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 per 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
 35PHONY := __modpost
 36__modpost:
 37
 38include $(objtree)/include/config/auto.conf
 39include $(srctree)/scripts/Kbuild.include
 40
 41MODPOST = $(objtree)/scripts/mod/modpost
 42
 43modpost-args =										\
 44	$(if $(CONFIG_MODULES),-M)							\
 45	$(if $(CONFIG_MODVERSIONS),-m)							\
 46	$(if $(CONFIG_BASIC_MODVERSIONS),-b)						\
 47	$(if $(CONFIG_EXTENDED_MODVERSIONS),-x)						\
 48	$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a)					\
 49	$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)					\
 50	$(if $(KBUILD_MODPOST_WARN),-w)							\
 51	$(if $(KBUILD_NSDEPS),-d modules.nsdeps)					\
 52	$(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N)	\
 53	$(if $(findstring 1, $(KBUILD_EXTRA_WARN)),-W)					\
 54	-o $@
 55
 56modpost-deps := $(MODPOST)
 57
 58# 'make -i -k' ignores compile errors, and builds as many modules as possible.
 59ifneq ($(findstring i,$(filter-out --%,$(MAKEFLAGS))),)
 60modpost-args += -n
 61endif
 62
 63# Read out modules.order to pass in modpost.
 64# Otherwise, allmodconfig would fail with "Argument list too long".
 65ifdef KBUILD_MODULES
 66modpost-args += -T modules.order
 67modpost-deps += modules.order
 68endif
 69
 70ifeq ($(KBUILD_EXTMOD),)
 71
 72# Generate the list of in-tree objects in vmlinux
 73# ---------------------------------------------------------------------------
 74
 75# This is used to retrieve symbol versions generated by genksyms.
 76ifdef CONFIG_MODVERSIONS
 77vmlinux.symvers Module.symvers: .vmlinux.objs
 78endif
 79
 80# Ignore libgcc.a
 81# Some architectures do '$(CC) --print-libgcc-file-name' to borrow libgcc.a
 82# from the toolchain, but there is no EXPORT_SYMBOL in it.
 83
 84quiet_cmd_vmlinux_objs = GEN     $@
 85      cmd_vmlinux_objs =		\
 86	for f in $(real-prereqs); do	\
 87		case $${f} in		\
 88		*libgcc.a) ;;		\
 89		*) $(AR) t $${f} ;;	\
 90		esac			\
 91	done > $@
 92
 93targets += .vmlinux.objs
 94.vmlinux.objs: vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
 95	$(call if_changed,vmlinux_objs)
 96
 97ifdef CONFIG_TRIM_UNUSED_KSYMS
 98ksym-wl := $(CONFIG_UNUSED_KSYMS_WHITELIST)
 99ksym-wl := $(if $(filter-out /%, $(ksym-wl)),$(if $(wildcard $(ksym-wl)),,$(srctree)/))$(ksym-wl)
100modpost-args += -t $(addprefix -u , $(ksym-wl))
101modpost-deps += $(ksym-wl)
102endif
103
104ifeq ($(wildcard vmlinux.o),)
105missing-input := vmlinux.o
106output-symdump := modules-only.symvers
107else
108modpost-args += vmlinux.o
109modpost-deps += vmlinux.o
110output-symdump := $(if $(KBUILD_MODULES), Module.symvers, vmlinux.symvers)
111endif
112
113else
114
115# set src + obj - they may be used in the modules's Makefile
116obj := .
117src := $(srcroot)
118
119# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
120include $(kbuild-file)
121
122output-symdump := Module.symvers
123
124ifeq ($(wildcard $(objtree)/Module.symvers),)
125missing-input := $(objtree)/Module.symvers
126else
127modpost-args += -i $(objtree)/Module.symvers
128modpost-deps += $(objtree)/Module.symvers
129endif
130
131modpost-args += -e $(addprefix -i , $(KBUILD_EXTRA_SYMBOLS))
132
133endif # ($(KBUILD_EXTMOD),)
134
135quiet_cmd_modpost = MODPOST $@
136      cmd_modpost = \
137	$(if $(missing-input), \
138		echo >&2 "WARNING: $(missing-input) is missing."; \
139		echo >&2 "         Modules may not have dependencies or modversions."; \
140		echo >&2 "         You may get many unresolved symbol errors."; \
141		echo >&2 "         You can set KBUILD_MODPOST_WARN=1 to turn errors into warning"; \
142		echo >&2 "         if you want to proceed at your own risk.";) \
143	$(MODPOST) $(modpost-args)
144
145targets += $(output-symdump)
146$(output-symdump): $(modpost-deps) FORCE
147	$(call if_changed,modpost)
148
149__modpost: $(output-symdump)
150PHONY += FORCE
151FORCE:
152
153existing-targets := $(wildcard $(sort $(targets)))
154
155-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
156
157.PHONY: $(PHONY)