linux-kernel - Re: [PATCH] RISC-V: uaccess: Wrap the get_user

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Message-ID: <mhng-6698D901-534C-4886-BDB3-BB4EDF14E7E8@palmerdabbelt-mac>
Date: Thu, 12 Jun 2025 12:42:32 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: Alexandre Ghiti <alex@...ti.fr>
CC: linux-riscv@...ts.infradead.org, Paul Walmsley <paul.walmsley@...ive.com>,
  aou@...s.berkeley.edu, cyrilbur@...storrent.com, jszhang@...nel.org, cleger@...osinc.com,
  samuel.holland@...ive.com, linux-kernel@...r.kernel.org
Subject:     Re: [PATCH] RISC-V: uaccess: Wrap the get_user_8 uaccess macro

On Wed, 11 Jun 2025 00:31:18 PDT (-0700), Alexandre Ghiti wrote:
> On 6/10/25 23:30, Palmer Dabbelt wrote:
>> From: Palmer Dabbelt <palmer@...belt.com>
>>
>> I must have lost this rebasing things during the merge window, I know I
>> got it at some point but it's not here now.  Without this I get warnings
>> along the lines of
>>
>>      include/linux/fs.h:3975:15: warning: label followed by a declaration is a C23 extension [-Wc23-extensions]
>>       3975 |         if (unlikely(get_user(c, path)))
>>            |                      ^
>>      arch/riscv/include/asm/uaccess.h:274:3: note: expanded from macro 'get_user'
>>        274 |                 __get_user((x), __p) :                          \
>>            |                 ^
>>      arch/riscv/include/asm/uaccess.h:244:2: note: expanded from macro '__get_user'
>>        244 |         __get_user_error(__gu_val, __gu_ptr, __gu_err);         \
>>            |         ^
>>      arch/riscv/include/asm/uaccess.h:207:2: note: expanded from macro '__get_user_error'
>>        207 |         __ge  LD [M]  net/802/psnap.ko
>>      t_user_nocheck(x, ptr, __gu_failed);                        \
>>            |         ^
>>      arch/riscv/include/asm/uaccess.h:196:3: note: expanded from macro '__get_user_nocheck'
>>        196 |                 __get_user_8((x), __gu_ptr, label);             \
>>            |                 ^
>>      arch/riscv/include/asm/uaccess.h:130:2: note: expanded from macro '__get_user_8'
>>        130 |         u32 __user *__ptr = (u32 __user *)(ptr);                \
>>            |         ^
>>
>> Signed-off-by: Palmer Dabbelt <palmer@...belt.com>
>> ---
>>   arch/riscv/include/asm/uaccess.h | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
>> index d472da4450e6..525e50db24f7 100644
>> --- a/arch/riscv/include/asm/uaccess.h
>> +++ b/arch/riscv/include/asm/uaccess.h
>> @@ -127,6 +127,7 @@ do {								\
>>
>>   #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
>>   #define __get_user_8(x, ptr, label)				\
>> +do {								\
>>   	u32 __user *__ptr = (u32 __user *)(ptr);		\
>>   	u32 __lo, __hi;						\
>>   	asm_goto_output(					\
>> @@ -141,7 +142,7 @@ do {								\
>>   		: : label);                                     \
>>   	(x) = (__typeof__(x))((__typeof__((x) - (x)))(		\
>>   		(((u64)__hi << 32) | __lo)));			\
>> -
>> +} while (0)
>>   #else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
>>   #define __get_user_8(x, ptr, label)				\
>>   do {								\
>
>
> I had come up with the same fix so:
>
> Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks, and I guess it should also be

Fixes: f6bff7827a48 ("riscv: uaccess: use 'asm_goto_output' for get_user()")

I'm going to put it on fixes.