1 //===-------------- ELF.cpp - JIT linker function for ELF -------------===//
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 // ELF jit-link function.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ExecutionEngine/JITLink/ELF.h"
15 
16 #include "llvm/BinaryFormat/ELF.h"
17 #include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
18 #include "llvm/Object/ELF.h"
19 #include "llvm/Support/Endian.h"
20 #include "llvm/Support/Format.h"
21 #include "llvm/Support/MemoryBuffer.h"
22 #include <cstring>
23 
24 using namespace llvm;
25 
26 #define DEBUG_TYPE "jitlink"
27 
28 namespace llvm {
29 namespace jitlink {
30 
31 Expected<uint16_t> readTargetMachineArch(StringRef Buffer) {
32   const char *Data = Buffer.data();
33 
34   if (Data[ELF::EI_DATA] == ELF::ELFDATA2LSB) {
35     if (Data[ELF::EI_CLASS] == ELF::ELFCLASS64) {
36       if (auto File = llvm::object::ELF64LEFile::create(Buffer)) {
37         return File->getHeader().e_machine;
38       } else {
39         return File.takeError();
40       }
41     } else if (Data[ELF::EI_CLASS] == ELF::ELFCLASS32) {
42       if (auto File = llvm::object::ELF32LEFile::create(Buffer)) {
43         return File->getHeader().e_machine;
44       } else {
45         return File.takeError();
46       }
47     }
48   }
49 
50   return ELF::EM_NONE;
51 }
52 
53 Expected<std::unique_ptr<LinkGraph>>
54 createLinkGraphFromELFObject(MemoryBufferRef ObjectBuffer) {
55   StringRef Buffer = ObjectBuffer.getBuffer();
56   if (Buffer.size() < ELF::EI_MAG3 + 1)
57     return make_error<JITLinkError>("Truncated ELF buffer");
58 
59   if (memcmp(Buffer.data(), ELF::ElfMagic, strlen(ELF::ElfMagic)) != 0)
60     return make_error<JITLinkError>("ELF magic not valid");
61 
62   Expected<uint16_t> TargetMachineArch = readTargetMachineArch(Buffer);
63   if (!TargetMachineArch)
64     return TargetMachineArch.takeError();
65 
66   switch (*TargetMachineArch) {
67   case ELF::EM_X86_64:
68     return createLinkGraphFromELFObject_x86_64(std::move(ObjectBuffer));
69   default:
70     return make_error<JITLinkError>(
71         "Unsupported target machine architecture in ELF object " +
72         ObjectBuffer.getBufferIdentifier());
73   }
74 }
75 
76 void link_ELF(std::unique_ptr<LinkGraph> G,
77               std::unique_ptr<JITLinkContext> Ctx) {
78   switch (G->getTargetTriple().getArch()) {
79   case Triple::x86_64:
80     link_ELF_x86_64(std::move(G), std::move(Ctx));
81     return;
82   default:
83     Ctx->notifyFailed(make_error<JITLinkError>(
84         "Unsupported target machine architecture in ELF link graph " +
85         G->getName()));
86     return;
87   }
88 }
89 
90 } // end namespace jitlink
91 } // end namespace llvm
92