linux-kernel - Re: [PATCH -next v2 1/2] riscv: uaccess: rename __get/put_user_nocheck to __get/put_mem

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Message-ID: <c0e286b4-3005-71fb-3bb2-476944099d4e@huawei.com>
Date:   Sat, 27 Aug 2022 18:43:06 +0800
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Arnd Bergmann <arnd@...db.de>
CC:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        <Conor.Dooley@...rochip.com>, <linux-riscv@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <wangkefeng.wang@...wei.com>,
        Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH -next v2 1/2] riscv: uaccess: rename
 __get/put_user_nocheck to __get/put_mem_nocheck



在 2022/8/26 17:30, Arnd Bergmann 写道:
> On Mon, Aug 15, 2022 at 5:20 AM Tong Tiangen <tongtiangen@...wei.com> wrote:
>>
>> Current, The helpers __get/put_user_nocheck() is used by get/put_user() and
>> __get/put_kernel_nofault(), which is not always uaccess, so the name with
>> *user* is not appropriate.
>>
>> Also rename xxx_user_xxx to xxx_mem_xx  on the call path of
>> __get/put_user_nocheck()
>>
>> Only refactor code without any functional changes.
>>
>> Signed-off-by: Tong Tiangen <tongtiangen@...wei.com>
> 
> I would prefer this not being done, it just makes riscv diverge from the
> code on other architectures. While the new name does make more sense,
> it ends up making it harder to refactor this across architectures in the end.
> 
> There are two important cleanups that I would like to see done in
> asm/uaccess.h across architectures:
> 
>   - generalize the __get_user()/__put_user()/__get_kernel_nofault()/
>    __put_kernel_nofault() wrappers to the point that architectures do not
>    need to worry about the variable type stuff but instead just provide
>    trivial fixed-length helpers of some sort
> 
> - change the calling conventions in a way that allows the use of the
>    asm-goto-with-output method for better object code on modern
>    compilers.
> 
> The x86 version already has most of this, with their
> __get_user_size() macro supporting both the asm-goto label
> and the error code assignment, so the generalized code should
> probably be based on that approach.

I am very interested in the implementation of X86. I need to investigate 
and consider a cross architecture implementation.
However, I understand that the modification of the current patch has 
little to do with the two points mentioned above. We can optimize the 
code step by step.

Thanks,
Tong.

> 
>         Arnd
> 
> .