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850ded46c6
With CONFIG_LTO_CLANG, we currently link modules into native code just before modpost, which means with TRIM_UNUSED_KSYMS enabled, we still look at the LLVM bitcode in the .o files when generating the list of used symbols. As the bitcode doesn't yet have calls to compiler intrinsics and llvm-nm doesn't see function references that only exist in function-level inline assembly, we currently need a whitelist for TRIM_UNUSED_KSYMS to work with LTO. This change moves module LTO linking to happen earlier, and thus avoids the issue with LLVM bitcode and TRIM_UNUSED_KSYMS entirely, allowing us to also drop the whitelist from gen_autoksyms.sh. Link: https://github.com/ClangBuiltLinux/linux/issues/1369 Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
152 lines
4.4 KiB
Makefile
152 lines
4.4 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ===========================================================================
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# Module versions
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# ===========================================================================
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#
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# Stage one of module building created the following:
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# a) The individual .o files used for the module
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# b) A <module>.o file which is the .o files above linked together
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# c) A <module>.mod file, listing the name of the preliminary <module>.o file,
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# plus all .o files
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# d) modules.order, which lists all the modules
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# Stage 2 is handled by this file and does the following
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# 1) Find all modules listed in modules.order
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# 2) modpost is then used to
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# 3) create one <module>.mod.c file pr. module
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# 4) create one Module.symvers file with CRC for all exported symbols
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# Step 3 is used to place certain information in the module's ELF
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# section, including information such as:
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# Version magic (see include/linux/vermagic.h for full details)
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# - Kernel release
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# - SMP is CONFIG_SMP
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# - PREEMPT is CONFIG_PREEMPT[_RT]
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# - GCC Version
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# Module info
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# - Module version (MODULE_VERSION)
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# - Module alias'es (MODULE_ALIAS)
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# - Module license (MODULE_LICENSE)
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# - See include/linux/module.h for more details
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# Step 4 is solely used to allow module versioning in external modules,
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# where the CRC of each module is retrieved from the Module.symvers file.
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# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
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# This is solely useful to speed up test compiles
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PHONY := __modpost
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__modpost:
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for mod-prelink-ext
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include $(srctree)/scripts/Makefile.lib
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MODPOST = scripts/mod/modpost \
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$(if $(CONFIG_MODVERSIONS),-m) \
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$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
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$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
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-o $@
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ifdef MODPOST_VMLINUX
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quiet_cmd_modpost = MODPOST $@
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cmd_modpost = $(MODPOST) $<
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vmlinux.symvers: vmlinux.o
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$(call cmd,modpost)
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__modpost: vmlinux.symvers
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else
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ifeq ($(KBUILD_EXTMOD),)
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input-symdump := vmlinux.symvers
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output-symdump := modules-only.symvers
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quiet_cmd_cat = GEN $@
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cmd_cat = cat $(real-prereqs) > $@
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ifneq ($(wildcard vmlinux.symvers),)
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__modpost: Module.symvers
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Module.symvers: vmlinux.symvers modules-only.symvers FORCE
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$(call if_changed,cat)
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targets += Module.symvers
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endif
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else
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# set src + obj - they may be used in the modules's Makefile
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obj := $(KBUILD_EXTMOD)
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src := $(obj)
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# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
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include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
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$(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
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# modpost option for external modules
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MODPOST += -e
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input-symdump := Module.symvers $(KBUILD_EXTRA_SYMBOLS)
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output-symdump := $(KBUILD_EXTMOD)/Module.symvers
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endif
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existing-input-symdump := $(wildcard $(input-symdump))
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# modpost options for modules (both in-kernel and external)
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MODPOST += \
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$(addprefix -i ,$(existing-input-symdump)) \
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$(if $(KBUILD_NSDEPS),-d $(MODULES_NSDEPS)) \
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$(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N)
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# 'make -i -k' ignores compile errors, and builds as many modules as possible.
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ifneq ($(findstring i,$(filter-out --%,$(MAKEFLAGS))),)
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MODPOST += -n
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endif
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# Clear VPATH to not search for *.symvers in $(srctree). Check only $(objtree).
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VPATH :=
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$(input-symdump):
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@echo >&2 'WARNING: Symbol version dump "$@" is missing.'
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@echo >&2 ' Modules may not have dependencies or modversions.'
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@echo >&2 ' You may get many unresolved symbol warnings.'
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modules := $(sort $(shell cat $(MODORDER)))
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# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined symbols
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ifneq ($(KBUILD_MODPOST_WARN)$(filter-out $(existing-input-symdump), $(input-symdump)),)
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MODPOST += -w
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endif
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# Read out modules.order to pass in modpost.
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# Otherwise, allmodconfig would fail with "Argument list too long".
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quiet_cmd_modpost = MODPOST $@
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cmd_modpost = sed 's/\.ko$$/$(mod-prelink-ext)\.o/' $< | $(MODPOST) -T -
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$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(mod-prelink-ext).o) FORCE
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$(call if_changed,modpost)
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targets += $(output-symdump)
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__modpost: $(output-symdump)
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ifneq ($(KBUILD_MODPOST_NOFINAL),1)
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$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
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endif
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PHONY += FORCE
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FORCE:
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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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endif
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.PHONY: $(PHONY)
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