ARM: 6166/1: Proper prefetch abort handling on pre-ARMv6

Instruction faults on pre-ARMv6 CPUs are interpreted as
a 'translation fault', but do_translation_fault doesn't
handle well if user mode trying to run instruction above
TASK_SIZE, and result in the infinite retry of that
instruction.

CC: <stable@kernel.org>
Signed-off-by: NAnfei Zhou <anfei.zhou@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/fault.c

@@ -393,6 +393,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 	if (addr < TASK_SIZE)
 		return do_page_fault(addr, fsr, regs);
 
+	if (user_mode(regs))
+		goto bad_area;
+
 	index = pgd_index(addr);
 
 	/*