linux-kernel - Re: [PATCH] LoongArch: Handle fp, lsx, lasx and lbt assembly symbols

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3019eada-7496-ca11-b645-f5efd7d215f4@loongson.cn>
Date: Fri, 11 Apr 2025 10:47:11 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Wentao Guan <guanwentao@...ontech.com>
Cc: chenhuacai@...nel.org, linux-kernel@...r.kernel.org,
 loongarch@...ts.linux.dev
Subject: Re: [PATCH] LoongArch: Handle fp, lsx, lasx and lbt assembly symbols

On 04/09/2025 12:12 AM, Wentao Guan wrote:
> Hello Yang,
>
> I don`t know why change it defination remove "asmlinkage",
> why not explain it in commit message?

$ grep -rnw "define asmlinkage" .
./arch/x86/include/asm/linkage.h:20:#define asmlinkage CPP_ASMLINKAGE 
__attribute__((regparm(0)))
./include/linux/linkage.h:22:#define asmlinkage CPP_ASMLINKAGE

include/linux/linkage.h

#ifdef __cplusplus
#define CPP_ASMLINKAGE extern "C"
#else
#define CPP_ASMLINKAGE
#endif

#ifndef asmlinkage
#define asmlinkage CPP_ASMLINKAGE
#endif

So for LoongArch, asmlinkage means extern "C" or NULL, there is no
need to use asmlinkage for these prototypes because they are not put
in uapi headers, that is to say, they will be called and built only
by C compiler rather than C++ compiler, so asmlinkage is actually
NULL in this case.

Furthermore, there are no asmlinkage for the other exist prototypes
such as _save_fp, _restore_fp in arch/loongarch/include/asm/fpu.h,
so in my opinion, just keep them consistent.

But according to Documentation/process/coding-style.rst, it seems
asmlinkage should be used.

"Large, non-trivial assembly functions should go in .S files, with 
corresponding
C prototypes defined in C header files.  The C prototypes for assembly
functions should use ``asmlinkage``."

There are two ways:
(1) no need to use asmlinkage for these new added prototypes for
     assembly functions in asm/fpu.h and asm/lbt.h to keep consistent.

(2) use asmlinkage for these new added prototypes for assembly functions
     in asm/fpu.h and asm/lbt.h according to Documentation, and then add
     asmlinkage for the other exist prototypes if necessary.

That's up to the arch maintainer Huacai.

Thanks,
Tiezhu