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bce74491c3
vgettimeofday.o is unnecessarily rebuilt. Adding it to 'targets' is not
enough to fix the issue. Kbuild is correctly rebuilding it because the
command line is changed.
PowerPC builds each vdso directory twice; first in vdso_prepare to
generate vdso{32,64}-offsets.h, second as part of the ordinary build
process to embed vdso{32,64}.so.dbg into the kernel.
The problem shows up when CONFIG_PPC_WERROR=y due to the following line
in arch/powerpc/Kbuild:
subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
In the preparation stage, Kbuild directly visits the vdso directories,
hence it does not inherit subdir-ccflags-y. In the second descend,
Kbuild adds -Werror, which results in the command line flipping
with/without -Werror.
It implies a potential danger; if a more critical flag that would impact
the resulted vdso, the offsets recorded in the headers might be different
from real offsets in the embedded vdso images.
Removing the unneeded second descend solves the problem.
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/linuxppc-dev/87tuslxhry.fsf@mpe.ellerman.id.au/
Link: https://lore.kernel.org/r/20201223171142.707053-1-masahiroy@kernel.org
73 lines
2.5 KiB
Makefile
73 lines
2.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# List of files in the vdso, has to be asm only for now
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ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN|R_PPC_REL24
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include $(srctree)/lib/vdso/Makefile
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obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
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CFLAGS_vgettimeofday.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
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CFLAGS_vgettimeofday.o += $(call cc-option, -fno-stack-protector)
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CFLAGS_vgettimeofday.o += -DDISABLE_BRANCH_PROFILING
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CFLAGS_vgettimeofday.o += -ffreestanding -fasynchronous-unwind-tables
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
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endif
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# Build rules
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ifdef CROSS32_COMPILE
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VDSOCC := $(CROSS32_COMPILE)gcc
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else
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VDSOCC := $(CC)
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endif
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CC32FLAGS :=
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ifdef CONFIG_PPC64
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CC32FLAGS += -m32
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KBUILD_CFLAGS := $(filter-out -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc,$(KBUILD_CFLAGS))
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endif
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targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday.o
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obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
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GCOV_PROFILE := n
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KCOV_INSTRUMENT := n
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UBSAN_SANITIZE := n
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KASAN_SANITIZE := n
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ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
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-Wl,-soname=linux-vdso32.so.1 -Wl,--hash-style=both
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asflags-y := -D__VDSO32__ -s
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obj-y += vdso32_wrapper.o
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targets += vdso32.lds
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CPPFLAGS_vdso32.lds += -P -C -Upowerpc
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# link rule for the .so file, .lds has to be first
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$(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday.o FORCE
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$(call if_changed,vdso32ld_and_check)
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# assembly rules for the .S files
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$(obj-vdso32): %.o: %.S FORCE
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$(call if_changed_dep,vdso32as)
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$(obj)/vgettimeofday.o: %.o: %.c FORCE
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$(call if_changed_dep,vdso32cc)
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# Generate VDSO offsets using helper script
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gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
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quiet_cmd_vdsosym = VDSOSYM $@
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cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
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include/generated/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE
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$(call if_changed,vdsosym)
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# actual build commands
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quiet_cmd_vdso32ld_and_check = VDSO32L $@
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cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
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quiet_cmd_vdso32as = VDSO32A $@
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cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
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quiet_cmd_vdso32cc = VDSO32C $@
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cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
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