From a32014b351662fd67c7e0f807855f527d0834d00 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 22 Jan 2019 22:45:28 -0800 Subject: nfp: bpf: support optimizing dead branches Verifier will now optimize out branches to dead code, implement the replace_insn callback to take advantage of that optimization. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Alexei Starovoitov --- drivers/net/ethernet/netronome/nfp/bpf/main.h | 14 ++++++++++ drivers/net/ethernet/netronome/nfp/bpf/offload.c | 1 + drivers/net/ethernet/netronome/nfp/bpf/verifier.c | 34 +++++++++++++++++++++++ 3 files changed, 49 insertions(+) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h index 07879eee3d46..a33aa7df1979 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/main.h +++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h @@ -412,6 +412,17 @@ static inline bool is_mbpf_div(const struct nfp_insn_meta *meta) return is_mbpf_alu(meta) && mbpf_op(meta) == BPF_DIV; } +static inline bool is_mbpf_cond_jump(const struct nfp_insn_meta *meta) +{ + u8 op; + + if (BPF_CLASS(meta->insn.code) != BPF_JMP) + return false; + + op = BPF_OP(meta->insn.code); + return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL; +} + static inline bool is_mbpf_helper_call(const struct nfp_insn_meta *meta) { struct bpf_insn insn = meta->insn; @@ -520,6 +531,9 @@ int nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx); int nfp_bpf_finalize(struct bpf_verifier_env *env); +int nfp_bpf_opt_replace_insn(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn); + extern const struct bpf_prog_offload_ops nfp_bpf_dev_ops; struct netdev_bpf; diff --git a/drivers/net/ethernet/netronome/nfp/bpf/offload.c b/drivers/net/ethernet/netronome/nfp/bpf/offload.c index c10aab392cf6..877c1b8f95e2 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/offload.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/offload.c @@ -592,6 +592,7 @@ int nfp_net_bpf_offload(struct nfp_net *nn, struct bpf_prog *prog, const struct bpf_prog_offload_ops nfp_bpf_dev_ops = { .insn_hook = nfp_verify_insn, .finalize = nfp_bpf_finalize, + .replace_insn = nfp_bpf_opt_replace_insn, .prepare = nfp_bpf_verifier_prep, .translate = nfp_bpf_translate, .destroy = nfp_bpf_destroy, diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c index 2712ab17d57c..32468e1b1b73 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c @@ -786,3 +786,37 @@ int nfp_bpf_finalize(struct bpf_verifier_env *env) return 0; } + +int nfp_bpf_opt_replace_insn(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn) +{ + struct nfp_prog *nfp_prog = env->prog->aux->offload->dev_priv; + struct bpf_insn_aux_data *aux_data = env->insn_aux_data; + struct nfp_insn_meta *meta = nfp_prog->verifier_meta; + + meta = nfp_bpf_goto_meta(nfp_prog, meta, aux_data[off].orig_idx); + nfp_prog->verifier_meta = meta; + + /* conditional jump to jump conversion */ + if (is_mbpf_cond_jump(meta) && + insn->code == (BPF_JMP | BPF_JA | BPF_K)) { + unsigned int tgt_off; + + tgt_off = off + insn->off + 1; + + if (!insn->off) { + meta->jmp_dst = list_next_entry(meta, l); + meta->jump_neg_op = false; + } else if (meta->jmp_dst->n != aux_data[tgt_off].orig_idx) { + pr_vlog(env, "branch hard wire at %d changes target %d -> %d\n", + off, meta->jmp_dst->n, + aux_data[tgt_off].orig_idx); + return -EINVAL; + } + return 0; + } + + pr_vlog(env, "unsupported instruction replacement %hhx -> %hhx\n", + meta->insn.code, insn->code); + return -EINVAL; +} -- cgit v1.2.3-59-g8ed1b