efi/libstub: Move arm-stub to a common file

Most of the arm-stub code is written in an architecture independent manner.
As a result, RISC-V can reuse most of the arm-stub code.

Rename the arm-stub.c to efi-stub.c so that ARM, ARM64 and RISC-V can use it.
This patch doesn't introduce any functional changes.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Link: https://lore.kernel.org/r/20200415195422.19866-2-atish.patra@wdc.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

arch/arm/Kconfig

@@ -1954,7 +1954,7 @@ config EFI
 	select UCS2_STRING
 	select EFI_PARAMS_FROM_FDT
 	select EFI_STUB
-	select EFI_ARMSTUB
+	select EFI_GENERIC_STUB
 	select EFI_RUNTIME_WRAPPERS
 	---help---
 	  This option provides support for runtime services provided

arch/arm64/Kconfig

@@ -1785,7 +1785,7 @@ config EFI
 	select EFI_PARAMS_FROM_FDT
 	select EFI_RUNTIME_WRAPPERS
 	select EFI_STUB
-	select EFI_ARMSTUB
+	select EFI_GENERIC_STUB
 	default y
 	help
 	  This option provides support for runtime services provided

drivers/firmware/efi/Kconfig

@@ -106,12 +106,12 @@ config EFI_PARAMS_FROM_FDT
 config EFI_RUNTIME_WRAPPERS
 	bool
 
-config EFI_ARMSTUB
+config EFI_GENERIC_STUB
 	bool
 
 config EFI_ARMSTUB_DTB_LOADER
 	bool "Enable the DTB loader"
-	depends on EFI_ARMSTUB
+	depends on EFI_GENERIC_STUB
 	default y
 	help
 	  Select this config option to add support for the dtb= command

drivers/firmware/efi/libstub/Makefile

@@ -23,7 +23,7 @@ cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   -fno-builtin -fpic \
 				   $(call cc-option,-mno-single-pic-base)
 
-cflags-$(CONFIG_EFI_ARMSTUB)	+= -I$(srctree)/scripts/dtc/libfdt
+cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt
 
 KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 				   -include $(srctree)/drivers/firmware/efi/libstub/hidden.h \
@@ -45,13 +45,13 @@ lib-y				:= efi-stub-helper.o gop.o secureboot.o tpm.o \
 				   skip_spaces.o lib-cmdline.o lib-ctype.o
 
 # include the stub's generic dependencies from lib/ when building for ARM/arm64
-arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
+efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
 
 $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
-lib-$(CONFIG_EFI_ARMSTUB)	+= arm-stub.o fdt.o string.o \
-				   $(patsubst %.c,lib-%.o,$(arm-deps-y))
+lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o fdt.o string.o \
+				   $(patsubst %.c,lib-%.o,$(efi-deps-y))
 
 lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= arm64-stub.o
@@ -73,8 +73,8 @@ CFLAGS_arm64-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 # a verification pass to see if any absolute relocations exist in any of the
 # object files.
 #
-extra-$(CONFIG_EFI_ARMSTUB)	:= $(lib-y)
-lib-$(CONFIG_EFI_ARMSTUB)	:= $(patsubst %.o,%.stub.o,$(lib-y))
+extra-$(CONFIG_EFI_GENERIC_STUB) := $(lib-y)
+lib-$(CONFIG_EFI_GENERIC_STUB)	:= $(patsubst %.o,%.stub.o,$(lib-y))
 
 STUBCOPY_FLAGS-$(CONFIG_ARM64)	+= --prefix-alloc-sections=.init \
 				   --prefix-symbols=__efistub_