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Loader: Support loading non-position independent executables

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This commit is contained in:
Itamar 2020-12-18 15:59:22 +02:00 • committed by Andreas Kling
parent 0cb636078a
commit a83a9f3a55
5 changed files with 88 additions and 41 deletions
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35
Libraries/LibELF/DynamicObject.cpp
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@ -50,6 +50,14 @@ DynamicObject::DynamicObject(VirtualAddress base_address, VirtualAddress dynamic
: m_base_address(base_address)
, m_dynamic_address(dynamic_section_addresss)
{
Elf32_Ehdr* header = (Elf32_Ehdr*)base_address.as_ptr();
Elf32_Phdr* pheader = (Elf32_Phdr*)(base_address.as_ptr() + header->e_phoff);
m_elf_base_address = VirtualAddress(pheader->p_vaddr - pheader->p_offset);
if (header->e_type == ET_DYN)
m_is_elf_dynamic = true;
else
m_is_elf_dynamic = false;
parse();
}
@ -82,31 +90,31 @@ void DynamicObject::parse()
for_each_dynamic_entry([&](const DynamicEntry& entry) {
switch (entry.tag()) {
case DT_INIT:
m_init_offset = entry.ptr();
m_init_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_FINI:
m_fini_offset = entry.ptr();
m_fini_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_INIT_ARRAY:
m_init_array_offset = entry.ptr();
m_init_array_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_INIT_ARRAYSZ:
m_init_array_size = entry.val();
break;
case DT_FINI_ARRAY:
m_fini_array_offset = entry.ptr();
m_fini_array_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_FINI_ARRAYSZ:
m_fini_array_size = entry.val();
break;
case DT_HASH:
m_hash_table_offset = entry.ptr();
m_hash_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_SYMTAB:
m_symbol_table_offset = entry.ptr();
m_symbol_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_STRTAB:
m_string_table_offset = entry.ptr();
m_string_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_STRSZ:
m_size_of_string_table = entry.val();
@ -115,7 +123,7 @@ void DynamicObject::parse()
m_size_of_symbol_table_entry = entry.val();
break;
case DT_PLTGOT:
m_procedure_linkage_table_offset = entry.ptr();
m_procedure_linkage_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_PLTRELSZ:
m_size_of_plt_relocation_entry_list = entry.val();
@ -125,11 +133,11 @@ void DynamicObject::parse()
ASSERT(m_procedure_linkage_table_relocation_type & (DT_REL | DT_RELA));
break;
case DT_JMPREL:
m_plt_relocation_offset_location = entry.ptr();
m_plt_relocation_offset_location = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_RELA:
case DT_REL:
m_relocation_table_offset = entry.ptr();
m_relocation_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
break;
case DT_RELASZ:
case DT_RELSZ:
@ -171,12 +179,13 @@ void DynamicObject::parse()
if (!m_size_of_relocation_entry) {
// TODO: FIXME, this shouldn't be hardcoded
// The reason we need this here is the for some reason, when there only PLT relocations, the compiler
// The reason we need this here is that for some reason, when there only PLT relocations, the compiler
// doesn't insert a 'PLTRELSZ' entry to the dynamic section
m_size_of_relocation_entry = sizeof(Elf32_Rel);
}
auto hash_section_address = hash_section().address().as_ptr();
// TODO: consider base address - it might not be zero
auto num_hash_chains = ((u32*)hash_section_address)[1];
m_symbol_count = num_hash_chains;
}
@ -287,9 +296,7 @@ const DynamicObject::Symbol DynamicObject::HashSection::lookup_symbol(const char
for (u32 i = buckets[hash_value % num_buckets]; i; i = chains[i]) {
auto symbol = m_dynamic.symbol(i);
if (strcmp(name, symbol.name()) == 0) {
#ifdef DYNAMIC_LOAD_DEBUG
dbgprintf("Returning dynamic symbol with index %u for %s: %p\n", i, symbol.name(), symbol.address().as_ptr());
#endif
VERBOSE("Returning dynamic symbol with index %u for %s: %p\n", i, symbol.name(), symbol.address().as_ptr());
return symbol;
}
}