On Mon, 2024-02-19 at 16:25 -0800, Yonghong Song wrote:
> On 2/16/24 6:27 AM, Eduard Zingerman wrote:
> > On Wed, 2024-02-14 at 09:42 -0800, Yonghong Song wrote:
> >
> > > > .------------------------------------- Checkpoint / State name
> > > > | .-------------------------------- Code point number
> > > > | | .---------------------------- Stack state {ctx.a,ctx.b,ctx.c}
> > > > | | | .------------------- Callback depth in frame #0
> > > > v v v v
> > > > 1 - (0) {7P,7P,7},depth=0
> > > > 2 - (3) {7P,7P,7},depth=1
> > > > 3 - (0) {7P,7P,42},depth=1
> > > > (a) - (3) {7P,7,42},depth=2
> > > > 4 - (0) {7P,7,42},depth=2 loop terminates because of depth limit
> > > > 5 - (4) {7P,7,42},depth=0 predicted false, ctx.a marked precise
> > > > 6 - (6) exit
> > > > 7 - (2) {7P,7,42},depth=2
> > > > 8 - (0) {7P,42,42},depth=2 loop terminates because of depth limit
> > > > 9 - (4) {7P,42,42},depth=0 predicted false, ctx.a marked precise
> > > > 10 - (6) exit
> > > > (b) - (1) {7P,7P,42},depth=2
> > > > 11 - (0) {42P,7P,42},depth=2 loop terminates because of depth limit
> > > > 12 - (4) {42P,7P,42},depth=0 predicted false, ctx.{a,b} marked precise
> > > > 13 - (6) exit
> > > > 14 - (2) {7P,7,7},depth=1
> > > > 15 - (0) {7P,42,7},depth=1 considered safe, pruned using checkpoint (a)
> > > > (c) - (1) {7P,7P,7},depth=1 considered safe, pruned using checkpoint (b)
> > > For the above line
> > > (c) - (1) {7P,7P,7},depth=1 considered safe, pruned using checkpoint (b)
> > > I would change to
> > > (c) - (1) {7P,7P,7},depth=1
> > > - (0) {42P, 7P, 7},depth = 1 considered safe, pruned using checkpoint (11)
> > At that point:
> > - there is a checkpoint at (1) with state {7P,7P,42}
> > - verifier is at (1) in state {7,7,7}
> > Thus, verifier won't proceed to (0) because {7,7,7} is states_equal to {7P,7P,42}.
>
> Okay, I think the above example has BPF_F_TEST_STATE_FREQ set as in Patch 3. It will
> be great if you can explicitly mention this (BPF_F_TEST_STATE_FREQ) in the commit message.
Will do.
[...]
> But then for
> 14 - (2) {7P,7,7},depth=1
> 15 - (0) {7P,42,7},depth=1 considered safe, pruned using checkpoint (a)
> The state
> 14 - (2) {7P,7,7},depth=1
> will have state equal to
> 7 - (2) {7P,7,42},depth=2
> right?
I think you are correct.
