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LibELF: Take TLS segment alignment into account in DynamicLoader

Browse source 
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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15
Userland/Libraries/LibELF/DynamicLoader.cpp
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@ -71,7 +71,7 @@ DynamicLoader::DynamicLoader(int fd, String filename, void* data, size_t size, S
m_elf_image = adopt_own(*new ELF::Image((u8*)m_file_data, m_file_size));
m_valid = validate();
if (m_valid)
m_tls_size_of_current_object = calculate_tls_size();
find_tls_size_and_alignment();
else
dbgln("Image validation failed for file {}", m_filename);
}
@ -105,15 +105,18 @@ DynamicObject const& DynamicLoader::dynamic_object() const
return *m_cached_dynamic_object;
}
size_t DynamicLoader::calculate_tls_size() const
void DynamicLoader::find_tls_size_and_alignment()
{
size_t tls_size = 0;
image().for_each_program_header([&tls_size](auto program_header) {
image().for_each_program_header([this](auto program_header) {
if (program_header.type() == PT_TLS) {
tls_size = program_header.size_in_memory();
m_tls_size_of_current_object = program_header.size_in_memory();
auto alignment = program_header.alignment();
VERIFY(!alignment || is_power_of_two(alignment));
m_tls_alignment_of_current_object = alignment > 1 ? alignment : 0; // No need to reserve extra space for single byte alignment
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
return tls_size;
}
bool DynamicLoader::validate()