On Sun, May 4, 2025 at 2:37 AM Kees Cook <k...@kernel.org> wrote:
>
> On Sat, May 03, 2025 at 06:39:28PM +0900, Masahiro Yamada wrote:
> > On Sat, May 3, 2025 at 7:54 AM Kees Cook <k...@kernel.org> wrote:
> > >
> > > v2:
> > > - switch from -include to -I with a -D gated include compiler-version.h
> > > v1: https://lore.kernel.org/lkml/20250501193839.work.525-k...@kernel.org/
> >
> >
> > What do you think of my patch as a prerequisite?
> > https://lore.kernel.org/linux-kbuild/20250503084145.1994176-1-masahi...@kernel.org/T/#u
> > Perhaps, can you implement this series more simply?
> >
> > My idea is to touch a single include/generated/global-rebuild.h
> > rather than multiple files such as gcc-plugins-deps.h, integer-wrap.h, etc.
> >
> > When the file is touched, the entire kernel source tree will be rebuilt.
> > This may rebuild more than needed (e.g. vdso) but I do not think
> > it is a big deal.
>
> This is roughly where I started when trying to implement this, but I
> didn't like the ergonomics of needing to scatter "touch" calls all over,
> which was especially difficult for targets that shared a build rule but
> may not all need to trigger a global rebuild. But what ultimately pushed
> me away from it was when I needed to notice if a non-built source file
> changed (the Clang .scl file), and I saw that I need to be dependency
> driven rather than target driven. (Though perhaps there is a way to
> address this with your global-rebuild.h?)
>
> As far as doing a full rebuild, if it had been available last week, I
> probably would have used it, but now given the work that Nicolas, you,
> and I have put into this, we have a viable way (I think) to make this
> more specific. It does end up being a waste of time/resources to rebuild
> stuff that doesn't need to be (efi-stub, vdso, boot code, etc), and that
> does add up when I'm iterating on something that keeps triggering a full
> rebuild. We already have to do the argument filtering for targets that
> don't want randstruct, etc, so why not capitalize on that and make the
> rebuild avoid those files too?
efi-stub, vdso are very small.
Unless this turns out to be painful, I prefer
a simpler implementation.
You will see how .scl file is handled.
See the below code:
diff --git a/Kbuild b/Kbuild
index f327ca86990c..85747239314c 100644
--- a/Kbuild
+++ b/Kbuild
@@ -67,10 +67,20 @@ targets += $(atomic-checks)
$(atomic-checks): $(obj)/.checked-%: include/linux/atomic/% FORCE
$(call if_changed,check_sha1)
+rebuild-$(CONFIG_GCC_PLUGINS) += $(addprefix
scripts/gcc-plugins/, $(GCC_PLUGIN))
+rebuild-$(CONFIG_RANDSTRUCT) += include/generated/randstruct_hash.h
+rebuild-$(CONFIG_UBSAN_INTEGER_WRAP) += scripts/integer-wrap-ignore.scl
+
+quiet_cmd_touch = TOUCH $@
+ cmd_touch = touch $@
+
+include/generated/global-rebuild.h: $(rebuild-y)
+ $(call cmd,touch)
+
# A phony target that depends on all the preparation targets
PHONY += prepare
-prepare: $(offsets-file) missing-syscalls $(atomic-checks)
+prepare: $(offsets-file) missing-syscalls $(atomic-checks)
include/generated/global-rebuild.h
@:
# Ordinary directory descending
diff --git a/Makefile b/Makefile
index b29cc321ffd9..f963a72b0761 100644
--- a/Makefile
+++ b/Makefile
@@ -558,7 +558,8 @@ USERINCLUDE := \
-I$(srctree)/include/uapi \
-I$(objtree)/include/generated/uapi \
-include $(srctree)/include/linux/compiler-version.h \
- -include $(srctree)/include/linux/kconfig.h
+ -include $(srctree)/include/linux/kconfig.h \
+ -include $(objtree)/include/generated/global-rebuild.h
# Use LINUXINCLUDE when you must reference the include/ directory.
# Needed to be compatible with the O= option
@@ -1250,6 +1251,12 @@ endif
include/config/kernel.release: FORCE
$(call filechk,kernel.release)
+quiet_cmd_touch = TOUCH $@
+ cmd_touch = touch $@
+
+include/generated/global-rebuild.h:
+ $(call cmd,touch)
+
# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parallel
@@ -1266,6 +1273,7 @@ scripts: scripts_basic scripts_dtc
PHONY += prepare archprepare
archprepare: outputmakefile archheaders archscripts scripts
include/config/kernel.release \
+ include/generated/global-rebuild.h \
asm-generic $(version_h) include/generated/utsrelease.h \
include/generated/compile.h include/generated/autoconf.h \
include/generated/rustc_cfg remove-stale-files
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 1d36a613aad8..f564a26c1364 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -73,7 +73,8 @@ USER_CFLAGS = $(patsubst
$(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
-D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \
-idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__ \
-include $(srctree)/include/linux/compiler-version.h \
- -include $(srctree)/include/linux/kconfig.h
+ -include $(srctree)/include/linux/kconfig.h \
+ -include $(objtree)/include/generated/global-rebuild.h
#This will adjust *FLAGS accordingly to the platform.
include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux
--
Best Regards
Masahiro Yamada
