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                                    $(call cc-option,-mbranch-protection=none)
  28 cflags-$(CONFIG_ARM)            += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
  29                                    -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
  30                                    -DEFI_HAVE_STRCMP -fno-builtin -fpic \
  31                                    $(call cc-option,-mno-single-pic-base)
  32 cflags-$(CONFIG_RISCV)          += -fpic
  33 cflags-$(CONFIG_LOONGARCH)      += -fpie
  34
  35 cflags-$(CONFIG_EFI_PARAMS_FROM_FDT)    += -I$(srctree)/scripts/dtc/libfdt
  36
  37 KBUILD_CFLAGS                   := $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
  38                                    -Os -DDISABLE_BRANCH_PROFILING \
  39                                    -include $(srctree)/include/linux/hidden.h \
  40                                    -D__NO_FORTIFY \
  41                                    -ffreestanding \
  42                                    -fno-stack-protector \
  43                                    $(call cc-option,-fno-addrsig) \
  44                                    -D__DISABLE_EXPORTS
  45
  46 #
  47 # struct randomization only makes sense for Linux internal types, which the EFI
  48 # stub code never touches, so let's turn off struct randomization for the stub
  49 # altogether
  50 #
  51 KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))
  52
  53 # remove SCS flags from all objects in this directory
  54 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
  55 # disable CFI
  56 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
  57 # disable LTO
  58 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
  59
  60 GCOV_PROFILE                    := n
  61 # Sanitizer runtimes are unavailable and cannot be linked here.
  62 KASAN_SANITIZE                  := n
  63 KCSAN_SANITIZE                  := n
  64 KMSAN_SANITIZE                  := n
  65 UBSAN_SANITIZE                  := n
  66 OBJECT_FILES_NON_STANDARD       := y
  67
  68 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
  69 KCOV_INSTRUMENT                 := n
  70
  71 lib-y                           := efi-stub-helper.o gop.o secureboot.o tpm.o \
  72                                    file.o mem.o random.o randomalloc.o pci.o \
  73                                    skip_spaces.o lib-cmdline.o lib-ctype.o \
  74                                    alignedmem.o relocate.o printk.o vsprintf.o
  75
  76 # include the stub's libfdt dependencies from lib/ when needed
  77 libfdt-deps                     := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
  78                                    fdt_empty_tree.c fdt_sw.c
  79
  80 lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
  81                                      $(patsubst %.c,lib-%.o,$(libfdt-deps))
  82
  83 $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
  84         $(call if_changed_rule,cc_o_c)
  85
  86 lib-$(CONFIG_EFI_GENERIC_STUB)  += efi-stub.o string.o intrinsics.o systable.o \
  87                                    screen_info.o efi-stub-entry.o
  88
  89 lib-$(CONFIG_ARM)               += arm32-stub.o
  90 lib-$(CONFIG_ARM64)             += arm64.o arm64-stub.o arm64-entry.o smbios.o
  91 lib-$(CONFIG_X86)               += x86-stub.o
  92 lib-$(CONFIG_RISCV)             += riscv.o riscv-stub.o
  93 lib-$(CONFIG_LOONGARCH)         += loongarch.o loongarch-stub.o
  94
  95 CFLAGS_arm32-stub.o             := -DTEXT_OFFSET=$(TEXT_OFFSET)
  96
  97 zboot-obj-$(CONFIG_RISCV)       := lib-clz_ctz.o lib-ashldi3.o
  98 lib-$(CONFIG_EFI_ZBOOT)         += zboot.o $(zboot-obj-y)
  99
 100 extra-y                         := $(lib-y)
 101 lib-y                           := $(patsubst %.o,%.stub.o,$(lib-y))
 102
 103 # Even when -mbranch-protection=none is set, Clang will generate a
 104 # .note.gnu.property for code-less object files (like lib/ctype.c),
 105 # so work around this by explicitly removing the unwanted section.
 106 # https://bugs.llvm.org/show_bug.cgi?id=46480
 107 STUBCOPY_FLAGS-y                += --remove-section=.note.gnu.property
 108
 109 #
 110 # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
 111 # .bss section, so the .bss section of the EFI stub needs to be included in the
 112 # .data section of the compressed kernel to ensure initialization. Rename the
 113 # .bss section here so it's easy to pick out in the linker script.
 114 #
 115 STUBCOPY_FLAGS-$(CONFIG_X86)    += --rename-section .bss=.bss.efistub,load,alloc
 116 STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32
 117 STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64
 118
 119 #
 120 # ARM discards the .data section because it disallows r/w data in the
 121 # decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
 122 # which are preserved explicitly by the decompressor linker script.
 123 #
 124 STUBCOPY_FLAGS-$(CONFIG_ARM)    += --rename-section .data=.data.efistub \
 125                                    --rename-section .bss=.bss.efistub,load,alloc
 126 STUBCOPY_RELOC-$(CONFIG_ARM)    := R_ARM_ABS
 127
 128 #
 129 # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
 130 # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
 131 # So let's apply the __init annotations at the section level, by prefixing
 132 # the section names directly. This will ensure that even all the inline string
 133 # literals are covered.
 134 # The fact that the stub and the kernel proper are essentially the same binary
 135 # also means that we need to be extra careful to make sure that the stub does
 136 # not rely on any absolute symbol references, considering that the virtual
 137 # kernel mapping that the linker uses is not active yet when the stub is
 138 # executing. So build all C dependencies of the EFI stub into libstub, and do
 139 # a verification pass to see if any absolute relocations exist in any of the
 140 # object files.
 141 #
 142 STUBCOPY_FLAGS-$(CONFIG_ARM64)  += --prefix-alloc-sections=.init \
 143                                    --prefix-symbols=__efistub_
 144 STUBCOPY_RELOC-$(CONFIG_ARM64)  := R_AARCH64_ABS64
 145
 146 # For RISC-V, we don't need anything special other than arm64. Keep all the
 147 # symbols in .init section and make sure that no absolute symbols references
 148 # doesn't exist.
 149 STUBCOPY_FLAGS-$(CONFIG_RISCV)  += --prefix-alloc-sections=.init \
 150                                    --prefix-symbols=__efistub_
 151 STUBCOPY_RELOC-$(CONFIG_RISCV)  := R_RISCV_HI20
 152
 153 # For LoongArch, keep all the symbols in .init section and make sure that no
 154 # absolute symbols references exist.
 155 STUBCOPY_FLAGS-$(CONFIG_LOONGARCH)      += --prefix-alloc-sections=.init \
 156                                            --prefix-symbols=__efistub_
 157 STUBCOPY_RELOC-$(CONFIG_LOONGARCH)      := R_LARCH_MARK_LA
 158
 159 $(obj)/%.stub.o: $(obj)/%.o FORCE
 160         $(call if_changed,stubcopy)
 161
 162 #
 163 # Strip debug sections and some other sections that may legally contain
 164 # absolute relocations, so that we can inspect the remaining sections for
 165 # such relocations. If none are found, regenerate the output object, but
 166 # this time, use objcopy and leave all sections in place.
 167 #
 168 quiet_cmd_stubcopy = STUBCPY $@
 169       cmd_stubcopy =                                                    \
 170         $(STRIP) --strip-debug -o $@ $<;                                \
 171         if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then            \
 172                 echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
 173                 /bin/false;                                             \
 174         fi;                                                             \
 175         $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@