Implement the -dynamic-linker option.
With this dynamic executables can be executed with just ./t instead of
/lib64/ld-2.20.so ./t
llvm-svn: 247446
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 5dc04c2..3dac96c 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -111,6 +111,20 @@
namespace {
template <bool Is64Bits>
+class InterpSection final : public OutputSectionBase<Is64Bits> {
+public:
+ InterpSection()
+ : OutputSectionBase<Is64Bits>(".interp", SHT_PROGBITS, SHF_ALLOC) {
+ this->Header.sh_size = Config->DynamicLinker.size() + 1;
+ this->Header.sh_addralign = 1;
+ }
+
+ void writeTo(uint8_t *Buf) override {
+ memcpy(Buf, Config->DynamicLinker.data(), Config->DynamicLinker.size());
+ }
+};
+
+template <bool Is64Bits>
class StringTableSection final : public OutputSectionBase<Is64Bits> {
public:
typedef typename OutputSectionBase<Is64Bits>::uintX_t uintX_t;
@@ -169,7 +183,7 @@
void writeTo(uint8_t *Buf) override;
- const SymbolTable &getSymTable() { return Table; }
+ const SymbolTable &getSymTable() const { return Table; }
void addSymbol(StringRef Name) {
StrTabSec.add(Name);
@@ -280,6 +294,10 @@
void openFile(StringRef OutputPath);
void writeHeader();
void writeSections();
+ bool needsInterpSection() const {
+ return !SymTabSec.getSymTable().getSharedFiles().empty() &&
+ !Config->DynamicLinker.empty();
+ }
std::unique_ptr<llvm::FileOutputBuffer> Buffer;
llvm::SpecificBumpPtrAllocator<OutputSection<ELFT>> CAlloc;
@@ -299,6 +317,8 @@
DynamicSection<ELFT> DynamicSec;
+ InterpSection<ELFT::Is64Bits> InterpSec;
+
OutputSection<ELFT> *BSSSec = nullptr;
};
} // anonymous namespace
@@ -611,6 +631,8 @@
OutputSections.push_back(&StrTabSec);
if (!SharedFiles.empty()) {
+ if (needsInterpSection())
+ OutputSections.push_back(&InterpSec);
OutputSections.push_back(&DynSymSec);
OutputSections.push_back(&DynamicSec);
OutputSections.push_back(&DynStrSec);
@@ -642,6 +664,11 @@
VA = RoundUpToAlignment(VA, PageSize);
NumPhdrs = 0;
+
+ // Add a PHDR for PT_INTERP.
+ if (needsInterpSection())
+ ++NumPhdrs;
+
// Add a PHDR for the elf header and program headers. Some dynamic linkers
// (musl at least) require them to be covered by a PT_LOAD.
++NumPhdrs;
@@ -692,6 +719,18 @@
return Ret;
}
+template <class ELFT>
+static void setValuesFromSection(typename ELFFile<ELFT>::Elf_Phdr &P,
+ OutputSectionBase<ELFT::Is64Bits> &S) {
+ P.p_flags = convertSectionFlagsToPHDRFlags(S.getFlags());
+ P.p_offset = S.getFileOff();
+ P.p_vaddr = S.getVA();
+ P.p_paddr = P.p_vaddr;
+ P.p_filesz = S.getSize();
+ P.p_memsz = P.p_filesz;
+ P.p_align = S.getAlign();
+}
+
template <class ELFT> void Writer<ELFT>::writeHeader() {
uint8_t *Buf = Buffer->getBufferStart();
auto *EHdr = reinterpret_cast<Elf_Ehdr *>(Buf);
@@ -726,6 +765,12 @@
EHdr->e_shstrndx = StrTabSec.getSectionIndex();
auto PHdrs = reinterpret_cast<Elf_Phdr *>(Buf + EHdr->e_phoff);
+ if (needsInterpSection()) {
+ PHdrs->p_type = PT_INTERP;
+ setValuesFromSection<ELFT>(*PHdrs, InterpSec);
+ ++PHdrs;
+ }
+
PHdrs->p_type = PT_LOAD;
PHdrs->p_flags = PF_R;
PHdrs->p_offset = 0;
@@ -752,13 +797,7 @@
if (HasDynamicSegment) {
PHdrs->p_type = PT_DYNAMIC;
- PHdrs->p_flags = convertSectionFlagsToPHDRFlags(DynamicSec.getFlags());
- PHdrs->p_offset = DynamicSec.getFileOff();
- PHdrs->p_vaddr = DynamicSec.getVA();
- PHdrs->p_paddr = PHdrs->p_vaddr;
- PHdrs->p_filesz = DynamicSec.getSize();
- PHdrs->p_memsz = DynamicSec.getSize();
- PHdrs->p_align = DynamicSec.getAlign();
+ setValuesFromSection<ELFT>(*PHdrs, DynamicSec);
}
auto SHdrs = reinterpret_cast<Elf_Shdr *>(Buf + EHdr->e_shoff);