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authorMasahiro Yamada <masahiroy@kernel.org>2020-08-22 23:56:16 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2020-08-27 00:44:33 +0900
commit3d32285fa99598f1885ac7022785b9c343407e62 (patch)
tree542ebca9df842df65d276836286d80a1f4cf7ff1 /Makefile
parentecca4fea1ede446e9ce3afa0b68b07fd1550f4f5 (diff)
downloadlwn-3d32285fa99598f1885ac7022785b9c343407e62.tar.gz
lwn-3d32285fa99598f1885ac7022785b9c343407e62.zip
kbuild: wire up the build rule of compile_commands.json to Makefile
Currently, you need to manually run scripts/gen_compile_commands.py to create compile_commands.json. It parses all the .*.cmd files found under the specified directory. If you rebuild the kernel over again without 'make clean', .*.cmd files from older builds will create stale entries in compile_commands.json. This commit wires up the compile_commands.json rule to Makefile, and makes it parse only the .*.cmd files involved in the current build. Pass $(KBUILD_VMLINUX_OBJS), $(KBUILD_VMLINUX_LIBS), and modules.order to the script. The objects or archives linked to vmlinux are listed in $(KBUILD_VMLINUX_OBJS) or $(KBUILD_VMLINUX_LIBS). All the modules are listed in modules.order. You can create compile_commands.json from Make: $ make -j$(nproc) CC=clang compile_commands.json You can also build vmlinux, modules, and compile_commands.json all together in a single command: $ make -j$(nproc) CC=clang all compile_commands.json It works for M= builds as well. In this case, compile_commands.json is created in the top directory of the external module. This is convenient, but it has a drawback; the coverage of the compile_commands.json is reduced because only the objects linked to vmlinux or modules are handled. For example, the following C files are not included in the compile_commands.json: - Decompressor source files (arch/*/boot/) - VDSO source files - C files used to generate intermediates (e.g. kernel/bounds.c) - Standalone host programs I think it is fine for most developers because our main interest is the kernel-space code. If you want to cover all the compiled C files, please build the kernel, then run the script manually as you did before: $ make clean # if you want to remove stale .cmd files [optional] $ make -j$(nproc) CC=clang $ scripts/gen_compile_commands.py Here is a note for out-of-tree builds. 'make compile_commands.json' works with O= option, but please notice compile_commands.json is created in the object tree instead of the source tree. Some people may want to have compile_commands.json in the source tree because Clang Tools searches for it through all parent paths of the first input source file. However, you cannot do this for O= builds. Kbuild should never generate any build artifact in the source tree when O= is given because the source tree might be read-only. Any write attempt to the source tree is monitored and the violation may be reported. See the commit log of 8ef14c2c41d9. So, the only possible way is to create compile_commands.json in the object tree, then specify '-p <build-path>' when you use clang-check, clang-tidy, etc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile29
1 files changed, 25 insertions, 4 deletions
diff --git a/Makefile b/Makefile
index d96f2feddbfb..07fd96a25a20 100644
--- a/Makefile
+++ b/Makefile
@@ -634,7 +634,7 @@ endif
# in addition to whatever we do anyway.
# Just "make" or "make all" shall build modules as well
-ifneq ($(filter all modules nsdeps,$(MAKECMDGOALS)),)
+ifneq ($(filter all modules nsdeps %compile_commands.json,$(MAKECMDGOALS)),)
KBUILD_MODULES := 1
endif
@@ -1470,7 +1470,8 @@ endif # CONFIG_MODULES
# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers \
- modules.builtin modules.builtin.modinfo modules.nsdeps
+ modules.builtin modules.builtin.modinfo modules.nsdeps \
+ compile_commands.json
# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated \
@@ -1704,9 +1705,12 @@ KBUILD_MODULES := 1
build-dirs := $(KBUILD_EXTMOD)
PHONY += modules
-modules: descend
+modules: $(MODORDER)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+$(MODORDER): descend
+ @:
+
PHONY += modules_install
modules_install: _emodinst_ _emodinst_post
@@ -1720,8 +1724,12 @@ PHONY += _emodinst_post
_emodinst_post: _emodinst_
$(call cmd,depmod)
+compile_commands.json: $(extmod-prefix)compile_commands.json
+PHONY += compile_commands.json
+
clean-dirs := $(KBUILD_EXTMOD)
-clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps
+clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \
+ $(KBUILD_EXTMOD)/compile_commands.json
PHONY += help
help:
@@ -1834,6 +1842,19 @@ nsdeps: export KBUILD_NSDEPS=1
nsdeps: modules
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
+# Clang Tooling
+# ---------------------------------------------------------------------------
+
+quiet_cmd_gen_compile_commands = GEN $@
+ cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
+
+$(extmod-prefix)compile_commands.json: scripts/gen_compile_commands.py \
+ $(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \
+ $(if $(CONFIG_MODULES), $(MODORDER)) FORCE
+ $(call if_changed,gen_compile_commands)
+
+targets += $(extmod-prefix)compile_commands.json
+
# Scripts to check various things for consistency
# ---------------------------------------------------------------------------