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Date:   Thu, 17 Sep 2020 16:25:18 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     liush <liush@allwinnertech.com>
Cc:     paul.walmsley@sifive.com, palmer@dabbelt.com,
        aou@eecs.berkeley.edu, akpm@linux-foundation.org,
        peterx@redhat.com, walken@google.com, daniel.m.jordan@oracle.com,
        vbabka@suse.cz, rppt@kernel.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: fix pfn_to_virt err in do_page_fault().
Message-ID: <20200917152518.GA8930@infradead.org>
References: <1600327549-3995-1-git-send-email-liush@allwinnertech.com>
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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@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.