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LibELF: Take TLS segment alignment into account in DynamicLoader

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Previously we would just tightly pack the different libraries' TLS
segments together, but that is incorrect, as they might require some
kind of minimum alignment for their TLS base address.

We now plumb the required TLS segment alignment down to the TLS block
linear allocator and align the base address down to the appropriate
alignment.
This commit is contained in:
Idan Horowitz 2022-07-05 01:18:40 +03:00 • committed by Andreas Kling
parent 33214c29d3
commit 753844ec96
3 changed files with 19 additions and 12 deletions
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12
Userland/Libraries/LibELF/DynamicLinker.cpp
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@ -96,6 +96,8 @@ static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(String c
s_loaders.set(get_library_name(filename), *loader);
s_current_tls_offset -= loader->tls_size_of_current_object();
if (loader->tls_alignment_of_current_object())
s_current_tls_offset = align_down_to(s_current_tls_offset, loader->tls_alignment_of_current_object());
loader->set_tls_offset(s_current_tls_offset);
// This actually maps the library at the intended and final place.
@ -196,8 +198,8 @@ static void allocate_tls()
{
s_total_tls_size = 0;
for (auto const& data : s_loaders) {
dbgln_if(DYNAMIC_LOAD_DEBUG, "{}: TLS Size: {}", data.key, data.value->tls_size_of_current_object());
s_total_tls_size += data.value->tls_size_of_current_object();
dbgln_if(DYNAMIC_LOAD_DEBUG, "{}: TLS Size: {}, TLS Alignment: {}", data.key, data.value->tls_size_of_current_object(), data.value->tls_alignment_of_current_object());
s_total_tls_size += data.value->tls_size_of_current_object() + data.value->tls_alignment_of_current_object();
}
if (!s_total_tls_size)
@ -393,7 +395,7 @@ static Optional<DlErrorMessage> verify_tls_for_dlopen(DynamicLoader const& loade
if (loader.tls_size_of_current_object() == 0)
return {};
if (s_total_tls_size + loader.tls_size_of_current_object() > s_allocated_tls_block_size)
if (s_total_tls_size + loader.tls_size_of_current_object() + loader.tls_alignment_of_current_object() > s_allocated_tls_block_size)
return DlErrorMessage("TLS size too large");
bool tls_data_is_all_zero = true;
@ -461,7 +463,7 @@ static Result<void*, DlErrorMessage> __dlopen(char const* filename, int flags)
if (result.is_error())
return result.error();
s_total_tls_size += result1.value()->tls_size_of_current_object();
s_total_tls_size += result1.value()->tls_size_of_current_object() + result1.value()->tls_alignment_of_current_object();
auto object = s_global_objects.get(library_name);
if (!object.has_value())
@ -586,7 +588,7 @@ void ELF::DynamicLinker::linker_main(String&& main_program_name, int main_progra
dbgln_if(DYNAMIC_LOAD_DEBUG, "loaded all dependencies");
for ([[maybe_unused]] auto& lib : s_loaders) {
dbgln_if(DYNAMIC_LOAD_DEBUG, "{} - tls size: {}, tls offset: {}", lib.key, lib.value->tls_size_of_current_object(), lib.value->tls_offset());
dbgln_if(DYNAMIC_LOAD_DEBUG, "{} - tls size: {}, tls alignment: {}, tls offset: {}", lib.key, lib.value->tls_size_of_current_object(), lib.value->tls_alignment_of_current_object(), lib.value->tls_offset());
}
allocate_tls();