[PATCH] ARM: asm: __und_usr_thumb need byteswap instructions in BE case

[PATCH] ARM: asm: __und_usr_thumb need byteswap instructions in BE case

[Victor Kamensky]

__und_usr_thumb function deals with thumb2 opcodes. In case of BE
image, it needs to byteswap half word thumb2 encoded instructions
before further processing them.

Without this fix BE image user-land thread executing first VFP
instruction encoded in thumb2 fails with SIGILL, because kernel
does not recognize instruction and does not enable VFP.

Reported-by: Corey Melton <comelton@cisco.com>
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
---
 arch/arm/kernel/entry-armv.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index b3fb8c9..1879e8d 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -451,9 +451,11 @@ __und_usr_thumb:
 	.arch	armv6t2
 #endif
 2:	ldrht	r5, [r4]
+ARM_BE8(rev16	r5, r5)				@ little endian instruction
 	cmp	r5, #0xe800			@ 32bit instruction if xx != 0
 	blo	__und_usr_fault_16		@ 16bit undefined instruction
 3:	ldrht	r0, [r2]
+ARM_BE8(rev16	r0, r0)				@ little endian instruction
 	add	r2, r2, #2			@ r2 is PC + 2, make it PC + 4
 	str	r2, [sp, #S_PC]			@ it's a 2x16bit instr, update
 	orr	r0, r0, r5, lsl #16
-- 
1.8.1.4

[PATCH] ARM: asm: __und_usr_thumb need byteswap instructions in BE case

[Dave Martin]

On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
> __und_usr_thumb function deals with thumb2 opcodes. In case of BE
> image, it needs to byteswap half word thumb2 encoded instructions
> before further processing them.
> 
> Without this fix BE image user-land thread executing first VFP
> instruction encoded in thumb2 fails with SIGILL, because kernel
> does not recognize instruction and does not enable VFP.
> 
> Reported-by: Corey Melton <comelton@cisco.com>
> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>

Good spot.  This looks like the correct fix to me.

Acked-by: Dave Martin <Dave.Martin@arm.com>

> ---
>  arch/arm/kernel/entry-armv.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
> index b3fb8c9..1879e8d 100644
> --- a/arch/arm/kernel/entry-armv.S
> +++ b/arch/arm/kernel/entry-armv.S
> @@ -451,9 +451,11 @@ __und_usr_thumb:
>  	.arch	armv6t2
>  #endif
>  2:	ldrht	r5, [r4]
> +ARM_BE8(rev16	r5, r5)				@ little endian instruction
>  	cmp	r5, #0xe800			@ 32bit instruction if xx != 0
>  	blo	__und_usr_fault_16		@ 16bit undefined instruction
>  3:	ldrht	r0, [r2]
> +ARM_BE8(rev16	r0, r0)				@ little endian instruction
>  	add	r2, r2, #2			@ r2 is PC + 2, make it PC + 4
>  	str	r2, [sp, #S_PC]			@ it's a 2x16bit instr, update
>  	orr	r0, r0, r5, lsl #16
> -- 
> 1.8.1.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH] ARM: asm: __und_usr_thumb need byteswap instructions in BE case

[Stephen Boyd]

On 01/14/14 01:05, Dave Martin wrote:
> On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
>> __und_usr_thumb function deals with thumb2 opcodes. In case of BE
>> image, it needs to byteswap half word thumb2 encoded instructions
>> before further processing them.
>>
>> Without this fix BE image user-land thread executing first VFP
>> instruction encoded in thumb2 fails with SIGILL, because kernel
>> does not recognize instruction and does not enable VFP.
>>
>> Reported-by: Corey Melton <comelton@cisco.com>
>> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
> Good spot.  This looks like the correct fix to me.
>
> Acked-by: Dave Martin <Dave.Martin@arm.com>
>

Can you please send this to the patch tracker? Feel free to add

Tested-by: Stephen Boyd <sboyd@codeaurora.org>

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[PATCH] ARM: asm: __und_usr_thumb need byteswap instructions in BE case

[Victor Kamensky]

On 20 January 2014 17:56, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 01/14/14 01:05, Dave Martin wrote:
>> On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
>>> __und_usr_thumb function deals with thumb2 opcodes. In case of BE
>>> image, it needs to byteswap half word thumb2 encoded instructions
>>> before further processing them.
>>>
>>> Without this fix BE image user-land thread executing first VFP
>>> instruction encoded in thumb2 fails with SIGILL, because kernel
>>> does not recognize instruction and does not enable VFP.
>>>
>>> Reported-by: Corey Melton <comelton@cisco.com>
>>> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
>> Good spot.  This looks like the correct fix to me.
>>
>> Acked-by: Dave Martin <Dave.Martin@arm.com>
>>
>
> Can you please send this to the patch tracker? Feel free to add
>
> Tested-by: Stephen Boyd <sboyd@codeaurora.org>

Thanks. It is done on both counts. Patch is submitted as [1].

Thanks,
Victor

[1] http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7946/1

> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
>