From 9a06927e778bc4e805acc8fa03573bbf7e597cc5 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 22 Jan 2019 22:45:29 -0800 Subject: [PATCH] nfp: bpf: support removing dead code Add a verifier callback to the nfp JIT to remove the instructions the verifier deemed to be dead. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Alexei Starovoitov --- drivers/net/ethernet/netronome/nfp/bpf/main.h | 6 ++++- .../net/ethernet/netronome/nfp/bpf/offload.c | 5 ++++ .../net/ethernet/netronome/nfp/bpf/verifier.c | 24 +++++++++++++++++++ 3 files changed, 34 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h index a33aa7df1979..5813c3e13ebe 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/main.h +++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h @@ -247,9 +247,12 @@ struct nfp_bpf_reg_state { #define FLAG_INSN_SKIP_NOOP BIT(3) /* Instruction is optimized out based on preceding instructions */ #define FLAG_INSN_SKIP_PREC_DEPENDENT BIT(4) +/* Instruction is optimized by the verifier */ +#define FLAG_INSN_SKIP_VERIFIER_OPT BIT(5) #define FLAG_INSN_SKIP_MASK (FLAG_INSN_SKIP_NOOP | \ - FLAG_INSN_SKIP_PREC_DEPENDENT) + FLAG_INSN_SKIP_PREC_DEPENDENT | \ + FLAG_INSN_SKIP_VERIFIER_OPT) /** * struct nfp_insn_meta - BPF instruction wrapper @@ -533,6 +536,7 @@ 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); +int nfp_bpf_opt_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); extern const struct bpf_prog_offload_ops nfp_bpf_dev_ops; diff --git a/drivers/net/ethernet/netronome/nfp/bpf/offload.c b/drivers/net/ethernet/netronome/nfp/bpf/offload.c index 877c1b8f95e2..55c7dbf8b421 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/offload.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/offload.c @@ -220,6 +220,10 @@ static int nfp_bpf_translate(struct bpf_prog *prog) unsigned int max_instr; int err; + /* We depend on dead code elimination succeeding */ + if (prog->aux->offload->opt_failed) + return -EINVAL; + max_instr = nn_readw(nn, NFP_NET_CFG_BPF_MAX_LEN); nfp_prog->__prog_alloc_len = max_instr * sizeof(u64); @@ -593,6 +597,7 @@ 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, + .remove_insns = nfp_bpf_opt_remove_insns, .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 32468e1b1b73..36f56eb4cbe2 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c @@ -820,3 +820,27 @@ int nfp_bpf_opt_replace_insn(struct bpf_verifier_env *env, u32 off, meta->insn.code, insn->code); return -EINVAL; } + +int nfp_bpf_opt_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) +{ + 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; + unsigned int i; + + meta = nfp_bpf_goto_meta(nfp_prog, meta, aux_data[off].orig_idx); + + for (i = 0; i < cnt; i++) { + if (WARN_ON_ONCE(&meta->l == &nfp_prog->insns)) + return -EINVAL; + + /* doesn't count if it already has the flag */ + if (meta->flags & FLAG_INSN_SKIP_VERIFIER_OPT) + i--; + + meta->flags |= FLAG_INSN_SKIP_VERIFIER_OPT; + meta = list_next_entry(meta, l); + } + + return 0; +} -- 2.30.2