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ARM: make gd a function for clang

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"clang does not support global register variables; this is
unlikely to be implemented soon because it requires additional
LLVM backend support" [1]

Workaround it by obtaining the value of gd/r9 by an inline
asm routine. Note there is no set routine added for ARM at the
moment, since most if not all updates of gd from c are actually
not needed for ARM.

[1] http://clang.llvm.org/docs/UsersManual.html

cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
This commit is contained in:
Jeroen Hofstee 2014-07-30 21:54:52 +02:00 committed by Albert ARIBAUD
parent 1401d87b44
commit c65a2abb6c
1 changed files with 25 additions and 0 deletions
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25
arch/arm/include/asm/global_data.h
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@ -44,10 +44,35 @@ struct arch_global_data {
#include <asm-generic/global_data.h>
#ifdef __clang__
#define DECLARE_GLOBAL_DATA_PTR
#define gd get_gd()
static inline gd_t *get_gd(void)
{
gd_t *gd_ptr;
#ifdef CONFIG_ARM64
/*
* Make will already error that reserving x18 is not supported at the
* time of writing, clang: error: unknown argument: '-ffixed-x18'
*/
__asm__ volatile("mov %0, x18\n" : "=r" (gd_ptr));
#else
__asm__ volatile("mov %0, r9\n" : "=r" (gd_ptr));
#endif
return gd_ptr;
}
#else
#ifdef CONFIG_ARM64
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("x18")
#else
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r9")
#endif
#endif
#endif /* __ASM_GBL_DATA_H */