[PATCH] ARM: fix Thumb2 regression with Spectre BHB

[PATCH] ARM: fix Thumb2 regression with Spectre BHB

[Russell King (Oracle)]

When building for Thumb2, the vectors make use of a local label. Sadly,
the Spectre BHB code also uses a local label with the same number which
results in the Thumb2 reference pointing at the wrong place. Fix this
by changing the number used for the Spectre BHB local label.

Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 arch/arm/kernel/entry-armv.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index faa0ca2ba576..63a9d59478fa 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -962,9 +962,9 @@ ENDPROC(vector_\name)
 
 	@ bhb workaround
 	mov	r0, #8
-1:	b	. + 4
+3:	b	. + 4
 	subs	r0, r0, #1
-	bne	1b
+	bne	3b
 	dsb
 	isb
 	b	2b
-- 
2.30.2


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Re: [PATCH] ARM: fix Thumb2 regression with Spectre BHB

[Russell King (Oracle)]

On Fri, Mar 11, 2022 at 05:08:07PM +0000, Russell King (Oracle) wrote:
> When building for Thumb2, the vectors make use of a local label. Sadly,
> the Spectre BHB code also uses a local label with the same number which
> results in the Thumb2 reference pointing at the wrong place. Fix this
> by changing the number used for the Spectre BHB local label.
> 
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Hmm, let me resend this with a Fixes tag and Cc stable!

-- 
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