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Date: Tue, 24 Mar 2015 20:34:22 +0100
From: Denys Vlasenko <dvlasenk@redhat.com>
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To: Ingo Molnar <mingo@kernel.org>
CC: Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/asm/entry/64: Merge the field offset into the THREAD_INFO()
 macro
References: <1426785469-15125-1-git-send-email-dvlasenk@redhat.com> <20150324184411.GB14760@gmail.com> <5511B1EA.1000100@redhat.com> <20150324192926.GA23521@gmail.com>
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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.