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From: "H. Peter Anvin" <hpa@zytor.com>
To: Joris van Rantwijk <jorispubl@xs4all.nl>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Inflation of vmlinux by linker on x86_64
Date: Fri, 26 Sep 2008 11:52:24 -0700	[thread overview]
Message-ID: <48DD2F68.6000609@zytor.com> (raw)
In-Reply-To: <20080926124222.GA49837@xs4all.nl>

Joris van Rantwijk wrote:
>  #endif
> -			memcpy(dest,
> -			       output + phdr->p_offset,
> -			       phdr->p_filesz);
> +			src = output + phdr->p_offset;
> +
> +			/* order the copying to avoid overwriting */
> +			if ((direction == 1  && dest <= src) ||
> +			    (direction == -1 && dest > src)) {
> +				/* note: unlike standard memcpy, this one
> +				 * is safe to use when dest and src overlap.
> +				 */
> +				memcpy(dest, src, phdr->p_filesz);
> +			}
> +
>  			break;

Instead of adding a comment like this, we should simply rename it memmove().

Furthermore, we probably spend enough time copying that using a real 
memmove() implementation, using string instructions, would be good.

	-hpa

  reply	other threads:[~2008-09-26 18:52 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-26 12:42 Inflation of vmlinux by linker on x86_64 Joris van Rantwijk
2008-09-26 18:52 ` H. Peter Anvin [this message]
2008-09-26 19:50   ` Joris van Rantwijk
2008-09-26 20:07     ` H. Peter Anvin
2008-09-26 21:55       ` Joris van Rantwijk
2008-09-26 21:57         ` H. Peter Anvin

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