Re: [PATCH v2 5/8] modpost: Integrate klp-convert

Joe Lawrence
2019-03-22T18:29:34Z

On 3/22/19 12:37 PM, Joao Moreira wrote:
> On 2019-03-22 11:54, Joe Lawrence wrote:
>> On Fri, Mar 01, 2019 at 11:13:10AM -0300, Joao Moreira wrote:
>>> From: Josh Poimboeuf <jpoimboe@redhat.com>
>>>
>>> Create cmd_klp_convert and hook it into scripts/Makefile.modpost.
>>> cmd_klp_convert invokes klp-convert with the right arguments for the
>>> conversion of unresolved symbols inside a livepatch.
>>>
>>> [khlebnikov:
>>> * save cmd_ld_ko_o into .module.cmd, if_changed_rule doesn't do that
>>> * fix bashisms for debian where /bin/sh is a symlink to /bin/dash
>>> * rename rule_link_module to rule_ld_ko_o, otherwise arg-check inside
>>> if_changed_rule compares cmd_link_module and cmd_ld_ko_o
>>> * check modinfo -F livepatch only if CONFIG_LIVEPATCH is true
>>> ]
>>>
>>> [mbenes:
>>> * remove modinfo call. LIVEPATCH_ in Makefiled
>>> ]
>>>
>>> [jmoreira:
>>> * split up: move the .livepatch file-based scheme for identifying
>>> livepatches to a previous patch, as it was required for correctly
>>> building Symbols.list there.
>>> ]
>>>
>>> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
>>> Signed-off-by: Miroslav Benes <mbenes@suse.cz>
>>> Signed-off-by: Joao Moreira <jmoreira@suse.de>
>>> ---
>>> scripts/Kbuild.include | 4 +++-
>>> scripts/Makefile.modpost | 16 +++++++++++++++-
>>> scripts/mod/modpost.c | 6 +++++-
>>> scripts/mod/modpost.h | 1 +
>>> 4 files changed, 24 insertions(+), 3 deletions(-)
>>>
>>>
>>> [ ... snip ... ]
>>>
>>> diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
>>> index 7d4af0d0accb..da779a185218 100644
>>> --- a/scripts/Makefile.modpost
>>> +++ b/scripts/Makefile.modpost
>>> @@ -125,8 +125,22 @@ quiet_cmd_ld_ko_o = LD [M] $@
>>> -o $@ $(filter-out FORCE,$^) ;
>>> \
>>> $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
>>>
>>> +SLIST = $(objtree)/Symbols.list
>>> +KLP_CONVERT = scripts/livepatch/klp-convert
>>> +quiet_cmd_klp_convert = KLP $@
>>> + cmd_klp_convert = mv $@ $(@:.ko=.klp.o); \
>>> + $(KLP_CONVERT) $(SLIST) $(@:.ko=.klp.o) $@
>>> +
>>> +define rule_ld_ko_o
>>> + $(call cmd,ld_ko_o) $(cmd_ld_ko_o) ; \
>> ^
>> Should there be a ';' semicolon here (and maybe a line-break) between
>> $(call cmd,ld_ko_o) and $(cmd_ld_ko_o)?
>>
>> I didn't see this in my x86_64 VM, but on a ppc64le box, I kept getting
>> really strange build errors that I traced to this line. Without a
>> semicolon, the build was trying to run a make command with a linker
>> command smashed onto the end of it:
>>
>> make -f ./arch/powerpc/Makefile.postlink crypto/xts.ko ld -r -EL -m
>> elf64lppc -T ./scripts/module-common.lds -T
>> ./arch/powerpc/kernel/module.lds --save-restore-funcs --build-id -o
>> crypto/xts.ko crypto/xts.o crypto/xts.mod.o
>>
>>
>> Now, klp-convert looks like will need some ppc64le work as well, as
>> it's
>> confused about .TOC. symbols:
>>
>> CC samples/livepatch/livepatch-annotated-sample.mod.o
>> CC samples/livepatch/livepatch-callbacks-busymod.mod.o
>> CC samples/livepatch/livepatch-callbacks-demo.mod.o
>> CC samples/livepatch/livepatch-callbacks-mod.mod.o
>> CC samples/livepatch/livepatch-sample.mod.o
>> CC samples/livepatch/livepatch-shadow-fix1.mod.o
>> CC samples/livepatch/livepatch-shadow-fix2.mod.o
>> CC samples/livepatch/livepatch-shadow-mod.mod.o
>> LD [M] samples/livepatch/livepatch-annotated-sample.ko
>> LD [M] samples/livepatch/livepatch-callbacks-demo.ko
>> KLP samples/livepatch/livepatch-annotated-sample.ko
>> LD [M] samples/livepatch/livepatch-callbacks-mod.ko
>> KLP samples/livepatch/livepatch-callbacks-demo.ko
>> LD [M] samples/livepatch/livepatch-sample.ko
>> LD [M] samples/livepatch/livepatch-shadow-fix1.ko
>> klp-convert: Define KLP_SYMPOS for the symbol: .TOC.
>> Valid KLP_SYMPOS for symbol .TOC.:
>>
>> [ ... snip listing of all .TOC's across the kernel ... ]
>>
>> but we can save that for another day.
>>
>
> Hi Joe, first of all, thank you for you in-depth review. I did not have
> the time to go through everything yet, and I'll reply properly to the
> other comments soon. Yet, I would like to add a quick note here, since
> you are testing ppc64le. ppc64le is exactly one of the things I have
> been dealing with in the last two days, specifically the .TOC. symbols
> (there is also another bug related to converting relocations of symbols
> with index 0, but this one is architecture agnostic).
>
> If you would like to take a look, the fix is in the latest commit here:
> - https://github.com/SUSE/klp-convert/tree/fixppc64le
>
> I would be very glad if you have any comment or input on that, and I
> guess that if the fix is that simple, I can manage to squash it into v3.

Hi João,

I added https://github.com/SUSE/klp-convert/commit/69b89ef5c366 on top
of my
https://github.com/joe-lawrence/linux/tree/klp-convert-v2-rebase-review
branch with positive results:

(No build klp-convert build complaints)

% uname -r
Linux ibm-p9z-21-lp26.mpc.lab.eng.bos.redhat.com 5.1.0-rc1+ #6 SMP
Thu Mar 21 11:40:24 EDT 2019 ppc64le ppc64le ppc64le GNU/Linux

% insmod samples/livepatch/livepatch-annotated-sample.ko
% grep -o 'livepatch.*' /proc/cmdline
livepatch=1

% ./tools/testing/selftests/livepatch/test-livepatch.sh
TEST: basic function patching ... ok
TEST: multiple livepatches ... ok
TEST: atomic replace livepatch ... ok
TEST: klp-convert symbols ... ok

There may be more ppc64le specifics lurking, but if we could get samples
and self-tests working, I think we'd be in good shape for v3.

-- Joe