* Re: [PATCH v3 03/13] arm64: improve CONFIG_STRICT_DEVMEM handling [not found] ` <1416315432-8534-4-git-send-email-ard.biesheuvel@linaro.org> @ 2014-11-25 17:39 ` Matt Fleming 2014-11-25 17:48 ` Borislav Petkov 0 siblings, 1 reply; 2+ messages in thread From: Matt Fleming @ 2014-11-25 17:39 UTC (permalink / raw) To: Ard Biesheuvel Cc: leif.lindholm, roy.franz, linux-arm-kernel, mark.rutland, msalter, dyoung, linux-efi, matt.fleming, will.deacon, catalin.marinas, grant.likely, geoff.levand, linux-kernel, Borislav Petkov, Peter Jones 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. Hooking this into the /dev/mem infrastructure just seems wrong to me. -- Matt Fleming, Intel Open Source Technology Center ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v3 03/13] arm64: improve CONFIG_STRICT_DEVMEM handling 2014-11-25 17:39 ` [PATCH v3 03/13] arm64: improve CONFIG_STRICT_DEVMEM handling Matt Fleming @ 2014-11-25 17:48 ` Borislav Petkov 0 siblings, 0 replies; 2+ messages in thread From: Borislav Petkov @ 2014-11-25 17:48 UTC (permalink / raw) To: Matt Fleming Cc: Ard Biesheuvel, leif.lindholm, roy.franz, linux-arm-kernel, mark.rutland, msalter, dyoung, linux-efi, matt.fleming, will.deacon, catalin.marinas, grant.likely, geoff.levand, linux-kernel, Peter Jones 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. -- ^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-11-25 17:39 ` [PATCH v3 03/13] arm64: improve CONFIG_STRICT_DEVMEM handling Matt Fleming
2014-11-25 17:48 ` Borislav Petkov
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