kernel.git/arch/arm64/kernel/efi-rt-wrapper.S, branch linux-4.19.yHosts the 0x221E linux distro kernel.
https://git.0xinfinity.dev/distro/kernel.git/atom?h=linux-4.19.y2018-03-09T07:58:22Zefi/arm64: Check whether x18 is preserved by runtime services calls2018-03-09T07:58:22ZArd Biesheuvel2018-03-08T08:00:13Zurn:sha1:7e611e7dbb235938fca1dd359bad5e5f86ceabcb
Whether or not we will ever decide to start using x18 as a platform
register in Linux is uncertain, but by that time, we will need to
ensure that UEFI runtime services calls don't corrupt it.
So let's start issuing warnings now for this, and increase the
likelihood that these firmware images have all been replaced by that time.
This has been fixed on the EDK2 side in commit:
6d73863b5464 ("BaseTools/tools_def AARCH64: mark register x18 as reserved")
dated July 13, 2017.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180308080020.22828-6-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>