netfilter: nf_tables: add direct calls for all builtin expressions

With CONFIG_RETPOLINE its faster to add an if (ptr == &foo_func)
check and and use direct calls for all the built-in expressions.

~15% improvement in pathological cases.

checkpatch doesn't like the X macro due to the embedded return statement,
but the macro has a very limited scope so I don't think its a problem.

I would like to avoid bugs of the form
  If (e->ops->eval == (unsigned long)nft_foo_eval)
	 nft_bar_eval();

and open-coded if ()/else if()/else cascade, thus the macro.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 18 insertions, 7 deletions

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index a50500232b0a9..2a00aef7b6d4a 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -124,14 +124,25 @@ static void expr_call_ops_eval(const struct nft_expr *expr,
 			       struct nft_regs *regs,
 			       struct nft_pktinfo *pkt)
 {
+#ifdef CONFIG_RETPOLINE
 	unsigned long e = (unsigned long)expr->ops->eval;
-
-	if (e == (unsigned long)nft_meta_get_eval)
-		nft_meta_get_eval(expr, regs, pkt);
-	else if (e == (unsigned long)nft_lookup_eval)
-		nft_lookup_eval(expr, regs, pkt);
-	else
-		expr->ops->eval(expr, regs, pkt);
+#define X(e, fun) \
+	do { if ((e) == (unsigned long)(fun)) \
+		return fun(expr, regs, pkt); } while (0)
+
+	X(e, nft_payload_eval);
+	X(e, nft_cmp_eval);
+	X(e, nft_meta_get_eval);
+	X(e, nft_lookup_eval);
+	X(e, nft_range_eval);
+	X(e, nft_immediate_eval);
+	X(e, nft_byteorder_eval);
+	X(e, nft_dynset_eval);
+	X(e, nft_rt_get_eval);
+	X(e, nft_bitwise_eval);
+#undef  X
+#endif /* CONFIG_RETPOLINE */
+	expr->ops->eval(expr, regs, pkt);
 }
 
 unsigned int