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d7a956441f
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>
(cherry picked from commit 850ded46c6)
Conflicts:
scripts/Makefile.modfinal
scripts/Makefile.modpost
Bug: 189327973
Change-Id: I61c3782619e6475cfff74c270b70e01e229dc8df
Signed-off-by: Eric Biggers <ebiggers@google.com>
172 lines
5.3 KiB
Makefile
172 lines
5.3 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_WARN can be set to avoid error out in case of undefined
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# symbols in the final module linking stage
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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 scripts/Kbuild.include
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# for mod-prelink-ext
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include scripts/Makefile.lib
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mixed-build-prefix = $(if $(KBUILD_MIXED_TREE),$(KBUILD_MIXED_TREE)/)
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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 $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
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$(if $(KBUILD_MODPOST_WARN),-w) \
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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 := $(mixed-build-prefix)vmlinux.symvers
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output-symdump := modules-only.symvers
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module_srcpath := $(srctree)
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quiet_cmd_cat = GEN $@
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cmd_cat = cat $(real-prereqs) > $@
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ifneq ($(wildcard $(mixed-build-prefix)vmlinux.symvers),)
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__modpost: Module.symvers
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Module.symvers: $(mixed-build-prefix)vmlinux.symvers modules-only.symvers FORCE
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$(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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# Get the external module's source path. KBUILD_EXTMOD could either be an
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# absolute path or relative path from $(srctree). This makes sure that we
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# aren't using a relative path from a separate working directory (O= or
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# KBUILD_OUTPUT) since that may not be the actual module's SCM project path. So
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# check the path relative to $(srctree) first.
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ifneq ($(realpath $(srctree)/$(KBUILD_EXTMOD) 2>/dev/null),)
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module_srcpath := $(srctree)/$(KBUILD_EXTMOD)
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else
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module_srcpath := $(KBUILD_EXTMOD)
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endif
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endif
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ifeq ($(CONFIG_MODULE_SCMVERSION),y)
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# Get the SCM version of the module. `sed` verifies setlocalversion returns
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# a proper revision based on the SCM type, e.g. git, mercurial, or svn.
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module_scmversion := $(shell $(srctree)/scripts/setlocalversion $(module_srcpath) | \
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sed -n 's/.*-\(\(g\|hg\)[a-fA-F0-9]\+\(-dirty\)\?\|svn[0-9]\+\).*/\1/p')
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ifneq ($(module_scmversion),)
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MODPOST += -v $(module_scmversion)
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endif
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endif
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# modpost options for modules (both in-kernel and external)
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MODPOST += \
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$(addprefix -i ,$(wildcard $(input-symdump))) \
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$(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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modules := $(sort $(shell cat $(MODORDER)))
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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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