[lld] r287549 - [ELF] Convert EhFrameHeader to input section
Eugene Leviant via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 21 07:52:10 PST 2016
Author: evgeny777
Date: Mon Nov 21 09:52:10 2016
New Revision: 287549
URL: http://llvm.org/viewvc/llvm-project?rev=287549&view=rev
Log:
[ELF] Convert EhFrameHeader to input section
Differential revision: https://reviews.llvm.org/D26906
Modified:
lld/trunk/ELF/OutputSections.cpp
lld/trunk/ELF/OutputSections.h
lld/trunk/ELF/SyntheticSections.cpp
lld/trunk/ELF/SyntheticSections.h
lld/trunk/ELF/Writer.cpp
Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=287549&r1=287548&r2=287549&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Mon Nov 21 09:52:10 2016
@@ -68,46 +68,6 @@ void OutputSectionBase::writeHeaderTo(ty
static unsigned getVerDefNum() { return Config->VersionDefinitions.size() + 1; }
template <class ELFT>
-EhFrameHeader<ELFT>::EhFrameHeader()
- : OutputSectionBase(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC) {}
-
-// .eh_frame_hdr contains a binary search table of pointers to FDEs.
-// Each entry of the search table consists of two values,
-// the starting PC from where FDEs covers, and the FDE's address.
-// It is sorted by PC.
-template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
- const endianness E = ELFT::TargetEndianness;
-
- // Sort the FDE list by their PC and uniqueify. Usually there is only
- // one FDE for a PC (i.e. function), but if ICF merges two functions
- // into one, there can be more than one FDEs pointing to the address.
- auto Less = [](const FdeData &A, const FdeData &B) { return A.Pc < B.Pc; };
- std::stable_sort(Fdes.begin(), Fdes.end(), Less);
- auto Eq = [](const FdeData &A, const FdeData &B) { return A.Pc == B.Pc; };
- Fdes.erase(std::unique(Fdes.begin(), Fdes.end(), Eq), Fdes.end());
-
- Buf[0] = 1;
- Buf[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4;
- Buf[2] = DW_EH_PE_udata4;
- Buf[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
- write32<E>(Buf + 4, Out<ELFT>::EhFrame->Addr - this->Addr - 4);
- write32<E>(Buf + 8, Fdes.size());
- Buf += 12;
-
- uintX_t VA = this->Addr;
- for (FdeData &Fde : Fdes) {
- write32<E>(Buf, Fde.Pc - VA);
- write32<E>(Buf + 4, Fde.FdeVA - VA);
- Buf += 8;
- }
-}
-
-template <class ELFT> void EhFrameHeader<ELFT>::finalize() {
- // .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
- this->Size = 12 + Out<ELFT>::EhFrame->NumFdes * 8;
-}
-
-template <class ELFT>
void EhFrameHeader<ELFT>::addFde(uint32_t Pc, uint32_t FdeVA) {
Fdes.push_back({Pc, FdeVA});
}
@@ -500,13 +460,13 @@ template <class ELFT> void EhOutputSecti
// Construct .eh_frame_hdr. .eh_frame_hdr is a binary search table
// to get a FDE from an address to which FDE is applied. So here
// we obtain two addresses and pass them to EhFrameHdr object.
- if (Out<ELFT>::EhFrameHdr) {
+ if (In<ELFT>::EhFrameHdr) {
for (CieRecord *Cie : Cies) {
uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece->data());
for (SectionPiece *Fde : Cie->FdePieces) {
uintX_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
uintX_t FdeVA = this->Addr + Fde->OutputOff;
- Out<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
+ In<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
}
}
}
@@ -828,11 +788,6 @@ template void OutputSectionBase::writeHe
template void OutputSectionBase::writeHeaderTo<ELF64LE>(ELF64LE::Shdr *Shdr);
template void OutputSectionBase::writeHeaderTo<ELF64BE>(ELF64BE::Shdr *Shdr);
-template class EhFrameHeader<ELF32LE>;
-template class EhFrameHeader<ELF32BE>;
-template class EhFrameHeader<ELF64LE>;
-template class EhFrameHeader<ELF64BE>;
-
template class OutputSection<ELF32LE>;
template class OutputSection<ELF32BE>;
template class OutputSection<ELF64LE>;
Modified: lld/trunk/ELF/OutputSections.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.h?rev=287549&r1=287548&r2=287549&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.h (original)
+++ lld/trunk/ELF/OutputSections.h Mon Nov 21 09:52:10 2016
@@ -42,7 +42,6 @@ public:
enum Kind {
Base,
EHFrame,
- EHFrameHdr,
Merge,
Regular,
VersDef,
@@ -272,37 +271,6 @@ private:
llvm::DenseMap<std::pair<ArrayRef<uint8_t>, SymbolBody *>, CieRecord> CieMap;
};
-// --eh-frame-hdr option tells linker to construct a header for all the
-// .eh_frame sections. This header is placed to a section named .eh_frame_hdr
-// and also to a PT_GNU_EH_FRAME segment.
-// At runtime the unwinder then can find all the PT_GNU_EH_FRAME segments by
-// calling dl_iterate_phdr.
-// This section contains a lookup table for quick binary search of FDEs.
-// Detailed info about internals can be found in Ian Lance Taylor's blog:
-// http://www.airs.com/blog/archives/460 (".eh_frame")
-// http://www.airs.com/blog/archives/462 (".eh_frame_hdr")
-template <class ELFT> class EhFrameHeader final : public OutputSectionBase {
- typedef typename ELFT::uint uintX_t;
-
-public:
- EhFrameHeader();
- void finalize() override;
- void writeTo(uint8_t *Buf) override;
- void addFde(uint32_t Pc, uint32_t FdeVA);
- Kind getKind() const override { return EHFrameHdr; }
- static bool classof(const OutputSectionBase *B) {
- return B->getKind() == EHFrameHdr;
- }
-
-private:
- struct FdeData {
- uint32_t Pc;
- uint32_t FdeVA;
- };
-
- std::vector<FdeData> Fdes;
-};
-
// All output sections that are hadnled by the linker specially are
// globally accessible. Writer initializes them, so don't use them
// until Writer is initialized.
@@ -311,7 +279,6 @@ template <class ELFT> struct Out {
typedef typename ELFT::Phdr Elf_Phdr;
static uint8_t First;
- static EhFrameHeader<ELFT> *EhFrameHdr;
static EhOutputSection<ELFT> *EhFrame;
static OutputSection<ELFT> *Bss;
static OutputSection<ELFT> *MipsRldMap;
@@ -363,7 +330,6 @@ template <class ELFT> uint64_t getHeader
}
template <class ELFT> uint8_t Out<ELFT>::First;
-template <class ELFT> EhFrameHeader<ELFT> *Out<ELFT>::EhFrameHdr;
template <class ELFT> EhOutputSection<ELFT> *Out<ELFT>::EhFrame;
template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
template <class ELFT> OutputSection<ELFT> *Out<ELFT>::MipsRldMap;
Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=287549&r1=287548&r2=287549&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Mon Nov 21 09:52:10 2016
@@ -27,6 +27,7 @@
#include "lld/Config/Version.h"
#include "lld/Core/Parallel.h"
+#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/RandomNumberGenerator.h"
@@ -35,6 +36,7 @@
#include <cstdlib>
using namespace llvm;
+using namespace llvm::dwarf;
using namespace llvm::ELF;
using namespace llvm::object;
using namespace llvm::support;
@@ -1403,6 +1405,46 @@ template <class ELFT> void GdbIndexSecti
}
}
+template <class ELFT>
+EhFrameHeader<ELFT>::EhFrameHeader()
+ : SyntheticSection<ELFT>(SHF_ALLOC, SHT_PROGBITS, 1, ".eh_frame_hdr") {}
+
+// .eh_frame_hdr contains a binary search table of pointers to FDEs.
+// Each entry of the search table consists of two values,
+// the starting PC from where FDEs covers, and the FDE's address.
+// It is sorted by PC.
+template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
+ const endianness E = ELFT::TargetEndianness;
+
+ // Sort the FDE list by their PC and uniqueify. Usually there is only
+ // one FDE for a PC (i.e. function), but if ICF merges two functions
+ // into one, there can be more than one FDEs pointing to the address.
+ auto Less = [](const FdeData &A, const FdeData &B) { return A.Pc < B.Pc; };
+ std::stable_sort(Fdes.begin(), Fdes.end(), Less);
+ auto Eq = [](const FdeData &A, const FdeData &B) { return A.Pc == B.Pc; };
+ Fdes.erase(std::unique(Fdes.begin(), Fdes.end(), Eq), Fdes.end());
+
+ Buf[0] = 1;
+ Buf[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4;
+ Buf[2] = DW_EH_PE_udata4;
+ Buf[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
+ write32<E>(Buf + 4, Out<ELFT>::EhFrame->Addr - this->getVA() - 4);
+ write32<E>(Buf + 8, Fdes.size());
+ Buf += 12;
+
+ uintX_t VA = this->getVA();
+ for (FdeData &Fde : Fdes) {
+ write32<E>(Buf, Fde.Pc - VA);
+ write32<E>(Buf + 4, Fde.FdeVA - VA);
+ Buf += 8;
+ }
+}
+
+template <class ELFT> size_t EhFrameHeader<ELFT>::getSize() const {
+ // .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
+ return 12 + Out<ELFT>::EhFrame->NumFdes * 8;
+}
+
template InputSection<ELF32LE> *elf::createCommonSection();
template InputSection<ELF32BE> *elf::createCommonSection();
template InputSection<ELF64LE> *elf::createCommonSection();
@@ -1517,3 +1559,8 @@ template class elf::GdbIndexSection<ELF3
template class elf::GdbIndexSection<ELF32BE>;
template class elf::GdbIndexSection<ELF64LE>;
template class elf::GdbIndexSection<ELF64BE>;
+
+template class elf::EhFrameHeader<ELF32LE>;
+template class elf::EhFrameHeader<ELF32BE>;
+template class elf::EhFrameHeader<ELF64LE>;
+template class elf::EhFrameHeader<ELF64BE>;
Modified: lld/trunk/ELF/SyntheticSections.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.h?rev=287549&r1=287548&r2=287549&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.h (original)
+++ lld/trunk/ELF/SyntheticSections.h Mon Nov 21 09:52:10 2016
@@ -529,6 +529,34 @@ private:
uint32_t CuTypesOffset;
};
+// --eh-frame-hdr option tells linker to construct a header for all the
+// .eh_frame sections. This header is placed to a section named .eh_frame_hdr
+// and also to a PT_GNU_EH_FRAME segment.
+// At runtime the unwinder then can find all the PT_GNU_EH_FRAME segments by
+// calling dl_iterate_phdr.
+// This section contains a lookup table for quick binary search of FDEs.
+// Detailed info about internals can be found in Ian Lance Taylor's blog:
+// http://www.airs.com/blog/archives/460 (".eh_frame")
+// http://www.airs.com/blog/archives/462 (".eh_frame_hdr")
+template <class ELFT>
+class EhFrameHeader final : public SyntheticSection<ELFT> {
+ typedef typename ELFT::uint uintX_t;
+
+public:
+ EhFrameHeader();
+ void writeTo(uint8_t *Buf) override;
+ size_t getSize() const override;
+ void addFde(uint32_t Pc, uint32_t FdeVA);
+
+private:
+ struct FdeData {
+ uint32_t Pc;
+ uint32_t FdeVA;
+ };
+
+ std::vector<FdeData> Fdes;
+};
+
template <class ELFT> InputSection<ELFT> *createCommonSection();
template <class ELFT> InputSection<ELFT> *createInterpSection();
template <class ELFT> MergeInputSection<ELFT> *createCommentSection();
@@ -540,6 +568,7 @@ template <class ELFT> struct In {
static DynamicSection<ELFT> *Dynamic;
static StringTableSection<ELFT> *DynStrTab;
static SymbolTableSection<ELFT> *DynSymTab;
+ static EhFrameHeader<ELFT> *EhFrameHdr;
static GnuHashTableSection<ELFT> *GnuHashTab;
static GdbIndexSection<ELFT> *GdbIndex;
static GotSection<ELFT> *Got;
@@ -563,6 +592,7 @@ template <class ELFT> InputSection<ELFT>
template <class ELFT> DynamicSection<ELFT> *In<ELFT>::Dynamic;
template <class ELFT> StringTableSection<ELFT> *In<ELFT>::DynStrTab;
template <class ELFT> SymbolTableSection<ELFT> *In<ELFT>::DynSymTab;
+template <class ELFT> EhFrameHeader<ELFT> *In<ELFT>::EhFrameHdr;
template <class ELFT> GdbIndexSection<ELFT> *In<ELFT>::GdbIndex;
template <class ELFT> GnuHashTableSection<ELFT> *In<ELFT>::GnuHashTab;
template <class ELFT> GotSection<ELFT> *In<ELFT>::Got;
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=287549&r1=287548&r2=287549&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Mon Nov 21 09:52:10 2016
@@ -261,7 +261,7 @@ template <class ELFT> void Writer<ELFT>:
}
if (Config->EhFrameHdr)
- Out<ELFT>::EhFrameHdr = make<EhFrameHeader<ELFT>>();
+ In<ELFT>::EhFrameHdr = make<EhFrameHeader<ELFT>>();
if (Config->GnuHash)
In<ELFT>::GnuHashTab = make<GnuHashTableSection<ELFT>>();
@@ -976,12 +976,13 @@ template <class ELFT> void Writer<ELFT>:
// Dynamic section must be the last one in this list and dynamic
// symbol table section (DynSymTab) must be the first one.
- finalizeSynthetic<ELFT>(
- {In<ELFT>::DynSymTab, In<ELFT>::GnuHashTab, In<ELFT>::HashTab,
- In<ELFT>::SymTab, In<ELFT>::ShStrTab, In<ELFT>::StrTab,
- In<ELFT>::DynStrTab, In<ELFT>::GdbIndex, In<ELFT>::Got,
- In<ELFT>::MipsGot, In<ELFT>::GotPlt, In<ELFT>::RelaDyn,
- In<ELFT>::RelaPlt, In<ELFT>::Plt, In<ELFT>::Dynamic});
+ finalizeSynthetic<ELFT>({In<ELFT>::DynSymTab, In<ELFT>::GnuHashTab,
+ In<ELFT>::HashTab, In<ELFT>::SymTab,
+ In<ELFT>::ShStrTab, In<ELFT>::StrTab,
+ In<ELFT>::DynStrTab, In<ELFT>::GdbIndex,
+ In<ELFT>::Got, In<ELFT>::MipsGot, In<ELFT>::GotPlt,
+ In<ELFT>::RelaDyn, In<ELFT>::RelaPlt, In<ELFT>::Plt,
+ In<ELFT>::EhFrameHdr, In<ELFT>::Dynamic});
}
template <class ELFT> bool Writer<ELFT>::needsGot() {
@@ -1051,7 +1052,7 @@ template <class ELFT> void Writer<ELFT>:
if (!In<ELFT>::Plt->empty())
addInputSec(In<ELFT>::Plt);
if (!Out<ELFT>::EhFrame->empty())
- Add(Out<ELFT>::EhFrameHdr);
+ addInputSec(In<ELFT>::EhFrameHdr);
if (Out<ELFT>::Bss->Size > 0)
Add(Out<ELFT>::Bss);
}
@@ -1202,9 +1203,10 @@ template <class ELFT> std::vector<PhdrEn
Ret.push_back(std::move(RelRo));
// PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr.
- if (!Out<ELFT>::EhFrame->empty() && Out<ELFT>::EhFrameHdr) {
- Phdr &Hdr = *AddHdr(PT_GNU_EH_FRAME, Out<ELFT>::EhFrameHdr->getPhdrFlags());
- Hdr.add(Out<ELFT>::EhFrameHdr);
+ if (!Out<ELFT>::EhFrame->empty() && In<ELFT>::EhFrameHdr) {
+ Phdr &Hdr =
+ *AddHdr(PT_GNU_EH_FRAME, In<ELFT>::EhFrameHdr->OutSec->getPhdrFlags());
+ Hdr.add(In<ELFT>::EhFrameHdr->OutSec);
}
// PT_OPENBSD_RANDOMIZE specifies the location and size of a part of the
@@ -1523,14 +1525,16 @@ template <class ELFT> void Writer<ELFT>:
Out<ELFT>::Opd->writeTo(Buf + Out<ELFT>::Opd->Offset);
}
+ OutputSectionBase *EhFrameHdr =
+ In<ELFT>::EhFrameHdr ? In<ELFT>::EhFrameHdr->OutSec : nullptr;
for (OutputSectionBase *Sec : OutputSections)
- if (Sec != Out<ELFT>::Opd && Sec != Out<ELFT>::EhFrameHdr)
+ if (Sec != Out<ELFT>::Opd && Sec != EhFrameHdr)
Sec->writeTo(Buf + Sec->Offset);
// The .eh_frame_hdr depends on .eh_frame section contents, therefore
// it should be written after .eh_frame is written.
- if (!Out<ELFT>::EhFrame->empty() && Out<ELFT>::EhFrameHdr)
- Out<ELFT>::EhFrameHdr->writeTo(Buf + Out<ELFT>::EhFrameHdr->Offset);
+ if (!Out<ELFT>::EhFrame->empty() && EhFrameHdr)
+ EhFrameHdr->writeTo(Buf + EhFrameHdr->Offset);
}
template <class ELFT> void Writer<ELFT>::writeBuildId() {
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