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Date: Tue, 26 Mar 2019 12:15:28 -0400 From: Joe Lawrence <joe.lawrence@...hat.com> To: Joao Moreira <jmoreira@...e.de>, Miroslav Benes <mbenes@...e.cz> Cc: live-patching@...r.kernel.org, pmladek@...e.cz, jikos@...e.cz, nstange@...e.de, jpoimboe@...hat.com, khlebnikov@...dex-team.ru, jeyu@...nel.org, matz@...e.de, linux-kernel@...r.kernel.org, yamada.masahiro@...ionext.com, linux-kbuild@...r.kernel.org, michal.lkml@...kovi.net Subject: Re: [PATCH v2 2/8] kbuild: Support for Symbols.list creation On 3/26/19 10:40 AM, Joao Moreira wrote: > > > On 3/20/19 4:08 PM, Miroslav Benes wrote: >>>> diff --git a/scripts/Makefile.build b/scripts/Makefile.build >>>> index fd03d60f6c5a..1e28ad21314c 100644 >>>> --- a/scripts/Makefile.build >>>> +++ b/scripts/Makefile.build >>>> @@ -247,6 +247,11 @@ cmd_gen_ksymdeps = \ >>>> $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd >>>> endif >>>> >>>> +ifdef CONFIG_LIVEPATCH >>>> +cmd_livepatch = $(if $(LIVEPATCH_$(basetarget).o), \ >>>> + $(shell touch $(MODVERDIR)/$(basetarget).livepatch)) >>>> +endif >>>> + >>>> define rule_cc_o_c >>>> $(call cmd,checksrc) >>>> $(call cmd_and_fixdep,cc_o_c) >>>> @@ -283,6 +288,7 @@ $(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) 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 $< && \ >>> >>> Since cmd_livepatch is only called for single-used-m, does this mean >>> that we can only klp-convert single object file livepatch modules? >>> >>> I stumbled upon this when trying to create a self-test module that >>> incorporated two object files. I tried adding a $(call cmd_livepatch) >>> in the recipe for $(obj)/%.o, but that didn't help. My kbuild foo >>> wasn't good enough to figure this one out. >> >> I looked at my original code and it is a bit different there. I placed it >> under rule_cc_o_c right after objtool command. If I remember correctly >> this is the correct recipe for .c->.o. Unfortunately I forgot the details >> and there is of course nothing about it in my notes. >> >> Does it help? >> >> Joao, is there a reason you moved it elsewhere? > > Hi, > > Unfortunately I can't remember why the chunk was moved to where it is in > this version of the patch, sorry. Yet, I did try to move this into the > rule cc_o_c and it seemed to work with not damage. > > Joe, would you kindly verify and squash properly the patch below, which > places cmd_livepatch in rule_cc_o_c? > > Thank you. > > Subject: [PATCH] Move cmd_klp_convert to the right place > > > > Signed-off-by: Joao Moreira <jmoreira@...e.de> > > --- > > scripts/Makefile.build | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index 1e28ad21314c..5f66106a47d6 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -260,6 +260,7 @@ define rule_cc_o_c > $(call cmd,objtool) > $(call cmd,modversions_c) > $(call cmd,record_mcount) > + $(call cmd,livepatch) > endef > > define rule_as_o_S > @@ -288,7 +289,6 @@ $(single-used-m): $(obj)/%.o: $(src)/%.c > $(recordmcount_source) $(objtool_dep) 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 $< && \ Hi Joao, This change seems to work okay for (again) single object modules, but I'm having issues with multi-object modules. Here are my sources: % head -n100 * ==> Makefile <== KDIR := /lib/modules/$(shell uname -r)/build PWD := $(shell pwd) LIVEPATCH_test_mod_a.o := y LIVEPATCH_test_mod_b.o := y obj-m += test_mod.o test_mod-y := \ test_mod_a.o \ test_mod_b.o default: $(MAKE) -C $(KDIR) M=$(PWD) clean: @rm -rf .tmp_versions/ @rm -f .*.cmd *.o *.mod.* *.ko modules.order Module.symvers ==> test_mod_a.c <== #include <linux/module.h> __used static void function(void) { } MODULE_LICENSE("GPL"); ==> test_mod_b.c <== __used static void function(void) { } But when I build, I don't see klp-convert invoked for any of the object files: % make make -C /lib/modules/5.0.0+/build M=/home/cloud-user/klp-convert-modtest make[1]: Entering directory '/home/cloud-user/disk/linux' CC [M] /home/cloud-user/klp-convert-modtest/test_mod_a.o CC [M] /home/cloud-user/klp-convert-modtest/test_mod_b.o LD [M] /home/cloud-user/klp-convert-modtest/test_mod.o Building modules, stage 2. MODPOST 1 modules CC /home/cloud-user/klp-convert-modtest/test_mod.mod.o LD [M] /home/cloud-user/klp-convert-modtest/test_mod.ko make[1]: Leaving directory '/home/cloud-user/disk/linux' However, if I modify the Makefile to build test_mod_a.o into its own module, I see "KLP /home/cloud-user/klp-convert-modtest/test_mod_a.ko" in the build output. -- Joe
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