ppc64: update for recent changes that require switch_to to return prev

arch/ppc64/kernel/entry.S

@@ -301,6 +301,8 @@ _GLOBAL(_switch)
 	REST_8GPRS(14, r1)
 	REST_10GPRS(22, r1)
 
+	/* convert old thread to its task_struct for return value */
+	addi	r3,r3,-THREAD
 	ld	r7,_NIP(r1)	/* Return to _switch caller in new task */
 	mtlr	r7
 	addi	r1,r1,SWITCH_FRAME_SIZE

arch/ppc64/kernel/process.c

@@ -82,11 +82,12 @@ dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 	return 1;
 }
 
-void
-__switch_to(struct task_struct *prev, struct task_struct *new)
+struct task_struct *__switch_to(struct task_struct *prev,
+				struct task_struct *new)
 {
 	struct thread_struct *new_thread, *old_thread;
 	unsigned long flags;
+	struct task_struct *last;
 
 #ifdef CONFIG_SMP
 	/* avoid complexity of lazy save/restore of fpu
@@ -106,8 +107,9 @@ __switch_to(struct task_struct *prev, struct task_struct *new)
 	old_thread = &current->thread;
 
 	local_irq_save(flags);
-	_switch(old_thread, new_thread);
+	last = _switch(old_thread, new_thread);
 	local_irq_restore(flags);
+	return last;
 }
 
 static void show_tsk_stack(struct task_struct *p, unsigned long sp);

include/asm-ppc64/system.h

@@ -89,11 +89,13 @@ extern void cvt_df(double *from, float *to, unsigned long *fpscr);
 extern int abs(int);
 
 struct task_struct;
-extern void __switch_to(struct task_struct *, struct task_struct *);
-#define switch_to(prev, next, last) __switch_to((prev), (next))
+extern struct task_struct *__switch_to(struct task_struct *,
+				       struct task_struct *);
+#define switch_to(prev, next, last)	((last) = __switch_to((prev), (next)))
 
 struct thread_struct;
-extern void _switch(struct thread_struct *prev, struct thread_struct *next);
+extern struct task_struct * _switch(struct thread_struct *prev,
+				    struct thread_struct *next);
 
 struct pt_regs;
 extern void dump_regs(struct pt_regs *);