Re: [PATCH v2 2/8] kbuild: Support for Symbols.list creation

[Joe Lawrence]

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@xxxxxxx>
>
> ---
>
>    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