Re: [PATCH v3 00/24] x86_64: Improvements at compressed kernel stage

[Evgeniy Baskov]

On 2022-12-13 21:13, Peter Jones wrote:
> On Tue, Dec 13, 2022 at 01:03:17PM -0500, Peter Jones wrote:
> > On Tue, Nov 22, 2022 at 02:12:09PM +0300, Evgeniy Baskov wrote:
> > > This patchset is aimed
> > > * to improve UEFI compatibility of compressed kernel code for x86_64
> > > * to setup proper memory access attributes for code and rodata sections
> > > * to implement W^X protection policy throughout the whole execution
> > >   of compressed kernel for EFISTUB code path.
> >
> > Hi Evgeniy,
> >
> > I've tested this patch set on hardware and QEMU+MU firmware, and it
> > works for me with a couple of minor issues:
> >
> > - on one machine that has the DXE protocol but not the EFI one, we get
> >   an error because the firmware doesn't support EFI_MEMORY_RP
> > - on QEMU I'm seeing the size of "(unsigned long)_head - image_base"
> >   wind up as 0, which leads to an EFI_INVALID_PARAMETER on the
> >   clear_memory_attributes() call.
> >
> > In both cases the system winds up working, but with unnecessary 
> > console
> > output.
>
> I just realized I've overstated here - I haven't actually hit the first
> problem on x86, only on ARM, where we don't currently use this code.  I
> discovered it in grub, and checked your patch set to see if you had the
> same issue I did.  That said, "in both cases the system winds up
> working" is probably still true - in that the edk2 code supports
> EFI_MEMORY_RP on x86 but not ARM, so x86 won't hit the issue when using
> DXE unless someone cooks up another implementation.  Nevertheless I
> believe the patch to fix it is correct and should be applied.
>
> Thanks!

Hi,

Thank you for testing and fixes!

I have also discovered one issue with v3, that can only be hit when
booting with grub -- there's one kernel_add_identity_map() missing in
the get_acpi_srat_table() function, before header->length is read.
So I'll prepare the v4 soon and include your new patches there.

Thanks,
Evgeniy Baskov