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From: Pavel Machek <pavel@ucw.cz>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: "Tony Lindgren" <tony@atomide.com>,
	"Pali Rohár" <pali.rohar@gmail.com>,
	linux-omap <linux-omap@vger.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Aaro Koskinen" <aaro.koskinen@iki.fi>,
	"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: Tue, 27 Jan 2015 14:37:39 +0100	[thread overview]
Message-ID: <20150127133739.GB25306@amd> (raw)
In-Reply-To: <alpine.LFD.2.11.1501261318590.1322@knanqh.ubzr>


> > > I would say, problem is because omap3-n900 binary DT is too large
> 
> I agree.
> 
> > OK if that's the case, then your patch makes sense to me. It also
> > seems we can have the temporary stack be larger than the initial
> > stack just for atags_to_fdt.
> 
> The stack size isn't the issue, but rather its location.  We need to 
> position it away from the DT data.  The DT size is known and we could 
> use that, plus some room for the insertion of new data coming from the
> ATAG conversion.
> 
> Something like the following would be a more robust solution:

Tested-by: Pavel Machek <pavel@ucw.cz>

(Note, that in 3.19 dts for n900 got too big, so we are actually
triggering old bugs. That means that this is a regression fix, and
should go in ASAP).



> 
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901759..89718de9dd 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -263,16 +263,37 @@ restart:	adr	r0, LC0
>  		 * OK... Let's do some funky business here.
>  		 * If we do have a DTB appended to zImage, and we do have
>  		 * an ATAG list around, we want the later to be translated
> -		 * and folded into the former here.  To be on the safe side,
> -		 * let's temporarily move  the stack away into the malloc
> -		 * area.  No GOT fixup has occurred yet, but none of the
> -		 * code we're about to call uses any global variable.
> +		 * and folded into the former here. No GOT fixup has occurred
> +		 * yet, but none of the code we're about to call uses any
> +		 * global variable.
>  		*/
> -		add	sp, sp, #0x10000
> +
> +		/* Get the initial DTB size */
> +		ldr	r5, [r6, #4]
> +#ifndef __ARMEB__
> +		/* convert to little endian */
> +		eor	r1, r5, r5, ror #16
> +		bic	r1, r1, #0x00ff0000
> +		mov	r5, r5, ror #8
> +		eor	r5, r5, r1, lsr #8
> +#endif
> +		/* 50% DTB growth should be good enough */
> +		add	r5, r5, r5, lsr #1
> +		/* preserve 64-bit alignment */
> +		add	r5, r5, #7
> +		bic	r5, r5, #7
> +		/* clamp to 32KB min and 1MB max */
> +		movs	r1, r5, lsr #15
> +		moveq	r5, #(1 << 15)
> +		movs	r1, r5, lsr #20
> +		movne	r5, #(1 << 20)
> +
> +		/* Temporarily relocate the stack past the DTB work space */
> +		add	sp, sp, r5
>  		stmfd	sp!, {r0-r3, ip, lr}
>  		mov	r0, r8
>  		mov	r1, r6
> -		sub	r2, sp, r6
> +		mov	r2, r5
>  		bl	atags_to_fdt
>  
>  		/*
> @@ -285,11 +306,11 @@ restart:	adr	r0, LC0
>  		bic	r0, r0, #1
>  		add	r0, r0, #0x100
>  		mov	r1, r6
> -		sub	r2, sp, r6
> +		mov	r2, r5
>  		bleq	atags_to_fdt
>  
>  		ldmfd	sp!, {r0-r3, ip, lr}
> -		sub	sp, sp, #0x10000
> +		sub	sp, sp, r5
>  #endif
>  
>  		mov	r8, r6			@ use the appended device tree
> @@ -306,7 +327,7 @@ restart:	adr	r0, LC0
>  		subs	r1, r5, r1
>  		addhi	r9, r9, r1
>  
> -		/* Get the dtb's size */
> +		/* Get the current DTB size */
>  		ldr	r5, [r6, #4]
>  #ifndef __ARMEB__
>  		/* convert r5 (dtb size) to little endian */



-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  parent reply	other threads:[~2015-01-27 13:37 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-23 21:39 Pali Rohár
2015-01-23 22:36 ` Pali Rohár
2015-01-23 23:48   ` Pavel Machek
2015-01-24  9:04     ` Pali Rohár
2015-01-26 16:14   ` Tony Lindgren
2015-01-26 16:23     ` Pali Rohár
2015-01-26 17:03       ` Tony Lindgren
2015-01-26 18:57         ` Nicolas Pitre
2015-01-26 21:48           ` Pavel Machek
2015-01-27  0:06             ` Nicolas Pitre
2015-01-27 13:37           ` Pavel Machek [this message]
2015-01-27 15:16             ` Nicolas Pitre
2015-01-27 15:26               ` Pali Rohár
2015-01-27 15:26               ` Tony Lindgren
2015-01-27 17:53               ` Russell King - ARM Linux
2015-01-27 18:50                 ` Nicolas Pitre
2015-01-27 23:09                   ` Aaro Koskinen
2015-01-27 23:17                   ` Pavel Machek
2015-02-02 13:39               ` Pavel Machek
2015-02-02 13:56                 ` Nicolas Pitre

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