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
19# Step 3 is used to place certain information in the module's ELF
20# section, including information such as:
21#   Version magic (see include/linux/vermagic.h for full details)
22#     - Kernel release
23#     - SMP is CONFIG_SMP
24#     - PREEMPT is CONFIG_PREEMPT[_RT]
25#     - GCC Version
26#   Module info
27#     - Module version (MODULE_VERSION)
28#     - Module alias'es (MODULE_ALIAS)
29#     - Module license (MODULE_LICENSE)
30#     - See include/linux/module.h for more details
31
32# Step 4 is solely used to allow module versioning in external modules,
33# where the CRC of each module is retrieved from the Module.symvers file.
34
35# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
36# symbols in the final module linking stage
37# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
38# This is solely useful to speed up test compiles
39
40PHONY := __modpost
41__modpost:
42
43include include/config/auto.conf
44include scripts/Kbuild.include
45
46kernelsymfile := $(objtree)/Module.symvers
47modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
48
49MODPOST = scripts/mod/modpost						\
50	$(if $(CONFIG_MODVERSIONS),-m)					\
51	$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a)			\
52	$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)			\
53	$(if $(KBUILD_EXTMOD),-I $(modulesymfile))			\
54	$(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS)))	\
55	$(if $(KBUILD_EXTMOD),-o $(modulesymfile))			\
56	$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)			\
57	$(if $(KBUILD_MODPOST_WARN),-w)					\
58	$(if $(filter nsdeps,$(MAKECMDGOALS)),-d)
59
60ifdef MODPOST_VMLINUX
61
62quiet_cmd_modpost = MODPOST vmlinux.o
63      cmd_modpost = $(MODPOST) vmlinux.o
64
65__modpost:
66	$(call cmd,modpost)
67
68else
69
70# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
71ifneq ($(KBUILD_EXTMOD),)
72
73# set src + obj - they may be used when building the .mod.c file
74obj := $(KBUILD_EXTMOD)
75src := $(obj)
76
77# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
78include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
79             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
80endif
81
82MODPOST += $(subst -i,-n,$(filter -i,$(MAKEFLAGS))) -s -T - $(wildcard vmlinux)
83
84# find all modules listed in modules.order
85modules := $(sort $(shell cat $(MODORDER)))
86
87# Read out modules.order instead of expanding $(modules) to pass in modpost.
88# Otherwise, allmodconfig would fail with "Argument list too long".
89quiet_cmd_modpost = MODPOST $(words $(modules)) modules
90      cmd_modpost = sed 's/ko$$/o/' $(MODORDER) | $(MODPOST)
91
92__modpost:
93	@$(kecho) '  Building modules, stage 2.'
94	$(call cmd,modpost)
95ifneq ($(KBUILD_MODPOST_NOFINAL),1)
96	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
97endif
98
99nsdeps: __modpost
100
101endif
102
103.PHONY: $(PHONY)
104