tree 4b5f75df708fedc9013d2efeefb3749707039283
parent 1cce91dfc8f7990ca3aea896bfb148f240b12860
author Ard Biesheuvel <ard.biesheuvel@linaro.org> 1508681697 +0100
committer Russell King <rmk+kernel@armlinux.org.uk> 1509142468 +0100

efi/libstub: arm: omit sorting of the UEFI memory map

ARM shares its EFI stub implementation with arm64, which has some
special handling in the virtual remapping code to
a) make sure that we can map everything even if the OS executes
   with 64k page size, and
b) make sure that adjacent regions with the same attributes are not
   reordered or moved apart in memory.

The latter is a workaround for a 'feature' that was shortly recommended
by UEFI spec v2.5, but deprecated shortly after, due to the fact that
it broke many OS installers, including non-Linux ones, and it was never
widely implemented for ARM systems. Before implementing b), the arm64
code simply rounded up all regions to 64 KB granularity, but given that
that results in moving adjacent regions apart, it had to be refined when
b) was implemented.

The adjacency check requires a sort() pass, due to the fact that the
UEFI spec does not mandate any ordering, and the inclusion of the
lib/sort.c code into the ARM EFI stub is causing some trouble with
the decompressor build due to the fact that its EXPORT_SYMBOL() call
triggers the creation of ksymtab/kcrctab sections.

So let's simply do away with the adjacency check for ARM, and simply put
all UEFI runtime regions together if they have the same memory attributes.
This is guaranteed to work, given that ARM only supports 4 KB pages,
and allows us to remove the sort() call entirely.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>