linux/arch/arm/boot/compressed/Makefile
Kees Cook 431a380f93 kstack_erase: Disable kstack_erase for all of arm compressed boot code
When building with CONFIG_KSTACK_ERASE=y and CONFIG_ARM_ATAG_DTB_COMPAT=y,
the compressed boot environment encounters an undefined symbol error:

    ld.lld: error: undefined symbol: __sanitizer_cov_stack_depth
    >>> referenced by atags_to_fdt.c:135

This occurs because the compiler instruments the atags_to_fdt() function
with sanitizer coverage calls, but the minimal compressed boot environment
lacks access to sanitizer runtime support.

The compressed boot environment already disables stack protector with
-fno-stack-protector. Similarly disable sanitizer coverage by adding
$(DISABLE_KSTACK_ERASE) to the general compiler flags (and remove it
from the one place it was noticed before), which contains the appropriate
flags to prevent sanitizer instrumentation.

This follows the same pattern used in other early boot contexts where
sanitizer runtime support is unavailable.

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYtBk8qnpWvoaFwymCx5s5i-5KXtPGpmf=_+UKJddCOnLA@mail.gmail.com
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20250726004313.GA3650901@ax162
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-26 14:27:33 -07:00

160 lines
4.6 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
#
# linux/arch/arm/boot/compressed/Makefile
#
# create a compressed vmlinuz image from the original vmlinux
#
OBJS =
HEAD = head.o
OBJS += misc.o decompress.o
ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
OBJS += debug.o
AFLAGS_head.o += -DDEBUG
endif
# string library code (-Os is enforced to keep it much smaller)
OBJS += string.o
CFLAGS_string.o := -Os
ifeq ($(CONFIG_ARM_VIRT_EXT),y)
OBJS += hyp-stub.o
endif
#
# Architecture dependencies
#
ifeq ($(CONFIG_ARCH_ACORN),y)
OBJS += ll_char_wr.o font.o
endif
ifeq ($(CONFIG_ARCH_SA1100),y)
OBJS += head-sa1100.o
endif
ifeq ($(CONFIG_CPU_XSCALE),y)
OBJS += head-xscale.o
endif
ifeq ($(CONFIG_PXA_SHARPSL_DETECT_MACH_ID),y)
OBJS += head-sharpsl.o
endif
ifeq ($(CONFIG_CPU_ENDIAN_BE32),y)
ifeq ($(CONFIG_CPU_CP15),y)
OBJS += big-endian.o
else
# The endian should be set by h/w design.
endif
endif
#
# We now have a PIC decompressor implementation. Decompressors running
# from RAM should not define ZTEXTADDR. Decompressors running directly
# from ROM or Flash must define ZTEXTADDR (preferably via the config)
# FIXME: Previous assignment to ztextaddr-y is lost here. See SHARK
ifeq ($(CONFIG_ZBOOT_ROM),y)
ZTEXTADDR := $(CONFIG_ZBOOT_ROM_TEXT)
ZBSSADDR := $(CONFIG_ZBOOT_ROM_BSS)
else
ZTEXTADDR := 0
ZBSSADDR := ALIGN(8)
endif
MALLOC_SIZE := 65536
AFLAGS_head.o += -DTEXT_OFFSET=$(TEXT_OFFSET) -DMALLOC_SIZE=$(MALLOC_SIZE)
CPPFLAGS_vmlinux.lds := -DTEXT_START="$(ZTEXTADDR)" -DBSS_START="$(ZBSSADDR)"
CPPFLAGS_vmlinux.lds += -DTEXT_OFFSET="$(TEXT_OFFSET)"
CPPFLAGS_vmlinux.lds += -DMALLOC_SIZE="$(MALLOC_SIZE)"
compress-$(CONFIG_KERNEL_GZIP) = gzip
compress-$(CONFIG_KERNEL_LZO) = lzo_with_size
compress-$(CONFIG_KERNEL_LZMA) = lzma_with_size
compress-$(CONFIG_KERNEL_XZ) = xzkern_with_size
compress-$(CONFIG_KERNEL_LZ4) = lz4_with_size
libfdt_objs := fdt_rw.o fdt_ro.o fdt_wip.o fdt.o
ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
CFLAGS_REMOVE_atags_to_fdt.o += -Wframe-larger-than=${CONFIG_FRAME_WARN}
CFLAGS_atags_to_fdt.o += -Wframe-larger-than=1280
OBJS += $(libfdt_objs) atags_to_fdt.o
endif
ifeq ($(CONFIG_USE_OF),y)
OBJS += $(libfdt_objs) fdt_check_mem_start.o
endif
OBJS += lib1funcs.o ashldi3.o bswapsdi2.o
targets := vmlinux vmlinux.lds piggy_data piggy.o \
head.o $(OBJS)
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
-I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
$(DISABLE_KSTACK_ERASE) \
-I$(obj)
ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg
asflags-y := -DZIMAGE
# Supply kernel BSS size to the decompressor via a linker symbol.
KBSS_SZ = $(shell echo $$(($$($(NM) vmlinux | \
sed -n -e 's/^\([^ ]*\) [ABD] __bss_start$$/-0x\1/p' \
-e 's/^\([^ ]*\) [ABD] __bss_stop$$/+0x\1/p') )) )
LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
# Supply ZRELADDR to the decompressor via a linker symbol.
ifneq ($(CONFIG_AUTO_ZRELADDR),y)
LDFLAGS_vmlinux += --defsym zreladdr=$(ZRELADDR)
endif
ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
LDFLAGS_vmlinux += --be8
endif
# Report unresolved symbol references
LDFLAGS_vmlinux += --no-undefined
# Delete all temporary local symbols
LDFLAGS_vmlinux += -X
# Report orphan sections
ifdef CONFIG_LD_ORPHAN_WARN
LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
endif
# Next argument is a linker script
LDFLAGS_vmlinux += -T
# We need to prevent any GOTOFF relocs being used with references
# to symbols in the .bss section since we cannot relocate them
# independently from the rest at run time. This can be achieved by
# ensuring that no private .bss symbols exist, as global symbols
# always have a GOT entry which is what we need.
# The .data section is already discarded by the linker script so no need
# to bother about it here.
check_for_bad_syms = \
bad_syms=$$($(NM) $@ | sed -n 's/^.\{8\} [bc] \(.*\)/\1/p') && \
[ -z "$$bad_syms" ] || \
( echo "following symbols must have non local/private scope:" >&2; \
echo "$$bad_syms" >&2; false )
check_for_multiple_zreladdr = \
if [ $(words $(ZRELADDR)) -gt 1 -a "$(CONFIG_AUTO_ZRELADDR)" = "" ]; then \
echo 'multiple zreladdrs: $(ZRELADDR)'; \
echo 'This needs CONFIG_AUTO_ZRELADDR to be set'; \
false; \
fi
efi-obj-$(CONFIG_EFI_STUB) := $(objtree)/drivers/firmware/efi/libstub/lib.a
$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
$(addprefix $(obj)/, $(OBJS)) \
$(efi-obj-y) FORCE
@$(check_for_multiple_zreladdr)
$(call if_changed,ld)
@$(check_for_bad_syms)
$(obj)/piggy_data: $(obj)/../Image FORCE
$(call if_changed,$(compress-y))
$(obj)/piggy.o: $(obj)/piggy_data
CFLAGS_font.o := -Dstatic=