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Kernel: Convert Processor::in_irq() to static current_in_irq()

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This closes the race window between Processor::current() and a context
switch happening before in_irq().
This commit is contained in:
Andreas Kling 2021-08-22 12:21:31 +02:00
parent 3e3f760808
commit d60635cb9d
14 changed files with 37 additions and 39 deletions
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6
Kernel/Arch/x86/Processor.h
View file

@ -120,7 +120,7 @@ class Processor {
u32 m_gdt_length;
u32 m_cpu;
u32 m_in_irq;
FlatPtr m_in_irq {};
volatile u32 m_in_critical {};
static Atomic<u32> s_idle_cpu_mask;
@ -329,9 +329,9 @@ public:
return Processor::id() == 0;
}
ALWAYS_INLINE u32& in_irq()
ALWAYS_INLINE static FlatPtr current_in_irq()
{
return m_in_irq;
return read_gs_ptr(__builtin_offsetof(Processor, m_in_irq));
}
ALWAYS_INLINE static void restore_in_critical(u32 critical)

2
Kernel/Arch/x86/common/Interrupts.cpp
View file

@ -288,7 +288,7 @@ void page_fault_handler(TrapFrame* trap)
bool faulted_in_kernel = !(regs.cs & 3);
if (faulted_in_kernel && Processor::current().in_irq()) {
if (faulted_in_kernel && Processor::current_in_irq()) {
// If we're faulting in an IRQ handler, first check if we failed
// due to safe_memcpy, safe_strnlen, or safe_memset. If we did,
// gracefully continue immediately. Because we're in an IRQ handler

2
Kernel/Arch/x86/i386/Processor.cpp
View file

@ -180,7 +180,7 @@ FlatPtr Processor::init_context(Thread& thread, bool leave_crit)
void Processor::switch_context(Thread*& from_thread, Thread*& to_thread)
{
VERIFY(!in_irq());
VERIFY(!m_in_irq);
VERIFY(m_in_critical == 1);
VERIFY(is_kernel_mode());

2
Kernel/Arch/x86/x86_64/Processor.cpp
View file

@ -164,7 +164,7 @@ FlatPtr Processor::init_context(Thread& thread, bool leave_crit)
void Processor::switch_context(Thread*& from_thread, Thread*& to_thread)
{
VERIFY(!in_irq());
VERIFY(!m_in_irq);
VERIFY(m_in_critical == 1);
VERIFY(is_kernel_mode());