Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434AbdH2TCW (ORCPT ); Tue, 29 Aug 2017 15:02:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:37094 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751186AbdH2TCT (ORCPT ); Tue, 29 Aug 2017 15:02:19 -0400 From: Joao Moreira To: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Cc: mbenes@suse.cz, mmarek@suse.cz, pmladek@suse.com, jikos@suse.cz, nstange@suse.de, jroedel@suse.de, matz@suse.de, jpoimboe@redhat.com, khlebnikov@yandex-team.ru, jeyu@kernel.org, jmoreira@suse.de Subject: [PATCH 2/8] kbuild: Support for Symbols.list creation Date: Tue, 29 Aug 2017 16:01:34 -0300 Message-Id: <20170829190140.401-3-jmoreira@suse.de> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20170829190140.401-1-jmoreira@suse.de> References: <20170829190140.401-1-jmoreira@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6413 Lines: 157 For automatic resolution of livepatch relocations, a file called Symbols.list is used. This file maps symbols within every compiled kernel object allowing the identification of symbols whose name is unique, thus relocation can be automatically inferred, or providing information that helps developers when code annotation is required for solving the matter. Add support for creating Symbols.list in the main Makefile. First, ensure that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required to achieve a complete Symbols.list file). Define the command to build Symbols.list (cmd_klp_map) and hook it in the modules rule. As it is undesirable to have symbols from livepatch objects inside Symbols.list, make livepatches discernible by modifying scripts/Makefile.build to create a .livepatch file for each livepatch in $(MODVERDIR). This file is then used by cmd_klp_map to identify and bypass livepatches. For identifying livepatches during the build process, a flag variable LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This way, set this flag for the livepatch sample Makefile in samples/livepatch/Makefile. Finally, Add a clean rule to ensure that Symbols.list is removed during clean. Notes: To achieve a correct Symbols.list file, all kernel objects must be considered, thus, its construction require these objects to be priorly built. On the other hand, invoking scripts/Makefile.modpost without having a complete Symbols.list in place would occasionally lead to in-tree livepatches being post-processed incorrectly. To prevent this from becoming a circular dependency, the construction of Symbols.list uses non-post-processed kernel objects and such does not cause harm as the symbols normally referenced from within livepatches are visible at this stage. Also due to these requirements, the spot in-between modules compilation and the invocation of scripts/Makefile.modpost was picked for hooking cmd_klp_map. The approach based on .livepatch files was proposed as an alternative to using MODULE_INFO statementes. This approach was originally proposed by Miroslav Benes as a workaround for identifying livepathces without depending on modinfo during the modpost stage. It was moved to this patch as the approach also shown to be useful while building Symbols.list. Signed-off-by: Joao Moreira --- .gitignore | 1 + Makefile | 27 ++++++++++++++++++++++++--- samples/livepatch/Makefile | 1 + scripts/Makefile.build | 6 ++++++ 4 files changed, 32 insertions(+), 3 deletions(-) diff --git a/.gitignore b/.gitignore index 0c39aa20b6ba..e6a67517a3bc 100644 --- a/.gitignore +++ b/.gitignore @@ -39,6 +39,7 @@ Module.symvers *.dwo *.su *.c.[012]*.* +Symbols.list # # Top-level generic files diff --git a/Makefile b/Makefile index e40c471abe29..e1d315e585d8 100644 --- a/Makefile +++ b/Makefile @@ -320,10 +320,13 @@ KBUILD_BUILTIN := 1 # If we have only "make modules", don't compile built-in objects. # When we're building modules with modversions, we need to consider # the built-in objects during the descend as well, in order to -# make sure the checksums are up to date before we record them. +# make sure the checksums are up to date before we record them. The +# same applies for building livepatches, as built-in objects may hold +# symbols which are referenced from livepatches and are required by +# klp-convert post-processing tool for resolving these cases. ifeq ($(MAKECMDGOALS),modules) - KBUILD_BUILTIN := $(if $(CONFIG_MODVERSIONS),1) + KBUILD_BUILTIN := $(if $(or $(CONFIG_MODVERSIONS), $(CONFIG_LIVEPATCH)),1) endif # If we have "make modules", compile modules @@ -1207,9 +1210,24 @@ all: modules # duplicate lines in modules.order files. Those are removed # using awk while concatenating to the final file. +quiet_cmd_klp_map = LIVEPATCH Symbols.list +SLIST = $(objtree)/Symbols.list + +define cmd_klp_map + $(shell echo "*vmlinux" > $(SLIST)) \ + $(shell nm -f posix $(objtree)/vmlinux | cut -d\ -f1 >> $(SLIST)) \ + $(foreach m, $(wildcard $(MODVERDIR)/*.mod), \ + $(eval mod = $(patsubst %.ko,%.o,$(shell head -n1 $(m)))) \ + $(if $(wildcard $(MODVERDIR)/$(shell basename -s .o $(mod)).livepatch),,\ + $(eval fmod = $(subst $(quote),_,$(subst -,_,$(mod)))) \ + $(shell echo "*$(shell basename -s .o $(fmod))" >> $(SLIST)) \ + $(shell nm -f posix $(mod) | cut -d\ -f1 >> $(SLIST)))) +endef + PHONY += modules modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin $(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order + $(if $(CONFIG_LIVEPATCH), $(call cmd,klp_map)) @$(kecho) ' Building modules, stage 2.'; $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modbuild @@ -1306,7 +1324,10 @@ vmlinuxclean: $(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean $(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean) -clean: archclean vmlinuxclean +klpclean: + $(Q) rm -f $(objtree)/Symbols.list + +clean: archclean vmlinuxclean klpclean # mrproper - Delete all generated files, including .config # diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile index 10319d7ea0b1..955e7ac12d2b 100644 --- a/samples/livepatch/Makefile +++ b/samples/livepatch/Makefile @@ -1 +1,2 @@ +LIVEPATCH_livepatch-sample.o := y obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-sample.o diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 733e044fff8b..d0c32a50cce7 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -276,6 +276,11 @@ objtool_obj = $(if $(patsubst y%,, \ endif # SKIP_STACK_VALIDATION endif # CONFIG_STACK_VALIDATION +ifdef CONFIG_LIVEPATCH +cmd_livepatch = $(if $(LIVEPATCH_$(basetarget).o), \ + $(shell touch $(MODVERDIR)/$(basetarget).livepatch)) +endif + define rule_cc_o_c $(call echo-cmd,checksrc) $(cmd_checksrc) \ $(call cmd_and_fixdep,cc_o_c) \ @@ -309,6 +314,7 @@ $(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) F $(call if_changed_rule,cc_o_c) @{ echo $(@:.o=.ko); echo $@; \ $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod) + $(call cmd_livepatch) quiet_cmd_cc_lst_c = MKLST $@ cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \ -- 2.12.0