[PATCH v3 2/8] kbuild: rebuild .vmlinux.export.o when its prerequisite is updated

Masahiro Yamada
2022-09-28T06:42:44Z

When include/linux/export-internal.h is updated, .vmlinux.export.o
must be rebuilt, but it does not happen because its rule is hidden
behind scripts/link-vmlinux.sh.

Move it out of the shell script, so that Make can see the dependency
between vmlinux and .vmlinux.export.o.

Move the vmlinux rule to scripts/Makefile.vmlinux.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v3:
- New patch

Makefile | 16 ++++------------
scripts/Makefile.vmlinux | 21 ++++++++++++++++++++-
scripts/link-vmlinux.sh | 5 -----
3 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/Makefile b/Makefile
index 83d8ff1d521a..79488f155fae 100644
--- a/Makefile
+++ b/Makefile
@@ -1160,17 +1160,9 @@ vmlinux_o: autoksyms_recursive vmlinux.a $(KBUILD_VMLINUX_LIBS)
vmlinux.o modules.builtin.modinfo modules.builtin: vmlinux_o
@:

-ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
-
-# Final link of vmlinux with optional arch pass after final link
-cmd_link-vmlinux = \
- $(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
- $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
-
-vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) modpost FORCE
- +$(call if_changed_dep,link-vmlinux)
-
-targets += vmlinux
+PHONY += vmlinux
+vmlinux: vmlinux.o $(KBUILD_LDS) modpost
+ $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux

# The actual objects are generated when descending,
# make sure no implicit rule kicks in
@@ -1501,7 +1493,7 @@ endif # CONFIG_MODULES
# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
modules.builtin modules.builtin.modinfo modules.nsdeps \
- compile_commands.json .thinlto-cache .vmlinux.objs
+ compile_commands.json .thinlto-cache .vmlinux.objs .vmlinux.export.c

# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated \
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index 7a63abf22399..49946cb96844 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -1,18 +1,37 @@
# SPDX-License-Identifier: GPL-2.0-only

+PHONY := __default
+__default: vmlinux
+
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include

# for c_flags
include $(srctree)/scripts/Makefile.lib

+targets :=
+
quiet_cmd_cc_o_c = CC $@
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

%.o: %.c FORCE
$(call if_changed_dep,cc_o_c)

-targets := $(MAKECMDGOALS)
+ifdef CONFIG_MODULES
+targets += .vmlinux.export.o
+vmlinux: .vmlinux.export.o
+endif
+
+ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
+
+# Final link of vmlinux with optional arch pass after final link
+cmd_link_vmlinux = \
+ $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
+ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
+
+targets += vmlinux
+vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
+ +$(call if_changed_dep,link_vmlinux)

# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index e3d42202e54c..918470d768e9 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -199,7 +199,6 @@ cleanup()
rm -f System.map
rm -f vmlinux
rm -f vmlinux.map
- rm -f .vmlinux.export.c
}

# Use "make V=1" to debug this script
@@ -214,10 +213,6 @@ if [ "$1" = "clean" ]; then
exit 0
fi

-if is_enabled CONFIG_MODULES; then
- ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o
-fi
-
${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o

btf_vmlinux_bin_o=""
--
2.34.1