linux-kernel - Re: [PATCH v2] arch: use ASM_NL instead of ';' for assembler new line character in the macro

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Message-ID: <528DE5F1.20609@gmail.com>
Date:	Thu, 21 Nov 2013 18:52:33 +0800
From:	Chen Gang <gang.chen.5i5j@...il.com>
To:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
CC:	Chen Gang <gang.chen@...anux.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Rusty Russell <rusty@...tcorp.com.au>,
	James Hogan <james.hogan@...tec.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	Max Filippov <jcmvbkbc@...il.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Tim Abbott <tabbott@...lice.com>,
	Joe Perches <joe@...ches.com>, Michal Marek <mmarek@...e.cz>,
	David Howells <dhowells@...hat.com>
Subject: Re: [PATCH v2] arch: use ASM_NL instead of ';' for assembler new
 line character in the macro

On 11/21/2013 05:58 PM, Vineet Gupta wrote:
> On 11/01/2013 11:15 AM, Vineet Gupta wrote:
>> +CC Sam, Tim, Joe, Michal, David
>>
>> Guys can you please take a look at this patch and suggest the best way to merge.
>>
>> The root cause is some gas ports (including ARC) use ';' for comment (vs. newline)
>> More background at https://lkml.org/lkml/2013/10/24/365
> 
> Ping ! Any objections to this. Given that this is exception case, it is simpler
> than defining a Kconfig control.
> 

Hmm... I guess your meaning is that define a macro (e.g. ASM_NL) in
Kconfig instead of in "asm/linkage.h".

For me, I still recommend to define a macro in "asm/linkage.h", "in
Kconfig" is not quite straight and simple than current way:

 - "in Kconfig" need 2 macros for it, but "asm/linkage.h" need 1.

 - Kconfig is normally for using configurations (face to downstream)
   upstream related configurations (e.g. related with compiler) are
   often in Makefile or specific header files (e.g "linkage.h")

Thanks.

> -Vineet
>>
>>
>> On 10/29/2013 07:21 AM, Chen Gang wrote:
>>> For some assemblers, they use another character as newline in a macro
>>> (e.g. arc uses '`'), so for generic assembly code, need use ASM_NL (a
>>> macro) instead of ';' for it.
>>>
>>> Also need notice about code styles ('\t' for each line).
>>>
>>>
>>> Signed-off-by: Chen Gang <gang.chen@...anux.com>
>>> ---
>>>  arch/arc/include/asm/linkage.h |    2 ++
>>>  include/linux/linkage.h        |   19 ++++++++++++-------
>>>  2 files changed, 14 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/arch/arc/include/asm/linkage.h b/arch/arc/include/asm/linkage.h
>>> index 0283e9e..66ee552 100644
>>> --- a/arch/arc/include/asm/linkage.h
>>> +++ b/arch/arc/include/asm/linkage.h
>>> @@ -11,6 +11,8 @@
>>>  
>>>  #ifdef __ASSEMBLY__
>>>  
>>> +#define ASM_NL		 `	/* use '`' to mark new line in macro */
>>> +
>>>  /* Can't use the ENTRY macro in linux/linkage.h
>>>   * gas considers ';' as comment vs. newline
>>>   */
>>> diff --git a/include/linux/linkage.h b/include/linux/linkage.h
>>> index d3e8ad2..a6a42dd 100644
>>> --- a/include/linux/linkage.h
>>> +++ b/include/linux/linkage.h
>>> @@ -6,6 +6,11 @@
>>>  #include <linux/export.h>
>>>  #include <asm/linkage.h>
>>>  
>>> +/* Some toolchains use other characters (e.g. '`') to mark new line in macro */
>>> +#ifndef ASM_NL
>>> +#define ASM_NL		 ;
>>> +#endif
>>> +
>>>  #ifdef __cplusplus
>>>  #define CPP_ASMLINKAGE extern "C"
>>>  #else
>>> @@ -75,21 +80,21 @@
>>>  
>>>  #ifndef ENTRY
>>>  #define ENTRY(name) \
>>> -  .globl name; \
>>> -  ALIGN; \
>>> -  name:
>>> +	.globl name ASM_NL \
>>> +	ALIGN ASM_NL \
>>> +	name:
>>>  #endif
>>>  #endif /* LINKER_SCRIPT */
>>>  
>>>  #ifndef WEAK
>>>  #define WEAK(name)	   \
>>> -	.weak name;	   \
>>> +	.weak name ASM_NL   \
>>>  	name:
>>>  #endif
>>>  
>>>  #ifndef END
>>>  #define END(name) \
>>> -  .size name, .-name
>>> +	.size name, .-name
>>>  #endif
>>>  
>>>  /* If symbol 'name' is treated as a subroutine (gets called, and returns)
>>> @@ -98,8 +103,8 @@
>>>   */
>>>  #ifndef ENDPROC
>>>  #define ENDPROC(name) \
>>> -  .type name, @function; \
>>> -  END(name)
>>> +	.type name, @function ASM_NL \
>>> +	END(name)
>>>  #endif
>>>  
>>>  #endif
>>>
>>
> 
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-- 
Chen Gang
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