From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from condef-09.nifty.com (condef-09.nifty.com [202.248.20.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A91D77C for ; Sun, 24 Apr 2022 19:19:21 +0000 (UTC) Received: from conuserg-10.nifty.com ([10.126.8.73])by condef-09.nifty.com with ESMTP id 23OJA568008065 for ; Mon, 25 Apr 2022 04:10:05 +0900 Received: from grover.sesame (133-32-177-133.west.xps.vectant.ne.jp [133.32.177.133]) (authenticated) by conuserg-10.nifty.com with ESMTP id 23OJ8o6L019069; Mon, 25 Apr 2022 04:09:08 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-10.nifty.com 23OJ8o6L019069 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1650827348; bh=OeAGgbUKAMDuhSSiJ6AiKj6PosUqdQFMdemfFg9heYQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F1YtJMWZG4cBDGz8Wtn15Pq/BDYKgGRK7BNu9Na/PI4zktqXCUdrGZ29PlKs3r/p8 vOg3jyh1BONb9k6RZ0yN0kGR6vlGohFq0ibUY9bB2R4Z7C/IjGb0T75tmqgiIZa0ab Dxkq03PTcXUP/cO2nNXcUqWFBKl9XkoSykYUYj3whBbV3M3Tyu6ZSTfMJKFvZy0WM6 ATH53t+jjZf4LA/nZtOAEzsLse2hZqtjXlEA4kRInsScbeXqAP+c5918ddFQpiQqcf usONMFWpR8h20w8peURiqFv0gFWxFwYbSe5hnU4wqUHB5tsvQ+2P0MDa70aymFwGfQ wganZFBLKZMyA== X-Nifty-SrcIP: [133.32.177.133] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Michal Marek , Nathan Chancellor , Nick Desaulniers , llvm@lists.linux.dev Subject: [PATCH 27/27] kbuild: do not create *.prelink.o for Clang LTO or IBT Date: Mon, 25 Apr 2022 04:08:11 +0900 Message-Id: <20220424190811.1678416-28-masahiroy@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220424190811.1678416-1-masahiroy@kernel.org> References: <20220424190811.1678416-1-masahiroy@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM bitcode is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look the same with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module [+objtool] $(CC) $(LD) $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM bitcode) (ELF) | | foo.mod.o --/ [2] multi-object module [+objtool] $(CC) $(AR) $(LD) $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | foo2.c -----> foo2.o --/ | (LLVM bitcode) foo.mod.o --/ One confusion is foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, we do not need to have the LLVM bitcode stage. Use $(CC)+$(LD) to generate an ELF object in one build rule. Of course, only $(CC) is used when LTO is disabled. $(CC)+$(LD)[+objtool] $(LD) foo.c ------------------------> foo.o -------> foo.ko (ELF) | | foo.mod.o --/ [2] multi-object module Previously, $(AR) was used to combine LLVM bitcode into an archive, but there was not a technical reason to do so. This commit just uses $(LD) to combine and convert them into a single ELF object. [+objtool] $(CC) $(LD) $(LD) foo1.c -------> foo1.o -------> foo.o -------> foo.ko | (ELF) | foo2.c -------> foo2.o ---/ | (LLVM bitcode) foo.mod.o --/ Signed-off-by: Masahiro Yamada --- scripts/Kbuild.include | 4 +++ scripts/Makefile.build | 58 ++++++++++++--------------------------- scripts/Makefile.lib | 7 ----- scripts/Makefile.modfinal | 5 ++-- scripts/Makefile.modpost | 9 ++---- scripts/mod/modpost.c | 7 ----- 6 files changed, 25 insertions(+), 65 deletions(-) diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 3514c2149e9d..455a0a6ce12d 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -15,6 +15,10 @@ pound := \# # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o dot-target = $(dir $@).$(notdir $@) +### +# Name of target with a '.tmp_' as filename prefix. foo/bar.o => foo/.tmp_bar.o +tmp-target = $(dir $@).tmp_$(notdir $@) + ### # The temporary file to save gcc -MMD generated dependencies must not # contain a comma diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 7f199b0a5170..fe4d3a908dd0 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -88,10 +88,6 @@ endif targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \ $(patsubst %.o, %.$x, $(filter %.o, $(obj-m)))) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -targets-for-modules += $(patsubst %.o, %.prelink.o, $(filter %.o, $(obj-m))) -endif - ifdef need-modorder targets-for-modules += $(obj)/modules.order endif @@ -153,8 +149,16 @@ $(obj)/%.ll: $(src)/%.c FORCE # The C file is compiled and updated dependency information is generated. # (See cmd_cc_o_c + relevant part of rule_cc_o_c) +is-single-obj-m = $(if $(part-of-module),$(if $(filter $@, $(obj-m)),y)) + +ifdef CONFIG_LTO_CLANG +cmd_ld_single = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@) +endif + quiet_cmd_cc_o_c = CC $(quiet_modtag) $@ - cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool) + cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \ + $(cmd_ld_single) \ + $(cmd_objtool) ifdef CONFIG_MODVERSIONS # When module versioning is enabled the following steps are executed: @@ -228,21 +232,16 @@ cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(o endif # CONFIG_STACK_VALIDATION -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) - -# Skip objtool for LLVM bitcode -$(obj)/%.o: objtool-enabled := - -else # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file -$(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \ - $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y) +is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y) -endif +delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT)) + +$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y)) ifdef CONFIG_TRIM_UNUSED_KSYMS cmd_gen_ksymdeps = \ @@ -271,24 +270,6 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE $(call if_changed_rule,cc_o_c) $(call cmd,force_checksrc) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -# Module .o files may contain LLVM bitcode, compile them into native code -# before ELF processing -quiet_cmd_cc_prelink_modules = LD [M] $@ - cmd_cc_prelink_modules = \ - $(LD) $(ld_flags) -r -o $@ \ - --whole-archive $(filter-out FORCE,$^) \ - $(cmd_objtool) - -# objtool was skipped for LLVM bitcode, run it now that we have compiled -# modules into native code -$(obj)/%.prelink.o: objtool-enabled = y -$(obj)/%.prelink.o: part-of-module := y - -$(obj)/%.prelink.o: $(obj)/%.o FORCE - $(call if_changed,cc_prelink_modules) -endif - cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \ $(AWK) -v RS='( |\n)' '!x[$$0]++' > $@ @@ -298,7 +279,7 @@ $(obj)/%.mod: FORCE # List module undefined symbols cmd_undefined_syms = $(NM) $< | sed -n 's/^ *U //p' > $@ -$(obj)/%.usyms: $(obj)/%$(mod-prelink-ext).o FORCE +$(obj)/%.usyms: $(obj)/%.o FORCE $(call if_changed,undefined_syms) quiet_cmd_cc_lst_c = MKLST $@ @@ -420,16 +401,11 @@ $(obj)/modules.order: $(obj-m) FORCE $(obj)/lib.a: $(lib-y) FORCE $(call if_changed,ar) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -quiet_cmd_link_multi-m = AR [M] $@ -cmd_link_multi-m = \ - rm -f $@; \ - $(AR) cDPrsT $@ @$(patsubst %.o,%.mod,$@) -else quiet_cmd_link_multi-m = LD [M] $@ - cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) -endif + cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool) +$(multi-obj-m): objtool-enabled := $(delay-objtool) +$(multi-obj-m): part-of-module := y $(multi-obj-m): %.o: %.mod FORCE $(call if_changed,link_multi-m) $(call multi_depend, $(multi-obj-m), .o, -objs -y -m) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 0453a1904646..f75138385449 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -225,13 +225,6 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ $(addprefix -I,$(DTC_INCLUDE)) \ -undef -D__DTS__ -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -# With CONFIG_LTO_CLANG, .o files in modules might be LLVM bitcode, so we -# need to run LTO to compile them into native code (.lto.o) before further -# processing. -mod-prelink-ext := .prelink -endif - # Useful for describing the dependency of composite objects # Usage: # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index d429e3f9ae1d..51d384a0e4f9 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -9,7 +9,7 @@ __modfinal: include include/config/auto.conf include $(srctree)/scripts/Kbuild.include -# for c_flags and mod-prelink-ext +# for c_flags include $(srctree)/scripts/Makefile.lib # find all modules listed in modules.order @@ -55,9 +55,8 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \ $(cmd); \ printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) - # Re-generate module BTFs if either module's .ko or vmlinux changed -$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o $(if $(CONFIG_MODVERSIONS), %.symver.lds) scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE +$(modules): %.ko: %.o %.mod.o $(if $(CONFIG_MODVERSIONS), %.symver.lds) scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE +$(call if_changed_except,ld_ko_o,vmlinux) ifdef CONFIG_DEBUG_INFO_BTF_MODULES +$(if $(newer-prereqs),$(call cmd,btf_ko)) diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost index 48585c4d04ad..f2ce411acd59 100644 --- a/scripts/Makefile.modpost +++ b/scripts/Makefile.modpost @@ -41,9 +41,6 @@ __modpost: include include/config/auto.conf include $(srctree)/scripts/Kbuild.include -# for mod-prelink-ext -include $(srctree)/scripts/Makefile.lib - MODPOST = scripts/mod/modpost \ $(if $(CONFIG_MODVERSIONS),-m) \ $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \ @@ -118,8 +115,6 @@ $(input-symdump): @echo >&2 ' Modules may not have dependencies or modversions.' @echo >&2 ' You may get many unresolved symbol warnings.' -modules := $(sort $(shell cat $(MODORDER))) - # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined symbols ifneq ($(KBUILD_MODPOST_WARN)$(filter-out $(existing-input-symdump), $(input-symdump)),) MODPOST += -w @@ -128,9 +123,9 @@ endif # Read out modules.order to pass in modpost. # Otherwise, allmodconfig would fail with "Argument list too long". quiet_cmd_modpost = MODPOST $@ - cmd_modpost = sed 's/\.ko$$/$(mod-prelink-ext)\.o/' $< | $(MODPOST) -T - + cmd_modpost = sed 's/ko$$/o/' $< | $(MODPOST) -T - -$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(mod-prelink-ext).o) FORCE +$(output-symdump): $(MODORDER) $(input-symdump) FORCE $(call if_changed,modpost) targets += $(output-symdump) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index ef779ada04c6..d8de62506939 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -2081,10 +2081,6 @@ static char *remove_dot(char *s) size_t m = strspn(s + n + 1, "0123456789"); if (m && (s[n + m] == '.' || s[n + m] == 0)) s[n] = 0; - - /* strip trailing .prelink */ - if (strends(s, ".prelink")) - s[strlen(s) - 8] = '\0'; } return s; } @@ -2108,9 +2104,6 @@ static void read_symbols(const char *modname) /* strip trailing .o */ tmp = NOFAIL(strdup(modname)); tmp[strlen(tmp) - 2] = '\0'; - /* strip trailing .prelink */ - if (strends(tmp, ".prelink")) - tmp[strlen(tmp) - 8] = '\0'; mod = new_module(tmp); if (modversions) -- 2.32.0