On Fri, Nov 17, 2023 at 1:53 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> On Fri, 2023-11-17 at 11:47 -0500, Andrii Nakryiko wrote:
> > On Wed, Nov 15, 2023 at 9:18 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> > >
> > > A test case to verify that imprecise scalars widening is applied to
> > > callback bodies on repetative iteration.
> >
> > typo: repetitive? repeating? successive? subsequent?
>
> I'll configure spell-checking, I promise.
no worries, I only notice it because gmail highlights it. I was rather
wondering if "repetitive iteration" is the right way to explain this.
>
> [...]
> > > +static int widening_cb(__u32 idx, struct num_context *ctx)
> > > +{
> > > + ++ctx->i;
> > > + return 0;
> > > +}
> > > +
> > > +SEC("?raw_tp")
> > > +__success
> > > +int widening(void *unused)
> > > +{
> > > + struct num_context loop_ctx = { .i = 0, .j = 1 };
> > > +
> > > + bpf_loop(100, widening_cb, &loop_ctx, 0);
> > > + /* loop_ctx.j is not changed during callback iteration,
> > > + * verifier should not apply widening to it.
> > > + */
> > > + return choice_arr[loop_ctx.j];
> >
> > would the test be a bit more interesting if you use loop_ctx.i here?
> > `return choice_arr[loop_ctx.i & 1];` ?
>
> It would force precision for 'loop_ctx.i', precise values are not widened.
ah, right, ok
>
> >
> > > +}
> > > +
>
>
