linux-kernel - Re: [PATCH 05/20] lto: Handle LTO common symbols in module loader

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Message-ID: <20140218145303.GC5339@phenom.dumpdata.com>
Date:	Tue, 18 Feb 2014 09:53:03 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, sam@...nborg.org, x86@...nel.org,
	linux-kbuild@...r.kernel.org, Joe Mario <jmario@...hat.com>,
	rusty@...tcorp.com.au, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 05/20] lto: Handle LTO common symbols in module loader

On Tue, Feb 18, 2014 at 03:28:43PM +0100, Andi Kleen wrote:
> From: Joe Mario <jmario@...hat.com>
> 
> Here is the workaround I made for having the kernel not reject modules
> built with -flto.  The clean solution would be to get the compiler to not
> emit the symbol.  Or if it has to emit the symbol, then emit it as
> initialized data but put it into a comdat/linkonce section.
> 
> Minor tweaks by AK over Joe's patch.

Should Joe's SOB be on this patch ?
> 
> Cc: rusty@...tcorp.com.au
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  kernel/module.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/module.c b/kernel/module.c
> index d24fcf2..b99e801 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1948,6 +1948,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
>  
>  		switch (sym[i].st_shndx) {
>  		case SHN_COMMON:
> +			/* Ignore common symbols */
> +			if (!strncmp(name, "__gnu_lto", 9))
> +				break;
> +
>  			/* We compiled with -fno-common.  These are not
>  			   supposed to happen.  */
>  			pr_debug("Common symbol: %s\n", name);
> -- 
> 1.8.5.2
> 
> --
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