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Kernel: Various context switch fixes

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These changes solve a number of problems with the software
context swithcing:

* The scheduler lock really should be held throughout context switches
* Transitioning from the initial (idle) thread to another needs to
  hold the scheduler lock
* Transitioning from a dying thread to another also needs to hold
  the scheduler lock
* Dying threads cannot necessarily be finalized if they haven't
  switched out of it yet, so flag them as active while a processor
  is running it (the Running state may be switched to Dying while
  it still is actually running)
This commit is contained in:
Tom 2020-07-05 14:32:07 -06:00 • committed by Andreas Kling
parent 49f5069b76
commit 2a82a25fec
9 changed files with 235 additions and 89 deletions
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26
Kernel/Arch/i386/CPU.h
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@ -751,6 +751,30 @@ public:
}
if (prev_flags & 0x200)
sti();
else
cli();
}
ALWAYS_INLINE u32 clear_critical(u32& prev_flags, bool enable_interrupts)
{
u32 prev_crit = m_in_critical;
m_in_critical = 0;
prev_flags = cpu_flags();
if (!m_in_irq)
check_invoke_scheduler();
if (enable_interrupts)
sti();
return prev_crit;
}
ALWAYS_INLINE void restore_critical(u32 prev_crit, u32 prev_flags)
{
ASSERT(m_in_critical == 0);
m_in_critical = prev_crit;
if (prev_flags & 0x200)
sti();
else
cli();
}
ALWAYS_INLINE u32& in_critical() { return m_in_critical; }
@ -772,7 +796,7 @@ public:
void exit_trap(TrapFrame& trap);
[[noreturn]] void initialize_context_switching(Thread& initial_thread);
void switch_context(Thread* from_thread, Thread* to_thread);
void switch_context(Thread*& from_thread, Thread*& to_thread);
[[noreturn]] static void assume_context(Thread& thread, u32 flags);
u32 init_context(Thread& thread, bool leave_crit);
static bool get_context_frame_ptr(Thread& thread, u32& frame_ptr, u32& eip);