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-rw-r--r--lld/ELF/Writer.cpp128
1 files changed, 59 insertions, 69 deletions
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 4bc5b99f74e..37c3705cfe8 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -67,6 +67,7 @@ private:
return !Symtab.getSharedFiles().empty() || Config->Shared;
}
uintX_t getVAStart() const { return Config->Shared ? 0 : Target->getVAStart(); }
+ int getPhdrsNum() const;
std::unique_ptr<llvm::FileOutputBuffer> Buffer;
@@ -78,7 +79,7 @@ private:
void addStartStopSymbols(OutputSectionBase<ELFT> *Sec);
void setPhdr(Elf_Phdr *PH, uint32_t Type, uint32_t Flags, uintX_t FileOff,
- uintX_t VA, uintX_t Align);
+ uintX_t VA, uintX_t Size, uintX_t Align);
void copyPhdr(Elf_Phdr *PH, OutputSectionBase<ELFT> *From);
SymbolTable<ELFT> &Symtab;
@@ -603,58 +604,38 @@ template <class ELFT> static bool needsPhdr(OutputSectionBase<ELFT> *Sec) {
return Sec->getFlags() & SHF_ALLOC;
}
-// Visits all sections to assign incremental, non-overlapping RVAs and
-// file offsets.
+// Visits all sections to create PHDRs and to assign incremental,
+// non-overlapping addresses to output sections.
template <class ELFT> void Writer<ELFT>::assignAddresses() {
- assert(!OutputSections.empty() && "No output sections to layout!");
uintX_t VA = getVAStart() + sizeof(Elf_Ehdr);
uintX_t FileOff = sizeof(Elf_Ehdr);
- // Reserve space for Phdrs.
- int NumPhdrs = 2; // 2 for PhdrPhdr and FileHeaderPhdr
- if (needsInterpSection())
- ++NumPhdrs;
- if (isOutputDynamic())
- ++NumPhdrs;
- uintX_t Last = PF_R;
- for (OutputSectionBase<ELFT> *Sec : OutputSections) {
- if (!Sec->getSize() || !needsPhdr<ELFT>(Sec))
- continue;
- uintX_t Flags = toPhdrFlags(Sec->getFlags());
- if (Last != Flags) {
- Last = Flags;
- ++NumPhdrs;
- }
- }
-
- // Reserve space needed for the program header so that the array
- // will never be resized.
- Phdrs.reserve(NumPhdrs);
+ // Calculate and reserve the space for the program header first so that
+ // the first section can start right after the program header.
+ Phdrs.resize(getPhdrsNum());
+ size_t PhdrSize = sizeof(Elf_Phdr) * Phdrs.size();
- // The first Phdr entry is PT_PHDR which describes the program header itself.
- Phdrs.emplace_back();
- Elf_Phdr *PhdrPhdr = &Phdrs.back();
- setPhdr(PhdrPhdr, PT_PHDR, PF_R, FileOff, VA, /*Align=*/8);
-
- FileOff += sizeof(Elf_Phdr) * NumPhdrs;
- VA += sizeof(Elf_Phdr) * NumPhdrs;
+ // The first phdr entry is PT_PHDR which describes the program header itself.
+ setPhdr(&Phdrs[0], PT_PHDR, PF_R, FileOff, VA, PhdrSize, /*Align=*/8);
+ FileOff += PhdrSize;
+ VA += PhdrSize;
+ // PT_INTERP must be the second entry if exists.
+ int PhdrIdx = 0;
Elf_Phdr *Interp = nullptr;
- if (needsInterpSection()) {
- Phdrs.emplace_back();
- Interp = &Phdrs.back();
- }
+ if (needsInterpSection())
+ Interp = &Phdrs[++PhdrIdx];
- // Create a Phdr for the file header.
- Phdrs.emplace_back();
- Elf_Phdr *FileHeader = &Phdrs.back();
- setPhdr(FileHeader, PT_LOAD, PF_R, 0, getVAStart(), Target->getPageSize());
+ // Add the first PT_LOAD segment for regular output sections.
+ setPhdr(&Phdrs[++PhdrIdx], PT_LOAD, PF_R, 0, getVAStart(), FileOff,
+ Target->getPageSize());
+ // Create phdrs as we assign VAs and file offsets to all output sections.
SmallPtrSet<Elf_Phdr *, 8> Closed;
for (OutputSectionBase<ELFT> *Sec : OutputSections) {
if (Sec->getSize()) {
uintX_t Flags = toPhdrFlags(Sec->getFlags());
- Elf_Phdr *Last = &Phdrs.back();
+ Elf_Phdr *Last = &Phdrs[PhdrIdx];
if (Last->p_flags != Flags || !needsPhdr<ELFT>(Sec)) {
// Flags changed. End current Phdr and potentially create a new one.
if (Closed.insert(Last).second) {
@@ -665,53 +646,59 @@ template <class ELFT> void Writer<ELFT>::assignAddresses() {
if (needsPhdr<ELFT>(Sec)) {
VA = RoundUpToAlignment(VA, Target->getPageSize());
FileOff = RoundUpToAlignment(FileOff, Target->getPageSize());
- Phdrs.emplace_back();
- Elf_Phdr *PH = &Phdrs.back();
- setPhdr(PH, PT_LOAD, Flags, FileOff, VA, Target->getPageSize());
+ Elf_Phdr *PH = &Phdrs[++PhdrIdx];
+ setPhdr(PH, PT_LOAD, Flags, FileOff, VA, 0, Target->getPageSize());
}
}
}
- uintX_t Align = Sec->getAlign();
- uintX_t Size = Sec->getSize();
if (Sec->getFlags() & SHF_ALLOC) {
- VA = RoundUpToAlignment(VA, Align);
+ VA = RoundUpToAlignment(VA, Sec->getAlign());
Sec->setVA(VA);
- VA += Size;
+ VA += Sec->getSize();
}
- FileOff = RoundUpToAlignment(FileOff, Align);
+ FileOff = RoundUpToAlignment(FileOff, Sec->getAlign());
Sec->setFileOffset(FileOff);
if (Sec->getType() != SHT_NOBITS)
- FileOff += Size;
+ FileOff += Sec->getSize();
}
- if (Interp) {
- Interp->p_type = PT_INTERP;
- copyPhdr(Interp, Out<ELFT>::Interp);
- }
+ // Add an entry for .dynamic.
if (isOutputDynamic()) {
- Phdrs.emplace_back();
- Elf_Phdr *PH = &Phdrs.back();
+ Elf_Phdr *PH = &Phdrs[++PhdrIdx];
PH->p_type = PT_DYNAMIC;
copyPhdr(PH, Out<ELFT>::Dynamic);
}
- // Fix up the first entry's size.
- PhdrPhdr->p_filesz = sizeof(Elf_Phdr) * Phdrs.size();
- PhdrPhdr->p_memsz = sizeof(Elf_Phdr) * Phdrs.size();
-
- // If nothing was merged into the file header PT_LOAD, set the size correctly.
- if (FileHeader->p_filesz == Target->getPageSize()) {
- uint64_t Size = sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Phdrs.size();
- FileHeader->p_filesz = Size;
- FileHeader->p_memsz = Size;
+ // Fix up PT_INTERP as we now know the address of .interp section.
+ if (Interp) {
+ Interp->p_type = PT_INTERP;
+ copyPhdr(Interp, Out<ELFT>::Interp);
}
// Add space for section headers.
- FileOff = RoundUpToAlignment(FileOff, ELFT::Is64Bits ? 8 : 4);
- SectionHeaderOff = FileOff;
- FileOff += getNumSections() * sizeof(Elf_Shdr);
- FileSize = FileOff;
+ SectionHeaderOff = RoundUpToAlignment(FileOff, ELFT::Is64Bits ? 8 : 4);
+ FileSize = SectionHeaderOff + getNumSections() * sizeof(Elf_Shdr);
+}
+
+// Returns the number of PHDR entries.
+template <class ELFT> int Writer<ELFT>::getPhdrsNum() const {
+ int I = 2; // 2 for PT_PHDR and the first PT_LOAD
+ if (needsInterpSection())
+ ++I;
+ if (isOutputDynamic())
+ ++I;
+ uintX_t Last = PF_R;
+ for (OutputSectionBase<ELFT> *Sec : OutputSections) {
+ if (!Sec->getSize() || !needsPhdr<ELFT>(Sec))
+ continue;
+ uintX_t Flags = toPhdrFlags(Sec->getFlags());
+ if (Last != Flags) {
+ Last = Flags;
+ ++I;
+ }
+ }
+ return I;
}
template <class ELFT> void Writer<ELFT>::writeHeader() {
@@ -786,12 +773,15 @@ template <class ELFT> void Writer<ELFT>::writeSections() {
template <class ELFT>
void Writer<ELFT>::setPhdr(Elf_Phdr *PH, uint32_t Type, uint32_t Flags,
- uintX_t FileOff, uintX_t VA, uintX_t Align) {
+ uintX_t FileOff, uintX_t VA, uintX_t Size,
+ uintX_t Align) {
PH->p_type = Type;
PH->p_flags = Flags;
PH->p_offset = FileOff;
PH->p_vaddr = VA;
PH->p_paddr = VA;
+ PH->p_filesz = Size;
+ PH->p_memsz = Size;
PH->p_align = Align;
}
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