ARM: assembler: add optimized ldr/str macros to load variables from memory

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We will be adding variable loads to various hot paths, so it makes sense
to add a helper macro that can load variables from asm code without the
use of literal pool entries. On v7 or later, we can simply use MOVW/MOVT
pairs, but on earlier cores, this requires a bit of hackery to emit a
instruction sequence that implements this using a sequence of ADD/LDR
instructions.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M

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Ard Biesheuvel 2021-11-26 19:37:27 +01:00

parent 1fa8c4b195

commit 4e918ab13e

3 changed files with 43 additions and 6 deletions

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45

arch/arm/include/asm/assembler.h

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2

arch/arm/kernel/entry-armv.S

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2

arch/arm/kernel/entry-header.S

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