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Kernel: Protect processes' master TLS with a fine-grained spinlock

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This moves it out of the scope of the big process lock, and allows us
to wean some syscalls off it, starting with sys$allocate_tls.
This commit is contained in:
Idan Horowitz 2023-12-16 12:37:28 +02:00 • committed by Andreas Kling
parent cd56ec6e5c
commit 6a4b93b3e0
7 changed files with 91 additions and 86 deletions
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62
Kernel/Syscalls/mmap.cpp
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@ -524,50 +524,52 @@ ErrorOr<FlatPtr> Process::sys$mremap(Userspace<Syscall::SC_mremap_params const*>
ErrorOr<FlatPtr> Process::sys$allocate_tls(Userspace<char const*> initial_data, size_t size)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_promise(Pledge::stdio));
if (!size || size % PAGE_SIZE != 0)
return EINVAL;
if (!m_master_tls_region.is_null())
return EEXIST;
return m_master_tls.with([&](auto& master_tls) -> ErrorOr<FlatPtr> {
if (!master_tls.region.is_null())
return EEXIST;
if (thread_count() != 1)
return EFAULT;
if (thread_count() != 1)
return EFAULT;
Thread* main_thread = nullptr;
bool multiple_threads = false;
for_each_thread([&main_thread, &multiple_threads](auto& thread) {
if (main_thread)
multiple_threads = true;
main_thread = &thread;
return IterationDecision::Break;
});
VERIFY(main_thread);
Thread* main_thread = nullptr;
bool multiple_threads = false;
for_each_thread([&main_thread, &multiple_threads](auto& thread) {
if (main_thread)
multiple_threads = true;
main_thread = &thread;
return IterationDecision::Break;
});
VERIFY(main_thread);
if (multiple_threads)
return EINVAL;
if (multiple_threads)
return EINVAL;
return address_space().with([&](auto& space) -> ErrorOr<FlatPtr> {
auto* region = TRY(space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, size, PAGE_SIZE, "Master TLS"sv, PROT_READ | PROT_WRITE));
return address_space().with([&](auto& space) -> ErrorOr<FlatPtr> {
auto* region = TRY(space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, size, PAGE_SIZE, "Master TLS"sv, PROT_READ | PROT_WRITE));
m_master_tls_region = TRY(region->try_make_weak_ptr());
m_master_tls_size = size;
m_master_tls_alignment = PAGE_SIZE;
master_tls.region = TRY(region->try_make_weak_ptr());
master_tls.size = size;
master_tls.alignment = PAGE_SIZE;
{
Kernel::SmapDisabler disabler;
void* fault_at;
if (!Kernel::safe_memcpy((char*)m_master_tls_region.unsafe_ptr()->vaddr().as_ptr(), (char*)initial_data.ptr(), size, fault_at))
return EFAULT;
}
{
Kernel::SmapDisabler disabler;
void* fault_at;
if (!Kernel::safe_memcpy((char*)master_tls.region.unsafe_ptr()->vaddr().as_ptr(), (char*)initial_data.ptr(), size, fault_at))
return EFAULT;
}
TRY(main_thread->make_thread_specific_region({}));
TRY(main_thread->make_thread_specific_region({}));
Processor::set_thread_specific_data(main_thread->thread_specific_data());
Processor::set_thread_specific_data(main_thread->thread_specific_data());
return m_master_tls_region.unsafe_ptr()->vaddr().get();
return master_tls.region.unsafe_ptr()->vaddr().get();
});
});
}