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Kernel: Implement more x86_64 context switching functionality

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This commit is contained in:
Gunnar Beutner 2021-06-27 19:49:19 +02:00 • committed by Andreas Kling
parent 076692b1ef
commit 32840dfa17
8 changed files with 151 additions and 132 deletions
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71
Kernel/Arch/x86/common/Processor.cpp
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@ -40,9 +40,11 @@ Atomic<u32> Processor::s_idle_cpu_mask { 0 };
extern "C" void thread_context_first_enter(void);
extern "C" void exit_kernel_thread(void);
// The compiler can't see the calls to this function inside assembly.
// Declare it, to avoid dead code warnings.
// The compiler can't see the calls to these functions inside assembly.
// Declare them, to avoid dead code warnings.
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) __attribute__((used));
extern "C" u32 do_init_context(Thread* thread, u32 flags) __attribute__((used));
UNMAP_AFTER_INIT static void sse_init()
{
@ -1165,4 +1167,69 @@ extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe
Scheduler::leave_on_first_switch(flags & ~0x200);
}
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
{
VERIFY(from_thread == to_thread || from_thread->state() != Thread::Running);
VERIFY(to_thread->state() == Thread::Running);
bool has_fxsr = Processor::current().has_feature(CPUFeature::FXSR);
Processor::set_current_thread(*to_thread);
auto& from_regs = from_thread->regs();
auto& to_regs = to_thread->regs();
if (has_fxsr)
asm volatile("fxsave %0"
: "=m"(from_thread->fpu_state()));
else
asm volatile("fnsave %0"
: "=m"(from_thread->fpu_state()));
#if ARCH(I386)
from_regs.fs = get_fs();
from_regs.gs = get_gs();
set_fs(to_regs.fs);
set_gs(to_regs.gs);
#endif
if (from_thread->process().is_traced())
read_debug_registers_into(from_thread->debug_register_state());
if (to_thread->process().is_traced()) {
write_debug_registers_from(to_thread->debug_register_state());
} else {
clear_debug_registers();
}
auto& processor = Processor::current();
#if ARCH(I386)
auto& tls_descriptor = processor.get_gdt_entry(GDT_SELECTOR_TLS);
tls_descriptor.set_base(to_thread->thread_specific_data());
tls_descriptor.set_limit(to_thread->thread_specific_region_size());
#endif
if (from_regs.cr3 != to_regs.cr3)
write_cr3(to_regs.cr3);
to_thread->set_cpu(processor.get_id());
processor.restore_in_critical(to_thread->saved_critical());
if (has_fxsr)
asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state()));
else
asm volatile("frstor %0" ::"m"(to_thread->fpu_state()));
// TODO: ioperm?
}
extern "C" u32 do_init_context(Thread* thread, u32 flags)
{
VERIFY_INTERRUPTS_DISABLED();
#if ARCH(I386)
thread->regs().eflags = flags;
#else
thread->regs().rflags = flags;
#endif
return Processor::current().init_context(*thread, true);
}
}