From: Ard Biesheuvel <ardb@kernel.org>
Date: Wed, 20 Apr 2022 08:46:17 +0000 (+0100)
Subject: ARM: 9197/1: spectre-bhb: fix loop8 sequence for Thumb2
X-Git-Tag: dma-mapping-5.19-2022-06-26~356^2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3cfb3019979666bdf33a1010147363cf05e0f17b;p=users%2Fhch%2Fdma-mapping.git

ARM: 9197/1: spectre-bhb: fix loop8 sequence for Thumb2

In Thumb2, 'b . + 4' produces a branch instruction that uses a narrow
encoding, and so it does not jump to the following instruction as
expected. So use W(b) instead.

Fixes: 6c7cb60bff7a ("ARM: fix Thumb2 regression with Spectre BHB")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 06508698abb8..7a8682468a84 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -1145,7 +1145,7 @@ vector_bhb_loop8_\name:
 
 	@ bhb workaround
 	mov	r0, #8
-3:	b	. + 4
+3:	W(b)	. + 4
 	subs	r0, r0, #1
 	bne	3b
 	dsb