Re: [PATCH RFC 12/67] MIPS: asm: asmmacro: Replace add instructions with "addui"

[Markos Chandras <Markos.Chandras@imgtec.com>]

On 01/11/2015 11:34 PM, Maciej W. Rozycki wrote:
> On Fri, 19 Dec 2014, Markos Chandras wrote:
> 
>>>> The use of "add" instruction for immediate operations is wrong and
>>>> relies to gas being smart enough to notice that and replace it with
>>>> either addi or addui. However, MIPS R6 removed the addi instruction
>>>> so, fix this problem properly by using the correct instruction
>>>> directly.
> 
>  Not true, depending on the arguments the ADD assembly macro expands to 
> either of the ADD and the ADDI hardware instructions; where an immediate 
> outside the 16-bit signed range is used it also expands to a longer 
> sequence involving LUI and the actual operation is ADD.  It never expands 
> to ADDIU (which I gather you meant).
> 
>>> This is another case of the use of "add" being a real bug.  We should
>>> never have faulting instructions like this in the kernel.
>>>
>>> Can you send all patches in this set that fix this bug as a separate
>>> patch?  Since they are obviously correct, and really should be used by
>>> all non-R6 processors, we can get them in sooner that the entire R6 thing.
>>>
>>> Thanks,
>>> David Daney
>>
>> sure i will move these patches away from R6 and post them separately.
> 
>  I think using the ADDU macro is preferred here as it allows arbitrary 
> 32-bit values for `off', just like with memory references in MIPS assembly 
> instructions.
> 
>   Maciej
> 
Hi,

What ADDU macro?

-- 
markos