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mirror of https://github.com/rui314/mold.git synced 2024-12-25 09:25:15 +03:00
mold/input_sections.cc
Rui Ueyama 570a3556c5 Fix exported weak symbol
This is needed by Gentoo's app-admin/filebeat-7.9.3 package.
2021-06-27 12:37:14 +09:00

155 lines
4.7 KiB
C++

#include "mold.h"
#include <limits>
template <typename E>
InputSection<E>::InputSection(Context<E> &ctx, ObjectFile<E> &file,
const ElfShdr<E> &shdr, std::string_view name,
std::string_view contents, i64 section_idx)
: file(file), shdr(shdr), nameptr(name.data()), namelen(name.size()),
contents(contents), section_idx(section_idx) {
// As a special case, we want to map .ctors and .dtors to
// .init_array and .fini_array, respectively. However, old CRT
// object files are not compatible with this translation, so we need
// to keep them as-is if a section came from crtbegin.o or crtend.o.
//
// Yeah, this is an ugly hack, but the fundamental problem is that
// we have two different mechanism, ctors/dtors and init_array/fini_array
// for the same purpose. The latter was introduced to replace the
// former, but as it is often the case, the former still lingers
// around, so we need to keep this code to conver the old mechanism
// to the new one.
std::string_view stem = path_filename(file.filename);
if (stem != "crtbegin.o" && stem != "crtend.o" &&
stem != "crtbeginS.o" && stem != "crtendS.o") {
if (name == ".ctors" || name.starts_with(".ctors."))
name = ".init_array";
else if (name == ".dtors" || name.starts_with(".dtors."))
name = ".fini_array";
}
output_section =
OutputSection<E>::get_instance(ctx, name, shdr.sh_type, shdr.sh_flags);
}
template <typename E>
void InputSection<E>::write_to(Context<E> &ctx, u8 *buf) {
if (shdr.sh_type == SHT_NOBITS || shdr.sh_size == 0)
return;
// Copy data
memcpy(buf, contents.data(), contents.size());
// Apply relocations
if (shdr.sh_flags & SHF_ALLOC)
apply_reloc_alloc(ctx, buf);
else
apply_reloc_nonalloc(ctx, buf);
// As a special case, .ctors and .dtors section contents are
// reversed. These sections are now obsolete and mapped to
// .init_array and .fini_array, but they have to be reversed to
// maintain the original semantics.
bool init_fini = output_section->name == ".init_array" ||
output_section->name == ".fini_array";
bool ctors_dtors = name().starts_with(".ctors") ||
name().starts_with(".dtors");
if (init_fini && ctors_dtors)
std::reverse((typename E::WordTy *)buf,
(typename E::WordTy *)(buf + shdr.sh_size));
}
template <typename E>
static i64 get_output_type(Context<E> &ctx) {
if (ctx.arg.shared)
return 0;
if (ctx.arg.pie)
return 1;
return 2;
}
template <typename E>
static i64 get_sym_type(Context<E> &ctx, Symbol<E> &sym) {
if (sym.is_absolute(ctx))
return 0;
if (!sym.is_imported)
return 1;
if (sym.get_type() != STT_FUNC)
return 2;
return 3;
}
template <typename E>
void InputSection<E>::dispatch(Context<E> &ctx, Action table[3][4],
u16 rel_type, i64 i) {
std::span<ElfRel<E>> rels = get_rels(ctx);
const ElfRel<E> &rel = rels[i];
Symbol<E> &sym = *file.symbols[rel.r_sym];
bool is_writable = (shdr.sh_flags & SHF_WRITE);
Action action = table[get_output_type(ctx)][get_sym_type(ctx, sym)];
switch (action) {
case NONE:
rel_types[i] = rel_type;
return;
case ERROR:
break;
case COPYREL:
if (!ctx.arg.z_copyreloc && !sym.esym().is_undef_weak())
break;
if (sym.esym().st_visibility == STV_PROTECTED)
Error(ctx) << *this << ": cannot make copy relocation for "
<< " protected symbol '" << sym << "', defined in "
<< *sym.file;
sym.flags |= NEEDS_COPYREL;
rel_types[i] = rel_type;
return;
case PLT:
sym.flags |= NEEDS_PLT;
rel_types[i] = rel_type;
return;
case DYNREL:
if (!is_writable) {
if (ctx.arg.z_text)
break;
ctx.has_textrel = true;
}
sym.flags |= NEEDS_DYNSYM;
rel_types[i] = R_DYN;
file.num_dynrel++;
return;
case BASEREL:
if (!is_writable) {
if (ctx.arg.z_text)
break;
ctx.has_textrel = true;
}
rel_types[i] = R_BASEREL;
file.num_dynrel++;
return;
default:
unreachable(ctx);
}
Error(ctx) << *this << ": " << rel_to_string<E>(rel.r_type)
<< " relocation against symbol `" << sym
<< "' can not be used; recompile with -fPIE";
}
template <typename E>
void InputSection<E>::report_undef(Context<E> &ctx, Symbol<E> &sym) {
switch (ctx.arg.unresolved_symbols) {
case UnresolvedKind::ERROR:
Error(ctx) << "undefined symbol: " << file << ": " << sym;
break;
case UnresolvedKind::WARN:
Warn(ctx) << "undefined symbol: " << file << ": " << sym;
break;
case UnresolvedKind::IGNORE:
break;
}
}
template class InputSection<X86_64>;
template class InputSection<I386>;