From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: Nathan Huckleberry <nhuck@google.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Roeder <tmroeder@google.com>,
clang-built-linux@googlegroups.com,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
linux-kernel@vger.kernel.org
Subject: [PATCH v3 08/10] kbuild: wire up the build rule of compile_commands.json to Makefile
Date: Sat, 22 Aug 2020 23:56:16 +0900 [thread overview]
Message-ID: <20200822145618.1222514-9-masahiroy@kernel.org> (raw)
In-Reply-To: <20200822145618.1222514-1-masahiroy@kernel.org>
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>
---
(no changes since v1)
Makefile | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 9cac6fde3479..65ed336a6de1 100644
--- a/Makefile
+++ b/Makefile
@@ -635,7 +635,7 @@ 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
@@ -1464,7 +1464,8 @@ 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 \
@@ -1698,9 +1699,12 @@ 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
@@ -1714,8 +1718,12 @@ 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:
@@ -1828,6 +1836,19 @@ 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
# ---------------------------------------------------------------------------
--
2.25.1
next prev parent reply other threads:[~2020-08-22 14:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-22 14:56 [PATCH v3 00/10] kbuild: clang-tidy Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 01/10] gen_compile_commands: parse only the first line of .*.cmd files Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 02/10] gen_compile_commands: use choices for --log_levels option Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 03/10] gen_compile_commands: do not support .cmd files under tools/ directory Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 04/10] gen_compile_commands: reword the help message of -d option Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 05/10] gen_compile_commands: make -o option independent " Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 06/10] gen_compile_commands: move directory walk to a generator function Masahiro Yamada
2020-08-22 14:56 ` [PATCH v3 07/10] gen_compile_commands: support *.o, *.a, modules.order in positional argument Masahiro Yamada
2020-08-23 0:40 ` Nick Desaulniers
2020-08-22 14:56 ` Masahiro Yamada [this message]
2020-08-22 14:56 ` [PATCH v3 09/10] gen_compile_commands: remove the warning about too few .cmd files Masahiro Yamada
2020-08-23 0:47 ` Nick Desaulniers
2020-08-22 14:56 ` [PATCH v3 10/10] Makefile: Add clang-tidy and static analyzer support to makefile Masahiro Yamada
2020-08-26 13:27 ` [PATCH v3 00/10] kbuild: clang-tidy Masahiro Yamada
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