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SubjectRe: [PATCH v14 04/19] x86/uaccess: Add unsafe_copy_from_user() implementation
On Wed, 6 May 2026 16:09:16 +0200
Jens Remus <jremus@linux.ibm.com> wrote:

> On 5/5/2026 2:17 PM, Jens Remus wrote:
> > From: Josh Poimboeuf <jpoimboe@kernel.org>
> >
> > Add an x86 implementation of unsafe_copy_from_user() similar to the
> > existing unsafe_copy_to_user().
>
> > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
>
> > -#define unsafe_copy_to_user(_dst,_src,_len,label) \
> > -do { \
> > - char __user *__ucu_dst = (_dst); \
> > - const char *__ucu_src = (_src); \
> > - size_t __ucu_len = (_len); \
> > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \
> > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \
> > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \
> > - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
> > +#define unsafe_copy_to_user(_dst, _src, _len, label) \
> > +do { \
> > + void __user *__dst = (_dst); \
> > + const void *__src = (_src); \
> > + size_t __len = (_len); \
> > + unsafe_copy_to_user_loop(__dst, __src, __len, u64, label); \
> > + unsafe_copy_to_user_loop(__dst, __src, __len, u32, label); \
> > + unsafe_copy_to_user_loop(__dst, __src, __len, u16, label); \
> > + unsafe_copy_to_user_loop(__dst, __src, __len, u8, label); \
> > +} while (0)
> > +
> > +#define unsafe_copy_from_user_loop(dst, src, len, type, label) \
> > + while (len >= sizeof(type)) { \
> > + unsafe_get_user(*(type *)(dst), (type __user *)(src), label); \
> > + dst += sizeof(type); \
> > + src += sizeof(type); \
> > + len -= sizeof(type); \
> > + }
> > +
> > +#define unsafe_copy_from_user(_dst, _src, _len, label) \
> > +do { \
> > + void *__dst = (_dst); \
> > + void __user *__src = (_src); \
>
> const void __user *__src = (_src); \
>
> This was suggested by Sashiko AI review. Any objections?

Try compiling it :-)

-- David

>
> > + size_t __len = (_len); \
> > + unsafe_copy_from_user_loop(__dst, __src, __len, u64, label); \
> > + unsafe_copy_from_user_loop(__dst, __src, __len, u32, label); \
> > + unsafe_copy_from_user_loop(__dst, __src, __len, u16, label); \
> > + unsafe_copy_from_user_loop(__dst, __src, __len, u8, label); \
> > } while (0)
> >
> > #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
>
> Thanks and regards,
> Jens


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