1 //===-- RuntimeDyldMachO.h - Run-time dynamic linker for MC-JIT ---*- C++ -*-=//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // MachO support for MC-JIT runtime dynamic linker.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDMACHO_H
14 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDMACHO_H
15 
16 #include "RuntimeDyldImpl.h"
17 #include "llvm/Object/MachO.h"
18 #include "llvm/Support/Format.h"
19 
20 #define DEBUG_TYPE "dyld"
21 
22 using namespace llvm;
23 using namespace llvm::object;
24 
25 namespace llvm {
26 class RuntimeDyldMachO : public RuntimeDyldImpl {
27 protected:
28   struct SectionOffsetPair {
29     unsigned SectionID;
30     uint64_t Offset;
31   };
32 
33   struct EHFrameRelatedSections {
34     EHFrameRelatedSections()
35         : EHFrameSID(RTDYLD_INVALID_SECTION_ID),
36           TextSID(RTDYLD_INVALID_SECTION_ID),
37           ExceptTabSID(RTDYLD_INVALID_SECTION_ID) {}
38 
39     EHFrameRelatedSections(SID EH, SID T, SID Ex)
40         : EHFrameSID(EH), TextSID(T), ExceptTabSID(Ex) {}
41     SID EHFrameSID;
42     SID TextSID;
43     SID ExceptTabSID;
44   };
45 
46   // When a module is loaded we save the SectionID of the EH frame section
47   // in a table until we receive a request to register all unregistered
48   // EH frame sections with the memory manager.
49   SmallVector<EHFrameRelatedSections, 2> UnregisteredEHFrameSections;
50 
51   RuntimeDyldMachO(RuntimeDyld::MemoryManager &MemMgr,
52                    JITSymbolResolver &Resolver)
53       : RuntimeDyldImpl(MemMgr, Resolver) {}
54 
55   /// This convenience method uses memcpy to extract a contiguous addend (the
56   /// addend size and offset are taken from the corresponding fields of the RE).
57   int64_t memcpyAddend(const RelocationEntry &RE) const;
58 
59   /// Given a relocation_iterator for a non-scattered relocation, construct a
60   /// RelocationEntry and fill in the common fields. The 'Addend' field is *not*
61   /// filled in, since immediate encodings are highly target/opcode specific.
62   /// For targets/opcodes with simple, contiguous immediates (e.g. X86) the
63   /// memcpyAddend method can be used to read the immediate.
64   RelocationEntry getRelocationEntry(unsigned SectionID,
65                                      const ObjectFile &BaseTObj,
66                                      const relocation_iterator &RI) const {
67     const MachOObjectFile &Obj =
68       static_cast<const MachOObjectFile &>(BaseTObj);
69     MachO::any_relocation_info RelInfo =
70       Obj.getRelocation(RI->getRawDataRefImpl());
71 
72     bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
73     unsigned Size = Obj.getAnyRelocationLength(RelInfo);
74     uint64_t Offset = RI->getOffset();
75     MachO::RelocationInfoType RelType =
76       static_cast<MachO::RelocationInfoType>(Obj.getAnyRelocationType(RelInfo));
77 
78     return RelocationEntry(SectionID, Offset, RelType, 0, IsPCRel, Size);
79   }
80 
81   /// Process a scattered vanilla relocation.
82   Expected<relocation_iterator>
83   processScatteredVANILLA(unsigned SectionID, relocation_iterator RelI,
84                           const ObjectFile &BaseObjT,
85                           RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID,
86                           bool TargetIsLocalThumbFunc = false);
87 
88   /// Construct a RelocationValueRef representing the relocation target.
89   /// For Symbols in known sections, this will return a RelocationValueRef
90   /// representing a (SectionID, Offset) pair.
91   /// For Symbols whose section is not known, this will return a
92   /// (SymbolName, Offset) pair, where the Offset is taken from the instruction
93   /// immediate (held in RE.Addend).
94   /// In both cases the Addend field is *NOT* fixed up to be PC-relative. That
95   /// should be done by the caller where appropriate by calling makePCRel on
96   /// the RelocationValueRef.
97   Expected<RelocationValueRef>
98   getRelocationValueRef(const ObjectFile &BaseTObj,
99                         const relocation_iterator &RI,
100                         const RelocationEntry &RE,
101                         ObjSectionToIDMap &ObjSectionToID);
102 
103   /// Make the RelocationValueRef addend PC-relative.
104   void makeValueAddendPCRel(RelocationValueRef &Value,
105                             const relocation_iterator &RI,
106                             unsigned OffsetToNextPC);
107 
108   /// Dump information about the relocation entry (RE) and resolved value.
109   void dumpRelocationToResolve(const RelocationEntry &RE, uint64_t Value) const;
110 
111   // Return a section iterator for the section containing the given address.
112   static section_iterator getSectionByAddress(const MachOObjectFile &Obj,
113                                               uint64_t Addr);
114 
115 
116   // Populate __pointers section.
117   Error populateIndirectSymbolPointersSection(const MachOObjectFile &Obj,
118                                               const SectionRef &PTSection,
119                                               unsigned PTSectionID);
120 
121 public:
122 
123   /// Create a RuntimeDyldMachO instance for the given target architecture.
124   static std::unique_ptr<RuntimeDyldMachO>
125   create(Triple::ArchType Arch,
126          RuntimeDyld::MemoryManager &MemMgr,
127          JITSymbolResolver &Resolver);
128 
129   std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
130   loadObject(const object::ObjectFile &O) override;
131 
132   SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
133 
134   bool isCompatibleFile(const object::ObjectFile &Obj) const override;
135 };
136 
137 /// RuntimeDyldMachOTarget - Templated base class for generic MachO linker
138 /// algorithms and data structures.
139 ///
140 /// Concrete, target specific sub-classes can be accessed via the impl()
141 /// methods. (i.e. the RuntimeDyldMachO hierarchy uses the Curiously
142 /// Recurring Template Idiom). Concrete subclasses for each target
143 /// can be found in ./Targets.
144 template <typename Impl>
145 class RuntimeDyldMachOCRTPBase : public RuntimeDyldMachO {
146 private:
147   Impl &impl() { return static_cast<Impl &>(*this); }
148   const Impl &impl() const { return static_cast<const Impl &>(*this); }
149 
150   unsigned char *processFDE(uint8_t *P, int64_t DeltaForText,
151                             int64_t DeltaForEH);
152 
153 public:
154   RuntimeDyldMachOCRTPBase(RuntimeDyld::MemoryManager &MemMgr,
155                            JITSymbolResolver &Resolver)
156     : RuntimeDyldMachO(MemMgr, Resolver) {}
157 
158   Error finalizeLoad(const ObjectFile &Obj,
159                      ObjSectionToIDMap &SectionMap) override;
160   void registerEHFrames() override;
161 };
162 
163 } // end namespace llvm
164 
165 #undef DEBUG_TYPE
166 
167 #endif
168