Re: [PATCH v2] ftrace: Introduce PERMANENT ftrace_ops flag

[Joe Lawrence]

On 10/15/19 7:23 AM, Miroslav Benes wrote:
> > Hi Miroslav,
> >
> > Maybe we should add a test to verify this new behavior?  See sample
> > version below (lightly tested).  We can add to this one, or patch
> > seperately if you prefer.
>
> Thanks a lot, Joe. It looks nice. I'll include it in v3. One question
> below.
>   
> > -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8--
> >
> >   
> > >From c8c9f22e3816ca4c90ab7e7159d2ce536eaa5fad Mon Sep 17 00:00:00 2001
> > From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> > Date: Mon, 14 Oct 2019 18:25:01 -0400
> > Subject: [PATCH] selftests/livepatch: test interaction with ftrace_enabled
> >
> > Since livepatching depends upon ftrace handlers to implement "patched"
> > functionality, verify that the ftrace_enabled sysctl value interacts
> > with livepatch registration as expected.
> >
> > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> > ---
> >   tools/testing/selftests/livepatch/Makefile    |  3 +-
> >   .../testing/selftests/livepatch/functions.sh  | 18 +++++
> >   .../selftests/livepatch/test-ftrace.sh        | 65 +++++++++++++++++++
> >   3 files changed, 85 insertions(+), 1 deletion(-)
> >   create mode 100755 tools/testing/selftests/livepatch/test-ftrace.sh
> >
> > diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
> > index fd405402c3ff..1886d9d94b88 100644
> > --- a/tools/testing/selftests/livepatch/Makefile
> > +++ b/tools/testing/selftests/livepatch/Makefile
> > @@ -4,6 +4,7 @@ TEST_PROGS_EXTENDED := functions.sh
> >   TEST_PROGS := \
> >   	test-livepatch.sh \
> >   	test-callbacks.sh \
> > -	test-shadow-vars.sh
> > +	test-shadow-vars.sh \
> > +	test-ftrace.sh
> >   
> >   include ../lib.mk
> > diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
> > index 79b0affd21fb..556252efece0 100644
> > --- a/tools/testing/selftests/livepatch/functions.sh
> > +++ b/tools/testing/selftests/livepatch/functions.sh
> > @@ -52,6 +52,24 @@ function set_dynamic_debug() {
> >   		EOF
> >   }
> >   
> > +function push_ftrace_enabled() {
> > +	FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
> > +}
>
> Shouldn't we call push_ftrace_enabled() somewhere at the beginning of the
> test script? set_dynamic_debug() calls its push_dynamic_debug() directly,
> but set_ftrace_enabled() is different, because it is called more than once
> in the script.
>
> One could argue that ftrace_enabled has to be true at the beginning of
> testing anyway, but I think it would be cleaner. Btw, we should probably
> guarantee that ftrace_enabled is true when livepatch selftests are
> invoked.

Ah yes, that occurred to me while creating that piece of the patch. 
Something like setup_test_config() that pushes both ftrace and the 
debugfs, etc. would be cleaner for all scripts.  If you're onboard with 
that idea, I can make that revision.

-- Joe