On Thu, 15 Feb 2024 at 02:01, Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> On Thu, 2024-02-01 at 04:20 +0000, Kumar Kartikeya Dwivedi wrote:
>
> [...]
>
> > +static int mark_exception_reachable_subprogs(struct bpf_verifier_env *env)
> > +{
>
> [...]
>
> > +restart:
> > + subprog_end = subprog[idx + 1].start;
> > + for (; i < subprog_end; i++) {
>
> [...]
>
> > + if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
> > + continue;
> > + /* remember insn and function to return to */
> > + ret_insn[frame] = i + 1;
> > + ret_prog[frame] = idx;
> > +
> > + /* find the callee */
> > + next_insn = i + insn[i].imm + 1;
> > + sidx = find_subprog(env, next_insn);
> > + if (sidx < 0) {
> > + WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", next_insn);
> > + return -EFAULT;
> > + }
>
> For programs like:
>
> foo():
> bar()
> bar()
>
> this algorithm would scan bar() multiple times.
> Would it be possible to remember if subprogram had been scanned
> already and reuse collected .is_throw_reachable info?
>
Good idea, I will look into avoiding this. I think
check_max_stack_depth would also benefit from such a change, and since
I plan on consolidating both to use similar logic, I will make the
change for both.
> [...]
>
>
