linux-kernel - Re: [PATCH] kernel/modsign_certificate.S: use real contents instead of macro GLOBAL()

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Message-ID: <526BD473.9040703@gmail.com>
Date:	Sat, 26 Oct 2013 22:40:51 +0800
From:	Chen Gang F T <chen.gang.flying.transformer@...il.com>
To:	Chen Gang <gang.chen@...anux.com>
CC:	Josh Boyer <jwboyer@...oraproject.org>,
	Joern Rennecke <joern.rennecke@...ecosm.com>,
	James Hogan <james.hogan@...tec.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Takashi Iwai <tiwai@...e.de>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	"jeremy.bennett@...ecosm.com" <jeremy.bennett@...ecosm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Claudiu Zissulescu <Claudiu.Zissulescu@...opsys.com>,
	Francois Bedard <Francois.Bedard@...opsys.com>
Subject: Re: [PATCH] kernel/modsign_certificate.S: use real contents instead
 of macro GLOBAL()

On 10/26/2013 10:42 AM, Chen Gang wrote:
> On 10/24/2013 11:29 PM, Josh Boyer wrote:
>> On Wed, Oct 23, 2013 at 10:31 PM, Chen Gang <gang.chen@...anux.com> wrote:
>>> For some architectures, tool chain is not smart enough to recognize the
>>> macro with multiple lines (e.g. arc tool chain), and for common ".S"
>>> file, this kind of macro is also rarely used.
>>>
>>> So expand the related contents of macro to let it pass compiling (can
>>> use "arc-elf32-objdump -x" to know about it).
>>>
>>> The related error (allmodconfig for arc):
>>>
>>>     LD      init/built-in.o
>>>   kernel/built-in.o: In function `load_module_signing_keys':
>>>   kernel/modsign_pubkey.c:66: undefined reference to `modsign_certificate_list'
>>>   kernel/modsign_pubkey.c:71: undefined reference to `modsign_certificate_list_end'
>>>   kernel/modsign_pubkey.c:67: undefined reference to `modsign_certificate_list_end'
>>>
>>> The related tool chain information:
>>>
>>>   [root@...enlinux linux-next]# arc-elf32-as -v
>>>   GNU assembler version 2.23.2 (arc-elf32) using BFD version (GNU Binutils) 2.23.2
>>>   [root@...enlinux linux-next]# arc-elf32-ld -v
>>>   GNU ld (GNU Binutils) 2.23.2
>>>   [root@...enlinux linux-next]# arc-elf32-gcc -v
>>>   Using built-in specs.
>>>   COLLECT_GCC=arc-elf32-gcc
>>>   COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/arc-elf32/4.8.0/lto-wrapper
>>>   Target: arc-elf32
>>>   Configured with: ../gcc/configure --without-header --disable-nls --enable-language=c --disable-threads --disable-shared --enable-werror=no target_configargs=enable_vtable_verify=yes --target=arc-elf32 --with-cpu=arc700 : (reconfigured) ../gcc/configure --disable-nls --enable-language=c --disable-threads --disable-shared --enable-werror=no target_configargs=enable_vtable_verify=yes --target=arc-elf32 --with-cpu=arc700 : (reconfigured) ../gcc/configure --without-header --disable-nls --enable-language=c --disable-threads --disable-shared --enable-werror=no target_configargs=enable_vtable_verify=yes --target=arc-elf32 --with-cpu=arc700 --disable-multilib --with-headers=../newlib/newlib/libc/include
>>>   Thread model: single
>>>   gcc version 4.8.0 (GCC)
>>
>> Is this only an issue with using multi-line macro definitions in .S
>> files?  The practice of using multi-line macro definitions isn't rare.
>>  Look at e.g. include/linux/module.h, and a number of other header
>> files.
>>

> 
> Yes, excluding "arch/*", for all ".S" files, except x86 driver and this
> file, no others use multi-line macro definition, and "arch/arc" don't
> use mulit-line macro definitions, either.
> 

Oh, sorry, what my written is not quite precise, and my real meaning is:
"no others *intend* to use multi-line macro definition in *.S".

> The related search command is:
> 
>   "find | grep -i "\.S$" | grep -v "/arch/"  | grep -v "Documentation" | xargs grep define".
> 
> Hmm... at least, in our case, we need not use the multi-line macro
> definition, if expand it, the total lines will be shrunk, that will
> be more clearer and simpler to source code readers and writers.
> 
> 
>> This seems like a toolchain bug that should be fixable if it works for
>> other architectures.
>>
> 
> Hmm... at least, we are sure the toolchain is not quite smart enough
> (but we can not say it must be a bug).
> 
> 
> So for me, I recommend to apply this patch (maybe the patch comment
> need improvement). It is quite valuable to continue discussing about
> it, but it is not related with whether applying this patch or not.
> 
>> josh
>>
>>
> 
> Thanks.
> 


-- 
Chen Gang
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