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References: <20201102073052.199638-1-changbin.du@gmail.com>
In-Reply-To: <20201102073052.199638-1-changbin.du@gmail.com>
From:   Anup Patel <anup@brainfault.org>
Date:   Fri, 6 Nov 2020 12:21:52 +0530
Message-ID: <CAAhSdy12JRy5uF5t-e=bw=K1Gk5PKuTErg0kmKOxBKBn4MnhJw@mail.gmail.com>
Subject: Re: [PATCH] riscv: uaccess: fix __put_kernel_nofault()
To:     Changbin Du <changbin.du@gmail.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>
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On Mon, Nov 2, 2020 at 1:01 PM Changbin Du <changbin.du@gmail.com> wrote:
>
> The copy_from_kernel_nofault() is broken on riscv because the 'dst' and
> 'src' are mistakenly reversed in __put_kernel_nofault() macro.
>
> copy_to_kernel_nofault:
> ...
> 0xffffffe0003159b8 <+30>:    sd      a4,0(a1) # a1 aka 'src'
>
> Fixes: d464118cdc ("riscv: implement __get_kernel_nofault and __put_user_nofault")
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> Cc: Christoph Hellwig <hch@lst.de>
> ---
>  arch/riscv/include/asm/uaccess.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index c47e6b35c551..824b2c9da75b 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -476,7 +476,7 @@ do {                                                                        \
>  do {                                                                   \
>         long __kr_err;                                                  \
>                                                                         \
> -       __put_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);  \
> +       __put_user_nocheck(*((type *)(src)), (type *)(dst), __kr_err);  \
>         if (unlikely(__kr_err))                                         \
>                 goto err_label;                                         \
>  } while (0)
> --
> 2.17.1
>
>

Looks good to me.

Tested-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Anup Patel <anup@brainfault.org>

@Palmer Dabbelt , This patch fixes jump label implementation in
Linux-5.10-rc2. In general, this patch fixes all kernel instruction
patching related features. Can you take this for Linux-5.10-rcX ??

Regards,
Anup