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SubjectRe: [PATCH] x86 page fault handler not interrupt safe
Linus Torvalds wrote:
>
> On Mon, 7 May 2001, Brian Gerst wrote:
> >
> > Keep in mind that regs->eflags could be from user space, and could have
> > some undesirable flags set. That's why I did a test/sti instead of
> > reloading eflags. Plus my patch leaves interrupts disabled for the
> > minimum time possible.
>
> The plain "popf" should be ok: the way intel works, you cannot actually
> use popf to set any of the strange flags (if vm86 mode etc).

TF (trap flag) would be one that I wouldn't want to get reset. You
could use
local_irq_restore(regs->eflags & ~(TF|RF|VM|NT))
which are all the flags cleared by an interrupt/trap gate. Or
if (regs->eflags & IF) sti();
Take your pick.

--

Brian Gerst
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