On Tue, Mar 26, 2019 at 02:29:47PM +0900, Masahiro Yamada wrote:
> On Tue, Mar 26, 2019 at 1:05 AM Joe Lawrence <joe.lawrence@xxxxxxxxxx> wrote:
> >
> > CC_FLAGS_FTRACE may contain trailing whitespace that interferes with
> > findstring.
> >
> > For example, commit 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on
> > GCC 4.9 and newer") introduced a change such that on my ppc64le box,
> > CC_FLAGS_FTRACE="-pg -mprofile-kernel ". (Note the trailing space.)
> > When cmd_record_mcount is now invoked, findstring fails as the ftrace
> > flags were found at very end of _c_flags, without the trailing space.
> >
> > _c_flags=" ... -pg -mprofile-kernel"
> > CC_FLAGS_FTRACE="-pg -mprofile-kernel "
> > ^
> > findstring is looking for this extra space
> >
> > Remove the redundant whitespaces from CC_FLAGS_FTRACE in
> > cmd_record_mcount to avoid this problem.
> >
> > Fixes: 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on GCC 4.9 and newer").
> > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> > ---
> >
> > Standard disclaimer: I'm not a kbuild expert, but this works around the
> > problem I reported where ftrace and livepatch self-tests were failing as
> > specified object files were not run through the recordmcount.pl script:
> >
> > ppc64le: ftrace self-tests and $(CC_FLAGS_FTRACE) broken?
> > https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-March/187298.html
> >
> > scripts/Makefile.build | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> > index 2554a15ecf2b..74d402b5aa3c 100644
> > --- a/scripts/Makefile.build
> > +++ b/scripts/Makefile.build
> > @@ -199,10 +199,10 @@ sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
> > "$(if $(part-of-module),1,0)" "$(@)";
> > recordmcount_source := $(srctree)/scripts/recordmcount.pl
> > endif # BUILD_C_RECORDMCOUNT
> > -cmd_record_mcount = \
> > - if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
> > - "$(CC_FLAGS_FTRACE)" ]; then \
> > - $(sub_cmd_record_mcount) \
> > +cmd_record_mcount = \
> > + if [ "$(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags))" = \
> > + "$(strip $(CC_FLAGS_FTRACE))" ]; then \
> > + $(sub_cmd_record_mcount) \
> > fi
> > endif # CC_USING_RECORD_MCOUNT
> > endif # CONFIG_FTRACE_MCOUNT_RECORD
> > --
> > 2.20.1
> >
>
>
>
> I do not see a point in using the shell command here
> in the first place.
>
> Instead of adding crappy workarounds,
> I guess the following simple code should work:
>
>
> index 2554a15..5f13021 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -199,11 +199,8 @@ sub_cmd_record_mcount = perl
> $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
> "$(if $(part-of-module),1,0)" "$(@)";
> recordmcount_source := $(srctree)/scripts/recordmcount.pl
> endif # BUILD_C_RECORDMCOUNT
> -cmd_record_mcount = \
> - if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
> - "$(CC_FLAGS_FTRACE)" ]; then \
> - $(sub_cmd_record_mcount) \
> - fi
> +cmd_record_mcount = $(if $(findstring $(CC_FLAGS_FTRACE),$(_c_flags)),\
> + $(sub_cmd_record_mcount))
> endif # CC_USING_RECORD_MCOUNT
> endif # CONFIG_FTRACE_MCOUNT_RECORD
>
Hi Masahiro,
Agreed on the shell command ugliness, however I still think we need to
strip the search pattern here. With your suggestion:
% rm -f kernel/trace/trace_selftest_dynamic.o
% make kernel/trace/trace_selftest_dynamic.o
CALL scripts/checksyscalls.sh
CALL scripts/atomic/check-atomics.sh
CC kernel/trace/trace_selftest_dynamic.o
% eu-readelf --sections kernel/trace/trace_selftest_dynamic.o | grep mcount
(nothing)
Adding it back as, as below, restores those sections and the self tests
work again.
Regards,
-- Joe
-->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8--
>From 6a85e8ecf4179b3e80601a327ec43d8d49f0e3cd Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Date: Tue, 26 Mar 2019 10:50:28 -0400
Subject: [PATCH v2] kbuild: strip whitespace in cmd_record_mcount findstring
CC_FLAGS_FTRACE may contain trailing whitespace that interferes with
findstring.
For example, commit 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on
GCC 4.9 and newer") introduced a change such that on my ppc64le box,
CC_FLAGS_FTRACE="-pg -mprofile-kernel ". (Note the trailing space.)
When cmd_record_mcount is now invoked, findstring fails as the ftrace
flags were found at very end of _c_flags, without the trailing space.
_c_flags=" ... -pg -mprofile-kernel"
CC_FLAGS_FTRACE="-pg -mprofile-kernel "
^
findstring is looking for this extra space
Remove the redundant whitespaces from CC_FLAGS_FTRACE in
cmd_record_mcount to avoid this problem.
Suggested-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> (refactoring)
Fixes: 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on GCC 4.9 and newer").
Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
---
scripts/Makefile.build | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2554a15ecf2b..76ca30cc4791 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -199,11 +199,8 @@ sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
"$(if $(part-of-module),1,0)" "$(@)";
recordmcount_source := $(srctree)/scripts/recordmcount.pl
endif # BUILD_C_RECORDMCOUNT
-cmd_record_mcount = \
- if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
- "$(CC_FLAGS_FTRACE)" ]; then \
- $(sub_cmd_record_mcount) \
- fi
+cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
+ $(sub_cmd_record_mcount))
endif # CC_USING_RECORD_MCOUNT
endif # CONFIG_FTRACE_MCOUNT_RECORD
--
2.20.1
