efi: efistub: Convert into static library

This patch changes both x86 and arm64 efistub implementations
from #including shared .c files under drivers/firmware/efi to
building 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>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

13 files changed, 39 insertions, 11 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2cc14cef01bd..3a0a4ce4c751 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -292,6 +292,9 @@ config CMDLINE_FORCE
           This is useful if you cannot or don't want to change the
           command-line options your boot loader passes to the kernel.
 
+config EFI_STUB
+        bool
+
 config EFI
         bool "UEFI runtime support"
         depends on OF && !CPU_BIG_ENDIAN
@@ -299,6 +302,8 @@ config EFI
         select UCS2_STRING
         select EFI_PARAMS_FROM_FDT
         select EFI_RUNTIME_WRAPPERS
+        select EFI_STUB
+        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..5836717d2f66 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_STUB) += drivers/firmware/efi/libstub/
 
 # Default target when executing plain make
 KBUILD_IMAGE    := Image.gz
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index cdaedad3afe5..afaeb734295a 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -4,8 +4,7 @@
 
 CPPFLAGS_vmlinux.lds    := -DTEXT_OFFSET=$(TEXT_OFFSET)
 AFLAGS_head.o           := -DTEXT_OFFSET=$(TEXT_OFFSET)
-CFLAGS_efi-stub.o       := -DTEXT_OFFSET=$(TEXT_OFFSET) \
-                           -I$(src)/../../../scripts/dtc/libfdt
+CFLAGS_efi-stub.o       := -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_insn.o = -pg
diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
index e4999021b07d..1317fef8dde9 100644
--- a/arch/arm64/kernel/efi-stub.c
+++ b/arch/arm64/kernel/efi-stub.c
@@ -13,12 +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,
                                  unsigned long *image_size,
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 916bbdd7dd28..3b5c66c8f749 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 588dc47e7075..f712d47f30d8 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -57,6 +57,9 @@ config EFI_PARAMS_FROM_FDT
 config EFI_RUNTIME_WRAPPERS
         bool
 
+config EFI_ARMSTUB
+        bool
+
 endmenu
 
 config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index e1096539eedb..a204d1474cec 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -7,3 +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-$(CONFIG_EFI_STUB)                  += libstub/
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
new file mode 100644
index 000000000000..b14bc2b9fb4d
--- /dev/null
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -0,0 +1,26 @@
+#
+# The stub may be linked into the kernel proper or into a separate boot binary,
+# but in either case, it executes before the kernel does (with MMU disabled) so
+# things like ftrace and stack-protector are likely to cause trouble if left
+# enabled, even if doing so doesn't break the build.
+#
+cflags-$(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
index 480339b6b110..480339b6b110 100644
--- a/drivers/firmware/efi/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 32d5cca30f49..32d5cca30f49 100644
--- a/drivers/firmware/efi/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
diff --git a/drivers/firmware/efi/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 304ab295ca1a..304ab295ca1a 100644
--- a/drivers/firmware/efi/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
diff --git a/drivers/firmware/efi/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 86d2934840e2..86d2934840e2 100644
--- a/drivers/firmware/efi/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c