netdev - Re: [PATCH 2/4] net: i825xx: Use absolute_pointer for memcpy on fixed memory location

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Date:   Sun, 12 Sep 2021 18:11:48 +0200
From:   Jeroen Roovers <jer@...all.nl>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        "James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-alpha@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org,
        netdev@...r.kernel.org, linux-sparse@...r.kernel.org
Subject: Re: [PATCH 2/4] net: i825xx: Use absolute_pointer for memcpy on
 fixed memory location

On Sun, 12 Sep 2021 09:01:47 -0700
Guenter Roeck <linux@...ck-us.net> wrote:

> gcc 11.x reports the following compiler warning/error.
> 
> drivers/net/ethernet/i825xx/82596.c: In function 'i82596_probe':
>     ./arch/m68k/include/asm/string.h:72:25: error:
>             '__builtin_memcpy' reading 6 bytes from a region of size 0
>                     [-Werror=stringop-overread]
> 
> Use absolute_address() to work around the problem.

=> absolute_pointer()

> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  drivers/net/ethernet/i825xx/82596.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/i825xx/82596.c
> b/drivers/net/ethernet/i825xx/82596.c index
> b8a40146b895..b482f6f633bd 100644 ---
> a/drivers/net/ethernet/i825xx/82596.c +++
> b/drivers/net/ethernet/i825xx/82596.c @@ -1144,7 +1144,7 @@ static
> struct net_device * __init i82596_probe(void) err = -ENODEV;
>  			goto out;
>  		}
> -		memcpy(eth_addr, (void *) 0xfffc1f2c,
> ETH_ALEN);	/* YUCK! Get addr from NOVRAM */
> +		memcpy(eth_addr, absolute_pointer(0xfffc1f2c),
> ETH_ALEN); /* YUCK! Get addr from NOVRAM */ dev->base_addr =
> MVME_I596_BASE; dev->irq = (unsigned) MVME16x_IRQ_I596;
>  		goto found;


Regards,
      jer