1//===- MipsPLT.cpp --------------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9#include <llvm/Support/Casting.h>
10#include <llvm/Support/ELF.h>
11#include "mcld/Support/MsgHandling.h"
12#include "MipsGOTPLT.h"
13#include "MipsPLT.h"
14
15namespace {
16
17const uint32_t PLT0[] = {
18    0x3c1c0000,  // lui $28, %hi(&GOTPLT[0])
19    0x8f990000,  // lw $25, %lo(&GOTPLT[0])($28)
20    0x279c0000,  // addiu $28, $28, %lo(&GOTPLT[0])
21    0x031cc023,  // subu $24, $24, $28
22    0x03e07821,  // move $15, $31
23    0x0018c082,  // srl $24, $24, 2
24    0x0320f809,  // jalr $25
25    0x2718fffe   // subu $24, $24, 2
26};
27
28const uint32_t PLTA[] = {
29    0x3c0f0000,  // lui $15, %hi(.got.plt entry)
30    0x8df90000,  // l[wd] $25, %lo(.got.plt entry)($15)
31    0x03200008,  // jr $25
32    0x25f80000   // addiu $24, $15, %lo(.got.plt entry)
33};
34
35}  // anonymous namespace
36
37namespace mcld {
38
39//===----------------------------------------------------------------------===//
40// MipsPLT0 Entry
41//===----------------------------------------------------------------------===//
42class MipsPLT0 : public PLT::Entry<sizeof(PLT0)> {
43 public:
44  MipsPLT0(SectionData& pParent) : PLT::Entry<sizeof(PLT0)>(pParent) {}
45};
46
47//===----------------------------------------------------------------------===//
48// MipsPLTA Entry
49//===----------------------------------------------------------------------===//
50class MipsPLTA : public PLT::Entry<sizeof(PLTA)> {
51 public:
52  MipsPLTA(SectionData& pParent) : PLT::Entry<sizeof(PLTA)>(pParent) {}
53};
54
55//===----------------------------------------------------------------------===//
56// MipsPLT
57//===----------------------------------------------------------------------===//
58MipsPLT::MipsPLT(LDSection& pSection) : PLT(pSection) {
59  new MipsPLT0(*m_pSectionData);
60}
61
62void MipsPLT::finalizeSectionSize() {
63  uint64_t size = sizeof(PLT0) + (m_pSectionData->size() - 1) * sizeof(PLTA);
64  m_Section.setSize(size);
65
66  uint32_t offset = 0;
67  SectionData::iterator frag, fragEnd = m_pSectionData->end();
68  for (frag = m_pSectionData->begin(); frag != fragEnd; ++frag) {
69    frag->setOffset(offset);
70    offset += frag->size();
71  }
72}
73
74bool MipsPLT::hasPLT1() const {
75  return m_pSectionData->size() > 1;
76}
77
78uint64_t MipsPLT::emit(MemoryRegion& pRegion) {
79  uint64_t result = 0x0;
80  iterator it = begin();
81
82  unsigned char* buffer = pRegion.begin();
83  memcpy(buffer, llvm::cast<MipsPLT0>((*it)).getValue(), MipsPLT0::EntrySize);
84  result += MipsPLT0::EntrySize;
85  ++it;
86
87  MipsPLTA* plta = 0;
88  for (iterator ie = end(); it != ie; ++it) {
89    plta = &(llvm::cast<MipsPLTA>(*it));
90    memcpy(buffer + result, plta->getValue(), MipsPLTA::EntrySize);
91    result += MipsPLTA::EntrySize;
92  }
93  return result;
94}
95
96PLTEntryBase* MipsPLT::create() {
97  return new MipsPLTA(*m_pSectionData);
98}
99
100void MipsPLT::applyAllPLT(MipsGOTPLT& pGOTPLT) {
101  assert(m_Section.addr() && ".plt base address is NULL!");
102
103  size_t count = 0;
104  for (iterator it = m_pSectionData->begin(); it != m_pSectionData->end();
105       ++it) {
106    PLTEntryBase* plt = &(llvm::cast<PLTEntryBase>(*it));
107
108    if (it == m_pSectionData->begin()) {
109      uint32_t* data = static_cast<uint32_t*>(malloc(plt->size()));
110
111      if (!data)
112        fatal(diag::fail_allocate_memory_plt);
113
114      memcpy(data, PLT0, plt->size());
115
116      uint64_t gotAddr = pGOTPLT.addr();
117
118      data[0] |= ((gotAddr + 0x8000) >> 16) & 0xffff;
119      data[1] |= gotAddr & 0xffff;
120      data[2] |= gotAddr & 0xffff;
121
122      plt->setValue(reinterpret_cast<unsigned char*>(data));
123    } else {
124      uint32_t* data = static_cast<uint32_t*>(malloc(plt->size()));
125
126      if (!data)
127        fatal(diag::fail_allocate_memory_plt);
128
129      memcpy(data, PLTA, plt->size());
130
131      uint64_t gotEntryAddr = pGOTPLT.getEntryAddr(count++);
132
133      data[0] |= ((gotEntryAddr + 0x8000) >> 16) & 0xffff;
134      data[1] |= gotEntryAddr & 0xffff;
135      data[3] |= gotEntryAddr & 0xffff;
136
137      plt->setValue(reinterpret_cast<unsigned char*>(data));
138    }
139  }
140}
141
142}  // namespace mcld
143