[PATCH] ARM: Fix relocation if image end past uncompressed kernel end

[Shawn Guo]

On Thu, Apr 21, 2011 at 11:23:22PM -0400, Nicolas Pitre wrote:
> On Thu, 21 Apr 2011, Nicolas Pitre wrote:
> 
> > On Thu, 21 Apr 2011, Nicolas Pitre wrote:
> > 
> > > On Thu, 21 Apr 2011, Tony Lindgren wrote:
> > > 
> > > > Otherwise we end up overwriting ourselves. This fixes booting
> > > > on n900 after commit 6d7d0ae51574943bf571d269da3243257a2d15db
> > > > (ARM: 6750/1: improvements to compressed/head.S).
> > > > 
> > > > Signed-off-by: Tony Lindgren <tony at atomide.com>
> > > 
> > > I don't understand why this is needed.  The copy loop is explicitly 
> > > copying from the end going backward exactly to cope with this 
> > > possibility.
> > 
> > I think your patch is 1) unneeded (see the copy loop code and the 
> > comment before it), and 2) simply hiding the real bug.
> > 
> > I just need to modify the code in compressed/misc.c slightly for the 
> > lzma decompressor to start or stop working randomly.  It seems that this 
> > code might be sensitive to slight displacement in memory caused by 
> > modifications to totally unrelated code.  I'm still trying to track this 
> > down.
> 
> I found the bugger.  The problem was a bad stack alignment.
> 
> ----- >8
> 
> From: Nicolas Pitre <nicolas.pitre at linaro.org>
> 
> ARM: zImage: make sure the stack is 64-bit aligned
> 
> With ARMv5+ and EABI, the compiler expects a 64-bit aligned stack so
> instructions like STRD and LDRD can be used.  Without this, mysterious
> boot failures were seen semi randomly with the LZMA decompressor.
> 
> While at it, let's align .bss as well.
> 
> Signed-off-by: Nicolas Pitre <nicolas.pitre at linaro.org>
> 
> diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
> index 58ac434..79b5c62 100644
> --- a/arch/arm/boot/compressed/Makefile
> +++ b/arch/arm/boot/compressed/Makefile
> @@ -74,7 +74,7 @@ ZTEXTADDR	:= $(CONFIG_ZBOOT_ROM_TEXT)
>  ZBSSADDR	:= $(CONFIG_ZBOOT_ROM_BSS)
>  else
>  ZTEXTADDR	:= 0
> -ZBSSADDR	:= ALIGN(4)
> +ZBSSADDR	:= ALIGN(8)
>  endif
>  
>  SEDFLAGS	= s/TEXT_START/$(ZTEXTADDR)/;s/BSS_START/$(ZBSSADDR)/
> diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
> index 5309909..ea80abe 100644
> --- a/arch/arm/boot/compressed/vmlinux.lds.in
> +++ b/arch/arm/boot/compressed/vmlinux.lds.in
> @@ -54,6 +54,7 @@ SECTIONS
>    .bss			: { *(.bss) }
>    _end = .;
>  
> +  . = ALIGN(8);		/* the stack must be 64-bit aligned */
>    .stack		: { *(.stack) }
>  
>    .stab 0		: { *(.stab) }
> 
So this is the [PATCH 1/3] in the same set with following two?

[PATCH 2/3] ARM: zImage: don't ignore error returned from decompress()
[PATCH 3/3] ARM: zImage: the page table memory must be considered before relocation

-- 
Regards,
Shawn