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Message-ID: <b1af8198-3291-149e-cd8b-c55d7321deb7@huawei.com>
Date:   Sat, 27 Aug 2022 18:39:42 +0800
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Subject: Re: [PATCH -next v2 1/2] riscv: uaccess: rename
 __get/put_user_nocheck to __get/put_mem_nocheck
To:     Andrew Jones <ajones@ventanamicro.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmer@rivosinc.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        <Conor.Dooley@microchip.com>, <linux-riscv@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <wangkefeng.wang@huawei.com>,
        Guohanjun <guohanjun@huawei.com>
References: <20220815032025.2685516-1-tongtiangen@huawei.com>
 <20220815032025.2685516-2-tongtiangen@huawei.com>
 <20220825105600.ezueddmwehob42rf@kamzik>
 <3541c980-7fcf-7047-cec7-3c2ca6381a99@huawei.com>
 <20220826074318.g6nwri5ziiutiio5@kamzik>
From:   Tong Tiangen <tongtiangen@huawei.com>
In-Reply-To: <20220826074318.g6nwri5ziiutiio5@kamzik>
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在 2022/8/26 15:43, Andrew Jones 写道:
> On Fri, Aug 26, 2022 at 02:33:47PM +0800, Tong Tiangen wrote:
>>
>>
>> 在 2022/8/25 18:56, Andrew Jones 写道:
>>> On Mon, Aug 15, 2022 at 03:20:24AM +0000, Tong Tiangen 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@huawei.com>
>>>> ---
>>>>    arch/riscv/include/asm/uaccess.h | 48 ++++++++++++++++----------------
>>>>    1 file changed, 24 insertions(+), 24 deletions(-)
>>>>
>>>> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
>>>> index 855450bed9f5..1370da055b44 100644
>>>> --- a/arch/riscv/include/asm/uaccess.h
>>>> +++ b/arch/riscv/include/asm/uaccess.h
>>>> @@ -50,7 +50,7 @@
>>>>     * call.
>>>>     */
>>>> -#define __get_user_asm(insn, x, ptr, err)			\
>>>> +#define __get_mem_asm(insn, x, ptr, err)			\
>>>>    do {								\
>>>>    	__typeof__(x) __x;					\
>>>>    	__asm__ __volatile__ (					\
>>>> @@ -64,12 +64,12 @@ do {								\
>>>>    } while (0)
>>>>    #ifdef CONFIG_64BIT
>>>> -#define __get_user_8(x, ptr, err) \
>>>> -	__get_user_asm("ld", x, ptr, err)
>>>> +#define __get_mem_8(x, ptr, err) \
>>>> +	__get_mem_asm("ld", x, ptr, err)
>>>>    #else /* !CONFIG_64BIT */
>>>> -#define __get_user_8(x, ptr, err)				\
>>>> +#define __get_mem_8(x, ptr, err)				\
>>>>    do {								\
>>>> -	u32 __user *__ptr = (u32 __user *)(ptr);		\
>>>> +	u32 *__ptr = (u32 *)(ptr);				\
>>>
>>> Doesn't casting away __user reduce sparse's utility?
>>
>>  From the call logic[1], the address passed into this macro is not
>> necessarily __user. I understand that no problem will be introduced for
>> sparse's utility.
>>
>> In addition, there is no need to do a pointer conversion here, will be fixed
>> next version.
>>
>> [1] __get_kernel_nofault -> __get_mem_nocheck -> __get_mem_8
> 
> Yes, I understood that. My concern was for the times that the address was
> __user as we'd no longer get that check for them.

Check __user ptr at __get_user() has the same effect? Is this 
understanding correct？

Thanks,
Tong.

> 
> Thanks,
> drew
> 
> .