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

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Date:   Tue, 26 Mar 2019 11:40:55 -0300
From:   Joao Moreira <jmoreira@...e.de>
To:     Miroslav Benes <mbenes@...e.cz>,
        Joe Lawrence <joe.lawrence@...hat.com>
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 3/20/19 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 $< && \ 

-- 

2.16.4


> 
> Miroslav
>