interrupt_exit_kernel_prepare() on booke/32 has a useless 'mfmsr' and two 'wrteei 0'

[Christophe Leroy]

44x/bamboo_defconfig

For the mfmsr, that's because mfmsr is defined as 'asm volatile'. Is that correct ? Reading MSR 
doesn't have any side effects as far as I know, should we remove the volatile ?

For the wrteei, that's because we are calling __hard_EE_RI_disable() after local_irq_save(). On 
booke those two fonctions do exactly the same because RI doesn't exist. Could we replace that by a 
__hard_RI_disable() that would be a nop on booke ?


00000364 <interrupt_exit_kernel_prepare>:
  364:	81 23 00 84 	lwz     r9,132(r3)
  368:	55 29 04 62 	rlwinm  r9,r9,0,17,17
  36c:	0f 09 00 00 	twnei   r9,0
  370:	81 22 00 4c 	lwz     r9,76(r2)
  374:	75 23 00 01 	andis.  r3,r9,1
  378:	40 82 00 14 	bne     38c <interrupt_exit_kernel_prepare+0x28>
  37c:	7d 20 00 a6 	mfmsr   r9
  380:	7c 00 01 46 	wrteei  0
  384:	7c 00 01 46 	wrteei  0
  388:	4e 80 00 20 	blr
  38c:	38 e2 00 4c 	addi    r7,r2,76
  390:	3d 20 00 01 	lis     r9,1
  394:	7c c0 38 28 	lwarx   r6,0,r7
  398:	7c c6 48 78 	andc    r6,r6,r9
  39c:	7c c0 39 2d 	stwcx.  r6,0,r7
  3a0:	40 a2 ff f4 	bne     394 <interrupt_exit_kernel_prepare+0x30>
  3a4:	38 60 00 01 	li      r3,1
  3a8:	4b ff ff d4 	b       37c <interrupt_exit_kernel_prepare+0x18>