Re: [PATCH] x86/asm/entry/64: Merge the field offset into the THREAD_INFO() macro

From: Denys Vlasenko
Date: Tue Mar 24 2015 - 15:34:58 EST


On 03/24/2015 08:29 PM, Ingo Molnar wrote:
>>> Before:
>>>
>>> TI_sysenter_return+THREAD_INFO(%rsp,3*8),%r10d
>>>
>>> After:
>>>
>>> movl THREAD_INFO(TI_sysenter_return, %rsp, 3*8), %r10d
>>>
>>> to turn it into a clear thread_info accessor.
>>
>> Good idea, I also wanted to do this.
>> I propose a more C-like order of arguments instead.
>> In C, field names are on the right: obj.field, ptr->field.
>>
>> THREAD_INFO(%rsp, 3*8, TI_field_name)
>>
>> would suggest to the reader a pseudo-C construct:
>>
>> THREAD_INFO(sp, offset)->field_name
>
> So I picked that order, because the C code we want to emulate here
> visually is:
>
> thread_info->field_name
>
> and visually this order represents just that:
>
> THREAD_INFO(TI_field_name, ...)
>
> " ,%reg, offset" in that sense is just a 'detail' to how to access
> thread_info.
>
> That order also resembles the assembly format more, which is usually
> in field(reg) order, i.e.:
>
> THREAD_INFO(field, %reg, ...)
>
> Hm?

Okay.

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