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3216484550
The objects placed at the head of vmlinux need special treatments: - arch/$(SRCARCH)/Makefile adds them to head-y in order to place them before other archives in the linker command line. - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of obj-y to avoid them going into built-in.a. This commit gets rid of the latter. Create vmlinux.a to collect all the objects that are unconditionally linked to vmlinux. The objects listed in head-y are moved to the head of vmlinux.a by using 'ar m'. With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y for builtin objects. There is no *.o that is directly linked to vmlinux. Drop unneeded code in scripts/clang-tools/gen_compile_commands.py. $(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested by Nathan Chancellor [1]. [1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
80 lines
2.5 KiB
Makefile
80 lines
2.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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PHONY := __default
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__default: vmlinux.o
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for objtool
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include $(srctree)/scripts/Makefile.lib
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# Generate a linker script to ensure correct ordering of initcalls for Clang LTO
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# ---------------------------------------------------------------------------
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quiet_cmd_gen_initcalls_lds = GEN $@
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cmd_gen_initcalls_lds = \
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$(PYTHON3) $(srctree)/scripts/jobserver-exec \
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$(PERL) $(real-prereqs) > $@
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.tmp_initcalls.lds: $(srctree)/scripts/generate_initcall_order.pl \
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vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
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$(call if_changed,gen_initcalls_lds)
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targets := .tmp_initcalls.lds
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ifdef CONFIG_LTO_CLANG
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initcalls-lds := .tmp_initcalls.lds
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endif
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# objtool for vmlinux.o
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# ---------------------------------------------------------------------------
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#
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# For LTO and IBT, objtool doesn't run on individual translation units.
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# Run everything on vmlinux instead.
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objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
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vmlinux-objtool-args-$(delay-objtool) += $(objtool-args-y)
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vmlinux-objtool-args-$(CONFIG_GCOV_KERNEL) += --no-unreachable
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vmlinux-objtool-args-$(CONFIG_NOINSTR_VALIDATION) += --noinstr $(if $(CONFIG_CPU_UNRET_ENTRY), --unret)
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objtool-args = $(vmlinux-objtool-args-y) --link
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# Link of vmlinux.o used for section mismatch analysis
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# ---------------------------------------------------------------------------
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quiet_cmd_ld_vmlinux.o = LD $@
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cmd_ld_vmlinux.o = \
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$(LD) ${KBUILD_LDFLAGS} -r -o $@ \
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$(addprefix -T , $(initcalls-lds)) \
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--whole-archive vmlinux.a --no-whole-archive \
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--start-group $(KBUILD_VMLINUX_LIBS) --end-group \
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$(cmd_objtool)
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define rule_ld_vmlinux.o
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$(call cmd_and_savecmd,ld_vmlinux.o)
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$(call cmd,gen_objtooldep)
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endef
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vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
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$(call if_changed_rule,ld_vmlinux.o)
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targets += vmlinux.o
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# Add FORCE to the prequisites of a target to force it to be always rebuilt.
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# ---------------------------------------------------------------------------
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PHONY += FORCE
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FORCE:
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# Read all saved command lines and dependencies for the $(targets) we
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# may be building above, using $(if_changed{,_dep}). As an
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# optimization, we don't need to read them if the target does not
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# exist, we will rebuild anyway in that case.
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existing-targets := $(wildcard $(sort $(targets)))
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-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
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.PHONY: $(PHONY)
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