[PATCH 1/2] powerpc/vdso64: Coarse timer support preparatory patch

[Michael Ellerman]

Thanks for reviewing Naveen.

"Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> writes:
> On 2017/09/18 09:23AM, Santosh Sivaraj wrote:
>> diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
>> index 382021324883..a0b4943811db 100644
>> --- a/arch/powerpc/kernel/vdso64/gettimeofday.S
>> +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
>> @@ -60,18 +60,20 @@ V_FUNCTION_END(__kernel_gettimeofday)
>>   */
>>  V_FUNCTION_BEGIN(__kernel_clock_gettime)
>>    .cfi_startproc
>> +	mr	r11,r4			/* r11 saves tp */
>> +	mflr	r12			/* r12 saves lr */
>> +	lis	r7,NSEC_PER_SEC at h	/* want nanoseconds */
>> +	ori	r7,r7,NSEC_PER_SEC at l
>> +
>>  	/* Check for supported clock IDs */
>>  	cmpwi	cr0,r3,CLOCK_REALTIME
>>  	cmpwi	cr1,r3,CLOCK_MONOTONIC
>>  	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>> -	bne	cr0,99f
>> +	beq	cr0,49f
>> 
>> -	mflr	r12			/* r12 saves lr */
>> +	b	99f		/* Fallback to syscall */
>
> 'beq', followed by a 'b' looks weird without considering the next patch.  
> I think this can be organized better to not have to update r7/r11/r12 if 
> using the system call. See next patch for my comments.
>
>>    .cfi_register lr,r12
>
> If you move the mflr, you should move the above line along with it.

s/should/must/.

It literally says "lr is saved in r12".

cheers