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

[Benoît Thébaudeau]

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?)?

Best regards,
Benoît