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Kernel: Support thread-local storage

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This patch adds support for TLS according to the x86 System V ABI.
Each thread gets a thread-specific memory region, and the GS segment
register always points _to a pointer_ to the thread-specific memory.

In other words, to access thread-local variables, userspace programs
start by dereferencing the pointer at [gs:0].

The Process keeps a master copy of the TLS segment that new threads
should use, and when a new thread is created, they get a copy of it.
It's basically whatever the PT_TLS program header in the ELF says.
This commit is contained in:
Andreas Kling 2019-09-07 15:50:44 +02:00
parent bcfdf9ffa7
commit ec6bceaa08
7 changed files with 92 additions and 5 deletions
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12
Kernel/Thread.h
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@ -30,6 +30,10 @@ struct SignalActionData {
int flags { 0 };
};
struct ThreadSpecificData {
ThreadSpecificData* self;
};
class Thread {
friend class Process;
friend class Scheduler;
@ -214,6 +218,8 @@ public:
const char* state_string() const;
u32 ticks() const { return m_ticks; }
VirtualAddress thread_specific_data() const { return m_thread_specific_data; }
u64 sleep(u32 ticks);
enum class BlockResult {
@ -301,6 +307,8 @@ public:
void make_userspace_stack_for_main_thread(Vector<String> arguments, Vector<String> environment);
void make_userspace_stack_for_secondary_thread(void* argument);
void make_thread_specific_region(Badge<Process>);
Thread* clone(Process&);
template<typename Callback>
@ -336,6 +344,7 @@ private:
RefPtr<Region> m_userspace_stack_region;
RefPtr<Region> m_kernel_stack_region;
RefPtr<Region> m_kernel_stack_for_signal_handler_region;
VirtualAddress m_thread_specific_data;
SignalActionData m_signal_action_data[32];
Region* m_signal_stack_user_region { nullptr };
IntrusiveList<Blocker, &Blocker::m_blocker_list_node> m_blockers;
@ -432,3 +441,6 @@ inline IterationDecision Scheduler::for_each_nonrunnable(Callback callback)
return IterationDecision::Continue;
}
u16 thread_specific_selector();
Descriptor& thread_specific_descriptor();