Re: [RFC] arm64/linux/loader: Use EFI CODE allocations for the linux kernel

[Leif Lindholm]

On Thu, Apr 04, 2019 at 06:57:29PM +0200, Daniel Kiper wrote:
> On Thu, Apr 04, 2019 at 07:54:55AM -0700, Jeffrey Hugo wrote:
> > Some UEFI implementations for ARM64 devices apply strict permissions on
> > the different allocation types.  In these implementations, DATA
> > allocations have XN (execute never) permissions, preventing code execution
> > from those pages.
> >
> > On these implementations, the Linux kernel is loaded to DATA pages, which
> > causes a permission fault when GRUB attempts to kick off the kernel.  This
> > results in a device crash.
> >
> > Fix this by allocating CODE pages for the Linux kernel.
> >
> > Signed-off-by: Jeffrey Hugo <address@hidden>
> 
> Make sense for me but I would like to hear Leif's opinion too. I treat
> this a fix and if he is OK with it I am happy to take it into release.

This complements f826330683675f0deb55b58fd229afd7d65fb053
("efi: change heap allocation type to GRUB_EFI_LOADER_CODE"), so I'm
all for it.

Reviewed-by: Leif Lindholm <address@hidden>

This does bring to mind the clunkiness of the above. Marking
*everything* executable bypasses the improved security provided by the
firmware. Should I register a bug on Savannah to address this?
(blatantly not for the upcoming release)

/
     Leif