[U-Boot] [PATCH] ARM: Fix __bss_start and __bss_end in linker scripts

[Benoît Thébaudeau]

On Friday, April 5, 2013 1:05:53 AM, Benoît Thébaudeau wrote:
> Hi Albert,
> 
> On Friday, April 5, 2013 12:13:53 AM, Albert ARIBAUD wrote:
> > Subject: [PATCH] ARM: Fix __bss_start and __bss_end in linker scripts
> > 
> > Commit 3ebd1cbc introduced compiler-generated __bss_start
> > and __bss_end__ and commit c23561e7 rewrote all __bss_end__
> > as __bss_end. Their merge caused silent and harmless but
> > potentially bug-inducing clashes between compiler- and linker-
> > enerated __bss_end symbols.
> > 
> > Make __bss_end and __bss_start compiler-only, and create
> > __bss_base and __bss_limit for linker-only use.
> > 
> > Reported-by: Benoît Thébaudeau <benoit.thebaudeau at advansee.com>
> > Signed-off-by: Albert ARIBAUD <albert.u.boot at aribaud.net>
> > ---
> >  arch/arm/cpu/ixp/u-boot.lds        |   14 ++++++++++----
> >  arch/arm/cpu/u-boot.lds            |   14 ++++++++++----
> >  board/actux1/u-boot.lds            |   14 ++++++++++----
> >  board/actux2/u-boot.lds            |   14 ++++++++++----
> >  board/actux3/u-boot.lds            |   14 ++++++++++----
> >  board/dvlhost/u-boot.lds           |   14 ++++++++++----
> >  board/freescale/mx31ads/u-boot.lds |   14 ++++++++++----
> >  7 files changed, 70 insertions(+), 28 deletions(-)
> > 
> > diff --git a/arch/arm/cpu/ixp/u-boot.lds b/arch/arm/cpu/ixp/u-boot.lds
> > index 8345b55..c999829 100644
> > --- a/arch/arm/cpu/ixp/u-boot.lds
> > +++ b/arch/arm/cpu/ixp/u-boot.lds
> > @@ -67,17 +67,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
> > index 3a1083d..0543b06 100644
> > --- a/arch/arm/cpu/u-boot.lds
> > +++ b/arch/arm/cpu/u-boot.lds
> > @@ -81,18 +81,24 @@ SECTIONS
> >  		*(.mmutable)
> >  	}
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> >  
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/board/actux1/u-boot.lds b/board/actux1/u-boot.lds
> > index c76728a..7e5c4d8 100644
> > --- a/board/actux1/u-boot.lds
> > +++ b/board/actux1/u-boot.lds
> > @@ -74,17 +74,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/board/actux2/u-boot.lds b/board/actux2/u-boot.lds
> > index 984f70e..ce1b7c9 100644
> > --- a/board/actux2/u-boot.lds
> > +++ b/board/actux2/u-boot.lds
> > @@ -74,17 +74,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/board/actux3/u-boot.lds b/board/actux3/u-boot.lds
> > index fc48cf0..3e091dd 100644
> > --- a/board/actux3/u-boot.lds
> > +++ b/board/actux3/u-boot.lds
> > @@ -74,17 +74,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/board/dvlhost/u-boot.lds b/board/dvlhost/u-boot.lds
> > index b13d3e1..fe3c21b 100644
> > --- a/board/dvlhost/u-boot.lds
> > +++ b/board/dvlhost/u-boot.lds
> > @@ -74,17 +74,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.dynstr*) }
> > diff --git a/board/freescale/mx31ads/u-boot.lds
> > b/board/freescale/mx31ads/u-boot.lds
> > index 264c4e8..e6885a5 100644
> > --- a/board/freescale/mx31ads/u-boot.lds
> > +++ b/board/freescale/mx31ads/u-boot.lds
> > @@ -80,17 +80,23 @@ SECTIONS
> >  
> >  	_end = .;
> >  
> > +/*
> > + * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
> > + * __bss_base and __bss_limit are for linker only (overlay ordering)
> > + */
> > +
> >  	.bss_start __rel_dyn_start (OVERLAY) : {
> >  		KEEP(*(.__bss_start));
> > +		HIDDEN(__bss_base = .);
> >  	}
> >  
> > -	.bss __bss_start (OVERLAY) : {
> > +	.bss __bss_base (OVERLAY) : {
> >  		*(.bss*)
> >  		 . = ALIGN(4);
> > -		 __bss_end = .;
> > +		 HIDDEN(__bss_limit = .);
> >  	}
> > -	.bss_end __bss_end (OVERLAY) : {
> > -		KEEP(*(__bss_end));
> > +	.bss_end __bss_limit (OVERLAY) : {
> > +		KEEP(*(.__bss_end));
> >  	}
> >  
> >  	/DISCARD/ : { *(.bss*) }
> > --
> > 1.7.10.4
> > 
> > 
> 
> Looks good, but what about the __bss_end in
> ASSERT(__bss_end < (CONFIG_SPL_TEXT_BASE + CONFIG_SPL_MAX_SIZE), "SPL image
> too big");
> ?
> 
> Shouldn't it be replaced with __bss_limit, or even better, with
> __image_copy_end
> (why should BSS be taken into account for SPL image size?)?

I meant __bss_base, not __image_copy_end.

Best regards,
Benoît