[PATCH] riscv: fix pfn_to_virt err in do_page_fault().

[Christoph Hellwig]

On Thu, Sep 17, 2020 at 03:25:49PM +0800, liush wrote:
> The argument to pfn_to_virt() should be pfn not the value of CSR_SATP.
> 
> Signed-off-by: liush <liush at allwinnertech.com>
> ---
>  arch/riscv/mm/fault.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 716d64e..9b4e088 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -212,7 +212,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
>  		 * of a task switch.
>  		 */
>  		index = pgd_index(addr);
> -		pgd = (pgd_t *)pfn_to_virt(csr_read(CSR_SATP)) + index;
> +		pgd = (pgd_t *)pfn_to_virt(csr_read(CSR_SATP) & SATP_PPN) + index;

This adds a crazy long line.  One nice way to clean this up would be to
add a local pfn variable, as it would also make the code more readable.