linux-kernel - Re: [PATCH] modpost: Fix section warnings for ARM for many compilers

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Message-ID: <20120213222652.GL14173@pengutronix.de>
Date:	Mon, 13 Feb 2012 23:26:52 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Tony Lindgren <tony@...mide.com>
Cc:	linux-kernel@...r.kernel.org, Anders Kaseorg <andersk@...lice.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Greg KH <gregkh@...uxfoundation.org>,
	Russell King <rmk+kernel@....linux.org.uk>,
	linux-omap@...r.kernel.org, Ben Hutchings <ben@...adent.org.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] modpost: Fix section warnings for ARM for many compilers

On Mon, Feb 13, 2012 at 01:24:01PM -0800, Tony Lindgren wrote:
> It turns out that many compilers don't show section warnings on ARM
> currently because handling for ARM_CALL relocs are missing from
> modpost.c.
> 
> Based on commit c2e26114 ([ARM] 3205/1: Handle new EABI relocations when
> loading kernel modules) it seems that R_ARM_PC24, R_ARM_CALL and
> R_ARM_JUMP24 can be handled the same way.
> 
> As modpost.c includes elf.h, we need to also consider that at least
> Debian libc6-dev is missing defines for both R_ARM_CALL and R_ARM_JUMP24
> in /usr/include/elf.h.
Huh, even unstable's /usr/include/elf.h doesn't have these symbols.

> So for now let's just use the numbers in modpost.c.
> 
> Cc: Rusty Russell <rusty@...tcorp.com.au>
> Cc: Ben Hutchings <ben@...adent.org.uk>
> Cc: Anders Kaseorg <andersk@...lice.com>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Russell King <rmk+kernel@....linux.org.uk>
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> 
> ---
> 
> Anybody got better ideas for dealing with the missing elf.h
> defines?
Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"
#define R_ARM_CALL 28
#endif

Best regards
Uwe

> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1505,6 +1505,8 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
>  		              (elf->symtab_start + ELF_R_SYM(r->r_info));
>  		break;
>  	case R_ARM_PC24:
> +	case 28:		/* R_ARM_CALL */
> +	case 29:		/* R_ARM_JUMP24 */
>  		/* From ARM ABI: ((S + A) | T) - P */
>  		r->r_addend = (int)(long)(elf->hdr +
>  		              sechdr->sh_offset +

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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