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: <b1af8198-3291-149e-cd8b-c55d7321deb7@huawei.com>
Date:   Sat, 27 Aug 2022 18:39:42 +0800
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Andrew Jones <ajones@...tanamicro.com>
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 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@...wei.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
> 
> .