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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Subject: [PATCH 09/14] netfilter: nf_tables: add register tracking infrastructure
Date: Sun,  9 Jan 2022 17:11:21 +0100	[thread overview]
Message-ID: <20220109161126.83917-10-pablo@netfilter.org> (raw)
In-Reply-To: <20220109161126.83917-1-pablo@netfilter.org>

This patch adds new infrastructure to skip redundant selector store
operations on the same register to achieve a performance boost from
the packet path.

This is particularly noticeable in pure linear rulesets but it also
helps in rulesets which are already heaving relying in maps to avoid
ruleset linear inspection.

The idea is to keep data of the most recurrent store operations on
register to reuse them with cmp and lookup expressions.

This infrastructure allows for dynamic ruleset updates since the ruleset
blob reduction happens from the kernel.

Userspace still needs to be updated to maximize register utilization to
cooperate to improve register data reuse / reduce number of store on
register operations.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h | 12 ++++++++++++
 net/netfilter/nf_tables_api.c     | 11 +++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 515e5db97e01..1c37ce61daea 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -122,6 +122,16 @@ struct nft_regs {
 	};
 };
 
+struct nft_regs_track {
+	struct {
+		const struct nft_expr		*selector;
+		const struct nft_expr		*bitwise;
+	} regs[NFT_REG32_NUM];
+
+	const struct nft_expr			*cur;
+	const struct nft_expr			*last;
+};
+
 /* Store/load an u8, u16 or u64 integer to/from the u32 data register.
  *
  * Note, when using concatenations, register allocation happens at 32-bit
@@ -886,6 +896,8 @@ struct nft_expr_ops {
 	int				(*validate)(const struct nft_ctx *ctx,
 						    const struct nft_expr *expr,
 						    const struct nft_data **data);
+	bool				(*reduce)(struct nft_regs_track *track,
+						  const struct nft_expr *expr);
 	bool				(*gc)(struct net *net,
 					      const struct nft_expr *expr);
 	int				(*offload)(struct nft_offload_ctx *ctx,
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index af1128fe79e0..eb12fc9b803d 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8259,6 +8259,7 @@ EXPORT_SYMBOL_GPL(nf_tables_trans_destroy_flush_work);
 static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *chain)
 {
 	const struct nft_expr *expr, *last;
+	struct nft_regs_track track = {};
 	unsigned int size, data_size;
 	void *data, *data_boundary;
 	struct nft_rule_dp *prule;
@@ -8298,7 +8299,17 @@ static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *cha
 		if (WARN_ON_ONCE(data > data_boundary))
 			return -ENOMEM;
 
+		size = 0;
+		track.last = last;
 		nft_rule_for_each_expr(expr, last, rule) {
+			track.cur = expr;
+
+			if (expr->ops->reduce &&
+			    expr->ops->reduce(&track, expr)) {
+				expr = track.cur;
+				continue;
+			}
+
 			if (WARN_ON_ONCE(data + expr->ops->size > data_boundary))
 				return -ENOMEM;
 
-- 
2.30.2


  parent reply	other threads:[~2022-01-09 16:11 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-09 16:11 [PATCH nf-next,v3 00/14] nf_tables datapath ruleset blob and register tracking Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 01/14] netfilter: nft_connlimit: move stateful fields out of expression data Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 02/14] netfilter: nft_last: " Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 03/14] netfilter: nft_quota: " Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 04/14] netfilter: nft_numgen: " Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 05/14] netfilter: nft_limit: rename stateful structure Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 06/14] netfilter: nft_limit: move stateful fields out of expression data Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 07/14] netfilter: nf_tables: add rule blob layout Pablo Neira Ayuso
2022-01-10 11:00   ` kernel test robot
2022-01-09 16:11 ` [PATCH 08/14] netfilter: nf_tables: add NFT_REG32_NUM Pablo Neira Ayuso
2022-01-09 16:11 ` Pablo Neira Ayuso [this message]
2022-01-09 16:11 ` [PATCH 10/14] netfilter: nft_payload: track register operations Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 11/14] netfilter: nft_meta: " Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 12/14] netfilter: nft_bitwise: " Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 13/14] netfilter: nft_payload: cancel register tracking after payload update Pablo Neira Ayuso
2022-01-09 16:11 ` [PATCH 14/14] netfilter: nft_meta: cancel register tracking after meta update Pablo Neira Ayuso

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