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x86: Allow use of global_data with EFI 

On x86 the global_data pointer is provided through a somewhat-bizarre and
x86-specific mechanism: the F segment register is set to a pointer to the
start of global_data, so that accesses can use this build-in register.

When running as an EFI application we don't want to mess with the Global
Descriptor Table (GDT) and there is little advantage (in terms of code size)
to doing so.

Allow global_data to be a simple variable in this case.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Simon Glass 2015-07-31 09:31:35 -06:00
parent 53292ad956
commit 8f3b9694b2
1 changed files with 7 additions and 0 deletions
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7
arch/x86/include/asm/global_data.h
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@ -76,6 +76,12 @@ struct arch_global_data {
#include <asm-generic/global_data.h>
#ifndef __ASSEMBLY__
# ifdef CONFIG_EFI_APP
#define gd global_data_ptr
#define DECLARE_GLOBAL_DATA_PTR extern struct global_data *global_data_ptr
# else
static inline __attribute__((no_instrument_function)) gd_t *get_fs_gd_ptr(void)
{
gd_t *gd_ptr;
@ -88,6 +94,7 @@ static inline __attribute__((no_instrument_function)) gd_t *get_fs_gd_ptr(void)
#define gd get_fs_gd_ptr()
#define DECLARE_GLOBAL_DATA_PTR
# endif
#endif