Re: [PATCH 0/2] efi/arm64: execute the kernel in place if possible

From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>, <mark.rutland@arm.com>,
	<catalin.marinas@arm.com>, <linux-efi@vger.kernel.org>,
	<will@kernel.org>
Subject: Re: [PATCH 0/2] efi/arm64: execute the kernel in place if possible
Date: Fri, 27 Mar 2020 13:19:00 +0000	[thread overview]
Message-ID: <20200327131900.000068aa@Huawei.com> (raw)
In-Reply-To: <20200326165905.2240-1-ardb@kernel.org>

On Thu, 26 Mar 2020 17:59:03 +0100
Ard Biesheuvel <ardb@kernel.org> wrote:

> Update the relocation logic in the EFI stub for arm64 so it runs the
> kernel in place if it was loaded by firmware at an address which allows
> doing so. Then, update the PE/COFF header metadata and increase the
> section alignment to force the UEFI image loader to honour the minimal
> alignment requirement imposed by the kernel proper.
> 
> Ard Biesheuvel (2):
>   efi/libstub/arm64: avoid copying the kernel unnecessarily
>   efi/arm64: increase the PE/COFF alignment so the kernel can run in
>     place
> 
>  arch/arm64/kernel/efi-header.S            | 2 +-
>  arch/arm64/kernel/image-vars.h            | 7 +++++++
>  drivers/firmware/efi/libstub/arm64-stub.c | 9 +++++++++
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
Hi Ard.

Seems sensible to me so I decided to give it a quick test.
As things stand RELOCATABLE is only selectable by selecting
RANDOMIZE_BASE.   Probably want to be able to configure it
separately (needs some help text, or a specific option to
select CONFIG_RELOCATABLE).

Otherwise, superficially seems to work good for me doing a
boot via pxe/grub on a Kunpeng 920 with some prints added to
make sure it's taking the right paths.

Thanks,

Jonathan