Re: [PATCH v1 1/3] LoongArch: Give more information if memory access failed

[Huacai Chen]

Applied with small modifications, thanks.

Huacai

On Tue, Mar 10, 2026 at 2:55 PM Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> wrote:
>
> If memory access such as copy_{from, to}_kernel_nofault failed,
> the users do not know what happened, it is very useful to print
> the exception code for such cases. Furthermore, it is better to
> print the caller function to know where is the entry.
>
> Here are the low level call chains:
>
>   copy_from_kernel_nofault()
>     copy_from_kernel_nofault_loop()
>       __get_kernel_nofault()
>
>   copy_to_kernel_nofault()
>     copy_to_kernel_nofault_loop()
>       __put_kernel_nofault()
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> ---
>  arch/loongarch/include/asm/uaccess.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/uaccess.h b/arch/loongarch/include/asm/uaccess.h
> index 4e259d490e45..4dacbb32854c 100644
> --- a/arch/loongarch/include/asm/uaccess.h
> +++ b/arch/loongarch/include/asm/uaccess.h
> @@ -253,8 +253,13 @@ do {                                                                       \
>                                                                         \
>         __get_kernel_common(*((type *)(dst)), sizeof(type),             \
>                             (__force type *)(src));                     \
> -       if (unlikely(__gu_err))                                         \
> +       if (unlikely(__gu_err)) {                                       \
> +               pr_info("%s: memory access failed, ecode is 0x%x\n",    \
> +                       __func__, read_csr_excode());                   \
> +               pr_info("%s: caller is %pS\n",                          \
> +                       __func__, __builtin_return_address(0));         \
>                 goto err_label;                                         \
> +       }                                                               \
>  } while (0)
>
>  #define __put_kernel_nofault(dst, src, type, err_label)                        \
> @@ -264,8 +269,13 @@ do {                                                                       \
>                                                                         \
>         __pu_val = *(__force type *)(src);                              \
>         __put_kernel_common(((type *)(dst)), sizeof(type));             \
> -       if (unlikely(__pu_err))                                         \
> +       if (unlikely(__pu_err)) {                                       \
> +               pr_info("%s: memory access failed, ecode is 0x%x\n",    \
> +                       __func__, read_csr_excode());                   \
> +               pr_info("%s: caller is %pS\n",                          \
> +                       __func__, __builtin_return_address(0));         \
>                 goto err_label;                                         \
> +       }                                                               \
>  } while (0)
>
>  extern unsigned long __copy_user(void *to, const void *from, __kernel_size_t n);
> --
> 2.42.0
>