Messages in this thread | | | From | Ard Biesheuvel <> | Date | Mon, 21 Aug 2017 17:08:50 +0100 | Subject | Re: [PATCH 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with cr3 |
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On 21 August 2017 at 16:59, Peter Zijlstra <peterz@infradead.org> wrote: > On Mon, Aug 21, 2017 at 08:23:10AM -0700, Andy Lutomirski wrote: >> > Ah, but only root can create per-cpu events or attach events to kernel >> > threads (with sensible paranoia levels). >> >> But this may not need to be percpu. If a non root user can trigger, say, an EFI variable read in their own thread context, boom. > > I was going by the proposed: "everything EFI in a kthread" model. But > yes, if that's not done, then you're quite right. >
How does this work in cases where we need to call into UEFI from non-process context? Or at least from a context where current != EFI's kthread. We have EFI pstore code, for instance, that records panic data. Should we make an exception for those?
I'm happy to have a stab at implementing the EFI kthread, but I'd like to get some of these details clarified first.
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