linux-kernel - Re: [PATCH net-next v2 2/2] selftests/bpf: activate the OP_NE login in range

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Message-ID: <CADxym3a58ALYnJH5HdVZEfgBUeKH3+mH9mHGf6SijxCOzFjD3g@mail.gmail.com>
Date:   Wed, 13 Dec 2023 10:35:53 +0800
From:   Menglong Dong <menglong8.dong@...il.com>
To:     Eduard Zingerman <eddyz87@...il.com>
Cc:     andrii@...nel.org, yonghong.song@...ux.dev, ast@...nel.org,
        daniel@...earbox.net, john.fastabend@...il.com,
        martin.lau@...ux.dev, song@...nel.org, kpsingh@...nel.org,
        sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/2] selftests/bpf: activate the OP_NE login
 in range_cond()

Hello,

On Wed, Dec 13, 2023 at 7:37 AM Eduard Zingerman <eddyz87@...il.com> wrote:
>
> On Tue, 2023-12-12 at 21:10 +0800, Menglong Dong wrote:
> > The edge range checking for the registers is supported by the verifier
> > now, so we can activate the extended login in
> > tools/testing/selftests/bpf/prog_tests/reg_bounds.c/range_cond() to test
> > such logic.
> >
> > Signed-off-by: Menglong Dong <menglong8.dong@...il.com>
> > ---
> >  tools/testing/selftests/bpf/prog_tests/reg_bounds.c | 7 +------
> >  1 file changed, 1 insertion(+), 6 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> > index 0c9abd279e18..49d8d4bafe99 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> > @@ -590,12 +590,7 @@ static void range_cond(enum num_t t, struct range x, struct range y,
> >               *newy = range(t, max_t(t, x.a, y.a), min_t(t, x.b, y.b));
> >               break;
> >       case OP_NE:
> > -             /* generic case, can't derive more information */
> > -             *newx = range(t, x.a, x.b);
> > -             *newy = range(t, y.a, y.b);
> > -             break;
> > -
> > -             /* below extended logic is not supported by verifier just yet */
> > +             /* below logic is supported by the verifier now */
> >               if (x.a == x.b && x.a == y.a) {
> >                       /* X is a constant matching left side of Y */
> >                       *newx = range(t, x.a, x.b);
>
> I think that some crafted tests have to be added.
> Note that reg_bounds only runs a subset of tests during CI
> (controlled by variable SLOW_TESTS).
> By default only randomized and crafted tests are run.
> It appears to me that probability of randomly generating specific
> ranges explored by this series is quite low.

You are right, I'll add some cases to the "crafted_cases" for
this logic.

Thanks!
Menglong Dong