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

[Matthias Brugger]

On 10/27/2017 05:28 PM, Russell King - ARM Linux wrote:
> On Fri, Oct 27, 2017 at 05:12:58PM +0200, Matthias Brugger wrote:
>> Hi Ard,
>>
>> On 10/22/2017 04:14 PM, Ard Biesheuvel wrote:
>>> 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 at linaro.org>
>>> ---
>>>  drivers/firmware/efi/libstub/Makefile   | 6 +++---
>>>  drivers/firmware/efi/libstub/arm-stub.c | 7 +++++--
>>>  2 files changed, 8 insertions(+), 5 deletions(-)
>>>
>>
>> I thought I already provided my tag, but just in case:
>> This fixes the boot problems I had on the bananapi-r2.
>>
>> Tested-by: Matthias Brugger <matthias.bgg at gmail.com>
> 
> Please test my "fixes" branch - that has all three patches merged.
> 
> We don't have linux-next running at the moment, so folk need to be
> manually fetching the appropriate git trees for testing.
> 

I gave your branch a shot, feel free to add my:

Tested-by: Matthias Brugger <mbrugger at suse.com>

Especially for commit
4c2b35b71ea3 ARM: verify size of zImage

Regards,
Matthias