[PATCH 12/14] ARM: traps: use to get correct instruction order

Will Deacon
2013-07-24T16:20:37Z

On Wed, Jul 24, 2013 at 11:28:00AM +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 <ben.dooks@codethink.co.uk>
> ---
> 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 18b32e8..c300e51 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"
>
> @@ -404,23 +405,24 @@ 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]);
> }
> } 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)) {
> goto die_sig;

Maybe it's also worth updating dump_instr, so that we don't confuse people
by printing the faulting instruction in the wrong endianness.

Will