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Kernel: Simplify x86 IOPL sanity check

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Move this architecture-specific sanity check (IOPL must be 0) out of
Scheduler and into the x86 enter_thread_context(). Also do this for
every thread and not just userspace ones.
This commit is contained in:
Andreas Kling 2022-01-30 14:17:46 +01:00
parent 684d5eed19
commit a6b5065d94
2 changed files with 4 additions and 10 deletions
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6
Kernel/Arch/x86/common/Processor.cpp
View file

@ -1312,6 +1312,10 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
auto& from_regs = from_thread->regs();
auto& to_regs = to_thread->regs();
// NOTE: IOPL should never be non-zero in any situation, so let's panic immediately
// instead of carrying on with elevated I/O privileges.
VERIFY(get_iopl_from_eflags(to_regs.flags()) == 0);
if (has_fxsr)
asm volatile("fxsave %0"
: "=m"(from_thread->fpu_state()));
@ -1358,8 +1362,6 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state()));
else
asm volatile("frstor %0" ::"m"(to_thread->fpu_state()));
// TODO: ioperm?
}
extern "C" FlatPtr do_init_context(Thread* thread, u32 flags)

8
Kernel/Scheduler.cpp
View file

@ -310,14 +310,6 @@ bool Scheduler::context_switch(Thread* thread)
enter_current(*from_thread);
VERIFY(thread == Thread::current());
if (thread->process().is_user_process() && thread->previous_mode() != Thread::PreviousMode::KernelMode && thread->current_trap()) {
auto& regs = thread->get_register_dump_from_stack();
auto iopl = get_iopl_from_eflags(regs.flags());
if (iopl != 0) {
PANIC("Switched to thread {} with non-zero IOPL={}", Thread::current()->tid().value(), iopl);
}
}
return true;
}