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