Messages in this thread |  | | Date | Mon, 07 May 2001 17:25:41 -0400 | From | Brian Gerst <> | Subject | Re: [PATCH] x86 page fault handler not interrupt safe |
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Nigel Gamble wrote: > > On Mon, 7 May 2001, Linus Torvalds wrote: > > On Mon, 7 May 2001, Brian Gerst wrote: > > > This patch will still cause the user process to seg fault: The error > > > code on the stack will not match the address in %cr2. > > > > You've convinced me. Good thinking. Let's do the irq thing. > > I've actually seen user processes seg faulting because of this with the > fully preemptible kernel patch applied. The fix we used in that patch > was to use an interrupt gate for the fault handler, then to simply > restore the interrupt state:
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.
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