scripts/Makefile.modpost

   1 # SPDX-License-Identifier: GPL-2.0
   2 # ===========================================================================
   3 # Module versions
   4 # ===========================================================================
   5 #
   6 # Stage one of module building created the following:
   7 # a) The individual .o files used for the module
   8 # b) A <module>.o file which is the .o files above linked together
   9 # c) A <module>.mod file in $(MODVERDIR)/, listing the name of the
  10 #    the preliminary <module>.o file, plus all .o files
  11
  12 # Stage 2 is handled by this file and does the following
  13 # 1) Find all modules from the files listed in $(MODVERDIR)/
  14 # 2) modpost is then used to
  15 # 3)  create one <module>.mod.c file pr. module
  16 # 4)  create one Module.symvers file with CRC for all exported symbols
  17 # 5) compile all <module>.mod.c files
  18 # 6) final link of the module to a <module.ko> file
  19
  20 # Step 3 is used to place certain information in the module's ELF
  21 # section, including information such as:
  22 #   Version magic (see include/linux/vermagic.h for full details)
  23 #     - Kernel release
  24 #     - SMP is CONFIG_SMP
  25 #     - PREEMPT is CONFIG_PREEMPT
  26 #     - GCC Version
  27 #   Module info
  28 #     - Module version (MODULE_VERSION)
  29 #     - Module alias'es (MODULE_ALIAS)
  30 #     - Module license (MODULE_LICENSE)
  31 #     - See include/linux/module.h for more details
  32
  33 # Step 4 is solely used to allow module versioning in external modules,
  34 # where the CRC of each module is retrieved from the Module.symvers file.
  35
  36 # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
  37 # symbols in the final module linking stage
  38 # KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
  39 # This is solely useful to speed up test compiles
  40 PHONY := _modpost
  41 _modpost: __modpost
  42
  43 include include/config/auto.conf
  44 include scripts/Kbuild.include
  45
  46 # When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
  47 ifneq ($(KBUILD_EXTMOD),)
  48
  49 # set src + obj - they may be used when building the .mod.c file
  50 obj := $(KBUILD_EXTMOD)
  51 src := $(obj)
  52
  53 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
  54 include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
  55              $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
  56 endif
  57
  58 include scripts/Makefile.lib
  59
  60 kernelsymfile := $(objtree)/Module.symvers
  61 modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
  62
  63 # Step 1), find all modules listed in $(MODVERDIR)/
  64 MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u
  65 __modules := $(shell $(MODLISTCMD))
  66 modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
  67
  68 # Stop after building .o files if NOFINAL is set. Makes compile tests quicker
  69 _modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
  70
  71 # Step 2), invoke modpost
  72 #  Includes step 3,4
  73 modpost = scripts/mod/modpost                    \
  74  $(if $(CONFIG_MODVERSIONS),-m)                  \
  75  $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)       \
  76  $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)   \
  77  $(if $(KBUILD_EXTMOD),-I $(modulesymfile))      \
  78  $(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
  79  $(if $(KBUILD_EXTMOD),-o $(modulesymfile))      \
  80  $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S)      \
  81  $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)  \
  82  $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
  83
  84 MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
  85
  86 # If CONFIG_LTO_CLANG is enabled, .o files are either LLVM IR, or empty, so we
  87 # need to link them into actual objects before passing them to modpost
  88 modpost-ext = $(if $(CONFIG_LTO_CLANG),.lto,)
  89
  90 ifdef CONFIG_LTO_CLANG
  91 quiet_cmd_cc_lto_link_modules = LD [M]  $@
  92 cmd_cc_lto_link_modules =                                               \
  93         $(LD) $(ld_flags) -r -o $(@)                                    \
  94                 $(shell [ -s $(@:$(modpost-ext).o=.o.symversions) ] &&  \
  95                         echo -T $(@:$(modpost-ext).o=.o.symversions))   \
  96                 --whole-archive $(filter-out FORCE,$^)
  97
  98 $(modules:.ko=$(modpost-ext).o): %$(modpost-ext).o: %.o FORCE
  99         $(call if_changed,cc_lto_link_modules)
 100 endif
 101
 102 # We can go over command line length here, so be careful.
 103 quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
 104       cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/$(modpost-ext)\.o/' | $(modpost) $(MODPOST_OPT) -s -T -
 105
 106 PHONY += __modpost
 107 __modpost: $(modules:.ko=$(modpost-ext).o) FORCE
 108         $(call cmd,modpost) $(wildcard vmlinux)
 109
 110 quiet_cmd_kernel-mod = MODPOST $@
 111       cmd_kernel-mod = $(modpost) $@
 112
 113 vmlinux.o: FORCE
 114         $(call cmd,kernel-mod)
 115
 116 # Declare generated files as targets for modpost
 117 $(modules:.ko=$(modpost-ext).mod.c): __modpost ;
 118
 119 # Step 5), compile all *.mod.c files
 120
 121 # modname is set to make c_flags define KBUILD_MODNAME
 122 modname = $(notdir $(@:.mod.o=))
 123
 124 quiet_cmd_cc_o_c = CC      $@
 125       cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
 126                    -c -o $@ $<
 127
 128 $(modules:.ko=.mod.o): %.mod.o: %$(modpost-ext).mod.c FORCE
 129         $(call if_changed_dep,cc_o_c)
 130
 131 targets += $(modules:.ko=$(modpost-ext).mod.o)
 132
 133 ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
 134
 135 # Step 6), final link of the modules with optional arch pass after final link
 136 quiet_cmd_ld_ko_o = LD [M]  $@
 137
 138 ifdef CONFIG_LTO_CLANG
 139       cmd_ld_ko_o =                                                     \
 140         $(LD) -r $(LDFLAGS)                                             \
 141                  $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
 142                  $(shell [ -s $(@:.ko=.o.symversions) ] &&              \
 143                         echo -T $(@:.ko=.o.symversions))                \
 144                  -o $@ --whole-archive                                  \
 145                  $(filter-out FORCE,$(^:$(modpost-ext).o=.o))
 146
 147   ifdef CONFIG_FTRACE_MCOUNT_RECORD
 148       cmd_ld_ko_o += ; $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) $@
 149   endif
 150 else
 151       cmd_ld_ko_o =                                                     \
 152         $(LD) -r $(LDFLAGS)                                             \
 153                  $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
 154                  -o $@ $(filter-out FORCE,$^) ;                         \
 155         $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 156 endif
 157
 158 $(modules): %.ko: %$(modpost-ext).o %.mod.o FORCE
 159         +$(call if_changed,ld_ko_o)
 160
 161 targets += $(modules)
 162
 163
 164 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 165 # ---------------------------------------------------------------------------
 166
 167 PHONY += FORCE
 168
 169 FORCE:
 170
 171 # Read all saved command lines and dependencies for the $(targets) we
 172 # may be building above, using $(if_changed{,_dep}). As an
 173 # optimization, we don't need to read them if the target does not
 174 # exist, we will rebuild anyway in that case.
 175
 176 targets := $(wildcard $(sort $(targets)))
 177 cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
 178
 179 ifneq ($(cmd_files),)
 180   include $(cmd_files)
 181 endif
 182
 183
 184 # Declare the contents of the .PHONY variable as phony.  We keep that
 185 # information in a variable se we can use it in if_changed and friends.
 186
 187 .PHONY: $(PHONY)