Re: [PATCH v3 03/13] arm64: improve CONFIG_STRICT_DEVMEM handling

[Borislav Petkov]

On Tue, Nov 25, 2014 at 05:39:25PM +0000, Matt Fleming wrote:
> On Tue, 18 Nov, at 01:57:02PM, Ard Biesheuvel wrote:
> > Improve the handling of /dev/mem mappings under CONFIG_STRICT_DEVMEM by:
> > - allowing read-only access to parts of System RAM that are not
> >   considered memory by the kernel, this is mainly intended for exposing
> >   UEFI Configuration tables to userland;
> > - avoid using non-cached mappings for those parts of System RAM, as it
> >   may result in mismatched attributes.
> 
> Is this really the best way to expose EFI config tables?
> 
> We already have parts in /sys/firmware/efi/ and in particular we expose
> the runtime mappings there for kexec on x86.

Yeah!

> Hooking this into the /dev/mem infrastructure just seems wrong to me.

And this virtmap.c thing is arm-only, AFAICT, but it looks like generic
code and like a wholly new way of doing the efi page table.

This thing needs to be properly split into generic pieces which go into
drivers/firmware/efi/ and arm-specific which would make that EFI_VIRTMAP
into an arch bit.

And so on and so on...

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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