linux-kernel - Re: [PATCH] sh: Remove memset

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <3ec5a6621cabddad686f727d20b725ed9658dddd.camel@physik.fu-berlin.de>
Date: Thu, 30 Jan 2025 09:32:04 +0100
From: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To: Julian Vetter <julian@...er-limits.org>, Arnd Bergmann <arnd@...db.de>, 
 Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker <dalias@...c.org>
Cc: linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sh: Remove memset_io from sh specific code

Hi Julian,

On Wed, 2024-12-04 at 17:40 +0100, Julian Vetter wrote:
> Remove memset_io from sh specific code and fall back to the new
> implementation from lib/iomem_copy.c. It uses word accesses if the
> buffer is aligned and only falls back to byte accesses for potentially
> unaligned parts of a buffer (i.e., at the beginning and end).
> 
> Signed-off-by: Julian Vetter <julian@...er-limits.org>
> ---
>  arch/sh/include/asm/io.h |  2 --
>  arch/sh/kernel/io.c      | 14 --------------
>  2 files changed, 16 deletions(-)
> 
> diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h
> index cf5eab840d57..3771bfa984af 100644
> --- a/arch/sh/include/asm/io.h
> +++ b/arch/sh/include/asm/io.h
> @@ -269,12 +269,10 @@ __BUILD_IOPORT_STRING(q, u64)
>  #define IO_SPACE_LIMIT 0xffffffff
>  
>  /* We really want to try and get these to memcpy etc */
> -#define memset_io memset_io
>  #define memcpy_fromio memcpy_fromio
>  #define memcpy_toio memcpy_toio
>  void memcpy_fromio(void *, const volatile void __iomem *, unsigned long);
>  void memcpy_toio(volatile void __iomem *, const void *, unsigned long);
> -void memset_io(volatile void __iomem *, int, unsigned long);
>  
>  /* Quad-word real-mode I/O, don't ask.. */
>  unsigned long long peek_real_address_q(unsigned long long addr);
> diff --git a/arch/sh/kernel/io.c b/arch/sh/kernel/io.c
> index da22f3b32d30..16e963bab595 100644
> --- a/arch/sh/kernel/io.c
> +++ b/arch/sh/kernel/io.c
> @@ -95,17 +95,3 @@ void memcpy_toio(volatile void __iomem *to, const void *from, unsigned long coun
>  	mb();
>  }
>  EXPORT_SYMBOL(memcpy_toio);
> -
> -/*
> - * "memset" on IO memory space.
> - * This needs to be optimized.
> - */
> -void memset_io(volatile void __iomem *dst, int c, unsigned long count)
> -{
> -        while (count) {
> -                count--;
> -                writeb(c, dst);
> -                dst++;
> -        }
> -}
> -EXPORT_SYMBOL(memset_io);

Looks good to me. I looked up the generic implementation in lib/iomem_copy.c and
it looks much better than the sh-specific implementation due to the smarter
use of conditional word-long memset.

Reviewed-by: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913