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mirror of https://github.com/rui314/mold.git synced 2024-12-25 17:34:02 +03:00
mold/input_sections.cc
2020-11-18 11:02:43 +09:00

187 lines
5.1 KiB
C++

#include "mold.h"
using namespace llvm;
using namespace llvm::ELF;
InputChunk::InputChunk(Kind kind, ObjectFile *file, const ELF64LE::Shdr &shdr,
StringRef name)
: kind(kind), file(file), shdr(shdr), name(name) {
output_section = OutputSection::get_instance(name, shdr.sh_flags, shdr.sh_type);
u64 align = (shdr.sh_addralign == 0) ? 1 : shdr.sh_addralign;
if (align > UINT32_MAX)
error(toString(file) + ": section sh_addralign is too large");
if (__builtin_popcount(align) != 1)
error(toString(file) + ": section sh_addralign is not a power of two");
}
void InputSection::copy_buf() {
if (shdr.sh_type == SHT_NOBITS || shdr.sh_size == 0)
return;
// Copy data
ArrayRef<u8> data = check(file->obj.getSectionContents(shdr));
memcpy(out::buf + output_section->shdr.sh_offset + offset, &data[0], data.size());
// Apply relocations
u8 *base = out::buf + output_section->shdr.sh_offset + offset;
u64 sh_addr = output_section->shdr.sh_addr + offset;
u64 GOT = out::got->shdr.sh_addr;
for (int i = 0; i < rels.size(); i++) {
const ELF64LE::Rela &rel = rels[i];
StringPieceRef &ref = rel_pieces[i];
Symbol &sym = *file->symbols[rel.getSymbol(false)];
u8 *loc = base + rel.r_offset;
u64 S = ref.piece ? ref.piece->get_addr() : sym.get_addr();
u64 A = ref.piece ? ref.addend : rel.r_addend;
u64 P = sh_addr + rel.r_offset;
switch (rel.getType(false)) {
case R_X86_64_NONE:
case R_X86_64_DTPOFF32:
break;
case R_X86_64_64:
*(u64 *)loc = S + A;
break;
case R_X86_64_PC32:
*(u32 *)loc = S + A - P;
break;
case R_X86_64_GOT32:
*(u64 *)loc = sym.get_got_addr() - GOT + A;
break;
case R_X86_64_PLT32:
if (sym.plt_idx != -1)
*(u32 *)loc = sym.get_plt_addr() + A - P;
else
*(u32 *)loc = S + A - P; // todo
break;
case R_X86_64_GOTPCREL:
*(u32 *)loc = sym.get_got_addr() + A - P;
break;
case R_X86_64_32:
case R_X86_64_32S:
*(u32 *)loc = S + A;
break;
case R_X86_64_16:
*(u16 *)loc = S + A;
break;
case R_X86_64_PC16:
*(u16 *)loc = S + A - P;
break;
case R_X86_64_8:
*loc = S + A;
break;
case R_X86_64_PC8:
*loc = S + A - P;
break;
case R_X86_64_TLSGD:
case R_X86_64_TLSLD:
// TODO
break;
case R_X86_64_GOTTPOFF:
*(u32 *)loc = sym.get_gottp_addr() + A - P;
break;
case R_X86_64_TPOFF32:
*(u32 *)loc = S - out::tls_end;
break;
case R_X86_64_PC64:
*(u64 *)loc = S + A - P;
break;
case R_X86_64_GOTPC32:
*(u32 *)loc = GOT + A - P;
break;
case R_X86_64_GOTPCRELX:
case R_X86_64_REX_GOTPCRELX:
*(u32 *)loc = sym.get_got_addr() + A - P;
break;
default:
error(toString(this) + ": unknown relocation: " +
std::to_string(rel.getType(false)));
}
}
static Counter counter("relocs");
counter.inc(rels.size());
}
void InputSection::scan_relocations() {
if (!(shdr.sh_flags & SHF_ALLOC))
return;
for (const ELF64LE::Rela &rel : rels) {
Symbol *sym = file->symbols[rel.getSymbol(false)];
if (!sym->file || !sym->file->is_alive)
continue;
switch (rel.getType(false)) {
case R_X86_64_NONE:
case R_X86_64_8:
case R_X86_64_16:
case R_X86_64_32:
case R_X86_64_32S:
case R_X86_64_64:
case R_X86_64_PC8:
case R_X86_64_PC16:
case R_X86_64_PC32:
case R_X86_64_PC64:
case R_X86_64_TPOFF32:
case R_X86_64_DTPOFF32:
break;
case R_X86_64_GOT32:
case R_X86_64_GOTPC32:
case R_X86_64_GOTPCREL:
case R_X86_64_GOTPCRELX:
case R_X86_64_REX_GOTPCRELX:
sym->flags |= Symbol::NEEDS_GOT;
break;
case R_X86_64_PLT32:
if (!config.is_static || sym->type == STT_GNU_IFUNC)
sym->flags |= Symbol::NEEDS_PLT;
break;
case R_X86_64_TLSGD:
sym->flags |= Symbol::NEEDS_TLSGD;
break;
case R_X86_64_TLSLD:
sym->flags |= Symbol::NEEDS_TLSLD;
break;
case R_X86_64_GOTTPOFF:
sym->flags |= Symbol::NEEDS_GOTTPOFF;
break;
default:
error(toString(this) + ": unknown relocation: " +
std::to_string(rel.getType(false)));
}
}
}
MergeableSection::MergeableSection(InputSection *isec, ArrayRef<u8> contents)
: InputChunk(MERGEABLE, isec->file, isec->shdr, isec->name),
parent(*MergedSection::get_instance(isec->name, isec->shdr.sh_flags,
isec->shdr.sh_type)) {
StringRef data((const char *)&contents[0], contents.size());
u32 offset = 0;
while (!data.empty()) {
size_t end = data.find('\0');
if (end == StringRef::npos)
error(toString(this) + ": string is not null terminated");
StringRef substr = data.substr(0, end + 1);
data = data.substr(end + 1);
StringPiece *piece = parent.map.insert(substr, StringPiece(substr));
pieces.push_back({piece, offset});
offset += substr.size();
}
static Counter counter("string_pieces");
counter.inc(pieces.size());
}
std::string toString(InputChunk *chunk) {
return (toString(chunk->file) + ":(" + chunk->name + ")").str();
}