Re: [PATCH] uaccess: decouple INLINE_COPY_FROM_USER and CONFIG_RUST

["Christophe Leroy (CS GROUP)" <chleroy@kernel.org>]

Le 23/10/2025 à 19:16, Yury Norov (NVIDIA) a écrit :
> Commit 1f9a8286bc0c ("uaccess: always export _copy_[from|to]_user with
> CONFIG_RUST") exports _copy_{from,to}_user() unconditionally, if RUST
> is enabled. This pollutes exported symbols namespace, and spreads RUST
> ifdefery in core files.
> 
> It's better to declare a corresponding helper under the rust/helpers,
> similarly to how non-underscored copy_{from,to}_user() is handled.
> 
> Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
> ---
>   lib/usercopy.c         |  4 ++--
>   rust/helpers/uaccess.c | 12 ++++++++++++
>   2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/usercopy.c b/lib/usercopy.c
> index 7b17b83c8042..b00a3a957de6 100644
> --- a/lib/usercopy.c
> +++ b/lib/usercopy.c
> @@ -12,7 +12,7 @@
>   
>   /* out-of-line parts */
>   
> -#if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)
> +#if !defined(INLINE_COPY_FROM_USER)
>   unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
>   {
>   	return _inline_copy_from_user(to, from, n);
> @@ -20,7 +20,7 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n
>   EXPORT_SYMBOL(_copy_from_user);
>   #endif
>   
> -#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
> +#if !defined(INLINE_COPY_TO_USER)
>   unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
>   {
>   	return _inline_copy_to_user(to, from, n);
> diff --git a/rust/helpers/uaccess.c b/rust/helpers/uaccess.c
> index f49076f813cd..4629b2d15529 100644
> --- a/rust/helpers/uaccess.c
> +++ b/rust/helpers/uaccess.c
> @@ -13,3 +13,15 @@ unsigned long rust_helper_copy_to_user(void __user *to, const void *from,
>   {
>   	return copy_to_user(to, from, n);
>   }
> +
> +#ifdef INLINE_COPY_FROM_USER
> +unsigned long rust_helper__copy_from_user(void *to, const void __user *from, unsigned long n)
> +{
> +	return _inline_copy_from_user(to, from, n);
> +}
> +

Shouldn't the below part be guarded by INLINE_COPY_TO_USER ?


> +unsigned long rust_helper__copy_to_user(void __user *to, const void *from, unsigned long n)
> +{
> +	return _inline_copy_to_user(to, from, n);
> +}
> +#endif