Commit 1b654b23 authored Dec 09, 2020 by Ard Biesheuvel Committed by Eric Biggers Nov 09, 2022

BACKPORT: ARM: 9039/1: assembler: generalize byte swapping macro into rev_l



Take the 4 instruction byte swapping sequence from the decompressor's
head.S, and turn it into a rev_l GAS macro for general use. While
at it, make it use the 'rev' instruction when compiling for v6 or
later.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

(cherry picked from commit 6468e898c67b905ec0f95d9678929135bcaf7f67)
(resolved conflict due to different patch context, caused by missing
 other macros in assembler.h)
Bug: 178411248
Change-Id: I8433e97d2880f75cace215f1a8daadec7f29929c
Signed-off-by: Eric Biggers <ebiggers@google.com>

parent 6f5e7693

arch/arm/boot/compressed/head.S

+1 −4

Original line number	Diff line number	Diff line
		@@ -117,10 +117,7 @@
		.macro be32tocpu, val, tmp
		#ifndef __ARMEB__
		/* convert to little endian */
		eor \tmp, \val, \val, ror #16
		bic \tmp, \tmp, #0x00ff0000
		mov \val, \val, ror #8
		eor \val, \val, \tmp, lsr #8
		rev_l \val, \tmp
		#endif
		.endm

arch/arm/include/asm/assembler.h

+17 −0

Original line number	Diff line number	Diff line
		@@ -506,4 +506,21 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
		#define _ASM_NOKPROBE(entry)
		#endif

		/*
		* rev_l - byte-swap a 32-bit value
		*
		* @val: source/destination register
		* @tmp: scratch register
		*/
		.macro rev_l, val:req, tmp:req
		.if __LINUX_ARM_ARCH__ < 6
		eor \tmp, \val, \val, ror #16
		bic \tmp, \tmp, #0x00ff0000
		mov \val, \val, ror #8
		eor \val, \val, \tmp, lsr #8
		.else
		rev \val, \val
		.endif
		.endm

		#endif /* __ASM_ASSEMBLER_H__ */