RelocVisitor.h revision 263508 
1//===-- RelocVisitor.h - Visitor for object file relocations -*- 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// This file provides a wrapper around all the different types of relocations
11// in different file formats, such that a client can handle them in a unified
12// manner by only implementing a minimal number of functions.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_OBJECT_RELOCVISITOR_H
17#define LLVM_OBJECT_RELOCVISITOR_H
18
19#include "llvm/ADT/StringRef.h"
20#include "llvm/Object/ObjectFile.h"
21#include "llvm/Object/ELFObjectFile.h"
22#include "llvm/Support/Debug.h"
23#include "llvm/Support/ELF.h"
24#include "llvm/Support/raw_ostream.h"
25
26namespace llvm {
27namespace object {
28
29struct RelocToApply {
30  // The computed value after applying the relevant relocations.
31  int64_t Value;
32
33  // The width of the value; how many bytes to touch when applying the
34  // relocation.
35  char Width;
36  RelocToApply(const RelocToApply &In) : Value(In.Value), Width(In.Width) {}
37  RelocToApply(int64_t Value, char Width) : Value(Value), Width(Width) {}
38  RelocToApply() : Value(0), Width(0) {}
39};
40
41/// @brief Base class for object file relocation visitors.
42class RelocVisitor {
43public:
44  explicit RelocVisitor(StringRef FileFormat)
45    : FileFormat(FileFormat), HasError(false) {}
46
47  // TODO: Should handle multiple applied relocations via either passing in the
48  // previously computed value or just count paired relocations as a single
49  // visit.
50  RelocToApply visit(uint32_t RelocType, RelocationRef R, uint64_t SecAddr = 0,
51                     uint64_t Value = 0) {
52    if (FileFormat == "ELF64-x86-64") {
53      switch (RelocType) {
54        case llvm::ELF::R_X86_64_NONE:
55          return visitELF_X86_64_NONE(R);
56        case llvm::ELF::R_X86_64_64:
57          return visitELF_X86_64_64(R, Value);
58        case llvm::ELF::R_X86_64_PC32:
59          return visitELF_X86_64_PC32(R, Value, SecAddr);
60        case llvm::ELF::R_X86_64_32:
61          return visitELF_X86_64_32(R, Value);
62        case llvm::ELF::R_X86_64_32S:
63          return visitELF_X86_64_32S(R, Value);
64        default:
65          HasError = true;
66          return RelocToApply();
67      }
68    } else if (FileFormat == "ELF32-i386") {
69      switch (RelocType) {
70      case llvm::ELF::R_386_NONE:
71        return visitELF_386_NONE(R);
72      case llvm::ELF::R_386_32:
73        return visitELF_386_32(R, Value);
74      case llvm::ELF::R_386_PC32:
75        return visitELF_386_PC32(R, Value, SecAddr);
76      default:
77        HasError = true;
78        return RelocToApply();
79      }
80    } else if (FileFormat == "ELF64-ppc64") {
81      switch (RelocType) {
82      case llvm::ELF::R_PPC64_ADDR32:
83        return visitELF_PPC64_ADDR32(R, Value);
84      case llvm::ELF::R_PPC64_ADDR64:
85        return visitELF_PPC64_ADDR64(R, Value);
86      default:
87        HasError = true;
88        return RelocToApply();
89      }
90    } else if (FileFormat == "ELF32-ppc") {
91      switch (RelocType) {
92      case llvm::ELF::R_PPC_ADDR32:
93        return visitELF_PPC_ADDR32(R, Value);
94      default:
95        HasError = true;
96        return RelocToApply();
97      }
98    } else if (FileFormat == "ELF32-mips") {
99      switch (RelocType) {
100      case llvm::ELF::R_MIPS_32:
101        return visitELF_MIPS_32(R, Value);
102      default:
103        HasError = true;
104        return RelocToApply();
105      }
106    } else if (FileFormat == "ELF64-aarch64") {
107      switch (RelocType) {
108      case llvm::ELF::R_AARCH64_ABS32:
109        return visitELF_AARCH64_ABS32(R, Value);
110      case llvm::ELF::R_AARCH64_ABS64:
111        return visitELF_AARCH64_ABS64(R, Value);
112      default:
113        HasError = true;
114        return RelocToApply();
115      }
116    } else if (FileFormat == "ELF64-s390") {
117      switch (RelocType) {
118      case llvm::ELF::R_390_32:
119        return visitELF_390_32(R, Value);
120      case llvm::ELF::R_390_64:
121        return visitELF_390_64(R, Value);
122      default:
123        HasError = true;
124        return RelocToApply();
125      }
126    }
127    HasError = true;
128    return RelocToApply();
129  }
130
131  bool error() { return HasError; }
132
133private:
134  StringRef FileFormat;
135  bool HasError;
136
137  int64_t getAddend32LE(RelocationRef R) {
138    const ELF32LEObjectFile *Obj = cast<ELF32LEObjectFile>(R.getObjectFile());
139    DataRefImpl DRI = R.getRawDataRefImpl();
140    int64_t Addend;
141    Obj->getRelocationAddend(DRI, Addend);
142    return Addend;
143  }
144
145  int64_t getAddend64LE(RelocationRef R) {
146    const ELF64LEObjectFile *Obj = cast<ELF64LEObjectFile>(R.getObjectFile());
147    DataRefImpl DRI = R.getRawDataRefImpl();
148    int64_t Addend;
149    Obj->getRelocationAddend(DRI, Addend);
150    return Addend;
151  }
152
153  int64_t getAddend32BE(RelocationRef R) {
154    const ELF32BEObjectFile *Obj = cast<ELF32BEObjectFile>(R.getObjectFile());
155    DataRefImpl DRI = R.getRawDataRefImpl();
156    int64_t Addend;
157    Obj->getRelocationAddend(DRI, Addend);
158    return Addend;
159  }
160
161  int64_t getAddend64BE(RelocationRef R) {
162    const ELF64BEObjectFile *Obj = cast<ELF64BEObjectFile>(R.getObjectFile());
163    DataRefImpl DRI = R.getRawDataRefImpl();
164    int64_t Addend;
165    Obj->getRelocationAddend(DRI, Addend);
166    return Addend;
167  }
168  /// Operations
169
170  /// 386-ELF
171  RelocToApply visitELF_386_NONE(RelocationRef R) {
172    return RelocToApply(0, 0);
173  }
174
175  // Ideally the Addend here will be the addend in the data for
176  // the relocation. It's not actually the case for Rel relocations.
177  RelocToApply visitELF_386_32(RelocationRef R, uint64_t Value) {
178    int64_t Addend = getAddend32LE(R);
179    return RelocToApply(Value + Addend, 4);
180  }
181
182  RelocToApply visitELF_386_PC32(RelocationRef R, uint64_t Value,
183                                 uint64_t SecAddr) {
184    int64_t Addend = getAddend32LE(R);
185    uint64_t Address;
186    R.getOffset(Address);
187    return RelocToApply(Value + Addend - Address, 4);
188  }
189
190  /// X86-64 ELF
191  RelocToApply visitELF_X86_64_NONE(RelocationRef R) {
192    return RelocToApply(0, 0);
193  }
194  RelocToApply visitELF_X86_64_64(RelocationRef R, uint64_t Value) {
195    int64_t Addend = getAddend64LE(R);
196    return RelocToApply(Value + Addend, 8);
197  }
198  RelocToApply visitELF_X86_64_PC32(RelocationRef R, uint64_t Value,
199                                    uint64_t SecAddr) {
200    int64_t Addend = getAddend64LE(R);
201    uint64_t Address;
202    R.getOffset(Address);
203    return RelocToApply(Value + Addend - Address, 4);
204  }
205  RelocToApply visitELF_X86_64_32(RelocationRef R, uint64_t Value) {
206    int64_t Addend = getAddend64LE(R);
207    uint32_t Res = (Value + Addend) & 0xFFFFFFFF;
208    return RelocToApply(Res, 4);
209  }
210  RelocToApply visitELF_X86_64_32S(RelocationRef R, uint64_t Value) {
211    int64_t Addend = getAddend64LE(R);
212    int32_t Res = (Value + Addend) & 0xFFFFFFFF;
213    return RelocToApply(Res, 4);
214  }
215
216  /// PPC64 ELF
217  RelocToApply visitELF_PPC64_ADDR32(RelocationRef R, uint64_t Value) {
218    int64_t Addend = getAddend64BE(R);
219    uint32_t Res = (Value + Addend) & 0xFFFFFFFF;
220    return RelocToApply(Res, 4);
221  }
222  RelocToApply visitELF_PPC64_ADDR64(RelocationRef R, uint64_t Value) {
223    int64_t Addend = getAddend64BE(R);
224    return RelocToApply(Value + Addend, 8);
225  }
226
227  /// PPC32 ELF
228  RelocToApply visitELF_PPC_ADDR32(RelocationRef R, uint64_t Value) {
229    int64_t Addend = getAddend32BE(R);
230    uint32_t Res = (Value + Addend) & 0xFFFFFFFF;
231    return RelocToApply(Res, 4);
232  }
233
234  /// MIPS ELF
235  RelocToApply visitELF_MIPS_32(RelocationRef R, uint64_t Value) {
236    int64_t Addend;
237    getELFRelocationAddend(R, Addend);
238    uint32_t Res = (Value + Addend) & 0xFFFFFFFF;
239    return RelocToApply(Res, 4);
240  }
241
242  // AArch64 ELF
243  RelocToApply visitELF_AARCH64_ABS32(RelocationRef R, uint64_t Value) {
244    int64_t Addend = getAddend64LE(R);
245    int64_t Res =  Value + Addend;
246
247    // Overflow check allows for both signed and unsigned interpretation.
248    if (Res < INT32_MIN || Res > UINT32_MAX)
249      HasError = true;
250
251    return RelocToApply(static_cast<uint32_t>(Res), 4);
252  }
253
254  RelocToApply visitELF_AARCH64_ABS64(RelocationRef R, uint64_t Value) {
255    int64_t Addend = getAddend64LE(R);
256    return RelocToApply(Value + Addend, 8);
257  }
258
259  // SystemZ ELF
260  RelocToApply visitELF_390_32(RelocationRef R, uint64_t Value) {
261    int64_t Addend = getAddend64BE(R);
262    int64_t Res = Value + Addend;
263
264    // Overflow check allows for both signed and unsigned interpretation.
265    if (Res < INT32_MIN || Res > UINT32_MAX)
266      HasError = true;
267
268    return RelocToApply(static_cast<uint32_t>(Res), 4);
269  }
270
271  RelocToApply visitELF_390_64(RelocationRef R, uint64_t Value) {
272    int64_t Addend = getAddend64BE(R);
273    return RelocToApply(Value + Addend, 8);
274  }
275};
276
277}
278}
279#endif
280