summaryrefslogtreecommitdiff
path: root/drivers/firmware/efi/libstub/Makefile
blob: 31eb1e287ce161a60da72da1b4ca30c683dec051 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
# SPDX-License-Identifier: GPL-2.0
#
# 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.
#

# non-x86 reuses KBUILD_CFLAGS, x86 does not
cflags-y			:= $(KBUILD_CFLAGS)

cflags-$(CONFIG_X86_32)		:= -march=i386
cflags-$(CONFIG_X86_64)		:= -mcmodel=small
cflags-$(CONFIG_X86)		+= -m$(BITS) -D__KERNEL__ \
				   -fPIC -fno-strict-aliasing -mno-red-zone \
				   -mno-mmx -mno-sse -fshort-wchar \
				   -Wno-pointer-sign \
				   $(call cc-disable-warning, address-of-packed-member) \
				   $(call cc-disable-warning, gnu) \
				   -fno-asynchronous-unwind-tables \
				   $(CLANG_FLAGS)

# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
# disable the stackleak plugin
cflags-$(CONFIG_ARM64)		+= -fpie $(DISABLE_STACKLEAK_PLUGIN) \
				   -fno-unwind-tables -fno-asynchronous-unwind-tables
cflags-$(CONFIG_ARM)		+= -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
				   -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
				   -DEFI_HAVE_STRCMP -fno-builtin -fpic \
				   $(call cc-option,-mno-single-pic-base)
cflags-$(CONFIG_RISCV)		+= -fpic -DNO_ALTERNATIVE -mno-relax
cflags-$(CONFIG_LOONGARCH)	+= -fpie

cflags-$(CONFIG_EFI_PARAMS_FROM_FDT)	+= -I$(srctree)/scripts/dtc/libfdt

KBUILD_CFLAGS			:= $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
				   -Os -DDISABLE_BRANCH_PROFILING \
				   -include $(srctree)/include/linux/hidden.h \
				   -D__NO_FORTIFY \
				   -ffreestanding \
				   -fno-stack-protector \
				   $(call cc-option,-fno-addrsig) \
				   -D__DISABLE_EXPORTS

#
# struct randomization only makes sense for Linux internal types, which the EFI
# stub code never touches, so let's turn off struct randomization for the stub
# altogether
#
KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))

# remove SCS flags from all objects in this directory
KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
# disable CFI
KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
# disable LTO
KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))

GCOV_PROFILE			:= n
# Sanitizer runtimes are unavailable and cannot be linked here.
KASAN_SANITIZE			:= n
KCSAN_SANITIZE			:= n
KMSAN_SANITIZE			:= n
UBSAN_SANITIZE			:= n
OBJECT_FILES_NON_STANDARD	:= y

# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
KCOV_INSTRUMENT			:= n

lib-y				:= efi-stub-helper.o gop.o secureboot.o tpm.o \
				   file.o mem.o random.o randomalloc.o pci.o \
				   skip_spaces.o lib-cmdline.o lib-ctype.o \
				   alignedmem.o relocate.o printk.o vsprintf.o

# include the stub's libfdt dependencies from lib/ when needed
libfdt-deps			:= fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
				   fdt_empty_tree.c fdt_sw.c

lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
				     $(patsubst %.c,lib-%.o,$(libfdt-deps))

$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
	$(call if_changed_rule,cc_o_c)

lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o string.o intrinsics.o systable.o \
				   screen_info.o efi-stub-entry.o

lib-$(CONFIG_ARM)		+= arm32-stub.o
lib-$(CONFIG_ARM64)		+= kaslr.o arm64.o arm64-stub.o smbios.o
lib-$(CONFIG_X86)		+= x86-stub.o
lib-$(CONFIG_X86_64)		+= x86-5lvl.o
lib-$(CONFIG_RISCV)		+= kaslr.o riscv.o riscv-stub.o
lib-$(CONFIG_LOONGARCH)		+= loongarch.o loongarch-stub.o

CFLAGS_arm32-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)

zboot-obj-$(CONFIG_RISCV)	:= lib-clz_ctz.o lib-ashldi3.o
lib-$(CONFIG_EFI_ZBOOT)		+= zboot.o $(zboot-obj-y)

lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o

extra-y				:= $(lib-y)
lib-y				:= $(patsubst %.o,%.stub.o,$(lib-y))

# Even when -mbranch-protection=none is set, Clang will generate a
# .note.gnu.property for code-less object files (like lib/ctype.c),
# so work around this by explicitly removing the unwanted section.
# https://llvm.org/pr46480
STUBCOPY_FLAGS-y		+= --remove-section=.note.gnu.property

STUBCOPY_RELOC-$(CONFIG_X86_32)	:= R_386_32
STUBCOPY_RELOC-$(CONFIG_X86_64)	:= R_X86_64_64

#
# ARM discards the .data section because it disallows r/w data in the
# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
# which are preserved explicitly by the decompressor linker script.
#
STUBCOPY_FLAGS-$(CONFIG_ARM)	+= --rename-section .data=.data.efistub	\
				   --rename-section .bss=.bss.efistub,load,alloc
STUBCOPY_RELOC-$(CONFIG_ARM)	:= R_ARM_ABS

#
# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
# So let's apply the __init annotations at the section level, by prefixing
# the section names directly. This will ensure that even all the inline string
# literals are covered.
# The fact that the stub and the kernel proper are essentially the same binary
# also means that we need to be extra careful to make sure that the stub does
# not rely on any absolute symbol references, considering that the virtual
# kernel mapping that the linker uses is not active yet when the stub is
# executing. So build all C dependencies of the EFI stub into libstub, and do
# a verification pass to see if any absolute relocations exist in any of the
# object files.
#
STUBCOPY_FLAGS-$(CONFIG_ARM64)	+= --prefix-alloc-sections=.init \
				   --prefix-symbols=__efistub_
STUBCOPY_RELOC-$(CONFIG_ARM64)	:= R_AARCH64_ABS

# For RISC-V, we don't need anything special other than arm64. Keep all the
# symbols in .init section and make sure that no absolute symbols references
# exist.
STUBCOPY_FLAGS-$(CONFIG_RISCV)	+= --prefix-alloc-sections=.init \
				   --prefix-symbols=__efistub_
STUBCOPY_RELOC-$(CONFIG_RISCV)	:= -E R_RISCV_HI20\|R_RISCV_$(BITS)\|R_RISCV_RELAX

# For LoongArch, keep all the symbols in .init section and make sure that no
# absolute symbols references exist.
STUBCOPY_FLAGS-$(CONFIG_LOONGARCH)	+= --prefix-alloc-sections=.init \
					   --prefix-symbols=__efistub_
STUBCOPY_RELOC-$(CONFIG_LOONGARCH)	:= R_LARCH_MARK_LA

$(obj)/%.stub.o: $(obj)/%.o FORCE
	$(call if_changed,stubcopy)

#
# Strip debug sections and some other sections that may legally contain
# absolute relocations, so that we can inspect the remaining sections for
# such relocations. If none are found, regenerate the output object, but
# this time, use objcopy and leave all sections in place.
#
quiet_cmd_stubcopy = STUBCPY $@
      cmd_stubcopy =							\
	$(STRIP) --strip-debug -o $@ $<;				\
	if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then		\
		echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
		/bin/false;						\
	fi;								\
	$(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@