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From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION
Date: Tue, 31 Aug 2021 16:39:56 +0900	[thread overview]
Message-ID: <20210831074004.3195284-6-masahiroy@kernel.org> (raw)
In-Reply-To: <20210831074004.3195284-1-masahiroy@kernel.org>

Redo commit 8852c5524029 ("kbuild: Fix objtool dependency for
'OBJECT_FILES_NON_STANDARD_<obj> := n'") to add the objtool
dependency in a cleaner way.

Using .SECONDEXPANSION ends up with unreadable code due to escaped
dollars. Also, it is not efficient because the second half of
Makefile.build is parsed twice every time.

Append the objtool dependency to the *.cmd files at the build time.

This is what fixdep and gen_ksymdeps.sh already do. So, following the
same pattern seems a natural solution.

This allows us to drop $$(objtool_deps) entirely.

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

 scripts/Makefile.build | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 720a86642f48..21b55f37a23f 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -246,14 +246,11 @@ objtool-enabled = $(if $(filter-out y%, \
 	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
 
 cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
-objtool_obj = $(if $(objtool-enabled), $(objtool))
+cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
 
 endif # CONFIG_LTO_CLANG
 endif # CONFIG_STACK_VALIDATION
 
-# Rebuild all objects when objtool changes
-objtool_dep = $(objtool_obj)
-
 ifdef CONFIG_TRIM_UNUSED_KSYMS
 cmd_gen_ksymdeps = \
 	$(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
@@ -267,6 +264,7 @@ define rule_cc_o_c
 	$(call cmd,gen_ksymdeps)
 	$(call cmd,checksrc)
 	$(call cmd,checkdoc)
+	$(call cmd,gen_objtooldep)
 	$(call cmd,modversions_c)
 	$(call cmd,record_mcount)
 endef
@@ -274,12 +272,12 @@ endef
 define rule_as_o_S
 	$(call cmd_and_fixdep,as_o_S)
 	$(call cmd,gen_ksymdeps)
+	$(call cmd,gen_objtooldep)
 	$(call cmd,modversions_S)
 endef
 
 # Built-in and composite module parts
-.SECONDEXPANSION:
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
@@ -380,7 +378,7 @@ cmd_modversions_S =								\
 	fi
 endif
 
-$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE
+$(obj)/%.o: $(src)/%.S FORCE
 	$(call if_changed_rule,as_o_S)
 
 targets += $(filter-out $(subdir-builtin), $(real-obj-y))
-- 
2.30.2


  parent reply	other threads:[~2021-08-31  7:40 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31  7:39 [PATCH v2 00/13] kbuild: second round of Clang LTO refactoring Masahiro Yamada
2021-08-31  7:39 ` [PATCH v2 01/13] kbuild: move objtool_args back to scripts/Makefile.build Masahiro Yamada
2021-09-04 18:18   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 02/13] kbuild: rename __objtool_obj to objtool Masahiro Yamada
2021-08-31 17:16   ` Nick Desaulniers
2021-08-31 17:29   ` Kees Cook
2021-09-04 18:19   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 03/13] kbuild: store the objtool command in *.cmd files Masahiro Yamada
2021-08-31 17:23   ` Nick Desaulniers
2021-08-31 17:30   ` Kees Cook
2021-09-04 18:04   ` Josh Poimboeuf
2021-09-04 18:45     ` Josh Poimboeuf
2021-09-08 16:12       ` Masahiro Yamada
2021-08-31  7:39 ` [PATCH v2 04/13] kbuild: factor out OBJECT_FILES_NON_STANDARD check into a macro Masahiro Yamada
2021-08-31 17:25   ` Nick Desaulniers
2021-08-31 17:31   ` Kees Cook
2021-09-04 18:59   ` Josh Poimboeuf
2021-08-31  7:39 ` Masahiro Yamada [this message]
2021-08-31 17:32   ` [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION Kees Cook
2021-09-03  0:43     ` Masahiro Yamada
2021-08-31 17:33   ` Nick Desaulniers
2021-09-02 23:42     ` Masahiro Yamada
2021-09-04 19:04   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 06/13] kbuild: reuse $(cmd_objtool) for cmd_cc_lto_link_modules Masahiro Yamada
2021-08-31 17:35   ` Kees Cook
2021-09-03  0:39     ` Masahiro Yamada
2021-09-03  1:49       ` Kees Cook
2021-09-04 19:11   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 07/13] kbuild: do not create built-in.a.symversions or lib.a.symversions Masahiro Yamada
2021-08-31 17:36   ` Kees Cook
2021-08-31  7:39 ` [PATCH v2 08/13] kbuild: build modules in the same way with/without Clang LTO Masahiro Yamada
2021-08-31 17:39   ` Kees Cook
2021-08-31 17:46   ` Nick Desaulniers
2021-08-31  7:40 ` [PATCH v2 09/13] kbuild: add cmd_and_savecmd macro Masahiro Yamada
2021-08-31 17:39   ` Kees Cook
2021-08-31  7:40 ` [PATCH v2 10/13] kbuild: rebuild modules when objtool is updated for CONFIG_LTO_CLANG Masahiro Yamada
2021-08-31 17:40   ` Kees Cook
2021-09-04 19:13   ` Josh Poimboeuf
2021-08-31  7:40 ` [PATCH v2 11/13] kbuild: always postpone CRC links for module versioning Masahiro Yamada
2021-08-31  7:40 ` [PATCH v2 12/13] kbuild: merge cmd_modversions_c and cmd_modversions_S Masahiro Yamada
2021-08-31  7:40 ` [PATCH v2 13/13] kbuild: merge cmd_ar_builtin and cmd_ar_module Masahiro Yamada

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