80d65e58e9
If CONFIG_MODULE_SIG is set, then this patch will cause all modules files to
to have signatures added. The following steps will occur:
(1) The module will be linked to foo.ko.unsigned instead of foo.ko
(2) The module will be stripped using both "strip -x -g" and "eu-strip" to
ensure minimal size for inclusion in an initramfs.
(3) The signature will be generated on the stripped module.
(4) The signature will be appended to the module, along with some information
about the signature and a magic string that indicates the presence of the
signature.
Step (3) requires private and public keys to be available. By default these
are expected to be found in files:
signing_key.priv
signing_key.x509
in the base directory of the build. The first is the private key in PEM form
and the second is the X.509 certificate in DER form as can be generated from
openssl:
openssl req \
-new -x509 -outform PEM -out signing_key.x509 \
-keyout signing_key.priv -nodes \
-subj "/CN=H2G2/O=Magrathea/CN=Slartibartfast"
If the secret key is not found then signing will be skipped and the unsigned
module from (1) will just be copied to foo.ko.
If signing occurs, lines like the following will be seen:
LD [M] fs/foo/foo.ko.unsigned
STRIP [M] fs/foo/foo.ko.stripped
SIGN [M] fs/foo/foo.ko
will appear in the build log. If the signature step will be skipped and the
following will be seen:
LD [M] fs/foo/foo.ko.unsigned
STRIP [M] fs/foo/foo.ko.stripped
NO SIGN [M] fs/foo/foo.ko
NOTE! After the signature step, the signed module _must_not_ be passed through
strip. The unstripped, unsigned module is still available at the name on the
LD [M] line. This restriction may affect packaging tools (such as rpmbuild)
and initramfs composition tools.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
228 lines
7.2 KiB
Text
228 lines
7.2 KiB
Text
# ===========================================================================
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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 in $(MODVERDIR)/, listing the name of the
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# the preliminary <module>.o file, plus all .o files
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# Stage 2 is handled by this file and does the following
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# 1) Find all modules from the files listed in $(MODVERDIR)/
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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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# 5) compile all <module>.mod.c files
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# 6) final link of the module to a <module.ko> (or <module.unsigned>) file
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# 7) signs the modules to a <module.ko> file
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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
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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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# Step 7 is dependent on CONFIG_MODULE_SIG being enabled.
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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: __modpost
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include include/config/auto.conf
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include scripts/Kbuild.include
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# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
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ifneq ($(KBUILD_EXTMOD),)
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# set src + obj - they may be used when building the .mod.c file
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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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endif
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include scripts/Makefile.lib
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kernelsymfile := $(objtree)/Module.symvers
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modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
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# Step 1), find all modules listed in $(MODVERDIR)/
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__modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
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modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
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# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
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_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
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ifneq ($(KBUILD_BUILDHOST),$(ARCH))
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cross_build := 1
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endif
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# Step 2), invoke modpost
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# Includes step 3,4
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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 $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
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$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
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$(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
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$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
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$(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S) \
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$(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w) \
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$(if $(cross_build),-c)
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quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
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cmd_modpost = $(modpost) -s
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PHONY += __modpost
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__modpost: $(modules:.ko=.o) FORCE
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$(call cmd,modpost) $(wildcard vmlinux) $(filter-out FORCE,$^)
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quiet_cmd_kernel-mod = MODPOST $@
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cmd_kernel-mod = $(modpost) $@
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vmlinux.o: FORCE
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$(call cmd,kernel-mod)
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# Declare generated files as targets for modpost
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$(symverfile): __modpost ;
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$(modules:.ko=.mod.c): __modpost ;
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# Step 5), compile all *.mod.c files
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# modname is set to make c_flags define KBUILD_MODNAME
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modname = $(notdir $(@:.mod.o=))
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quiet_cmd_cc_o_c = CC $@
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cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
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-c -o $@ $<
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$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
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$(call if_changed_dep,cc_o_c)
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targets += $(modules:.ko=.mod.o)
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# Step 6), final link of the modules
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ifneq ($(CONFIG_MODULE_SIG),y)
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quiet_cmd_ld_ko_o = LD [M] $@
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cmd_ld_ko_o = $(LD) -r $(LDFLAGS) \
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$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
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-o $@ $(filter-out FORCE,$^)
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$(modules): %.ko :%.o %.mod.o FORCE
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$(call if_changed,ld_ko_o)
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targets += $(modules)
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else
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quiet_cmd_ld_ko_unsigned_o = LD [M] $@
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cmd_ld_ko_unsigned_o = \
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$(LD) -r $(LDFLAGS) \
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$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
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-o $@ $(filter-out FORCE,$^) \
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$(if $(AFTER_LINK),; $(AFTER_LINK))
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$(modules:.ko=.ko.unsigned): %.ko.unsigned :%.o %.mod.o FORCE
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$(call if_changed,ld_ko_unsigned_o)
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targets += $(modules:.ko=.ko.unsigned)
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# Step 7), sign the modules
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MODSECKEY = ./signing_key.priv
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MODPUBKEY = ./signing_key.x509
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ifeq ($(wildcard $(MODSECKEY))+$(wildcard $(MODPUBKEY)),$(MODSECKEY)+$(MODPUBKEY))
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ifeq ($(KBUILD_SRC),)
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# no O= is being used
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SCRIPTS_DIR := scripts
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else
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SCRIPTS_DIR := $(KBUILD_SRC)/scripts
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endif
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SIGN_MODULES := 1
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else
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SIGN_MODULES := 0
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endif
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# only sign if it's an in-tree module
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ifneq ($(KBUILD_EXTMOD),)
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SIGN_MODULES := 0
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endif
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# We strip the module as best we can - note that using both strip and eu-strip
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# results in a smaller module than using either alone.
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EU_STRIP = $(shell which eu-strip || echo true)
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quiet_cmd_sign_ko_stripped_ko_unsigned = STRIP [M] $@
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cmd_sign_ko_stripped_ko_unsigned = \
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cp $< $@ && \
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strip -x -g $@ && \
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$(EU_STRIP) $@
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ifeq ($(SIGN_MODULES),1)
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quiet_cmd_genkeyid = GENKEYID $@
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cmd_genkeyid = \
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perl $(SCRIPTS_DIR)/x509keyid $< $<.signer $<.keyid
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%.signer %.keyid: %
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$(call if_changed,genkeyid)
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KEYRING_DEP := $(MODSECKEY) $(MODPUBKEY) $(MODPUBKEY).signer $(MODPUBKEY).keyid
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quiet_cmd_sign_ko_ko_stripped = SIGN [M] $@
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cmd_sign_ko_ko_stripped = \
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sh $(SCRIPTS_DIR)/sign-file $(MODSECKEY) $(MODPUBKEY) $< $@
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else
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KEYRING_DEP :=
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quiet_cmd_sign_ko_ko_unsigned = NO SIGN [M] $@
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cmd_sign_ko_ko_unsigned = \
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cp $< $@
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endif
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$(modules): %.ko :%.ko.stripped $(KEYRING_DEP) FORCE
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$(call if_changed,sign_ko_ko_stripped)
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$(patsubst %.ko,%.ko.stripped,$(modules)): %.ko.stripped :%.ko.unsigned FORCE
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$(call if_changed,sign_ko_stripped_ko_unsigned)
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targets += $(modules)
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endif
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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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targets := $(wildcard $(sort $(targets)))
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cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
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ifneq ($(cmd_files),)
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include $(cmd_files)
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endif
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# Declare the contents of the .PHONY variable as phony. We keep that
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# information in a variable se we can use it in if_changed and friends.
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.PHONY: $(PHONY)
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