[PATCH v2 5/5] efi: efistub: convert into static library

[ard.biesheuvel@linaro.org (Ard Biesheuvel)]

This patch changes both x86 and arm64 efistub implementations from #including
shared .c files under drivers/firmware/efi to building the shared code as a
static library.

The x86 code uses a stub built into the boot executable which uncompresses the
kernel at boot time. In this case, the library is linked into the decompressor.

In the arm64 case, the stub is part of the kernel proper so the library is
linked into the kernel proper as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/arm64/Kconfig                                 |  1 +
 arch/arm64/Makefile                                |  1 +
 arch/arm64/kernel/efi-stub.c                       |  5 -----
 arch/x86/boot/compressed/Makefile                  |  3 ++-
 arch/x86/boot/compressed/eboot.c                   |  2 --
 drivers/firmware/efi/Kconfig                       |  3 +++
 drivers/firmware/efi/Makefile                      |  2 +-
 drivers/firmware/efi/libstub/Makefile              | 26 ++++++++++++++++++++++
 drivers/firmware/efi/{ => libstub}/arm-stub.c      | 14 ++++++------
 .../firmware/efi/{ => libstub}/efi-stub-helper.c   |  0
 drivers/firmware/efi/{ => libstub}/efistub.h       |  0
 drivers/firmware/efi/{ => libstub}/fdt.c           |  0
 12 files changed, 41 insertions(+), 16 deletions(-)
 create mode 100644 drivers/firmware/efi/libstub/Makefile
 rename drivers/firmware/efi/{ => libstub}/arm-stub.c (96%)
 rename drivers/firmware/efi/{ => libstub}/efi-stub-helper.c (100%)
 rename drivers/firmware/efi/{ => libstub}/efistub.h (100%)
 rename drivers/firmware/efi/{ => libstub}/fdt.c (100%)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 93e11f4d9513..f766f346022d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -300,6 +300,7 @@ config EFI
 	select UCS2_STRING
 	select EFI_PARAMS_FROM_FDT
 	select EFI_RUNTIME_WRAPPERS
+	select EFI_ARMSTUB
 	default y
 	help
 	  This option provides support for runtime services provided
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 8185a913c5ed..bb8f21a626c0 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -48,6 +48,7 @@ core-$(CONFIG_XEN) += arch/arm64/xen/
 core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
 libs-y		:= arch/arm64/lib/ $(libs-y)
 libs-y		+= $(LIBGCC)
+libs-$(CONFIG_EFI) += drivers/firmware/efi/libstub/
 
 # Default target when executing plain make
 KBUILD_IMAGE	:= Image.gz
diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
index e4999021b07d..12456a7d3fa2 100644
--- a/arch/arm64/kernel/efi-stub.c
+++ b/arch/arm64/kernel/efi-stub.c
@@ -13,11 +13,6 @@
 #include <asm/efi.h>
 #include <asm/sections.h>
 
-/* Include shared EFI stub code */
-#include "../../../drivers/firmware/efi/efi-stub-helper.c"
-#include "../../../drivers/firmware/efi/fdt.c"
-#include "../../../drivers/firmware/efi/arm-stub.c"
-
 
 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
 				 unsigned long *image_addr,
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 0fcd9133790c..7a801a310e37 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -33,7 +33,8 @@ VMLINUX_OBJS = $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \
 $(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone
 
 ifeq ($(CONFIG_EFI_STUB), y)
-	VMLINUX_OBJS += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o
+	VMLINUX_OBJS += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \
+				$(objtree)/drivers/firmware/efi/libstub/lib.a
 endif
 
 $(obj)/vmlinux: $(VMLINUX_OBJS) FORCE
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index d338c134c659..d4d865438a0c 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -280,8 +280,6 @@ void efi_char16_printk(efi_system_table_t *table, efi_char16_t *str)
 	}
 }
 
-#include "../../../../drivers/firmware/efi/efi-stub-helper.c"
-
 static void find_bits(unsigned long mask, u8 *pos, u8 *size)
 {
 	u8 first, len;
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 04a7af46736a..395e76d9a1b5 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -61,6 +61,9 @@ config EFI_RUNTIME_WRAPPERS
 	  in which case it needs to provide #definitions of efi_call_virt and
 	  __efi_call_virt in <asm/efi.h>
 
+config EFI_ARMSTUB
+	bool
+
 endmenu
 
 config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index e1096539eedb..d9abdbc962f1 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -1,7 +1,7 @@
 #
 # Makefile for linux kernel
 #
-obj-$(CONFIG_EFI)			+= efi.o vars.o
+obj-$(CONFIG_EFI)			+= efi.o vars.o libstub/
 obj-$(CONFIG_EFI_VARS)			+= efivars.o
 obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
 obj-$(CONFIG_UEFI_CPER)			+= cper.o
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
new file mode 100644
index 000000000000..b14bc2b9fb4d
--- /dev/null
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -0,0 +1,26 @@
+#
+# The stub may be linked into the kernel proper or into a separate boot binary,
+# but in either case, it executes before the kernel does (with MMU disabled) so
+# things like ftrace and stack-protector are likely to cause trouble if left
+# enabled, even if doing so doesn't break the build.
+#
+cflags-$(CONFIG_X86_32)		:= -march=i386
+cflags-$(CONFIG_X86_64)		:= -mcmodel=small
+cflags-$(CONFIG_X86)		+= -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
+				   -fPIC -fno-strict-aliasing -mno-red-zone \
+				   -mno-mmx -mno-sse -DDISABLE_BRANCH_PROFILING
+
+cflags-$(CONFIG_ARM64)		:= $(subst -pg,,$(KBUILD_CFLAGS))
+cflags-$(CONFIG_ARM)		:= $(subst -pg,,$(KBUILD_CFLAGS)) \
+				   -fno-builtin -fpic -mno-single-pic-base
+
+KBUILD_CFLAGS			:= $(cflags-y) \
+				   $(call cc-option,-ffreestanding) \
+				   $(call cc-option,-fno-stack-protector)
+
+GCOV_PROFILE			:= n
+
+lib-y				:= efi-stub-helper.o
+lib-$(CONFIG_EFI_ARMSTUB)	+= arm-stub.o fdt.o
+
+CFLAGS_fdt.o			+= -I$(srctree)/scripts/dtc/libfdt/
diff --git a/drivers/firmware/efi/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
similarity index 96%
rename from drivers/firmware/efi/arm-stub.c
rename to drivers/firmware/efi/libstub/arm-stub.c
index 34614d6f9698..480339b6b110 100644
--- a/drivers/firmware/efi/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -151,13 +151,13 @@ void efi_char16_printk(efi_system_table_t *sys_table_arg,
  * must be reserved. On failure it is required to free all
  * all allocations it has made.
  */
-static efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
-					unsigned long *image_addr,
-					unsigned long *image_size,
-					unsigned long *reserve_addr,
-					unsigned long *reserve_size,
-					unsigned long dram_base,
-					efi_loaded_image_t *image);
+efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
+				 unsigned long *image_addr,
+				 unsigned long *image_size,
+				 unsigned long *reserve_addr,
+				 unsigned long *reserve_size,
+				 unsigned long dram_base,
+				 efi_loaded_image_t *image);
 /*
  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
  * that is described in the PE/COFF header.  Most of the code is the same
diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
similarity index 100%
rename from drivers/firmware/efi/efi-stub-helper.c
rename to drivers/firmware/efi/libstub/efi-stub-helper.c
diff --git a/drivers/firmware/efi/efistub.h b/drivers/firmware/efi/libstub/efistub.h
similarity index 100%
rename from drivers/firmware/efi/efistub.h
rename to drivers/firmware/efi/libstub/efistub.h
diff --git a/drivers/firmware/efi/fdt.c b/drivers/firmware/efi/libstub/fdt.c
similarity index 100%
rename from drivers/firmware/efi/fdt.c
rename to drivers/firmware/efi/libstub/fdt.c
-- 
1.8.3.2