[PATCH] ARM: proc-v7: fix Thumb annotation of cpu_v7_hvc_switch_mm

[marc.zyngier@arm.com (Marc Zyngier)]

Hi all,

On 19/06/18 17:29, Ard Biesheuvel wrote:
> Due to what appears to be a copy/paste error, the opening ENTRY()
> of cpu_v7_hvc_switch_mm() lacks a matching ENDPROC(), and instead,
> the one for cpu_v7_smc_switch_mm() is duplicated.
> 
> Given that it is ENDPROC() that emits the Thumb annotation, the
> cpu_v7_hvc_switch_mm() routine will be called in ARM mode on a
> Thumb2 kernel, resulting in the following splat:
> 
>   Internal error: Oops - undefined instruction: 0 [#1] SMP THUMB2
>   Modules linked in:
>   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc1-00030-g4d28ad89189d-dirty #488
>   Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
>   PC is at cpu_v7_hvc_switch_mm+0x12/0x18
>   LR is at flush_old_exec+0x31b/0x570
>   pc : [<c0316efe>]    lr : [<c04117c7>]    psr: 00000013
>   sp : ee899e50  ip : 00000000  fp : 00000001
>   r10: eda28f34  r9 : eda31800  r8 : c12470e0
>   r7 : eda1fc00  r6 : eda53000  r5 : 00000000  r4 : ee88c000
>   r3 : c0316eec  r2 : 00000001  r1 : eda53000  r0 : 6da6c000
>   Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> 
> Note the 'ISA ARM' in the last line.
> 
> Fix this by using the correct name in ENDPROC().
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  arch/arm/mm/proc-v7.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index 6fe52819e014..339eb17c9808 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -112,7 +112,7 @@ ENTRY(cpu_v7_hvc_switch_mm)
>  	hvc	#0
>  	ldmfd	sp!, {r0 - r3}
>  	b	cpu_v7_switch_mm
> -ENDPROC(cpu_v7_smc_switch_mm)
> +ENDPROC(cpu_v7_hvc_switch_mm)
>  #endif
>  ENTRY(cpu_v7_iciallu_switch_mm)
>  	mov	r3, #0
> 

I've just spent a couple of hours chasing this exact bug, only to notice
that the problem was already known. Ard, can you please send this to
RMK's patch system so that it doesn't get dropped?

Please add my: Acked-by: Marc Zyngier <marc.zyngier@arm.com>
and Cc stable, as this is quite an annoying regression.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...