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The LLVM ld.lld linker uses a different symbol type for __bss_start, resulting in the calculation of KBSS_SZ to be thrown off. Up until now, this has gone unnoticed as it only affects the appended DTB case, but pending changes for ARM in the way the decompressed kernel is cleaned from the caches has uncovered this problem. On a ld.lld build: $ nm vmlinux |grep bss_ c1c22034 D __bss_start c1c86e98 B __bss_stop resulting in $ readelf -s arch/arm/boot/compressed/vmlinux | grep bss_size 433: c1c86e98 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size which is obviously incorrect, and may cause the cache clean to access unmapped memory, or cause the size calculation to wrap, resulting in no cache clean to be performed at all. Fix this by updating the sed regex to take D type symbols into account. Link: https://lore.kernel.org/linux-arm-kernel/6c65bcef-d4e7-25fa-43cf-2c435bb61bb9@collabora.com/ Link: https://lore.kernel.org/linux-arm-kernel/20210205085220.31232-1-ardb@kernel.org/ Cc: <stable@vger.kernel.org> # v4.19+ Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com> Reported-by: "kernelci.org bot" <bot@kernelci.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
203 lines
5.8 KiB
Makefile
203 lines
5.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# linux/arch/arm/boot/compressed/Makefile
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#
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# create a compressed vmlinuz image from the original vmlinux
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#
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OBJS =
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HEAD = head.o
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OBJS += misc.o decompress.o
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ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
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OBJS += debug.o
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AFLAGS_head.o += -DDEBUG
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endif
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FONTC = $(srctree)/lib/fonts/font_acorn_8x8.c
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# string library code (-Os is enforced to keep it much smaller)
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OBJS += string.o
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CFLAGS_string.o := -Os
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ifeq ($(CONFIG_ARM_VIRT_EXT),y)
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OBJS += hyp-stub.o
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endif
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GCOV_PROFILE := n
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KASAN_SANITIZE := n
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# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
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KCOV_INSTRUMENT := n
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#
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# Architecture dependencies
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#
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ifeq ($(CONFIG_ARCH_ACORN),y)
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OBJS += ll_char_wr.o font.o
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endif
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ifeq ($(CONFIG_ARCH_SA1100),y)
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OBJS += head-sa1100.o
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endif
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ifeq ($(CONFIG_CPU_XSCALE),y)
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OBJS += head-xscale.o
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endif
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ifeq ($(CONFIG_PXA_SHARPSL_DETECT_MACH_ID),y)
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OBJS += head-sharpsl.o
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endif
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ifeq ($(CONFIG_CPU_ENDIAN_BE32),y)
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ifeq ($(CONFIG_CPU_CP15),y)
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OBJS += big-endian.o
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else
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# The endian should be set by h/w design.
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endif
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endif
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#
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# We now have a PIC decompressor implementation. Decompressors running
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# from RAM should not define ZTEXTADDR. Decompressors running directly
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# from ROM or Flash must define ZTEXTADDR (preferably via the config)
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# FIXME: Previous assignment to ztextaddr-y is lost here. See SHARK
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ifeq ($(CONFIG_ZBOOT_ROM),y)
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ZTEXTADDR := $(CONFIG_ZBOOT_ROM_TEXT)
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ZBSSADDR := $(CONFIG_ZBOOT_ROM_BSS)
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else
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ZTEXTADDR := 0
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ZBSSADDR := ALIGN(8)
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endif
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MALLOC_SIZE := 65536
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AFLAGS_head.o += -DTEXT_OFFSET=$(TEXT_OFFSET) -DMALLOC_SIZE=$(MALLOC_SIZE)
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CPPFLAGS_vmlinux.lds := -DTEXT_START="$(ZTEXTADDR)" -DBSS_START="$(ZBSSADDR)"
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CPPFLAGS_vmlinux.lds += -DTEXT_OFFSET="$(TEXT_OFFSET)"
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CPPFLAGS_vmlinux.lds += -DMALLOC_SIZE="$(MALLOC_SIZE)"
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compress-$(CONFIG_KERNEL_GZIP) = gzip
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compress-$(CONFIG_KERNEL_LZO) = lzo
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compress-$(CONFIG_KERNEL_LZMA) = lzma
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compress-$(CONFIG_KERNEL_XZ) = xzkern
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compress-$(CONFIG_KERNEL_LZ4) = lz4
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libfdt_objs := fdt_rw.o fdt_ro.o fdt_wip.o fdt.o
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ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
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OBJS += $(libfdt_objs) atags_to_fdt.o
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endif
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ifeq ($(CONFIG_USE_OF),y)
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OBJS += $(libfdt_objs) fdt_check_mem_start.o
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endif
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# -fstack-protector-strong triggers protection checks in this code,
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# but it is being used too early to link to meaningful stack_chk logic.
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$(foreach o, $(libfdt_objs) atags_to_fdt.o fdt_check_mem_start.o, \
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$(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt -fno-stack-protector))
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# These were previously generated C files. When you are building the kernel
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# with O=, make sure to remove the stale files in the output tree. Otherwise,
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# the build system wrongly compiles the stale ones.
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ifdef building_out_of_srctree
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$(shell rm -f $(addprefix $(obj)/, fdt_rw.c fdt_ro.c fdt_wip.c fdt.c))
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endif
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targets := vmlinux vmlinux.lds piggy_data piggy.o \
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lib1funcs.o ashldi3.o bswapsdi2.o \
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head.o $(OBJS)
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clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S
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KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
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ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
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-I$(obj) $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)
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ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg
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asflags-y := -DZIMAGE
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# Supply kernel BSS size to the decompressor via a linker symbol.
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KBSS_SZ = $(shell echo $$(($$($(NM) $(obj)/../../../../vmlinux | \
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sed -n -e 's/^\([^ ]*\) [ABD] __bss_start$$/-0x\1/p' \
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-e 's/^\([^ ]*\) [ABD] __bss_stop$$/+0x\1/p') )) )
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LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
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# Supply ZRELADDR to the decompressor via a linker symbol.
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ifneq ($(CONFIG_AUTO_ZRELADDR),y)
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LDFLAGS_vmlinux += --defsym zreladdr=$(ZRELADDR)
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endif
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ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
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LDFLAGS_vmlinux += --be8
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endif
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# Report unresolved symbol references
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LDFLAGS_vmlinux += --no-undefined
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# Delete all temporary local symbols
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LDFLAGS_vmlinux += -X
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# Report orphan sections
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ifdef CONFIG_LD_ORPHAN_WARN
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LDFLAGS_vmlinux += --orphan-handling=warn
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endif
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# Next argument is a linker script
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LDFLAGS_vmlinux += -T
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# For __aeabi_uidivmod
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lib1funcs = $(obj)/lib1funcs.o
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$(obj)/lib1funcs.S: $(srctree)/arch/$(SRCARCH)/lib/lib1funcs.S
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$(call cmd,shipped)
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# For __aeabi_llsl
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ashldi3 = $(obj)/ashldi3.o
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$(obj)/ashldi3.S: $(srctree)/arch/$(SRCARCH)/lib/ashldi3.S
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$(call cmd,shipped)
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# For __bswapsi2, __bswapdi2
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bswapsdi2 = $(obj)/bswapsdi2.o
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$(obj)/bswapsdi2.S: $(srctree)/arch/$(SRCARCH)/lib/bswapsdi2.S
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$(call cmd,shipped)
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# We need to prevent any GOTOFF relocs being used with references
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# to symbols in the .bss section since we cannot relocate them
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# independently from the rest at run time. This can be achieved by
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# ensuring that no private .bss symbols exist, as global symbols
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# always have a GOT entry which is what we need.
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# The .data section is already discarded by the linker script so no need
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# to bother about it here.
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check_for_bad_syms = \
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bad_syms=$$($(NM) $@ | sed -n 's/^.\{8\} [bc] \(.*\)/\1/p') && \
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[ -z "$$bad_syms" ] || \
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( echo "following symbols must have non local/private scope:" >&2; \
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echo "$$bad_syms" >&2; false )
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check_for_multiple_zreladdr = \
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if [ $(words $(ZRELADDR)) -gt 1 -a "$(CONFIG_AUTO_ZRELADDR)" = "" ]; then \
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echo 'multiple zreladdrs: $(ZRELADDR)'; \
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echo 'This needs CONFIG_AUTO_ZRELADDR to be set'; \
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false; \
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fi
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efi-obj-$(CONFIG_EFI_STUB) := $(objtree)/drivers/firmware/efi/libstub/lib.a
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$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
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$(addprefix $(obj)/, $(OBJS)) $(lib1funcs) $(ashldi3) \
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$(bswapsdi2) $(efi-obj-y) FORCE
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@$(check_for_multiple_zreladdr)
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$(call if_changed,ld)
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@$(check_for_bad_syms)
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$(obj)/piggy_data: $(obj)/../Image FORCE
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$(call if_changed,$(compress-y))
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$(obj)/piggy.o: $(obj)/piggy_data
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CFLAGS_font.o := -Dstatic=
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$(obj)/font.c: $(FONTC)
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$(call cmd,shipped)
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AFLAGS_hyp-stub.o := -Wa,-march=armv7-a
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$(obj)/hyp-stub.S: $(srctree)/arch/$(SRCARCH)/kernel/hyp-stub.S
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$(call cmd,shipped)
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