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With CONFIG_MODVERSIONS, version information is linked into each compilation unit that exports symbols. With LTO, we cannot use this method as all C code is compiled into LLVM bitcode instead. This change collects symbol versions into .symversions files and merges them in link-vmlinux.sh where they are all linked into vmlinux.o at the same time. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20201211184633.3213045-4-samitolvanen@google.com
151 lines
4.4 KiB
Makefile
151 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_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 ld_flags
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include 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 $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
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$(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 := vmlinux.symvers
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output-symdump := Module.symvers
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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 := $(KBUILD_EXTMOD)/Module.symvers
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endif
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# modpost options for modules (both in-kernel and external)
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MODPOST += \
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$(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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ifdef CONFIG_LTO_CLANG
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# With CONFIG_LTO_CLANG, .o files might be LLVM bitcode, so we need to run
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# LTO to compile them into native code before running modpost
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prelink-ext := .lto
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quiet_cmd_cc_lto_link_modules = LTO [M] $@
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cmd_cc_lto_link_modules = \
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$(LD) $(ld_flags) -r -o $@ \
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$(shell [ -s $(@:.lto.o=.o.symversions) ] && \
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echo -T $(@:.lto.o=.o.symversions)) \
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--whole-archive $^
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%.lto.o: %.o
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$(call if_changed,cc_lto_link_modules)
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endif
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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$$/$(prelink-ext)\.o/' $< | $(MODPOST) -T -
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$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(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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