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LibELF: Perform weak relocations in much more straight-forward manner

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There is no need to defer unresolved weak relocations until stage 3 --
it is not like we will magically find new symbols in the same objects.
This commit is contained in:
Dan Klishch 2024-04-23 14:30:30 -04:00 • committed by Andrew Kaster
commit 49e09507d7
Notes: sideshowbarker 2024-07-17 23:07:41 +09:00
2 changed files with 10 additions and 42 deletions
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36
Userland/Libraries/LibELF/DynamicLoader.cpp
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@ -196,13 +196,10 @@ void DynamicLoader::do_main_relocations()
Optional<DynamicLoader::CachedLookupResult> cached_result;
m_dynamic_object->relocation_section().for_each_relocation([&](DynamicObject::Relocation const& relocation) {
switch (do_direct_relocation(relocation, cached_result, ShouldInitializeWeak::No, ShouldCallIfuncResolver::No)) {
switch (do_direct_relocation(relocation, cached_result, ShouldCallIfuncResolver::No)) {
case RelocationResult::Failed:
dbgln("Loader.so: {} unresolved symbol '{}'", m_filepath, relocation.symbol().name());
VERIFY_NOT_REACHED();
case RelocationResult::ResolveLater:
m_unresolved_relocations.append(relocation);
break;
case RelocationResult::CallIfuncResolver:
m_direct_ifunc_relocations.append(relocation);
break;
@ -226,8 +223,8 @@ void DynamicLoader::do_main_relocations()
if (static_cast<GenericDynamicRelocationType>(relocation.type()) == GenericDynamicRelocationType::TLSDESC) {
// GNU ld for some reason puts TLSDESC relocations into .rela.plt
// https://sourceware.org/bugzilla/show_bug.cgi?id=28387
VERIFY(do_direct_relocation(relocation, cached_result, ShouldInitializeWeak::No, ShouldCallIfuncResolver::No) == RelocationResult::Success);
auto result = do_direct_relocation(relocation, cached_result, ShouldCallIfuncResolver::No);
VERIFY(result == RelocationResult::Success);
return;
}
@ -237,8 +234,6 @@ void DynamicLoader::do_main_relocations()
case RelocationResult::Failed:
dbgln("Loader.so: {} unresolved symbol '{}'", m_filepath, relocation.symbol().name());
VERIFY_NOT_REACHED();
case RelocationResult::ResolveLater:
VERIFY_NOT_REACHED();
case RelocationResult::CallIfuncResolver:
m_plt_ifunc_relocations.append(relocation);
// Set up lazy binding, in case an IFUNC resolver calls another IFUNC that hasn't been resolved yet.
@ -255,7 +250,6 @@ void DynamicLoader::do_main_relocations()
Result<NonnullRefPtr<DynamicObject>, DlErrorMessage> DynamicLoader::load_stage_3(unsigned flags)
{
do_lazy_relocations();
if (flags & RTLD_LAZY) {
if (m_dynamic_object->has_plt())
setup_plt_trampoline();
@ -270,7 +264,7 @@ Result<NonnullRefPtr<DynamicObject>, DlErrorMessage> DynamicLoader::load_stage_3
Optional<DynamicLoader::CachedLookupResult> cached_result;
for (auto const& relocation : m_direct_ifunc_relocations) {
auto result = do_direct_relocation(relocation, cached_result, ShouldInitializeWeak::No, ShouldCallIfuncResolver::Yes);
auto result = do_direct_relocation(relocation, cached_result, ShouldCallIfuncResolver::Yes);
VERIFY(result == RelocationResult::Success);
}
@ -307,17 +301,6 @@ void DynamicLoader::load_stage_4()
m_fully_initialized = true;
}
void DynamicLoader::do_lazy_relocations()
{
Optional<DynamicLoader::CachedLookupResult> cached_result;
for (auto const& relocation : m_unresolved_relocations) {
if (auto res = do_direct_relocation(relocation, cached_result, ShouldInitializeWeak::Yes, ShouldCallIfuncResolver::Yes); res != RelocationResult::Success) {
dbgln("Loader.so: {} unresolved symbol '{}'", m_filepath, relocation.symbol().name());
VERIFY_NOT_REACHED();
}
}
}
void DynamicLoader::load_program_headers()
{
FlatPtr ph_load_start = SIZE_MAX;
@ -520,7 +503,6 @@ void DynamicLoader::load_program_headers()
DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObject::Relocation const& relocation,
Optional<DynamicLoader::CachedLookupResult>& cached_result,
ShouldInitializeWeak should_initialize_weak,
ShouldCallIfuncResolver should_call_ifunc_resolver)
{
FlatPtr* patch_ptr = nullptr;
@ -571,10 +553,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
auto res = lookup_symbol(symbol);
VirtualAddress symbol_address;
if (!res.has_value()) {
if (symbol.bind() == STB_WEAK) {
if (should_initialize_weak == ShouldInitializeWeak::No)
return RelocationResult::ResolveLater;
} else {
if (symbol.bind() != STB_WEAK) {
dbgln("ERROR: symbol not found: {}.", symbol.name());
return RelocationResult::Failed;
}
@ -598,10 +577,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
auto res = lookup_symbol(symbol);
VirtualAddress symbol_location;
if (!res.has_value()) {
if (symbol.bind() == STB_WEAK) {
if (should_initialize_weak == ShouldInitializeWeak::No)
return RelocationResult::ResolveLater;
} else {
if (symbol.bind() != STB_WEAK) {
// Symbol not found
return RelocationResult::Failed;
}