mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-03-20 04:10:52 -04:00
745e3ed85f
UEFI Specification version 2.9 introduces the concept of memory acceptance: Some Virtual Machine platforms, such as Intel TDX or AMD SEV-SNP, requiring memory to be accepted before it can be used by the guest. Accepting happens via a protocol specific for the Virtual Machine platform. Accepting memory is costly and it makes VMM allocate memory for the accepted guest physical address range. It's better to postpone memory acceptance until memory is needed. It lowers boot time and reduces memory overhead. The kernel needs to know what memory has been accepted. Firmware communicates this information via memory map: a new memory type -- EFI_UNACCEPTED_MEMORY -- indicates such memory. Range-based tracking works fine for firmware, but it gets bulky for the kernel: e820 (or whatever the arch uses) has to be modified on every page acceptance. It leads to table fragmentation and there's a limited number of entries in the e820 table. Another option is to mark such memory as usable in e820 and track if the range has been accepted in a bitmap. One bit in the bitmap represents a naturally aligned power-2-sized region of address space -- unit. For x86, unit size is 2MiB: 4k of the bitmap is enough to track 64GiB or physical address space. In the worst-case scenario -- a huge hole in the middle of the address space -- It needs 256MiB to handle 4PiB of the address space. Any unaccepted memory that is not aligned to unit_size gets accepted upfront. The bitmap is allocated and constructed in the EFI stub and passed down to the kernel via EFI configuration table. allocate_e820() allocates the bitmap if unaccepted memory is present, according to the size of unaccepted region. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20230606142637.5171-4-kirill.shutemov@linux.intel.com
177 lines
6.9 KiB
Makefile
177 lines
6.9 KiB
Makefile
# 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
|
|
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) += arm64.o arm64-stub.o smbios.o
|
|
lib-$(CONFIG_X86) += x86-stub.o
|
|
lib-$(CONFIG_RISCV) += 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://bugs.llvm.org/show_bug.cgi?id=46480
|
|
STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
|
|
|
|
#
|
|
# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
|
|
# .bss section, so the .bss section of the EFI stub needs to be included in the
|
|
# .data section of the compressed kernel to ensure initialization. Rename the
|
|
# .bss section here so it's easy to pick out in the linker script.
|
|
#
|
|
STUBCOPY_FLAGS-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc
|
|
STUBCOPY_RELOC-$(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-$(CONFIG_ARM64) := R_AARCH64_ABS
|
|
|
|
# For RISC-V, we don't need anything special other than arm64. Keep all the
|
|
# symbols in .init section and make sure that no absolute symbols references
|
|
# doesn't exist.
|
|
STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
|
|
--prefix-symbols=__efistub_
|
|
STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
|
|
|
|
# For LoongArch, keep all the symbols in .init section and make sure that no
|
|
# absolute symbols references exist.
|
|
STUBCOPY_FLAGS-$(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) $< $@
|