[ARM] Pass prev task_struct through __switch_to

arch/arm/kernel/entry-armv.S

@@ -997,11 +997,11 @@ ENTRY(fp_enter)
  * previous and next are guaranteed not to be the same.
  */
 ENTRY(__switch_to)
-		add	ip, r0, #TI_CPU_SAVE
-		ldr	r2, [r1, #TI_CPU_DOMAIN]!
+		add	ip, r1, #TI_CPU_SAVE
+		ldr	r3, [r2, #TI_CPU_DOMAIN]!
 		stmia	ip, {r4 - sl, fp, sp, lr}	@ Store most regs on stack
-		mcr	p15, 0, r2, c3, c0		@ Set domain register
-		ldmib	r1, {r4 - sl, fp, sp, pc}	@ Load all regs saved previously
+		mcr	p15, 0, r3, c3, c0, 0		@ Set domain register
+		ldmib	r2, {r4 - sl, fp, sp, pc}	@ Load all regs saved previously
 
 		__INIT
 /*

arch/arm/kernel/entry-common.S

@@ -75,7 +75,6 @@ no_work_pending:
  * This is how we return from a fork.
  */
 ENTRY(ret_from_fork)
-	ldr	r0, [r0, #TI_TASK]
 	bl	schedule_tail
 	get_thread_info tsk
 	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing

include/asm-arm/system.h

@@ -65,11 +65,12 @@ extern int cpu_architecture(void);
  * The `mb' is to tell GCC not to cache `current' across this call.
  */
 struct thread_info;
-extern struct thread_info *__switch_to(struct thread_info *, struct thread_info *);
+struct task_struct;
+extern struct task_struct *__switch_to(struct task_struct *, struct thread_info *, struct thread_info *);
 
 #define switch_to(prev,next,last)						\
 	do {									\
-		__switch_to(prev->thread_info,next->thread_info);	\
+		last = __switch_to(prev,prev->thread_info,next->thread_info);	\
 		mb();								\
 	} while (0)