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SubjectRe: [PATCH 7/8] riscv: implement __get_kernel_nofault and __put_user_nofault
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On Sun, 06 Sep 2020 22:58:24 PDT (-0700), Christoph Hellwig wrote:
> Implement the non-faulting kernel access helpers directly instead of
> abusing the uaccess routines under set_fs(KERNEL_DS).
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/riscv/include/asm/uaccess.h | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index b67d1c616ec348..264e52fb62b143 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -486,6 +486,26 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
> __ret; \
> })
>
> +#define HAVE_GET_KERNEL_NOFAULT
> +
> +#define __get_kernel_nofault(dst, src, type, err_label) \
> +do { \
> + long __kr_err; \
> + \
> + __get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \
> + if (unlikely(__kr_err)) \
> + goto err_label; \
> +} while (0)
> +
> +#define __put_kernel_nofault(dst, src, type, err_label) \
> +do { \
> + long __kr_err; \
> + \
> + __put_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \
> + if (unlikely(__kr_err)) \
> + goto err_label; \
> +} while (0)
> +
> #else /* CONFIG_MMU */
> #include <asm-generic/uaccess.h>
> #endif /* CONFIG_MMU */

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

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