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92a4728608
Dirk Gouders reported that two consecutive "make" invocations on an
already compiled tree will show alternating behaviors:
$ make
CALL scripts/checksyscalls.sh
DESCEND objtool
CHK include/generated/compile.h
DATAREL arch/x86/boot/compressed/vmlinux
Kernel: arch/x86/boot/bzImage is ready (#48)
Building modules, stage 2.
MODPOST 165 modules
$ make
CALL scripts/checksyscalls.sh
DESCEND objtool
CHK include/generated/compile.h
LD arch/x86/boot/compressed/vmlinux
ZOFFSET arch/x86/boot/zoffset.h
AS arch/x86/boot/header.o
LD arch/x86/boot/setup.elf
OBJCOPY arch/x86/boot/setup.bin
OBJCOPY arch/x86/boot/vmlinux.bin
BUILD arch/x86/boot/bzImage
Setup is 15644 bytes (padded to 15872 bytes).
System is 6663 kB
CRC 3eb90f40
Kernel: arch/x86/boot/bzImage is ready (#48)
Building modules, stage 2.
MODPOST 165 modules
He bisected it back to:
commit 98f7852537 ("x86/boot: Refuse to build with data relocations")
The root cause was the use of the "if_changed" kbuild function multiple
times for the same target. It was designed to only be used once per
target, otherwise it will effectively always trigger, flipping back and
forth between the two commands getting recorded by "if_changed". Instead,
this patch merges the two commands into a single function to get stable
build artifacts (i.e. .vmlinux.cmd), and a single build behavior.
Bisected-and-Reported-by: Dirk Gouders <dirk@gouders.net>
Fix-Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180724230827.GA37823@beast
Signed-off-by: Ingo Molnar <mingo@kernel.org>
158 lines
5.4 KiB
Makefile
158 lines
5.4 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# linux/arch/x86/boot/compressed/Makefile
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#
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# create a compressed vmlinux image from the original vmlinux
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#
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# vmlinuz is:
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# decompression code (*.o)
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# asm globals (piggy.S), including:
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# vmlinux.bin.(gz|bz2|lzma|...)
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#
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# vmlinux.bin is:
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# vmlinux stripped of debugging and comments
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# vmlinux.bin.all is:
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# vmlinux.bin + vmlinux.relocs
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# vmlinux.bin.(gz|bz2|lzma|...) is:
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# (see scripts/Makefile.lib size_append)
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# compressed vmlinux.bin.all + u32 size of vmlinux.bin.all
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KASAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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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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targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
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vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4
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KBUILD_CFLAGS := -m$(BITS) -O2
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KBUILD_CFLAGS += -fno-strict-aliasing $(call cc-option, -fPIE, -fPIC)
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KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
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cflags-$(CONFIG_X86_32) := -march=i386
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cflags-$(CONFIG_X86_64) := -mcmodel=small
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_CFLAGS += -mno-mmx -mno-sse
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KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
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KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
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KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
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KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
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KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
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GCOV_PROFILE := n
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UBSAN_SANITIZE :=n
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LDFLAGS := -m elf_$(UTS_MACHINE)
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# Compressed kernel should be built as PIE since it may be loaded at any
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# address by the bootloader.
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ifeq ($(CONFIG_X86_32),y)
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LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
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else
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# To build 64-bit compressed kernel as PIE, we disable relocation
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# overflow check to avoid relocation overflow error with a new linker
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# command-line option, -z noreloc-overflow.
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LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
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&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
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endif
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LDFLAGS_vmlinux := -T
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hostprogs-y := mkpiggy
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HOST_EXTRACFLAGS += -I$(srctree)/tools/include
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sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(_text\|__bss_start\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'
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quiet_cmd_voffset = VOFFSET $@
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cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@
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targets += ../voffset.h
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$(obj)/../voffset.h: vmlinux FORCE
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$(call if_changed,voffset)
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$(obj)/misc.o: $(obj)/../voffset.h
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vmlinux-objs-y := $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \
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$(obj)/string.o $(obj)/cmdline.o $(obj)/error.o \
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$(obj)/piggy.o $(obj)/cpuflags.o
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vmlinux-objs-$(CONFIG_EARLY_PRINTK) += $(obj)/early_serial_console.o
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vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr.o
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ifdef CONFIG_X86_64
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vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr_64.o
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vmlinux-objs-y += $(obj)/mem_encrypt.o
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vmlinux-objs-y += $(obj)/pgtable_64.o
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endif
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$(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone
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vmlinux-objs-$(CONFIG_EFI_STUB) += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \
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$(objtree)/drivers/firmware/efi/libstub/lib.a
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vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
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# The compressed kernel is built with -fPIC/-fPIE so that a boot loader
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# can place it anywhere in memory and it will still run. However, since
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# it is executed as-is without any ELF relocation processing performed
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# (and has already had all relocation sections stripped from the binary),
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# none of the code can use data relocations (e.g. static assignments of
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# pointer values), since they will be meaningless at runtime. This check
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# will refuse to link the vmlinux if any of these relocations are found.
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quiet_cmd_check_data_rel = DATAREL $@
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define cmd_check_data_rel
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for obj in $(filter %.o,$^); do \
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${CROSS_COMPILE}readelf -S $$obj | grep -qF .rel.local && { \
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echo "error: $$obj has data relocations!" >&2; \
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exit 1; \
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} || true; \
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done
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endef
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# We need to run two commands under "if_changed", so merge them into a
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# single invocation.
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quiet_cmd_check-and-link-vmlinux = LD $@
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cmd_check-and-link-vmlinux = $(cmd_check_data_rel); $(cmd_ld)
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$(obj)/vmlinux: $(vmlinux-objs-y) FORCE
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$(call if_changed,check-and-link-vmlinux)
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OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
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$(obj)/vmlinux.bin: vmlinux FORCE
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$(call if_changed,objcopy)
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targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
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CMD_RELOCS = arch/x86/tools/relocs
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quiet_cmd_relocs = RELOCS $@
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cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
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$(obj)/vmlinux.relocs: vmlinux FORCE
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$(call if_changed,relocs)
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vmlinux.bin.all-y := $(obj)/vmlinux.bin
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vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs
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$(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,gzip)
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$(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,bzip2)
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$(obj)/vmlinux.bin.lzma: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,lzma)
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$(obj)/vmlinux.bin.xz: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,xzkern)
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$(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,lzo)
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$(obj)/vmlinux.bin.lz4: $(vmlinux.bin.all-y) FORCE
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$(call if_changed,lz4)
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suffix-$(CONFIG_KERNEL_GZIP) := gz
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suffix-$(CONFIG_KERNEL_BZIP2) := bz2
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suffix-$(CONFIG_KERNEL_LZMA) := lzma
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suffix-$(CONFIG_KERNEL_XZ) := xz
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suffix-$(CONFIG_KERNEL_LZO) := lzo
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suffix-$(CONFIG_KERNEL_LZ4) := lz4
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quiet_cmd_mkpiggy = MKPIGGY $@
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cmd_mkpiggy = $(obj)/mkpiggy $< > $@ || ( rm -f $@ ; false )
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targets += piggy.S
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$(obj)/piggy.S: $(obj)/vmlinux.bin.$(suffix-y) $(obj)/mkpiggy FORCE
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$(call if_changed,mkpiggy)
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