1//===- AArch64LongBranchStub.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
10#include "AArch64LongBranchStub.h"
11#include "AArch64LDBackend.h"
12#include "AArch64RelocationHelpers.h"
13
14#include "mcld/Fragment/Relocation.h"
15#include "mcld/LD/BranchIsland.h"
16#include "mcld/LD/LDSymbol.h"
17#include "mcld/LD/ResolveInfo.h"
18
19#include <llvm/Support/ELF.h>
20
21#include <cassert>
22
23namespace mcld {
24
25//===----------------------------------------------------------------------===//
26// AArch64LongBranchStub
27//===----------------------------------------------------------------------===//
28const uint32_t AArch64LongBranchStub::PIC_TEMPLATE[] = {
29  0x58000090,  // ldr   ip0, 0x10
30  0x10000011,  // adr   ip1, #0
31  0x8b110210,  // add   ip0, ip0, ip1
32  0xd61f0200,  // br    ip0
33  0x00000000,  // .xword <-- R_AARCH64_PREL64(X+12)
34  0x00000000,
35};
36
37const uint32_t AArch64LongBranchStub::TEMPLATE[] = {
38  0x58000050,  // ldr   ip0, 0x8
39  0xd61f0200,  // br    ip0
40  0x00000000,  // .xword <-- R_AARCH64_PREL64(X)
41  0x00000000,
42};
43
44const uint32_t AArch64LongBranchStub::ADRP_TEMPLATE[] = {
45  0x90000010,  // adrp  ip0, X <-- R_AARCH64_ADR_PREL_PG_HI21(X)
46  0x91000210,  // add   ip0, ip0, :lo12:X <-- R_AARCH64_ADD_ABS_LO12_NC(X)
47  0xd61f0200,  // br    ip0
48};
49
50AArch64LongBranchStub::AArch64LongBranchStub(bool pIsOutputPIC)
51    : m_pData(NULL),
52      m_Name("ljmp_prototype"),
53      m_Size(0x0) {
54  if (pIsOutputPIC) {
55    m_pData = PIC_TEMPLATE;
56    m_Size = sizeof(PIC_TEMPLATE);
57    addFixup(0x10, 12, llvm::ELF::R_AARCH64_PREL64);
58  } else {
59    m_pData = TEMPLATE;
60    m_Size = sizeof(TEMPLATE);
61    addFixup(0x8, 0, llvm::ELF::R_AARCH64_PREL64);
62  }
63}
64
65/// for doClone
66AArch64LongBranchStub::AArch64LongBranchStub(const uint32_t* pData,
67                                             size_t pSize,
68                                             const_fixup_iterator pBegin,
69                                             const_fixup_iterator pEnd)
70    : m_pData(pData),
71      m_Name("ljmp_veneer"),
72      m_Size(pSize) {
73  for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it) {
74    addFixup(**it);
75  }
76}
77
78AArch64LongBranchStub::~AArch64LongBranchStub() {
79}
80
81bool AArch64LongBranchStub::isMyDuty(const Relocation& pReloc,
82                                     uint64_t pSource,
83                                     uint64_t pTargetSymValue) const {
84  assert((pReloc.type() == llvm::ELF::R_AARCH64_CALL26) ||
85         (pReloc.type() == llvm::ELF::R_AARCH64_JUMP26));
86  int64_t dest = pTargetSymValue + pReloc.addend();
87  int64_t branch_offset = dest - pSource;
88  if ((branch_offset > AArch64GNULDBackend::MAX_FWD_BRANCH_OFFSET) ||
89      (branch_offset < AArch64GNULDBackend::MAX_BWD_BRANCH_OFFSET)) {
90    return true;
91  }
92  return false;
93}
94
95static bool isValidForADRP(uint64_t pSource, uint64_t pDest) {
96  int64_t imm = static_cast<int64_t>((helper_get_page_address(pDest) -
97                                      helper_get_page_address(pSource))) >> 12;
98  return ((imm <= AArch64GNULDBackend::MAX_ADRP_IMM) &&
99          (imm >= AArch64GNULDBackend::MIN_ADRP_IMM));
100}
101
102void AArch64LongBranchStub::applyFixup(Relocation& pSrcReloc,
103                                       IRBuilder& pBuilder,
104                                       BranchIsland& pIsland) {
105  // Try to relax the stub itself.
106  LDSymbol* symbol = pSrcReloc.symInfo()->outSymbol();
107  uint64_t dest = symbol->fragRef()->frag()->getParent()->getSection().addr() +
108                  symbol->fragRef()->getOutputOffset();
109  uint64_t src = pIsland.getParent()->getSection().addr() +
110                 pIsland.offset() +
111                 pIsland.size();
112  if (isValidForADRP(src, dest)) {
113    m_pData = ADRP_TEMPLATE;
114    m_Name = "adrp_veneer";
115    m_Size = sizeof(ADRP_TEMPLATE);
116
117    getFixupList().clear();
118    addFixup(0x0, 0, llvm::ELF::R_AARCH64_ADR_PREL_PG_HI21);
119    addFixup(0x4, 0, llvm::ELF::R_AARCH64_ADD_ABS_LO12_NC);
120  }
121
122  Stub::applyFixup(pSrcReloc, pBuilder, pIsland);
123}
124
125const std::string& AArch64LongBranchStub::name() const {
126  return m_Name;
127}
128
129const uint8_t* AArch64LongBranchStub::getContent() const {
130  return reinterpret_cast<const uint8_t*>(m_pData);
131}
132
133size_t AArch64LongBranchStub::size() const {
134  return m_Size;
135}
136
137size_t AArch64LongBranchStub::alignment() const {
138  return 8;
139}
140
141Stub* AArch64LongBranchStub::doClone() {
142  return new AArch64LongBranchStub(m_pData, m_Size, fixup_begin(), fixup_end());
143}
144
145}  // namespace mcld
146