[PATCH 11/14] ARM: alignment: correctly decode instructions in BE8 mode.

Ben Dooks
2013-07-24T10:27:59Z

If we are in BE8 mode, we must deal with the instruction stream being
in LE order when data is being loaded in BE order. Ensure the data is
swapped before processing to avoid thre following:

Change to using <asm/opcodes.h> to provide the necessary conversion
functions to change the byte ordering.

Alignment trap: not handling instruction 030091e8 at [<80333e8c>]
Unhandled fault: alignment exception (0x001) at 0xbfa09567

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
arch/arm/mm/alignment.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 6f4585b..f38145a 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -25,6 +25,7 @@
#include <asm/cp15.h>
#include <asm/system_info.h>
#include <asm/unaligned.h>
+#include <asm/opcodes.h>

#include "fault.h"

@@ -762,21 +763,24 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (thumb_mode(regs)) {
u16 *ptr = (u16 *)(instrptr & ~1);
fault = probe_kernel_address(ptr, tinstr);
+ tinstr = __mem_to_opcode_thumb16(tinstr);
if (!fault) {
if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
IS_T32(tinstr)) {
/* Thumb-2 32-bit */
u16 tinst2 = 0;
fault = probe_kernel_address(ptr + 1, tinst2);
+ tinst2 = __mem_to_opcode_thumb16(tinst2);
instr = (tinstr << 16) | tinst2;
thumb2_32b = 1;
} else {
isize = 2;
- instr = thumb2arm(tinstr);
}
}
- } else
+ } else {
fault = probe_kernel_address(instrptr, instr);
+ instr = __mem_to_opcode_arm(instr);
+ }

if (fault) {
type = TYPE_FAULT;
--
1.7.10.4