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, listing the name of the preliminary <module>.o file,
  10 #    plus all .o files
  11 # d) modules.order, which lists all the modules
  12
  13 # Stage 2 is handled by this file and does the following
  14 # 1) Find all modules listed in modules.order
  15 # 2) modpost is then used to
  16 # 3)  create one <module>.mod.c file pr. module
  17 # 4)  create one Module.symvers file with CRC for all exported symbols
  18 # 5) compile all <module>.mod.c files
  19 # 6) final link of the module to a <module.ko> file
  20
  21 # Step 3 is used to place certain information in the module's ELF
  22 # section, including information such as:
  23 #   Version magic (see include/linux/vermagic.h for full details)
  24 #     - Kernel release
  25 #     - SMP is CONFIG_SMP
  26 #     - PREEMPT is CONFIG_PREEMPT
  27 #     - GCC Version
  28 #   Module info
  29 #     - Module version (MODULE_VERSION)
  30 #     - Module alias'es (MODULE_ALIAS)
  31 #     - Module license (MODULE_LICENSE)
  32 #     - See include/linux/module.h for more details
  33
  34 # Step 4 is solely used to allow module versioning in external modules,
  35 # where the CRC of each module is retrieved from the Module.symvers file.
  36
  37 # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
  38 # symbols in the final module linking stage
  39 # KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
  40 # This is solely useful to speed up test compiles
  41
  42 PHONY := __modpost
  43 __modpost:
  44
  45 include include/config/auto.conf
  46 include scripts/Kbuild.include
  47
  48 kernelsymfile := $(objtree)/Module.symvers
  49 modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
  50
  51 MODPOST = scripts/mod/modpost                                           \
  52         $(if $(CONFIG_MODVERSIONS),-m)                                  \
  53         $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a)                        \
  54         $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)                   \
  55         $(if $(KBUILD_EXTMOD),-I $(modulesymfile))                      \
  56         $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
  57         $(if $(KBUILD_EXTMOD),-o $(modulesymfile))                      \
  58         $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)                  \
  59         $(if $(KBUILD_MODPOST_WARN),-w)
  60
  61 ifdef MODPOST_VMLINUX
  62
  63 __modpost: vmlinux.o
  64
  65 quiet_cmd_modpost = MODPOST $@
  66       cmd_modpost = $(MODPOST) $@
  67
  68 PHONY += vmlinux.o
  69 vmlinux.o:
  70         $(call cmd,modpost)
  71
  72 else
  73
  74 # When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
  75 ifneq ($(KBUILD_EXTMOD),)
  76
  77 # set src + obj - they may be used when building the .mod.c file
  78 obj := $(KBUILD_EXTMOD)
  79 src := $(obj)
  80
  81 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
  82 include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
  83              $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
  84 endif
  85
  86 include scripts/Makefile.lib
  87
  88 # find all modules listed in modules.order
  89 modules := $(sort $(shell cat $(MODORDER)))
  90
  91 # Stop after building .o files if NOFINAL is set. Makes compile tests quicker
  92 __modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
  93         @:
  94
  95 MODPOST += $(subst -i,-n,$(filter -i,$(MAKEFLAGS))) -s -T - $(wildcard vmlinux)
  96
  97 # We can go over command line length here, so be careful.
  98 quiet_cmd_modpost = MODPOST $(words $(modules)) modules
  99       cmd_modpost = sed 's/ko$$/o/' $(MODORDER) | $(MODPOST)
 100
 101 PHONY += modules-modpost
 102 modules-modpost:
 103         $(call cmd,modpost)
 104
 105 # Declare generated files as targets for modpost
 106 $(modules:.ko=.mod.c): modules-modpost
 107
 108 # Step 5), compile all *.mod.c files
 109
 110 # modname is set to make c_flags define KBUILD_MODNAME
 111 modname = $(notdir $(@:.mod.o=))
 112
 113 quiet_cmd_cc_o_c = CC      $@
 114       cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
 115                    -c -o $@ $<
 116
 117 $(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
 118         $(call if_changed_dep,cc_o_c)
 119
 120 targets += $(modules:.ko=.mod.o)
 121
 122 ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
 123
 124 # Step 6), final link of the modules with optional arch pass after final link
 125 quiet_cmd_ld_ko_o = LD [M]  $@
 126       cmd_ld_ko_o =                                                     \
 127         $(LD) -r $(KBUILD_LDFLAGS)                                      \
 128                  $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
 129                  -o $@ $(real-prereqs) ;                                \
 130         $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 131
 132 $(modules): %.ko :%.o %.mod.o FORCE
 133         +$(call if_changed,ld_ko_o)
 134
 135 targets += $(modules)
 136
 137
 138 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 139 # ---------------------------------------------------------------------------
 140
 141 PHONY += FORCE
 142
 143 FORCE:
 144
 145 # Read all saved command lines and dependencies for the $(targets) we
 146 # may be building above, using $(if_changed{,_dep}). As an
 147 # optimization, we don't need to read them if the target does not
 148 # exist, we will rebuild anyway in that case.
 149
 150 existing-targets := $(wildcard $(sort $(targets)))
 151
 152 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 153
 154 endif
 155
 156 .PHONY: $(PHONY)