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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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10
Kernel/Tasks/Process.h
View file

@ -924,8 +924,6 @@ private:
Vector<NonnullOwnPtr<KString>> m_arguments;
Vector<NonnullOwnPtr<KString>> m_environment;
LockWeakPtr<Memory::Region> m_master_tls_region;
IntrusiveListNode<Process> m_jail_process_list_node;
IntrusiveListNode<Process> m_all_processes_list_node;
@ -937,8 +935,12 @@ private:
SpinlockProtected<RefPtr<ProcessList>, LockRank::None> m_jail_process_list;
SpinlockProtected<RefPtr<Jail>, LockRank::Process> m_attached_jail {};
size_t m_master_tls_size { 0 };
size_t m_master_tls_alignment { 0 };
struct MasterThreadLocalStorage {
LockWeakPtr<Memory::Region> region;
size_t size { 0 };
size_t alignment { 0 };
};
SpinlockProtected<MasterThreadLocalStorage, LockRank::None> m_master_tls;
Mutex m_big_lock { "Process"sv, Mutex::MutexBehavior::BigLock };
Mutex m_ptrace_lock { "ptrace"sv };

42
Kernel/Tasks/Thread.cpp
View file

@ -1360,37 +1360,31 @@ ErrorOr<NonnullOwnPtr<KString>> Thread::backtrace()
return KString::try_create(builder.string_view());
}
size_t Thread::thread_specific_region_alignment() const
{
return max(process().m_master_tls_alignment, alignof(ThreadSpecificData));
}
size_t Thread::thread_specific_region_size() const
{
return align_up_to(process().m_master_tls_size, thread_specific_region_alignment()) + sizeof(ThreadSpecificData);
}
ErrorOr<void> Thread::make_thread_specific_region(Badge<Process>)
{
// The process may not require a TLS region, or allocate TLS later with sys$allocate_tls (which is what dynamically loaded programs do)
if (!process().m_master_tls_region)
return {};
return process().m_master_tls.with([&](auto& master_tls) -> ErrorOr<void> {
// The process may not require a TLS region, or allocate TLS later with sys$allocate_tls (which is what dynamically loaded programs do)
if (!master_tls.region)
return {};
return process().address_space().with([&](auto& space) -> ErrorOr<void> {
auto* region = TRY(space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, thread_specific_region_size(), PAGE_SIZE, "Thread-specific"sv, PROT_READ | PROT_WRITE));
return process().address_space().with([&](auto& space) -> ErrorOr<void> {
auto region_alignment = max(master_tls.alignment, alignof(ThreadSpecificData));
auto region_size = align_up_to(master_tls.size, region_alignment) + sizeof(ThreadSpecificData);
auto* region = TRY(space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, region_size, PAGE_SIZE, "Thread-specific"sv, PROT_READ | PROT_WRITE));
m_thread_specific_range = region->range();
m_thread_specific_range = region->range();
SmapDisabler disabler;
auto* thread_specific_data = (ThreadSpecificData*)region->vaddr().offset(align_up_to(process().m_master_tls_size, thread_specific_region_alignment())).as_ptr();
auto* thread_local_storage = (u8*)((u8*)thread_specific_data) - align_up_to(process().m_master_tls_size, process().m_master_tls_alignment);
m_thread_specific_data = VirtualAddress(thread_specific_data);
thread_specific_data->self = thread_specific_data;
SmapDisabler disabler;
auto* thread_specific_data = (ThreadSpecificData*)region->vaddr().offset(align_up_to(master_tls.size, region_alignment)).as_ptr();
auto* thread_local_storage = (u8*)((u8*)thread_specific_data) - align_up_to(master_tls.size, master_tls.size);
m_thread_specific_data = VirtualAddress(thread_specific_data);
thread_specific_data->self = thread_specific_data;
if (process().m_master_tls_size != 0)
memcpy(thread_local_storage, process().m_master_tls_region.unsafe_ptr()->vaddr().as_ptr(), process().m_master_tls_size);
if (master_tls.size != 0)
memcpy(thread_local_storage, master_tls.region.unsafe_ptr()->vaddr().as_ptr(), master_tls.size);
return {};
return {};
});
});
}

2
Kernel/Tasks/Thread.h
View file

@ -788,8 +788,6 @@ public:
StringView state_string() const;
VirtualAddress thread_specific_data() const { return m_thread_specific_data; }
size_t thread_specific_region_size() const;
size_t thread_specific_region_alignment() const;
ALWAYS_INLINE void yield_if_stopped()
{