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

[ Upstream commit e0e949cd829171b87327cba8fdf0b8f984432a8f ]

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: 07cd9e9e75d8 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 46b697dfa4cfc3075a3686dbadb0ac340fc974e2..68261a83b7ad84d56984721fd44e920a1fc2261a 100644 (file)
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -1038,7 +1038,7 @@ vector_bhb_loop8_\name:
 
        @ bhb workaround
        mov     r0, #8
-3:     b       . + 4
+3:     W(b)    . + 4
        subs    r0, r0, #1
        bne     3b
        dsb