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authorDimitry Andric <dim@FreeBSD.org>2017-06-10 13:44:49 +0000
committerDimitry Andric <dim@FreeBSD.org>2017-06-10 13:44:49 +0000
commit2079716dfb3fb7e4e24b8b2e85eb6780b981a0af (patch)
tree3b0c58e50948b450b50b20ae5a38c005128edfb5 /ELF/LinkerScript.cpp
parentb9a1baec33e911ca24f51abf882d454e62047ea6 (diff)
downloadsrc-2079716dfb3fb7e4e24b8b2e85eb6780b981a0af.tar.gz
src-2079716dfb3fb7e4e24b8b2e85eb6780b981a0af.zip
Vendor import of lld trunk r305145:vendor/lld/lld-trunk-r305145
Notes
Notes: svn path=/vendor/lld/dist/; revision=319788 svn path=/vendor/lld/lld-trunk-r305145/; revision=319789; tag=vendor/lld/lld-trunk-r305145
Diffstat (limited to 'ELF/LinkerScript.cpp')
-rw-r--r--ELF/LinkerScript.cpp153
1 files changed, 97 insertions, 56 deletions
diff --git a/ELF/LinkerScript.cpp b/ELF/LinkerScript.cpp
index 1ced3e8e8d71..9dd7ba52be19 100644
--- a/ELF/LinkerScript.cpp
+++ b/ELF/LinkerScript.cpp
@@ -25,9 +25,9 @@
#include "Writer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compression.h"
-#include "llvm/Support/ELF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
@@ -54,7 +54,7 @@ uint64_t ExprValue::getValue() const {
if (Sec) {
if (OutputSection *OS = Sec->getOutputSection())
return alignTo(Sec->getOffset(Val) + OS->Addr, Alignment);
- error("unable to evaluate expression: input section " + Sec->Name +
+ error(Loc + ": unable to evaluate expression: input section " + Sec->Name +
" has no output section assigned");
}
return alignTo(Val, Alignment);
@@ -431,6 +431,8 @@ void LinkerScript::processCommands(OutputSectionFactory &Factory) {
if (OutputSection *Sec = Cmd->Sec) {
assert(Sec->SectionIndex == INT_MAX);
Sec->SectionIndex = I;
+ if (Cmd->Noload)
+ Sec->Type = SHT_NOBITS;
SecToCommand[Sec] = Cmd;
}
}
@@ -442,7 +444,7 @@ void LinkerScript::fabricateDefaultCommands() {
std::vector<BaseCommand *> Commands;
// Define start address
- uint64_t StartAddr = Config->ImageBase + elf::getHeaderSize();
+ uint64_t StartAddr = -1;
// The Sections with -T<section> have been sorted in order of ascending
// address. We must lower StartAddr if the lowest -T<section address> as
@@ -450,8 +452,12 @@ void LinkerScript::fabricateDefaultCommands() {
for (auto& KV : Config->SectionStartMap)
StartAddr = std::min(StartAddr, KV.second);
- Commands.push_back(
- make<SymbolAssignment>(".", [=] { return StartAddr; }, ""));
+ Commands.push_back(make<SymbolAssignment>(
+ ".",
+ [=] {
+ return std::min(StartAddr, Config->ImageBase + elf::getHeaderSize());
+ },
+ ""));
// For each OutputSection that needs a VA fabricate an OutputSectionCommand
// with an InputSectionDescription describing the InputSections
@@ -870,51 +876,6 @@ void LinkerScript::processNonSectionCommands() {
}
}
-// Do a last effort at synchronizing the linker script "AST" and the section
-// list. This is needed to account for last minute changes, like adding a
-// .ARM.exidx terminator and sorting SHF_LINK_ORDER sections.
-//
-// FIXME: We should instead create the "AST" earlier and the above changes would
-// be done directly in the "AST".
-//
-// This can only handle new sections being added and sections being reordered.
-void LinkerScript::synchronize() {
- for (BaseCommand *Base : Opt.Commands) {
- auto *Cmd = dyn_cast<OutputSectionCommand>(Base);
- if (!Cmd)
- continue;
- ArrayRef<InputSection *> Sections = Cmd->Sec->Sections;
- std::vector<InputSection **> ScriptSections;
- DenseSet<InputSection *> ScriptSectionsSet;
- for (BaseCommand *Base : Cmd->Commands) {
- auto *ISD = dyn_cast<InputSectionDescription>(Base);
- if (!ISD)
- continue;
- for (InputSection *&IS : ISD->Sections) {
- if (IS->Live) {
- ScriptSections.push_back(&IS);
- ScriptSectionsSet.insert(IS);
- }
- }
- }
- std::vector<InputSection *> Missing;
- for (InputSection *IS : Sections)
- if (!ScriptSectionsSet.count(IS))
- Missing.push_back(IS);
- if (!Missing.empty()) {
- auto ISD = make<InputSectionDescription>("");
- ISD->Sections = Missing;
- Cmd->Commands.push_back(ISD);
- for (InputSection *&IS : ISD->Sections)
- if (IS->Live)
- ScriptSections.push_back(&IS);
- }
- assert(ScriptSections.size() == Sections.size());
- for (int I = 0, N = Sections.size(); I < N; ++I)
- *ScriptSections[I] = Sections[I];
- }
-}
-
static bool
allocateHeaders(std::vector<PhdrEntry> &Phdrs,
ArrayRef<OutputSectionCommand *> OutputSectionCommands,
@@ -1071,6 +1032,81 @@ static void writeInt(uint8_t *Buf, uint64_t Data, uint64_t Size) {
llvm_unreachable("unsupported Size argument");
}
+static bool compareByFilePosition(InputSection *A, InputSection *B) {
+ // Synthetic doesn't have link order dependecy, stable_sort will keep it last
+ if (A->kind() == InputSectionBase::Synthetic ||
+ B->kind() == InputSectionBase::Synthetic)
+ return false;
+ InputSection *LA = A->getLinkOrderDep();
+ InputSection *LB = B->getLinkOrderDep();
+ OutputSection *AOut = LA->getParent();
+ OutputSection *BOut = LB->getParent();
+ if (AOut != BOut)
+ return AOut->SectionIndex < BOut->SectionIndex;
+ return LA->OutSecOff < LB->OutSecOff;
+}
+
+template <class ELFT>
+static void finalizeShtGroup(OutputSection *OS,
+ ArrayRef<InputSection *> Sections) {
+ // sh_link field for SHT_GROUP sections should contain the section index of
+ // the symbol table.
+ OS->Link = InX::SymTab->getParent()->SectionIndex;
+
+ // sh_info then contain index of an entry in symbol table section which
+ // provides signature of the section group.
+ elf::ObjectFile<ELFT> *Obj = Sections[0]->getFile<ELFT>();
+ assert(Config->Relocatable && Sections.size() == 1);
+ ArrayRef<SymbolBody *> Symbols = Obj->getSymbols();
+ OS->Info = InX::SymTab->getSymbolIndex(Symbols[Sections[0]->Info - 1]);
+}
+
+template <class ELFT> void OutputSectionCommand::finalize() {
+ // Link order may be distributed across several InputSectionDescriptions
+ // but sort must consider them all at once.
+ std::vector<InputSection **> ScriptSections;
+ std::vector<InputSection *> Sections;
+ for (BaseCommand *Base : Commands)
+ if (auto *ISD = dyn_cast<InputSectionDescription>(Base))
+ for (InputSection *&IS : ISD->Sections) {
+ ScriptSections.push_back(&IS);
+ Sections.push_back(IS);
+ }
+
+ if ((Sec->Flags & SHF_LINK_ORDER)) {
+ std::sort(Sections.begin(), Sections.end(), compareByFilePosition);
+ for (int I = 0, N = Sections.size(); I < N; ++I)
+ *ScriptSections[I] = Sections[I];
+
+ // We must preserve the link order dependency of sections with the
+ // SHF_LINK_ORDER flag. The dependency is indicated by the sh_link field. We
+ // need to translate the InputSection sh_link to the OutputSection sh_link,
+ // all InputSections in the OutputSection have the same dependency.
+ if (auto *D = Sections.front()->getLinkOrderDep())
+ Sec->Link = D->getParent()->SectionIndex;
+ }
+
+ uint32_t Type = Sec->Type;
+ if (Type == SHT_GROUP) {
+ finalizeShtGroup<ELFT>(Sec, Sections);
+ return;
+ }
+
+ if (!Config->CopyRelocs || (Type != SHT_RELA && Type != SHT_REL))
+ return;
+
+ InputSection *First = Sections[0];
+ if (isa<SyntheticSection>(First))
+ return;
+
+ Sec->Link = InX::SymTab->getParent()->SectionIndex;
+ // sh_info for SHT_REL[A] sections should contain the section header index of
+ // the section to which the relocation applies.
+ InputSectionBase *S = First->getRelocatedSection();
+ Sec->Info = S->getOutputSection()->SectionIndex;
+ Sec->Flags |= SHF_INFO_LINK;
+}
+
// Compress section contents if this section contains debug info.
template <class ELFT> void OutputSectionCommand::maybeCompress() {
typedef typename ELFT::Chdr Elf_Chdr;
@@ -1099,6 +1135,9 @@ template <class ELFT> void OutputSectionCommand::maybeCompress() {
}
template <class ELFT> void OutputSectionCommand::writeTo(uint8_t *Buf) {
+ if (Sec->Type == SHT_NOBITS)
+ return;
+
Sec->Loc = Buf;
// We may have already rendered compressed content when using
@@ -1110,9 +1149,6 @@ template <class ELFT> void OutputSectionCommand::writeTo(uint8_t *Buf) {
return;
}
- if (Sec->Type == SHT_NOBITS)
- return;
-
// Write leading padding.
std::vector<InputSection *> Sections;
for (BaseCommand *Cmd : Commands)
@@ -1156,12 +1192,12 @@ bool LinkerScript::hasLMA(OutputSection *Sec) {
ExprValue LinkerScript::getSymbolValue(const Twine &Loc, StringRef S) {
if (S == ".")
- return {CurOutSec, Dot - CurOutSec->Addr};
+ return {CurOutSec, Dot - CurOutSec->Addr, Loc};
if (SymbolBody *B = findSymbol(S)) {
if (auto *D = dyn_cast<DefinedRegular>(B))
- return {D->Section, D->Value};
+ return {D->Section, D->Value, Loc};
if (auto *C = dyn_cast<DefinedCommon>(B))
- return {InX::Common, C->Offset};
+ return {InX::Common, C->Offset, Loc};
}
error(Loc + ": symbol not found: " + S);
return 0;
@@ -1201,3 +1237,8 @@ template void OutputSectionCommand::maybeCompress<ELF32LE>();
template void OutputSectionCommand::maybeCompress<ELF32BE>();
template void OutputSectionCommand::maybeCompress<ELF64LE>();
template void OutputSectionCommand::maybeCompress<ELF64BE>();
+
+template void OutputSectionCommand::finalize<ELF32LE>();
+template void OutputSectionCommand::finalize<ELF32BE>();
+template void OutputSectionCommand::finalize<ELF64LE>();
+template void OutputSectionCommand::finalize<ELF64BE>();