Commit 243b6754 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Matt Fleming
Browse files

efi/x86: Move x86 back to libstub 



This reverts commit 84be8805, which itself reverted my original
attempt to move x86 from #include'ing .c files from across the tree
to using the EFI stub built as a static library.

The issue that affected the original approach was that splitting
the implementation into several .o files resulted in the variable
'efi_early' becoming a global with external linkage, which under
-fPIC implies that references to it must go through the GOT. However,
dealing with this additional GOT entry turned out to be troublesome
on some EFI implementations. (GCC's visibility=hidden attribute is
supposed to lift this requirement, but it turned out not to work on
the 32-bit build.)

Instead, use a pure getter function to get a reference to efi_early.
This approach results in no additional GOT entries being generated,
so there is no need for any changes in the early GOT handling.

Tested-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent af5a29ae

arch/x86/boot/compressed/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -35,7 +35,8 @@ vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/aslr.o 


$(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone



vmlinux-objs-$(CONFIG_EFI_STUB) += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o

vmlinux-objs-$(CONFIG_EFI_STUB) += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \

	$(objtree)/drivers/firmware/efi/libstub/lib.a



$(obj)/vmlinux: $(vmlinux-objs-y) FORCE

	$(call if_changed,ld)

arch/x86/boot/compressed/eboot.c

+4 −4
Original line number Diff line number Diff line
@@ -21,8 +21,10 @@ static efi_system_table_t *sys_table; 


static struct efi_config *efi_early;



#define efi_call_early(f, ...)						\

	efi_early->call(efi_early->f, __VA_ARGS__);

__pure const struct efi_config *__efi_early(void)

{

	return efi_early;

}



#define BOOT_SERVICES(bits)						\

static void setup_boot_services##bits(struct efi_config *c)		\
@@ -285,8 +287,6 @@ void efi_char16_printk(efi_system_table_t *table, efi_char16_t *str) 
	}

}



#include "../../../../drivers/firmware/efi/libstub/efi-stub-helper.c"



static void find_bits(unsigned long mask, u8 *pos, u8 *size)

{

	u8 first, len;

arch/x86/boot/compressed/eboot.h

+0 −16
Original line number Diff line number Diff line
@@ -103,20 +103,4 @@ struct efi_uga_draw_protocol { 
	void *blt;

};



struct efi_config {

	u64 image_handle;

	u64 table;

	u64 allocate_pool;

	u64 allocate_pages;

	u64 get_memory_map;

	u64 free_pool;

	u64 free_pages;

	u64 locate_handle;

	u64 handle_protocol;

	u64 exit_boot_services;

	u64 text_output;

	efi_status_t (*call)(unsigned long, ...);

	bool is64;

} __packed;



#endif /* BOOT_COMPRESSED_EBOOT_H */

arch/x86/include/asm/efi.h

+24 −0
Original line number Diff line number Diff line
@@ -158,6 +158,30 @@ static inline efi_status_t efi_thunk_set_virtual_address_map( 
}

#endif /* CONFIG_EFI_MIXED */





/* arch specific definitions used by the stub code */



struct efi_config {

	u64 image_handle;

	u64 table;

	u64 allocate_pool;

	u64 allocate_pages;

	u64 get_memory_map;

	u64 free_pool;

	u64 free_pages;

	u64 locate_handle;

	u64 handle_protocol;

	u64 exit_boot_services;

	u64 text_output;

	efi_status_t (*call)(unsigned long, ...);

	bool is64;

} __packed;



__pure const struct efi_config *__efi_early(void);



#define efi_call_early(f, ...)						\

	__efi_early()->call(__efi_early()->f, __VA_ARGS__);



extern bool efi_reboot_required(void);



#else

drivers/firmware/efi/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -7,4 +7,4 @@ obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o 
obj-$(CONFIG_UEFI_CPER)			+= cper.o

obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o

obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o

obj-$(CONFIG_EFI_ARM_STUB)		+= libstub/
 
obj-$(CONFIG_EFI_STUB)			+= libstub/

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