On Mon, Jun 13, 2022 at 1:50 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> +
> +static bool loop_flag_is_zero(struct bpf_verifier_env *env)
> +{
> + struct bpf_reg_state *regs = cur_regs(env);
> + struct bpf_reg_state *reg = ®s[BPF_REG_4];
> +
> + return register_is_const(reg) && reg->var_off.value == 0;
> +}
Great catch here by Daniel.
It needs mark_chain_precision().
> +
> +static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno)
> +{
> + struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state;
> +
> + if (!state->initialized) {
> + state->initialized = 1;
> + state->fit_for_inline = loop_flag_is_zero(env);
> + state->callback_subprogno = subprogno;
> + return;
> + }
> +
> + if (!state->fit_for_inline)
> + return;
> +
> + state->fit_for_inline =
> + loop_flag_is_zero(env) &&
> + state->callback_subprogno == subprogno;
No need to heavy indent. Up to 100 char is fine.
> +static int optimize_bpf_loop(struct bpf_verifier_env *env)
> +{
> + struct bpf_subprog_info *subprogs = env->subprog_info;
> + int i, cur_subprog = 0, cnt, delta = 0;
> + struct bpf_insn *insn = env->prog->insnsi;
> + int insn_cnt = env->prog->len;
> + u16 stack_depth = subprogs[cur_subprog].stack_depth;
> + u16 stack_depth_extra = 0;
> +
> + for (i = 0; i < insn_cnt; i++, insn++) {
> + struct bpf_loop_inline_state *inline_state =
> + &env->insn_aux_data[i + delta].loop_inline_state;
> +
> + if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) {
> + struct bpf_prog *new_prog;
> +
> + stack_depth_extra = BPF_REG_SIZE * 3;
> + new_prog = inline_bpf_loop(env,
> + i + delta,
> + -(stack_depth + stack_depth_extra),
See the fix that just landed:
https://lore.kernel.org/bpf/20220616162037.535469-2-jakub@xxxxxxxxxxxxxx/
subprogs[cur_subprog].stack_depth may not be a multiple of 8.
But spill slots for r[678] have to be.
We need to round_up(,8) here and
increase stack_depth_extra accordingly.
The rest looks great.
Thank you for working on it!
