linux-kernel - Re: [PATCH] __crc_... is intended to be absolute

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Date:	Fri, 2 Feb 2007 14:00:27 +0530
From:	Vivek Goyal <vgoyal@...ibm.com>
To:	Al Viro <viro@....linux.org.uk>
Cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] __crc_... is intended to be absolute

On Thu, Feb 01, 2007 at 01:52:23PM +0000, Al Viro wrote:
> 
> i386 boot/compressed/relocs checks for absolute symbols and warns about
> unexpected ones.  If you build with modversions, you get ~2500 warnings
> about __crc_<symbol>.  These suckers are really absolute symbols - we
> do _not_ want to modify them on relocation.
> 
> They are generated by genksyms - EXPORT_... generates a weak alias, then
> genksyms produces an ld script with __crc_<symbol> = <checksum> and it's
> fed to ld to produce the final object file.  Their only use is to match
> kernel and module at modprobe time; they _must_ be absolute.
> 
> boot/compressed/relocs has a whitelist of known absolute symbols, but
> it doesn't know about __crc_... stuff.  As the result, we get shitloads
> of false positives on any ld(1) version.
> 
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>  arch/i386/boot/compressed/relocs.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/i386/boot/compressed/relocs.c b/arch/i386/boot/compressed/relocs.c
> index 468da89..881951c 100644
> --- a/arch/i386/boot/compressed/relocs.c
> +++ b/arch/i386/boot/compressed/relocs.c
> @@ -43,6 +43,8 @@ static int is_safe_abs_reloc(const char* sym_name)
>  			/* Match found */
>  			return 1;
>  	}
> +	if (strncmp(sym_name, "__crc_", 6) == 0)
> +		return 1;
>  	return 0;
>  }

Thanks Viro. Sorry, I missed this case.

Thanks
Vivek
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