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
   9 # non-x86 reuses KBUILD_CFLAGS, x86 does not
  10 cflags-y                        := $(KBUILD_CFLAGS)
  11
  12 cflags-$(CONFIG_X86_32)         := -march=i386
  13 cflags-$(CONFIG_X86_64)         := -mcmodel=small
  14 cflags-$(CONFIG_X86)            += -m$(BITS) -D__KERNEL__ \
  15                                    -fPIC -fno-strict-aliasing -mno-red-zone \
  16                                    -mno-mmx -mno-sse -fshort-wchar \
  17                                    -Wno-pointer-sign \
  18                                    $(call cc-disable-warning, address-of-packed-member) \
  19                                    $(call cc-disable-warning, gnu) \
  20                                    -fno-asynchronous-unwind-tables \
  21                                    $(CLANG_FLAGS)
  22
  23 # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
  24 # disable the stackleak plugin
  25 cflags-$(CONFIG_ARM64)          += -fpie $(DISABLE_STACKLEAK_PLUGIN) \
  26                                    -fno-unwind-tables -fno-asynchronous-unwind-tables
  27 cflags-$(CONFIG_ARM)            += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
  28                                    -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
  29                                    -DEFI_HAVE_STRCMP -fno-builtin -fpic \
  30                                    $(call cc-option,-mno-single-pic-base) \
  31                                    $(DISABLE_STACKLEAK_PLUGIN)
  32 cflags-$(CONFIG_RISCV)          += -fpic -DNO_ALTERNATIVE -mno-relax \
  33                                    $(DISABLE_STACKLEAK_PLUGIN)
  34 cflags-$(CONFIG_LOONGARCH)      += -fpie
  35
  36 cflags-$(CONFIG_EFI_PARAMS_FROM_FDT)    += -I$(srctree)/scripts/dtc/libfdt
  37
  38 KBUILD_CFLAGS                   := $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
  39                                    -Os -DDISABLE_BRANCH_PROFILING \
  40                                    -include $(srctree)/include/linux/hidden.h \
  41                                    -D__NO_FORTIFY \
  42                                    -ffreestanding \
  43                                    -fno-stack-protector \
  44                                    $(call cc-option,-fno-addrsig) \
  45                                    -D__DISABLE_EXPORTS
  46
  47 #
  48 # struct randomization only makes sense for Linux internal types, which the EFI
  49 # stub code never touches, so let's turn off struct randomization for the stub
  50 # altogether
  51 #
  52 KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))
  53
  54 # remove SCS flags from all objects in this directory
  55 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
  56 # disable CFI
  57 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
  58 # disable LTO
  59 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
  60
  61 # The .data section would be renamed to .data.efistub, therefore, remove
  62 # `-fdata-sections` flag from KBUILD_CFLAGS_KERNEL
  63 KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNEL))
  64
  65 lib-y                           := efi-stub-helper.o gop.o secureboot.o tpm.o \
  66                                    file.o mem.o random.o randomalloc.o pci.o \
  67                                    skip_spaces.o lib-cmdline.o lib-ctype.o \
  68                                    alignedmem.o relocate.o printk.o vsprintf.o
  69
  70 # include the stub's libfdt dependencies from lib/ when needed
  71 libfdt-deps                     := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
  72                                    fdt_empty_tree.c fdt_sw.c
  73
  74 lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
  75                                      $(patsubst %.c,lib-%.o,$(libfdt-deps))
  76
  77 $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
  78         $(call if_changed_rule,cc_o_c)
  79
  80 lib-$(CONFIG_EFI_GENERIC_STUB)  += efi-stub.o string.o intrinsics.o systable.o \
  81                                    screen_info.o efi-stub-entry.o
  82
  83 lib-$(CONFIG_ARM)               += arm32-stub.o
  84 lib-$(CONFIG_ARM64)             += kaslr.o arm64.o arm64-stub.o smbios.o
  85 lib-$(CONFIG_X86)               += x86-stub.o smbios.o
  86 lib-$(CONFIG_X86_64)            += x86-5lvl.o
  87 lib-$(CONFIG_RISCV)             += kaslr.o riscv.o riscv-stub.o
  88 lib-$(CONFIG_LOONGARCH)         += loongarch.o loongarch-stub.o
  89
  90 CFLAGS_arm32-stub.o             := -DTEXT_OFFSET=$(TEXT_OFFSET)
  91
  92 zboot-obj-$(CONFIG_RISCV)       := lib-clz_ctz.o lib-ashldi3.o
  93 lib-$(CONFIG_EFI_ZBOOT)         += zboot.o $(zboot-obj-y)
  94
  95 lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o
  96
  97 extra-y                         := $(lib-y)
  98 lib-y                           := $(patsubst %.o,%.stub.o,$(lib-y))
  99
 100 # Even when -mbranch-protection=none is set, Clang will generate a
 101 # .note.gnu.property for code-less object files (like lib/ctype.c),
 102 # so work around this by explicitly removing the unwanted section.
 103 # https://llvm.org/pr46480
 104 STUBCOPY_FLAGS-y                += --remove-section=.note.gnu.property
 105
 106 STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32
 107 STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64
 108
 109 #
 110 # ARM discards the .data section because it disallows r/w data in the
 111 # decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
 112 # which are preserved explicitly by the decompressor linker script.
 113 #
 114 STUBCOPY_FLAGS-$(CONFIG_ARM)    += --rename-section .data=.data.efistub \
 115                                    --rename-section .bss=.bss.efistub,load,alloc
 116 STUBCOPY_RELOC-$(CONFIG_ARM)    := R_ARM_ABS
 117
 118 #
 119 # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
 120 # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
 121 # So let's apply the __init annotations at the section level, by prefixing
 122 # the section names directly. This will ensure that even all the inline string
 123 # literals are covered.
 124 # The fact that the stub and the kernel proper are essentially the same binary
 125 # also means that we need to be extra careful to make sure that the stub does
 126 # not rely on any absolute symbol references, considering that the virtual
 127 # kernel mapping that the linker uses is not active yet when the stub is
 128 # executing. So build all C dependencies of the EFI stub into libstub, and do
 129 # a verification pass to see if any absolute relocations exist in any of the
 130 # object files.
 131 #
 132 STUBCOPY_FLAGS-$(CONFIG_ARM64)  += --prefix-alloc-sections=.init \
 133                                    --prefix-symbols=__efistub_
 134 STUBCOPY_RELOC-$(CONFIG_ARM64)  := R_AARCH64_ABS
 135
 136 # For RISC-V, we don't need anything special other than arm64. Keep all the
 137 # symbols in .init section and make sure that no absolute symbols references
 138 # exist.
 139 STUBCOPY_FLAGS-$(CONFIG_RISCV)  += --prefix-alloc-sections=.init \
 140                                    --prefix-symbols=__efistub_
 141 STUBCOPY_RELOC-$(CONFIG_RISCV)  := -E R_RISCV_HI20\|R_RISCV_$(BITS)\|R_RISCV_RELAX
 142
 143 # For LoongArch, keep all the symbols in .init section and make sure that no
 144 # absolute symbols references exist.
 145 STUBCOPY_FLAGS-$(CONFIG_LOONGARCH)      += --prefix-alloc-sections=.init \
 146                                            --prefix-symbols=__efistub_
 147 STUBCOPY_RELOC-$(CONFIG_LOONGARCH)      := R_LARCH_MARK_LA
 148
 149 $(obj)/%.stub.o: $(obj)/%.o FORCE
 150         $(call if_changed,stubcopy)
 151
 152 #
 153 # Strip debug sections and some other sections that may legally contain
 154 # absolute relocations, so that we can inspect the remaining sections for
 155 # such relocations. If none are found, regenerate the output object, but
 156 # this time, use objcopy and leave all sections in place.
 157 #
 158 quiet_cmd_stubcopy = STUBCPY $@
 159       cmd_stubcopy =                                                    \
 160         $(STRIP) --strip-debug -o $@ $<;                                \
 161         if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then            \
 162                 echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
 163                 /bin/false;                                             \
 164         fi;                                                             \
 165         $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@