[PATCH 3/3] ARM: zImage: fix issues with missing GOT entries for some global variables

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

On Wed, Apr 20, 2011 at 12:15:04AM -0400, Nicolas Pitre wrote:
> Many architecture specific versions of uncompress.h make use of global
> variables marked static.  In such case the GOT is bypassed and the
> code in head.S can't relocate them.
> 
> Instead of removing the static keyword from all those files and hope that
> it won't come back, let's simply
> define it out.
> 
> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
> ---
> 
> This should fix remaining issues some people have with the DT append patch.
> 
>  arch/arm/boot/compressed/misc.c |   13 +++++++++++++
>  1 files changed, 13 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
> index a565853..0125dae 100644
> --- a/arch/arm/boot/compressed/misc.c
> +++ b/arch/arm/boot/compressed/misc.c
> @@ -30,7 +30,20 @@ unsigned int __machine_arch_type;
>  static void putstr(const char *ptr);
>  extern void error(char *x);
>  
> +/*
> + * Many instances of mach/uncompress.h are including global variables.
> + * Contrary to standard usage, we should _not_ mark those variables
> + * static otherwise they get accessed via GOTOFF references which cannot
> + * be modified at run time.  The entry code in head.S relies on the ability
> + * to move writable sections around, and for that to work, we must have all
> + * references going through the GOT which works only with non static
> + * variables.  So, instead of asking for a non intuitive requirement
> + * making many files non standard according to accepted coding practices
> + * we fix the issue here by simply defining the static keyword to nothing.
> + */
> +#define static /* non-static */
>  #include <mach/uncompress.h>
> +#undef static
This has a strange side effect, i.e. 

	static something *ptr;

isn't initialised to NULL anymore IIRC. So the maintainers of
the various mach/uncompress.h still need to be aware of the issue.

Best regards
Uwe

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