intel/llvm
1
0
Fork 0
mirror of https://github.com/intel/llvm.git synced 2026-01-31 16:29:50 +08:00
Code Issues Packages Projects Releases Wiki Activity

[ELF][ARM] Add veneer generation to branch instructions

Browse Source 
When calling ARM code from Thumb and vice versa,
a veneer that switches instruction set should be generated.
Added veneer generation for ARM_JUMP24 ARM_THM_JUMP24 instructions.

Differential Revision: http://reviews.llvm.org/D7502

llvm-svn: 228680
This commit is contained in:
Denis Protivensky
2015-02-10 09:31:42 +00:00
parent d4637fb433
commit e35908b18f
4 changed files with 488 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

189
lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp
View File

@@ -31,6 +31,85 @@ using namespace lld::elf;
using namespace llvm::ELF;
namespace {
// ARM B/BL instructions of static relocation veneer.
// TODO: consider different instruction set for archs below ARMv5
// (one as for Thumb may be used though it's less optimal).
const uint8_t Veneer_ARM_B_BL_StaticAtomContent[8] = {
0x04, 0xf0, 0x1f, 0xe5, // ldr pc, [pc, #-4]
0x00, 0x00, 0x00, 0x00 // <target_symbol_address>
};
// Thumb B/BL instructions of static relocation veneer.
// TODO: consider different instruction set for archs above ARMv5
// (one as for ARM may be used since it's more optimal).
const uint8_t Veneer_THM_B_BL_StaticAtomContent[8] = {
0x78, 0x47, // bx pc
0x00, 0x00, // nop
0xfe, 0xff, 0xff, 0xea // b <target_symbol_address>
};
/// \brief Atoms that hold veneer code.
class VeneerAtom : public SimpleELFDefinedAtom {
StringRef _section;
public:
VeneerAtom(const File &f, StringRef secName)
: SimpleELFDefinedAtom(f), _section(secName) {}
Scope scope() const override { return DefinedAtom::scopeTranslationUnit; }
SectionChoice sectionChoice() const override {
return DefinedAtom::sectionBasedOnContent;
}
StringRef customSectionName() const override { return _section; }
ContentType contentType() const override {
return DefinedAtom::typeCode;
}
uint64_t size() const override { return rawContent().size(); }
ContentPermissions permissions() const override { return permR_X; }
Alignment alignment() const override { return Alignment(2); }
#ifndef NDEBUG
StringRef name() const override { return _name; }
std::string _name;
#else
StringRef name() const override { return ""; }
#endif
};
/// \brief Atoms that hold veneer for statically relocated
/// ARM B/BL instructions.
class Veneer_ARM_B_BL_StaticAtom : public VeneerAtom {
public:
Veneer_ARM_B_BL_StaticAtom(const File &f, StringRef secName)
: VeneerAtom(f, secName) {}
ArrayRef<uint8_t> rawContent() const override {
return llvm::makeArrayRef(Veneer_ARM_B_BL_StaticAtomContent);
}
};
/// \brief Atoms that hold veneer for statically relocated
/// Thumb B/BL instructions.
class Veneer_THM_B_BL_StaticAtom : public VeneerAtom {
public:
Veneer_THM_B_BL_StaticAtom(const File &f, StringRef secName)
: VeneerAtom(f, secName) {}
DefinedAtom::CodeModel codeModel() const override {
return DefinedAtom::codeARMThumb;
}
ArrayRef<uint8_t> rawContent() const override {
return llvm::makeArrayRef(Veneer_THM_B_BL_StaticAtomContent);
}
};
class ELFPassFile : public SimpleFile {
public:
ELFPassFile(const ELFLinkingContext &eti) : SimpleFile("ELFPassFile") {
@@ -51,12 +130,67 @@ template <class Derived> class ARMRelocationPass : public Pass {
if (ref.kindNamespace() != Reference::KindNamespace::ELF)
return;
assert(ref.kindArch() == Reference::KindArch::ARM);
switch (ref.kindValue()) {
case R_ARM_JUMP24:
case R_ARM_THM_JUMP24:
static_cast<Derived *>(this)->handleVeneer(atom, ref);
break;
}
}
protected:
std::error_code handleVeneer(const DefinedAtom &atom, const Reference &ref) {
// Target symbol and relocated place should have different
// instruction sets in order a veneer to be generated in between.
const auto *target = dyn_cast_or_null<DefinedAtom>(ref.target());
if (!target || target->codeModel() == atom.codeModel())
return std::error_code();
// TODO: For unconditional jump instructions (R_ARM_CALL and R_ARM_THM_CALL)
// fixup isn't possible without veneer generation for archs below ARMv5.
// Veneers may only be generated for STT_FUNC target symbols
// or for symbols located in sections different to the place of relocation.
const auto kindValue = ref.kindValue();
StringRef secName = atom.customSectionName();
if (DefinedAtom::typeCode != target->contentType() &&
!target->customSectionName().equals(secName)) {
StringRef kindValStr;
if (!this->_ctx.registry().referenceKindToString(
ref.kindNamespace(), ref.kindArch(), kindValue, kindValStr)) {
kindValStr = "unknown";
}
std::string errStr =
(Twine("Reference of type ") + Twine(kindValue) + " (" + kindValStr +
") from " + atom.name() + "+" + Twine(ref.offsetInAtom()) + " to " +
ref.target()->name() + "+" + Twine(ref.addend()) +
" cannot be effected without a veneer").str();
llvm_unreachable(errStr.c_str());
}
const Atom *veneer = nullptr;
switch (kindValue) {
case R_ARM_JUMP24:
veneer = static_cast<Derived *>(this)
->getVeneer_ARM_B_BL(target, secName);
break;
case R_ARM_THM_JUMP24:
veneer = static_cast<Derived *>(this)
->getVeneer_THM_B_BL(target, secName);
break;
default:
llvm_unreachable("Unhandled reference type for veneer generation");
}
assert(veneer && "The veneer is not set");
const_cast<Reference &>(ref).setTarget(veneer);
return std::error_code();
}
public:
ARMRelocationPass(const ELFLinkingContext &ctx)
: _file(ctx), _ctx(ctx) {}
ARMRelocationPass(const ELFLinkingContext &ctx) : _file(ctx), _ctx(ctx) {}
/// \brief Do the pass.
///
@@ -99,12 +233,25 @@ public:
handleReference(*atom, *ref);
}
}
// Add all created atoms to the link.
uint64_t ordinal = 0;
for (auto &veneer : _veneerVector) {
veneer->setOrdinal(ordinal++);
mf->addAtom(*veneer);
}
}
protected:
/// \brief Owner of all the Atoms created by this pass.
ELFPassFile _file;
const ELFLinkingContext &_ctx;
/// \brief Map Atoms to their veneers.
llvm::DenseMap<const Atom *, VeneerAtom *> _veneerMap;
/// \brief the list of veneer atoms.
std::vector<VeneerAtom *> _veneerVector;
};
/// This implements the static relocation model. Meaning GOT and PLT entries are
@@ -118,6 +265,44 @@ class ARMStaticRelocationPass final
public:
ARMStaticRelocationPass(const elf::ARMLinkingContext &ctx)
: ARMRelocationPass(ctx) {}
/// \brief Get the veneer for ARM B/BL instructions.
const VeneerAtom *getVeneer_ARM_B_BL(const DefinedAtom *da,
StringRef secName) {
auto veneer = _veneerMap.find(da);
if (_veneerMap.end() != veneer)
return veneer->second;
auto v = new (_file._alloc) Veneer_ARM_B_BL_StaticAtom(_file, secName);
v->addReferenceELF_ARM(R_ARM_ABS32, 4, da, 0);
#ifndef NDEBUG
v->_name = "__";
v->_name += da->name();
v->_name += "_from_arm";
#endif
_veneerMap[da] = v;
_veneerVector.push_back(v);
return v;
}
/// \brief Get the veneer for Thumb B/BL instructions.
const VeneerAtom *getVeneer_THM_B_BL(const DefinedAtom *da,
StringRef secName) {
auto veneer = _veneerMap.find(da);
if (_veneerMap.end() != veneer)
return veneer->second;
auto v = new (_file._alloc) Veneer_THM_B_BL_StaticAtom(_file, secName);
v->addReferenceELF_ARM(R_ARM_JUMP24, 4, da, 0);
#ifndef NDEBUG
v->_name = "__";
v->_name += da->name();
v->_name += "_from_thumb";
#endif
_veneerMap[da] = v;
_veneerVector.push_back(v);
return v;
}
};
} // end of anon namespace

101
lld/test/elf/ARM/rel-arm-jump24-veneer-b.test Normal file
View File

@@ -0,0 +1,101 @@
# Check veneer generation for R_ARM_JUMP24 relocation (B instruction call).
# RUN: yaml2obj -format=elf -docnum 1 %s > %t-arm.o
# RUN: yaml2obj -format=elf -docnum 2 %s > %t-thm.o
# RUN: lld -flavor gnu -target arm -m armelf_linux_eabi -Bstatic \
# RUN: --noinhibit-exec %t-arm.o %t-thm.o -o %t
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=B-VENEER %s
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=B-ADDR %s
# B-VENEER: Contents of section .text:
# B-VENEER: 400074 010000ea
# Call from main:
# offset = 0x4 ^^
# call site offset PC(arm) ___Z1fv_from_arm addr
# 0x400074 + 0x4 + 0x8 = 0x400080
#
# Code of the veneer:
# B-VENEER: {{[0-9a-f]+}} {{[0-9a-f]+}} 04f01fe5
# B-VENEER: 400084 79004000
# call addr = 0x400079 ^^
# call addr _Z1fv addr Thumb mode
# 0x400079 = 0x400078 | 0x1
#
# B-ADDR: SYMBOL TABLE:
# B-ADDR: 00400080 l F .text {{[0-9a-f]+}} ___Z1fv_from_arm
# B-ADDR: 00400074 g F .text {{[0-9a-f]+}} main
# B-ADDR: 00400078 g F .text {{[0-9a-f]+}} _Z1fv
# arm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: FEFFFFEA
- Name: .rel.text
Type: SHT_REL
Link: .symtab
AddressAlign: 0x0000000000000004
Info: .text
Relocations:
- Offset: 0x0000000000000000
Symbol: _Z1fv
Type: R_ARM_JUMP24
Addend: 0
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: main
Type: STT_FUNC
Section: .text
- Name: _Z1fv
# thm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: 4FF0000318467047
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: _Z1fv
Type: STT_FUNC
Section: .text
Value: 0x0000000000000001
...

100
lld/test/elf/ARM/rel-arm-jump24-veneer-bl.test Normal file
View File

@@ -0,0 +1,100 @@
# Check veneer generation for R_ARM_JUMP24 relocation (BL<c> instruction call).
# RUN: yaml2obj -format=elf -docnum 1 %s > %t-arm.o
# RUN: yaml2obj -format=elf -docnum 2 %s > %t-thm.o
# RUN: lld -flavor gnu -target arm -m armelf_linux_eabi -Bstatic \
# RUN: --noinhibit-exec %t-arm.o %t-thm.o -o %t
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=BL-VENEER %s
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=BL-ADDR %s
# BL-VENEER: Contents of section .text:
# BL-VENEER: 400084 0400000b
# Call from main:
# offset = 0x10 ^^
# call site offset PC(arm) ___Z1fv_from_arm addr
# 0x400084 + 0x10 + 0x8 = 0x40009c
#
# Code of the veneer:
# BL-VENEER: 400094 {{[0-9a-f]+}} {{[0-9a-f]+}} {{[0-9a-f]+}} 95004000
# call addr = 0x400095 ^^
# call addr _Z1fv addr Thumb mode
# 0x400095 = 0x400094 | 0x1
#
# BL-ADDR: SYMBOL TABLE:
# BL-ADDR: 0040009c l F .text {{[0-9a-f]+}} ___Z1fv_from_arm
# BL-ADDR: 00400074 g F .text {{[0-9a-f]+}} main
# BL-ADDR: 00400094 g F .text {{[0-9a-f]+}} _Z1fv
# arm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: 00482DE904B08DE20030A0E3000053E3FEFFFF0B0030A0E30300A0E10088BDE8
- Name: .rel.text
Type: SHT_REL
Link: .symtab
AddressAlign: 0x0000000000000004
Info: .text
Relocations:
- Offset: 0x0000000000000010
Symbol: _Z1fv
Type: R_ARM_JUMP24
Addend: 0
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: main
Type: STT_FUNC
Section: .text
- Name: _Z1fv
# thm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: 4FF0000318467047
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: _Z1fv
Type: STT_FUNC
Section: .text
Value: 0x0000000000000001
...

100
lld/test/elf/ARM/rel-thm-jump24-veneer.test Normal file
View File

@@ -0,0 +1,100 @@
# Check veneer generation for R_ARM_THM_JUMP24 relocation (B instruction call).
# RUN: yaml2obj -format=elf -docnum 1 %s > %t-arm.o
# RUN: yaml2obj -format=elf -docnum 2 %s > %t-thm.o
# RUN: lld -flavor gnu -target arm -m armelf_linux_eabi -Bstatic \
# RUN: --noinhibit-exec %t-arm.o %t-thm.o -o %t
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=B-VENEER %s
# RUN: llvm-objdump -s -t %t | FileCheck -check-prefix=B-ADDR %s
# B-VENEER: Contents of section .text:
# B-VENEER: 400074 {{[0-9a-f]+}} {{[0-9a-f]+}} {{[0-9a-f]+}} 00f000b8
# Call from main:
# offset = 0x0 ^^
# call site offset PC(thm) ___Z1fv_from_thumb addr
# 0x400080 + 0x0 + 0x4 = 0x400084
#
# Code of the veneer:
# B-VENEER: 400084 78470000 f9ffffea
# offset = -0x1C ^^
# call site offset PC(arm) _Z1fv
# 0x400088 + (-0x1C) + 0x8 = 0x400074
#
# B-ADDR: SYMBOL TABLE:
# B-ADDR: 00400084 l F .text {{[0-9a-f]+}} ___Z1fv_from_thumb
# B-ADDR: 00400074 g F .text {{[0-9a-f]+}} _Z1fv
# B-ADDR: 00400080 g F .text {{[0-9a-f]+}} main
# arm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: 0030A0E30300A0E11EFF2FE1
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: _Z1fv
Type: STT_FUNC
Section: .text
# thm.o
---
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_ARM
Flags: [ EF_ARM_EABI_VER5 ]
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000004
Content: FFF7FEBF
- Name: .rel.text
Type: SHT_REL
Link: .symtab
AddressAlign: 0x0000000000000004
Info: .text
Relocations:
- Offset: 0x0000000000000000
Symbol: _Z1fv
Type: R_ARM_THM_JUMP24
Addend: 0
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
AddressAlign: 0x0000000000000001
Content: ''
Symbols:
Global:
- Name: main
Type: STT_FUNC
Section: .text
Value: 0x0000000000000001
- Name: _Z1fv
...