Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken

From: Pavel Machek <pavel@ucw.cz>
To: "Pali Rohár" <pali.rohar@gmail.com>
Cc: linux-omap <linux-omap@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Aaro Koskinen <aaro.koskinen@iki.fi>,
	Tony Lindgren <tony@atomide.com>,
	Sebastian Reichel <sre@kernel.org>,
	Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
	Russell King <linux@arm.linux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Laura Abbott <lauraa@codeaurora.org>
Subject: Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
Date: Sat, 24 Jan 2015 00:48:55 +0100	[thread overview]
Message-ID: <20150123234855.GB27111@amd> (raw)
In-Reply-To: <201501232336.36187@pali>

On Fri 2015-01-23 23:36:36, Pali Rohár wrote:
> On Friday 23 January 2015 22:39:55 Pali Rohár wrote:
> > Hello,
> > 
> > when I boot zImage with appended DT n900 in qemu
> > fdt_open_into() function called from file
> > arch/arm/boot/compressed/atags_to_fdt.c (in function
> > atags_to_fdt) always returns -FDT_ERR_NOSPACE.
> > 
> > It means that all ATAGS (including cmdline arguments) passed
> > by bootloader are ignored.
> > 
> > On real n900 device I see that booted DT version also ignore
> > cmdline arguments from bootloader. I cannot debug decompress
> > code on real device, but I think it is same problem as in
> > qemu.
> 
> Looks like this quick patch is fixing above problem:

So... something overruns stack, and bigger stack fixes it...?

							Pavel

> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901..4a7d75b 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -268,7 +268,7 @@ restart:	adr	r0, LC0
>  		 * area.  No GOT fixup has occurred yet, but none of the
>  		 * code we're about to call uses any global variable.
>  		*/
> -		add	sp, sp, #0x10000
> +		add	sp, sp, #0x20000
>  		stmfd	sp!, {r0-r3, ip, lr}
>  		mov	r0, r8
>  		mov	r1, r6
> @@ -289,7 +289,7 @@ restart:	adr	r0, LC0
>  		bleq	atags_to_fdt
>  
>  		ldmfd	sp!, {r0-r3, ip, lr}
> -		sub	sp, sp, #0x10000
> +		sub	sp, sp, #0x20000
>  #endif
>  
>  		mov	r8, r6			@ use the appended device tree
> 
> 

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