linux-kernel - Re: [PATCH V3 17/22] LoongArch: Add some library functions

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Message-ID: <CAK8P3a0HfWmBgp6ZagVALDoeoJsJaU9h9tLKHM0-5GZGtnT-hg@mail.gmail.com>
Date:   Fri, 17 Sep 2021 10:33:40 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Huacai Chen <chenhuacai@...ngson.cn>
Cc:     Arnd Bergmann <arnd@...db.de>, Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Airlie <airlied@...ux.ie>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Yanteng Si <siyanteng@...ngson.cn>,
        Huacai Chen <chenhuacai@...il.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: Re: [PATCH V3 17/22] LoongArch: Add some library functions

On Fri, Sep 17, 2021 at 5:57 AM Huacai Chen <chenhuacai@...ngson.cn> wrote:
>
> diff --git a/arch/loongarch/lib/strncpy_user.S b/arch/loongarch/lib/strncpy_user.S
> new file mode 100644
> index 000000000000..b42d81045929
> --- /dev/null
> +++ b/arch/loongarch/lib/strncpy_user.S
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
> + */
> +#include <linux/errno.h>
> +#include <asm/asm.h>
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +#define _ASM_EXTABLE(from, to)                 \
> +       .section __ex_table, "a";               \
> +       PTR     from, to;                       \
> +       .previous
> +
> +/*
> + * long __strncpy_from_user(char *to, const char *from, long len)
> + *
> + * a0: to
> + * a1: from
> + * a2: len
> + */
> +SYM_FUNC_START(__strncpy_from_user)
> +       move    a3, zero
> +

I just removed most custom __strncpy_from_user/__strnlen_user
implementations from architectures, and I think you should remove
these as well. Your current version probably does not work any more
with v5.15-rc1, and it is neither efficient nor robust.

        Arnd