARM64_PAGEOFF:
32    return MCSymbolRefExpr::VK_PAGEOFF;
33  case LLVMDisassembler_VariantKind_ARM64_GOTPAGE:
34    return MCSymbolRefExpr::VK_GOTPAGE;
35  case LLVMDisassembler_VariantKind_ARM64_GOTPAGEOFF:
36    return MCSymbolRefExpr::VK_GOTPAGEOFF;
37  case LLVMDisassembler_VariantKind_ARM64_TLVP:
38  case LLVMDisassembler_VariantKind_ARM64_TLVOFF:
39  default:
40    llvm_unreachable("bad LLVMDisassembler_VariantKind");
41  }
42}
43
44/// tryAddingSymbolicOperand - tryAddingSymbolicOperand trys to add a symbolic
45/// operand in place of the immediate Value in the MCInst.  The immediate
46/// Value has not had any PC adjustment made by the caller. If the instruction
47/// is a branch that adds the PC to the immediate Value then isBranch is
48/// Success, else Fail. If GetOpInfo is non-null, then it is called to get any
49/// symbolic information at the Address for this instrution.  If that returns
50/// non-zero then the symbolic information it returns is used to create an
51/// MCExpr and that is added as an operand to the MCInst.  If GetOpInfo()
52/// returns zero and isBranch is Success then a symbol look up for
53/// Address + Value is done and if a symbol is found an MCExpr is created with
54/// that, else an MCExpr with Address + Value is created.  If GetOpInfo()
55/// returns zero and isBranch is Fail then the the Opcode of the MCInst is
56/// tested and for ADRP an other instructions that help to load of pointers
57/// a symbol look up is done to see it is returns a specific reference type
58/// to add to the comment stream.  This function returns Success if it adds
59/// an operand to the MCInst and Fail otherwise.
60bool AArch64ExternalSymbolizer::tryAddingSymbolicOperand(
61    MCInst &MI, raw_ostream &CommentStream, int64_t Value, uint64_t Address,
62    bool IsBranch, uint64_t Offset, uint64_t InstSize) {
63  // FIXME: This method shares a lot of code with
64  //        MCExternalSymbolizer::tryAddingSymbolicOperand. It may be possible
65  //        refactor the MCExternalSymbolizer interface to allow more of this
66  //        implementation to be shared.
67  //
68  struct LLVMOpInfo1 SymbolicOp;
69  memset(&SymbolicOp, '\0', sizeof(struct LLVMOpInfo1));
70  SymbolicOp.Value = Value;
71  uint64_t ReferenceType;
72  const char *ReferenceName;
73  if (!GetOpInfo ||
74      !GetOpInfo(DisInfo, Address, 0 /* Offset */, InstSize, 1, &SymbolicOp)) {
75    if (IsBranch) {
76      ReferenceType = LLVMDisassembler_ReferenceType_In_Branch;
77      const char *Name = SymbolLookUp(DisInfo, Address + Value, &ReferenceType,
78                                      Address, &ReferenceName);
79      if (Name) {
80        SymbolicOp.AddSymbol.Name = Name;
81        SymbolicOp.AddSymbol.Present = true;
82        SymbolicOp.Value = 0;
83      } else {
84        SymbolicOp.Value = Address + Value;
85      }
86      if (ReferenceType == LLVMDisassembler_ReferenceType_Out_SymbolStub)
87        CommentStream << "symbol stub for: " << ReferenceName;
88      else if (ReferenceType ==
89               LLVMDisassembler_ReferenceType_Out_Objc_Message)
90        CommentStream << "Objc message: " << ReferenceName;
91    } else if (MI.getOpcode() == AArch64::ADRP) {
92        ReferenceType = LLVMDisassembler_ReferenceType_In_ARM64_ADRP;
93        // otool expects the fully encoded ADRP instruction to be passed in as
94        // the value here, so reconstruct it:
95        const MCRegisterInfo &MCRI = *Ctx.getRegisterInfo();
96        uint32_t EncodedInst = 0x90000000;
97        EncodedInst |= (Value & 0x3) << 29; // immlo
98        EncodedInst |= ((Value >> 2) & 0x7FFFF) << 5; // immhi
99        EncodedInst |= MCRI.getEncodingValue(MI.getOperand(0).getReg()); // reg
100        SymbolLookUp(DisInfo, EncodedInst, &ReferenceType, Address,
101                     &ReferenceName);
102        CommentStream << format("0x%llx",
103                                0xfffffffffffff000LL & (Address + Value));
104    } else if (MI.getOpcode() == AArch64::ADDXri ||
105               MI.getOpcode() == AArch64::LDRXui ||
106               MI.getOpcode() == AArch64::LDRXl ||
107               MI.getOpcode() == AArch64::ADR) {
108      if (MI.getOpcode() == AArch64::ADDXri)
109        ReferenceType = LLVMDisassembler_ReferenceType_In_ARM64_ADDXri;
110      else if (MI.getOpcode() == AArch64::LDRXui)
111        ReferenceType = LLVMDisassembler_ReferenceType_In_ARM64_LDRXui;
112      if (MI.getOpcode() == AArch64::LDRXl) {
113        ReferenceType = LLVMDisassembler_ReferenceType_In_ARM64_LDRXl;
114        SymbolLookUp(DisInfo, Address + Value, &ReferenceType, Address,
115                     &ReferenceName);
116      } else if (MI.getOpcode() == AArch64::ADR) {
117        ReferenceType = LLVMDisassembler_ReferenceType_In_ARM64_ADR;
118        SymbolLookUp(DisInfo, Address + Value, &ReferenceType, Address,
119                            &ReferenceName);
120      } else {
121        const MCRegisterInfo &MCRI = *Ctx.getRegisterInfo();
122        // otool expects the fully encoded ADD/LDR instruction to be passed in
123        // as the value here, so reconstruct it:
124        unsigned EncodedInst =
125          MI.getOpcode() == AArch64::ADDXri ? 0x91000000: 0xF9400000;
126        EncodedInst |= Value << 10; // imm12 [+ shift:2 for ADD]
127        EncodedInst |=
128          MCRI.getEncodingValue(MI.getOperand(1).getReg()) << 5; // Rn
129        EncodedInst |= MCRI.getEncodingValue(MI.getOperand(0).getReg()); // Rd
130
131        SymbolLookUp(DisInfo, EncodedInst, &ReferenceType, Address,
132                     &ReferenceName);
133      }
134      if (ReferenceType == LLVMDisassembler_ReferenceType_Out_LitPool_SymAddr)
135        CommentStream << "literal pool symbol address: " << ReferenceName;
136      else if (ReferenceType ==
137               LLVMDisassembler_ReferenceType_Out_LitPool_CstrAddr)
138        CommentStream << "literal pool for: \"" << ReferenceName << "\"";
139      else if (ReferenceType ==
140               LLVMDisassembler_ReferenceType_Out_Objc_CFString_Ref)
141        CommentStream << "Objc cfstring ref: @\"" << ReferenceName << "\"";
142      else if (ReferenceType ==
143               LLVMDisassembler_ReferenceType_Out_Objc_Message)
144        CommentStream << "Objc message: " << ReferenceName;
145      else if (ReferenceType ==
146               LLVMDisassembler_ReferenceType_Out_Objc_Message_Ref)
147        CommentStream << "Objc message ref: " << ReferenceName;
148      else if (ReferenceType ==
149               LLVMDisassembler_ReferenceType_Out_Objc_Selector_Ref)
150        CommentStream << "Objc selector ref: " << ReferenceName;
151      else if (ReferenceType ==
152               LLVMDisassembler_ReferenceType_Out_Objc_Class_Ref)
153        CommentStream << "Objc class ref: " << ReferenceName;
154      // For these instructions, the SymbolLookUp() above is just to get the
155      // ReferenceType and ReferenceName.  We want to make sure not to
156      // fall through so we don't build an MCExpr to leave the disassembly
157      // of the immediate values of these instructions to the InstPrinter.
158      return false;
159    } else {
160      return false;
161    }
162  }
163
164  const MCExpr *Add = nullptr;
165  if (SymbolicOp.AddSymbol.Present) {
166    if (SymbolicOp.AddSymbol.Name) {
167      StringRef Name(SymbolicOp.AddSymbol.Name);
168      MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
169      MCSymbolRefExpr::VariantKind Variant = getVariant(SymbolicOp.VariantKind);
170      if (Variant != MCSymbolRefExpr::VK_None)
171        Add = MCSymbolRefExpr::Create(Sym, Variant, Ctx);
172      else
173        Add = MCSymbolRefExpr::Create(Sym, Ctx);
174    } else {
175      Add = MCConstantExpr::Create(SymbolicOp.AddSymbol.Value, Ctx);
176    }
177  }
178
179  const MCExpr *Sub = nullptr;
180  if (SymbolicOp.SubtractSymbol.Present) {
181    if (SymbolicOp.SubtractSymbol.Name) {
182      StringRef Name(SymbolicOp.SubtractSymbol.Name);
183      MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
184      Sub = MCSymbolRefExpr::Create(Sym, Ctx);
185    } else {
186      Sub = MCConstantExpr::Create(SymbolicOp.SubtractSymbol.Value, Ctx);
187    }
188  }
189
190  const MCExpr *Off = nullptr;
191  if (SymbolicOp.Value != 0)
192    Off = MCConstantExpr::Create(SymbolicOp.Value, Ctx);
193
194  const MCExpr *Expr;
195  if (Sub) {
196    const MCExpr *LHS;
197    if (Add)
198      LHS = MCBinaryExpr::CreateSub(Add, Sub, Ctx);
199    else
200      LHS = MCUnaryExpr::CreateMinus(Sub, Ctx);
201    if (Off)
202      Expr = MCBinaryExpr::CreateAdd(LHS, Off, Ctx);
203    else
204      Expr = LHS;
205  } else if (Add) {
206    if (Off)
207      Expr = MCBinaryExpr::CreateAdd(Add, Off, Ctx);
208    else
209      Expr = Add;
210  } else {
211    if (Off)
212      Expr = Off;
213    else
214      Expr = MCConstantExpr::Create(0, Ctx);
215  }
216
217  MI.addOperand(MCOperand::CreateExpr(Expr));
218
219  return true;
220}
221