From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: alexei.starovoitov@gmail.com, daniel@iogearbox.net
Cc: yhs@fb.com, netdev@vger.kernel.org, oss-drivers@netronome.com,
kafai@fb.com, Jakub Kicinski <jakub.kicinski@netronome.com>
Subject: [PATCH bpf-next v5 11/12] nfp: bpf: support optimizing dead branches
Date: Tue, 22 Jan 2019 22:45:28 -0800 [thread overview]
Message-ID: <20190123064529.13518-12-jakub.kicinski@netronome.com> (raw)
In-Reply-To: <20190123064529.13518-1-jakub.kicinski@netronome.com>
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 <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
---
drivers/net/ethernet/netronome/nfp/bpf/main.h | 14 ++++++++
.../net/ethernet/netronome/nfp/bpf/offload.c | 1 +
.../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;
+}
--
2.19.2
next prev parent reply other threads:[~2019-01-23 6:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-23 6:45 [PATCH bpf-next v5 00/12] bpf: dead code elimination Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 01/12] bpf: change parameters of call/branch offset adjustment Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 02/12] bpf: verifier: hard wire branches to dead code Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 03/12] bpf: verifier: remove " Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 04/12] bpf: verifier: remove unconditional branches by 0 Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 05/12] selftests: bpf: add tests for dead code removal Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 06/12] bpf: verifier: record original instruction index Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 07/12] bpf: notify offload JITs about optimizations Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 08/12] nfp: bpf: don't use instruction number for jump target Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 09/12] nfp: bpf: split up the skip flag Jakub Kicinski
2019-01-23 6:45 ` [PATCH bpf-next v5 10/12] nfp: bpf: save original program length Jakub Kicinski
2019-01-23 6:45 ` Jakub Kicinski [this message]
2019-01-23 6:45 ` [PATCH bpf-next v5 12/12] nfp: bpf: support removing dead code Jakub Kicinski
2019-01-24 1:42 ` [PATCH bpf-next v5 00/12] bpf: dead code elimination Alexei Starovoitov
-- strict thread matches above, loose matches on Subject: below --
2019-01-19 18:06 [PATCH bpf-next v4 " Jakub Kicinski
2019-01-19 18:06 ` [PATCH bpf-next v5 11/12] nfp: bpf: support optimizing dead branches Jakub Kicinski
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