drivers/firmware/efi/libstub/Makefile

   1 # SPDX-License-Identifier: GPL-2.0
   2 #
   3 # The stub may be linked into the kernel proper or into a separate boot binary,
   4 # but in either case, it executes before the kernel does (with MMU disabled) so
   5 # things like ftrace and stack-protector are likely to cause trouble if left
   6 # enabled, even if doing so doesn't break the build.
   7 #
   8 cflags-$(CONFIG_X86_32)         := -march=i386
   9 cflags-$(CONFIG_X86_64)         := -mcmodel=small
  10 cflags-$(CONFIG_X86)            += -m$(BITS) -D__KERNEL__ -O2 \
  11                                    -fPIC -fno-strict-aliasing -mno-red-zone \
  12                                    -mno-mmx -mno-sse
  13
  14 cflags-$(CONFIG_ARM64)          := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie
  15 cflags-$(CONFIG_ARM)            := $(subst -pg,,$(KBUILD_CFLAGS)) \
  16                                    -fno-builtin -fpic -mno-single-pic-base
  17
  18 cflags-$(CONFIG_EFI_ARMSTUB)    += -I$(srctree)/scripts/dtc/libfdt
  19
  20 KBUILD_CFLAGS                   := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
  21                                    -D__NO_FORTIFY \
  22                                    $(call cc-option,-ffreestanding) \
  23                                    $(call cc-option,-fno-stack-protector)
  24
  25 GCOV_PROFILE                    := n
  26 KASAN_SANITIZE                  := n
  27 UBSAN_SANITIZE                  := n
  28 OBJECT_FILES_NON_STANDARD       := y
  29
  30 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
  31 KCOV_INSTRUMENT                 := n
  32
  33 lib-y                           := efi-stub-helper.o gop.o secureboot.o tpm.o
  34
  35 # include the stub's generic dependencies from lib/ when building for ARM/arm64
  36 arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
  37 arm-deps-$(CONFIG_ARM64) += sort.c
  38
  39 $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
  40         $(call if_changed_rule,cc_o_c)
  41
  42 lib-$(CONFIG_EFI_ARMSTUB)       += arm-stub.o fdt.o string.o random.o \
  43                                    $(patsubst %.c,lib-%.o,$(arm-deps-y))
  44
  45 lib-$(CONFIG_ARM)               += arm32-stub.o
  46 lib-$(CONFIG_ARM64)             += arm64-stub.o
  47 CFLAGS_arm64-stub.o             := -DTEXT_OFFSET=$(TEXT_OFFSET)
  48
  49 #
  50 # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
  51 # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
  52 # So let's apply the __init annotations at the section level, by prefixing
  53 # the section names directly. This will ensure that even all the inline string
  54 # literals are covered.
  55 # The fact that the stub and the kernel proper are essentially the same binary
  56 # also means that we need to be extra careful to make sure that the stub does
  57 # not rely on any absolute symbol references, considering that the virtual
  58 # kernel mapping that the linker uses is not active yet when the stub is
  59 # executing. So build all C dependencies of the EFI stub into libstub, and do
  60 # a verification pass to see if any absolute relocations exist in any of the
  61 # object files.
  62 #
  63 extra-$(CONFIG_EFI_ARMSTUB)     := $(lib-y)
  64 lib-$(CONFIG_EFI_ARMSTUB)       := $(patsubst %.o,%.stub.o,$(lib-y))
  65
  66 STUBCOPY_RM-y                   := -R *ksymtab* -R *kcrctab*
  67 STUBCOPY_FLAGS-$(CONFIG_ARM64)  += --prefix-alloc-sections=.init \
  68                                    --prefix-symbols=__efistub_
  69 STUBCOPY_RELOC-$(CONFIG_ARM64)  := R_AARCH64_ABS
  70
  71 $(obj)/%.stub.o: $(obj)/%.o FORCE
  72         $(call if_changed,stubcopy)
  73
  74 #
  75 # Strip debug sections and some other sections that may legally contain
  76 # absolute relocations, so that we can inspect the remaining sections for
  77 # such relocations. If none are found, regenerate the output object, but
  78 # this time, use objcopy and leave all sections in place.
  79 #
  80 quiet_cmd_stubcopy = STUBCPY $@
  81       cmd_stubcopy = if $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<; \
  82                      then if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); \
  83                      then (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \
  84                            rm -f $@; /bin/false);                         \
  85                      else $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; fi        \
  86                      else /bin/false; fi
  87
  88 #
  89 # ARM discards the .data section because it disallows r/w data in the
  90 # decompressor. So move our .data to .data.efistub, which is preserved
  91 # explicitly by the decompressor linker script.
  92 #
  93 STUBCOPY_FLAGS-$(CONFIG_ARM)    += --rename-section .data=.data.efistub
  94 STUBCOPY_RELOC-$(CONFIG_ARM)    := R_ARM_ABS