MIPS: Idle: Break r4k_wait into two functions and fix it.

local_irq_enable() may expand into very different code, so it rather should
stay in C.  Also this keeps the assembler code size constant which keeps
the rollback code simple.  So it's best to split r4k_wait into two parts,
one C and one assembler.

Finally add the local_irq_enable() to r4k_wait to ensure the WAIT
instruction in __r4k_wait() will work properly.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/idle.h

@@ -4,7 +4,8 @@
 #include <linux/linkage.h>
 
 extern void (*cpu_wait)(void);
-extern asmlinkage void r4k_wait(void);
+extern void r4k_wait(void);
+extern asmlinkage void __r4k_wait(void);
 extern void r4k_wait_irqoff(void);
 extern void __pastwait(void);
 

arch/mips/kernel/genex.S

@@ -122,7 +122,7 @@ handle_vcei:
 	__FINIT
 
 	.align	5	/* 32 byte rollback region */
-LEAF(r4k_wait)
+LEAF(__r4k_wait)
 	.set	push
 	.set	noreorder
 	/* start of rollback region */
@@ -146,14 +146,14 @@ LEAF(r4k_wait)
 	jr	ra
 	nop
 	.set	pop
-	END(r4k_wait)
+	END(__r4k_wait)
 
 	.macro	BUILD_ROLLBACK_PROLOGUE handler
 	FEXPORT(rollback_\handler)
 	.set	push
 	.set	noat
 	MFC0	k0, CP0_EPC
-	PTR_LA	k1, r4k_wait
+	PTR_LA	k1, __r4k_wait
 	ori	k0, 0x1f	/* 32 byte rollback region */
 	xori	k0, 0x1f
 	bne	k0, k1, 9f

arch/mips/kernel/idle.c

@@ -45,6 +45,12 @@ static void r39xx_wait(void)
 	local_irq_enable();
 }
 
+void r4k_wait(void)
+{
+	local_irq_enable();
+	__r4k_wait();
+}
+
 /*
  * This variant is preferable as it allows testing need_resched and going to
  * sleep depending on the outcome atomically.  Unfortunately the "It is