This is a note to let you know that I've just added the patch titled
arm64: reduce el2_setup branching
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-reduce-el2_setup-branching.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sun Jan 9 01:56:51 PM CET 2022
From: Nathan Chancellor <nathan@xxxxxxxxxx>
Date: Fri, 7 Jan 2022 12:43:33 -0700
Subject: arm64: reduce el2_setup branching
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Sasha Levin <sashal@xxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Will Deacon <will@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>, Marc Zyngier <maz@xxxxxxxxxx>, Nick Desaulniers <ndesaulniers@xxxxxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx, llvm@xxxxxxxxxxxxxxx
Message-ID: <20220107194335.3090066-4-nathan@xxxxxxxxxx>
From: Mark Rutland <mark.rutland@xxxxxxx>
commit 3ad47d055aa88d9f4189253f5b5c485f4c4626b2 upstream.
The early el2_setup code is a little convoluted, with two branches where
one would do. This makes the code more painful to read than is
necessary.
We can remove a branch and simplify the logic by moving the early return
in the booted-at-EL1 case earlier in the function. This separates it
from all the setup logic that only makes sense for EL2.
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/head.S | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -489,13 +489,8 @@ ENTRY(el2_setup)
msr SPsel, #1 // We want to use SP_EL{1,2}
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL2
- b.ne 1f
- mrs x0, sctlr_el2
-CPU_BE( orr x0, x0, #(1 << 25) ) // Set the EE bit for EL2
-CPU_LE( bic x0, x0, #(1 << 25) ) // Clear the EE bit for EL2
- msr sctlr_el2, x0
- b 2f
-1: mrs x0, sctlr_el1
+ b.eq 1f
+ mrs x0, sctlr_el1
CPU_BE( orr x0, x0, #(3 << 24) ) // Set the EE and E0E bits for EL1
CPU_LE( bic x0, x0, #(3 << 24) ) // Clear the EE and E0E bits for EL1
msr sctlr_el1, x0
@@ -503,7 +498,11 @@ CPU_LE( bic x0, x0, #(3 << 24) ) // Clea
isb
ret
-2:
+1: mrs x0, sctlr_el2
+CPU_BE( orr x0, x0, #(1 << 25) ) // Set the EE bit for EL2
+CPU_LE( bic x0, x0, #(1 << 25) ) // Clear the EE bit for EL2
+ msr sctlr_el2, x0
+
#ifdef CONFIG_ARM64_VHE
/*
* Check for VHE being present. For the rest of the EL2 setup,
Patches currently in stable-queue which might be from nathan@xxxxxxxxxx are
queue-4.9/arm64-sysreg-move-to-use-definitions-for-all-the-sctlr-bits.patch
queue-4.9/bug-split-build_bug-stuff-out-into-linux-build_bug.h.patch
queue-4.9/arm64-move-vhe-work-to-end-of-el2_setup.patch
queue-4.9/arm64-remove-a-redundancy-in-sysreg.h.patch
queue-4.9/arm64-reduce-el2_setup-branching.patch
