From efcda22aa541bbda827e54302baf9ae4fd44cdf2 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Thu, 18 Sep 2025 19:18:38 -0700 Subject: bpf: compute instructions postorder per subprogram The next patch would require doing postorder traversal of individual subprograms. Facilitate this by moving env->cfg.insn_postorder computation from check_cfg() to a separate pass, as check_cfg() descends into called subprograms (and it needs to, because of merge_callee_effects() logic). env->cfg.insn_postorder is used only by compute_live_registers(), this function does not track cross subprogram dependencies, thus the change does not affect it's operation. Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-5-c3cd27bacc60@gmail.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 93563564bde5..bd87e80f9423 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -665,6 +665,7 @@ struct bpf_subprog_info { /* 'start' has to be the first field otherwise find_subprog() won't work */ u32 start; /* insn idx of function entry point */ u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ + u32 postorder_start; /* The idx to the env->cfg.insn_postorder */ u16 stack_depth; /* max. stack depth used by this function */ u16 stack_extra; /* offsets in range [stack_depth .. fastcall_stack_off) @@ -794,7 +795,10 @@ struct bpf_verifier_env { struct { int *insn_state; int *insn_stack; - /* vector of instruction indexes sorted in post-order */ + /* + * vector of instruction indexes sorted in post-order, grouped by subprogram, + * see bpf_subprog_info->postorder_start. + */ int *insn_postorder; int cur_stack; /* current position in the insn_postorder vector */ -- cgit v1.2.3