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Date: Wed, 28 Mar 2018 17:48:27 -0700
From: Jakub Kicinski <jakub.kicinski@...ronome.com>
To: alexei.starovoitov@...il.com, daniel@...earbox.net
Cc: netdev@...r.kernel.org, oss-drivers@...ronome.com,
Jan Gossens <jan.gossens@...h-aachen.de>,
Jiong Wang <jiong.wang@...ronome.com>
Subject: [PATCH bpf-next 03/14] nfp: bpf: detect packet reads could be cached, enable the optimisation
From: Jiong Wang <jiong.wang@...ronome.com>
This patch is the front end of this optimisation, it detects and marks
those packet reads that could be cached. Then the optimisation "backend"
will be activated automatically.
Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
drivers/net/ethernet/netronome/nfp/bpf/jit.c | 115 ++++++++++++++++++++++++++
drivers/net/ethernet/netronome/nfp/bpf/main.h | 30 +++++++
2 files changed, 145 insertions(+)
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 38ed2f72a4b0..0701590e8302 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -2964,6 +2964,120 @@ static void nfp_bpf_opt_ldst_gather(struct nfp_prog *nfp_prog)
}
}
+static void nfp_bpf_opt_pkt_cache(struct nfp_prog *nfp_prog)
+{
+ struct nfp_insn_meta *meta, *range_node = NULL;
+ s16 range_start = 0, range_end = 0;
+ bool cache_avail = false;
+ struct bpf_insn *insn;
+ s32 range_ptr_off = 0;
+ u32 range_ptr_id = 0;
+
+ list_for_each_entry(meta, &nfp_prog->insns, l) {
+ if (meta->flags & FLAG_INSN_IS_JUMP_DST)
+ cache_avail = false;
+
+ if (meta->skip)
+ continue;
+
+ insn = &meta->insn;
+
+ if (is_mbpf_store_pkt(meta) ||
+ insn->code == (BPF_JMP | BPF_CALL) ||
+ is_mbpf_classic_store_pkt(meta) ||
+ is_mbpf_classic_load(meta)) {
+ cache_avail = false;
+ continue;
+ }
+
+ if (!is_mbpf_load(meta))
+ continue;
+
+ if (meta->ptr.type != PTR_TO_PACKET || meta->ldst_gather_len) {
+ cache_avail = false;
+ continue;
+ }
+
+ if (!cache_avail) {
+ cache_avail = true;
+ if (range_node)
+ goto end_current_then_start_new;
+ goto start_new;
+ }
+
+ /* Check ID to make sure two reads share the same
+ * variable offset against PTR_TO_PACKET, and check OFF
+ * to make sure they also share the same constant
+ * offset.
+ *
+ * OFFs don't really need to be the same, because they
+ * are the constant offsets against PTR_TO_PACKET, so
+ * for different OFFs, we could canonicalize them to
+ * offsets against original packet pointer. We don't
+ * support this.
+ */
+ if (meta->ptr.id == range_ptr_id &&
+ meta->ptr.off == range_ptr_off) {
+ s16 new_start = range_start;
+ s16 end, off = insn->off;
+ s16 new_end = range_end;
+ bool changed = false;
+
+ if (off < range_start) {
+ new_start = off;
+ changed = true;
+ }
+
+ end = off + BPF_LDST_BYTES(insn);
+ if (end > range_end) {
+ new_end = end;
+ changed = true;
+ }
+
+ if (!changed)
+ continue;
+
+ if (new_end - new_start <= 64) {
+ /* Install new range. */
+ range_start = new_start;
+ range_end = new_end;
+ continue;
+ }
+ }
+
+end_current_then_start_new:
+ range_node->pkt_cache.range_start = range_start;
+ range_node->pkt_cache.range_end = range_end;
+start_new:
+ range_node = meta;
+ range_node->pkt_cache.do_init = true;
+ range_ptr_id = range_node->ptr.id;
+ range_ptr_off = range_node->ptr.off;
+ range_start = insn->off;
+ range_end = insn->off + BPF_LDST_BYTES(insn);
+ }
+
+ if (range_node) {
+ range_node->pkt_cache.range_start = range_start;
+ range_node->pkt_cache.range_end = range_end;
+ }
+
+ list_for_each_entry(meta, &nfp_prog->insns, l) {
+ if (meta->skip)
+ continue;
+
+ if (is_mbpf_load_pkt(meta) && !meta->ldst_gather_len) {
+ if (meta->pkt_cache.do_init) {
+ range_start = meta->pkt_cache.range_start;
+ range_end = meta->pkt_cache.range_end;
+ } else {
+ meta->pkt_cache.range_start = range_start;
+ meta->pkt_cache.range_end = range_end;
+ }
+ }
+ }
+}
+
static int nfp_bpf_optimize(struct nfp_prog *nfp_prog)
{
nfp_bpf_opt_reg_init(nfp_prog);
@@ -2971,6 +3085,7 @@ static int nfp_bpf_optimize(struct nfp_prog *nfp_prog)
nfp_bpf_opt_ld_mask(nfp_prog);
nfp_bpf_opt_ld_shift(nfp_prog);
nfp_bpf_opt_ldst_gather(nfp_prog);
+ nfp_bpf_opt_pkt_cache(nfp_prog);
return 0;
}
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 861211e27ea6..c220ac5a734a 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -278,6 +278,36 @@ static inline bool is_mbpf_store(const struct nfp_insn_meta *meta)
return (meta->insn.code & ~BPF_SIZE_MASK) == (BPF_STX | BPF_MEM);
}
+static inline bool is_mbpf_load_pkt(const struct nfp_insn_meta *meta)
+{
+ return is_mbpf_load(meta) && meta->ptr.type == PTR_TO_PACKET;
+}
+
+static inline bool is_mbpf_store_pkt(const struct nfp_insn_meta *meta)
+{
+ return is_mbpf_store(meta) && meta->ptr.type == PTR_TO_PACKET;
+}
+
+static inline bool is_mbpf_classic_load(const struct nfp_insn_meta *meta)
+{
+ u8 code = meta->insn.code;
+
+ return BPF_CLASS(code) == BPF_LD &&
+ (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND);
+}
+
+static inline bool is_mbpf_classic_store(const struct nfp_insn_meta *meta)
+{
+ u8 code = meta->insn.code;
+
+ return BPF_CLASS(code) == BPF_ST && BPF_MODE(code) == BPF_MEM;
+}
+
+static inline bool is_mbpf_classic_store_pkt(const struct nfp_insn_meta *meta)
+{
+ return is_mbpf_classic_store(meta) && meta->ptr.type == PTR_TO_PACKET;
+}
+
/**
* struct nfp_prog - nfp BPF program
* @bpf: backpointer to the bpf app priv structure
--
2.16.2
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