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: <3541c980-7fcf-7047-cec7-3c2ca6381a99@huawei.com>
Date:   Fri, 26 Aug 2022 14:33:47 +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 2022/8/25 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
> 
>>   	u32 __lo, __hi;						\
>>   	__asm__ __volatile__ (					\
>>   		"1:\n"						\
>> @@ -88,20 +88,20 @@ do {								\
>>   } while (0)
>>   #endif /* CONFIG_64BIT */
>>   
>> -#define __get_user_nocheck(x, __gu_ptr, __gu_err)		\
>> +#define __get_mem_nocheck(x, __gu_ptr, __gu_err)		\
> 
> The patch replaces all get/put_user instances with get/put_mem,
> but what about 'gu' and 'pu' instances (which are presumably short
> for get/put_user)?

ok, missing that, It is not appropriate to use __gu_xxx，will be fixed 
next version.

Thanks,
Tong.

> 
> Thanks,
> drew
> .