patchoat.h revision 2d7210188805292e463be4bcf7a133b654d7e0ea 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_PATCHOAT_PATCHOAT_H_
18#define ART_PATCHOAT_PATCHOAT_H_
19
20#include "arch/instruction_set.h"
21#include "base/macros.h"
22#include "base/mutex.h"
23#include "elf_file.h"
24#include "elf_utils.h"
25#include "gc/accounting/space_bitmap.h"
26#include "gc/heap.h"
27#include "os.h"
28#include "utils.h"
29
30namespace art {
31
32class ImageHeader;
33class OatHeader;
34
35namespace mirror {
36class Object;
37class Reference;
38class Class;
39class ArtMethod;
40}  // namespace mirror
41
42class PatchOat {
43 public:
44  // Patch only the oat file
45  static bool Patch(File* oat_in, off_t delta, File* oat_out, TimingLogger* timings,
46                    bool output_oat_opened_from_fd,  // Was this using --oatput-oat-fd ?
47                    bool new_oat_out);               // Output oat was a new file created by us?
48
49  // Patch only the image (art file)
50  static bool Patch(const std::string& art_location, off_t delta, File* art_out, InstructionSet isa,
51                    TimingLogger* timings);
52
53  // Patch both the image and the oat file
54  static bool Patch(File* oat_in, const std::string& art_location,
55                    off_t delta, File* oat_out, File* art_out, InstructionSet isa,
56                    TimingLogger* timings,
57                    bool output_oat_opened_from_fd,  // Was this using --oatput-oat-fd ?
58                    bool new_oat_out);               // Output oat was a new file created by us?
59
60 private:
61  // Takes ownership only of the ElfFile. All other pointers are only borrowed.
62  PatchOat(ElfFile* oat_file, off_t delta, TimingLogger* timings)
63      : oat_file_(oat_file), image_(nullptr), bitmap_(nullptr), heap_(nullptr), delta_(delta),
64        isa_(kNone), timings_(timings) {}
65  PatchOat(InstructionSet isa, MemMap* image, gc::accounting::ContinuousSpaceBitmap* bitmap,
66           MemMap* heap, off_t delta, TimingLogger* timings)
67      : image_(image), bitmap_(bitmap), heap_(heap),
68        delta_(delta), isa_(isa), timings_(timings) {}
69  PatchOat(InstructionSet isa, ElfFile* oat_file, MemMap* image,
70           gc::accounting::ContinuousSpaceBitmap* bitmap, MemMap* heap, off_t delta,
71           TimingLogger* timings)
72      : oat_file_(oat_file), image_(image), bitmap_(bitmap), heap_(heap),
73        delta_(delta), isa_(isa), timings_(timings) {}
74  ~PatchOat() {}
75
76  // Was the .art image at image_path made with --compile-pic ?
77  static bool IsImagePic(const ImageHeader& image_header, const std::string& image_path);
78
79  enum MaybePic {
80      NOT_PIC,            // Code not pic. Patch as usual.
81      PIC,                // Code was pic. Create symlink; skip OAT patching.
82      ERROR_OAT_FILE,     // Failed to symlink oat file
83      ERROR_FIRST = ERROR_OAT_FILE,
84  };
85
86  // Was the .oat image at oat_in made with --compile-pic ?
87  static MaybePic IsOatPic(const ElfFile* oat_in);
88
89  // Attempt to replace the file with a symlink
90  // Returns false if it fails
91  static bool ReplaceOatFileWithSymlink(const std::string& input_oat_filename,
92                                        const std::string& output_oat_filename,
93                                        bool output_oat_opened_from_fd,
94                                        bool new_oat_out);  // Output oat was newly created?
95
96  static void BitmapCallback(mirror::Object* obj, void* arg)
97      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
98    reinterpret_cast<PatchOat*>(arg)->VisitObject(obj);
99  }
100
101  void VisitObject(mirror::Object* obj)
102      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
103  void FixupMethod(mirror::ArtMethod* object, mirror::ArtMethod* copy)
104      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
105  bool InHeap(mirror::Object*);
106
107  // Patches oat in place, modifying the oat_file given to the constructor.
108  bool PatchElf();
109  template <typename ElfFileImpl>
110  bool PatchElf(ElfFileImpl* oat_file);
111  template <typename ElfFileImpl>
112  bool PatchTextSection(ElfFileImpl* oat_file);
113  // Templatized version to actually do the patching with the right sized offsets.
114  template <typename ElfFileImpl, typename patch_loc_t> bool PatchTextSection(ElfFileImpl* oat_file);
115  template <typename ElfFileImpl, typename patch_loc_t> bool CheckOatFile(ElfFileImpl* oat_filec);
116  template <typename ElfFileImpl>
117  bool PatchOatHeader(ElfFileImpl* oat_file);
118
119  bool PatchImage() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
120
121  bool WriteElf(File* out);
122  bool WriteImage(File* out);
123
124  mirror::Object* RelocatedCopyOf(mirror::Object*);
125  mirror::Object* RelocatedAddressOf(mirror::Object* obj);
126
127  // Look up the oat header from any elf file.
128  static const OatHeader* GetOatHeader(const ElfFile* elf_file);
129
130  // Templatized version to actually look up the oat header
131  template <typename ElfFileImpl>
132  static const OatHeader* GetOatHeader(const ElfFileImpl* elf_file);
133
134  // Walks through the old image and patches the mmap'd copy of it to the new offset. It does not
135  // change the heap.
136  class PatchVisitor {
137  public:
138    PatchVisitor(PatchOat* patcher, mirror::Object* copy) : patcher_(patcher), copy_(copy) {}
139    ~PatchVisitor() {}
140    void operator() (mirror::Object* obj, MemberOffset off, bool b) const
141      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
142    // For reference classes.
143    void operator() (mirror::Class* cls, mirror::Reference* ref) const
144      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
145  private:
146    PatchOat* const patcher_;
147    mirror::Object* const copy_;
148  };
149
150  // The elf file we are patching.
151  std::unique_ptr<ElfFile> oat_file_;
152  // A mmap of the image we are patching. This is modified.
153  const MemMap* const image_;
154  // The bitmap over the image within the heap we are patching. This is not modified.
155  gc::accounting::ContinuousSpaceBitmap* const bitmap_;
156  // The heap we are patching. This is not modified.
157  const MemMap* const heap_;
158  // The amount we are changing the offset by.
159  const off_t delta_;
160  // Active instruction set, used to know the entrypoint size.
161  const InstructionSet isa_;
162
163  TimingLogger* timings_;
164
165  DISALLOW_IMPLICIT_CONSTRUCTORS(PatchOat);
166};
167
168}  // namespace art
169#endif  // ART_PATCHOAT_PATCHOAT_H_
170