efi/x86: Move x86 back to libstub

This reverts commit 84be880560fb, 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: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 704f58a..20db5b3 100644 (file)
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -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)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 1acf605..92b9a5f 100644 (file)
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -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;

diff --git a/arch/x86/boot/compressed/eboot.h b/arch/x86/boot/compressed/eboot.h
index c88c31e..d487e72 100644 (file)
--- a/arch/x86/boot/compressed/eboot.h
+++ b/arch/x86/boot/compressed/eboot.h
@@ -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 */

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 9b11757..25bce45 100644 (file)
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -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

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index aef6a95..d8be608 100644 (file)
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -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/