Re: [PATCH 5/8] riscv: use memcpy based uaccess for nommu again

[Palmer Dabbelt <palmer@dabbelt.com>]

On Sun, 06 Sep 2020 22:58:22 PDT (-0700), Christoph Hellwig wrote:
> This reverts commit adccfb1a805ea84d2db38eb53032533279bdaa97.
>
> Now that the generic uaccess by mempcy code handles unaligned addresses
> the generic code can be used for all RISC-V CPUs.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/riscv/Kconfig               |  1 +
>  arch/riscv/include/asm/uaccess.h | 36 ++++++++++++++++----------------
>  arch/riscv/lib/Makefile          |  2 +-
>  3 files changed, 20 insertions(+), 19 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 07d53044013ede..460e3971a80fde 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -87,6 +87,7 @@ config RISCV
>  	select SYSCTL_EXCEPTION_TRACE
>  	select THREAD_INFO_IN_TASK
>  	select SET_FS
> +	select UACCESS_MEMCPY if !MMU
>
>  config ARCH_MMAP_RND_BITS_MIN
>  	default 18 if 64BIT
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index f56c66b3f5fe21..e8eedf22e90747 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -13,24 +13,6 @@
>  /*
>   * User space memory access functions
>   */
> -
> -extern unsigned long __must_check __asm_copy_to_user(void __user *to,
> -	const void *from, unsigned long n);
> -extern unsigned long __must_check __asm_copy_from_user(void *to,
> -	const void __user *from, unsigned long n);
> -
> -static inline unsigned long
> -raw_copy_from_user(void *to, const void __user *from, unsigned long n)
> -{
> -	return __asm_copy_from_user(to, from, n);
> -}
> -
> -static inline unsigned long
> -raw_copy_to_user(void __user *to, const void *from, unsigned long n)
> -{
> -	return __asm_copy_to_user(to, from, n);
> -}
> -
>  #ifdef CONFIG_MMU
>  #include <linux/errno.h>
>  #include <linux/compiler.h>
> @@ -385,6 +367,24 @@ do {								\
>  		-EFAULT;					\
>  })
>
> +
> +unsigned long __must_check __asm_copy_to_user(void __user *to,
> +	const void *from, unsigned long n);
> +unsigned long __must_check __asm_copy_from_user(void *to,
> +	const void __user *from, unsigned long n);
> +
> +static inline unsigned long
> +raw_copy_from_user(void *to, const void __user *from, unsigned long n)
> +{
> +	return __asm_copy_from_user(to, from, n);
> +}
> +
> +static inline unsigned long
> +raw_copy_to_user(void __user *to, const void *from, unsigned long n)
> +{
> +	return __asm_copy_to_user(to, from, n);
> +}
> +
>  extern long strncpy_from_user(char *dest, const char __user *src, long count);
>
>  extern long __must_check strlen_user(const char __user *str);
> diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
> index 0d0db80800c4ed..47e7a82044608d 100644
> --- a/arch/riscv/lib/Makefile
> +++ b/arch/riscv/lib/Makefile
> @@ -2,5 +2,5 @@
>  lib-y			+= delay.o
>  lib-y			+= memcpy.o
>  lib-y			+= memset.o
> -lib-y			+= uaccess.o
> +lib-$(CONFIG_MMU)	+= uaccess.o
>  lib-$(CONFIG_64BIT)	+= tishift.o

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