Subject: [PATCH 2/4] ARM: traps: use <asm/opcodes.h> to get correct instruction order

From: [email-masked] (Dave Martin)
Date: Wed, 24 Jul 2013 18:34:35 +0100

On Mon, Jul 22, 2013 at 05:33:51PM +0100, Ben Dooks wrote:
> The trap handler needs to take into account the endian configuration of
> the system when loading instructions. Use <asm/opcodes.h> to provide the
> necessary conversion functions.
> 
> Signed-off-by: Ben Dooks <[email-masked]>
> ---
>  arch/arm/kernel/traps.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 1c08911..0a56e13 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -34,6 +34,7 @@
>  #include <asm/unwind.h>
>  #include <asm/tls.h>
>  #include <asm/system_misc.h>
> +#include <asm/opcodes.h>
>  
>  #include "signal.h"

Looks like is_valid_bugaddr() might need fixing too?

That will need __mem_to_opcode_thumb16() or __mem_to_opcode_arm()
depending on CONFIG_THUMB2_KERNEL.

>  
> @@ -411,23 +412,24 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
>  	if (processor_mode(regs) == SVC_MODE) {
>  #ifdef CONFIG_THUMB2_KERNEL
>  		if (thumb_mode(regs)) {
> -			instr = ((u16 *)pc)[0];
> +			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>  			if (is_wide_instruction(instr)) {
>  				instr <<= 16;
> -				instr |= ((u16 *)pc)[1];
> +				instr |= __mem_to_opcode_thumb16(((u16 *)pc)[1]);

Could use __opcode_thumb32_compose(), in which case it might look like

			if (is_wide_instruction(instr)) {
				unsigned int instr2 = __mem_to_opcode_thumb16(
					((u16 *)pc)[1]);
				instr = __opcode_thumb32_compose(instr, instr2);

(Hmmm, I just noticed that is_wide_instruction and __opcode_is_thumb16()
kinda duplicate each other.  Could change that too, but it would look
more like pointless churn...  is_wide_instruction() is used in a fair
few places already.)

>  			}
>  		} else
>  #endif
> -			instr = *(u32 *) pc;
> +			instr = __mem_to_opcode_arm(*(u32 *) pc);
>  	} else if (thumb_mode(regs)) {
>  		if (get_user(instr, (u16 __user *)pc))
>  			goto die_sig;
> +		instr = __mem_to_opcode_thumb16(instr);
>  		if (is_wide_instruction(instr)) {
>  			unsigned int instr2;
>  			if (get_user(instr2, (u16 __user *)pc+1))
>  				goto die_sig;
>  			instr <<= 16;
> -			instr |= instr2;
> +			instr |= __mem_to_opcode_thumb16(instr2);
>  		}
>  	} else if (get_user(instr, (u32 __user *)pc)) {

This also needs mem-to-opcode'ing.

Cheers
---Dave