From 12b16dadbc2406144d408754f96d0f44aa016239 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 15 Dec 2010 19:45:28 +0000 Subject: [PATCH] filter: optimize accesses to ancillary data We can translate pseudo load instructions at filter check time to dedicated instructions to speed up filtering and avoid one switch(). libpcap currently uses SKF_AD_PROTOCOL, but custom filters probably use other ancillary accesses. Note : I made the assertion that ancillary data was always accessed with BPF_LD|BPF_?|BPF_ABS instructions, not with BPF_LD|BPF_?|BPF_IND ones (offset given by K constant, not by K + X register) On x86_64, this saves a few bytes of text : # size net/core/filter.o.* text data bss dec hex filename 4864 0 0 4864 1300 net/core/filter.o.new 4944 0 0 4944 1350 net/core/filter.o.old Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/filter.c | 72 +++++++++++++++++++++++++++++++++---------------------- 1 file changed, 44 insertions(+), 28 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index e8a6ac4..2b27d4e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -85,6 +85,17 @@ enum { BPF_S_JMP_JGT_X, BPF_S_JMP_JSET_K, BPF_S_JMP_JSET_X, + /* Ancillary data */ + BPF_S_ANC_PROTOCOL, + BPF_S_ANC_PKTTYPE, + BPF_S_ANC_IFINDEX, + BPF_S_ANC_NLATTR, + BPF_S_ANC_NLATTR_NEST, + BPF_S_ANC_MARK, + BPF_S_ANC_QUEUE, + BPF_S_ANC_HATYPE, + BPF_S_ANC_RXHASH, + BPF_S_ANC_CPU, }; /* No hurry in this branch */ @@ -107,11 +118,7 @@ static inline void *load_pointer(const struct sk_buff *skb, int k, { if (k >= 0) return skb_header_pointer(skb, k, size, buffer); - else { - if (k >= SKF_AD_OFF) - return NULL; - return __load_pointer(skb, k, size); - } + return __load_pointer(skb, k, size); } /** @@ -269,7 +276,7 @@ load_w: A = get_unaligned_be32(ptr); continue; } - break; + return 0; case BPF_S_LD_H_ABS: k = K; load_h: @@ -278,7 +285,7 @@ load_h: A = get_unaligned_be16(ptr); continue; } - break; + return 0; case BPF_S_LD_B_ABS: k = K; load_b: @@ -287,7 +294,7 @@ load_b: A = *(u8 *)ptr; continue; } - break; + return 0; case BPF_S_LD_W_LEN: A = skb->len; continue; @@ -338,45 +345,35 @@ load_b: case BPF_S_STX: mem[K] = X; continue; - default: - WARN_ON(1); - return 0; - } - - /* - * Handle ancillary data, which are impossible - * (or very difficult) to get parsing packet contents. - */ - switch (k-SKF_AD_OFF) { - case SKF_AD_PROTOCOL: + case BPF_S_ANC_PROTOCOL: A = ntohs(skb->protocol); continue; - case SKF_AD_PKTTYPE: + case BPF_S_ANC_PKTTYPE: A = skb->pkt_type; continue; - case SKF_AD_IFINDEX: + case BPF_S_ANC_IFINDEX: if (!skb->dev) return 0; A = skb->dev->ifindex; continue; - case SKF_AD_MARK: + case BPF_S_ANC_MARK: A = skb->mark; continue; - case SKF_AD_QUEUE: + case BPF_S_ANC_QUEUE: A = skb->queue_mapping; continue; - case SKF_AD_HATYPE: + case BPF_S_ANC_HATYPE: if (!skb->dev) return 0; A = skb->dev->type; continue; - case SKF_AD_RXHASH: + case BPF_S_ANC_RXHASH: A = skb->rxhash; continue; - case SKF_AD_CPU: + case BPF_S_ANC_CPU: A = raw_smp_processor_id(); continue; - case SKF_AD_NLATTR: { + case BPF_S_ANC_NLATTR: { struct nlattr *nla; if (skb_is_nonlinear(skb)) @@ -392,7 +389,7 @@ load_b: A = 0; continue; } - case SKF_AD_NLATTR_NEST: { + case BPF_S_ANC_NLATTR_NEST: { struct nlattr *nla; if (skb_is_nonlinear(skb)) @@ -412,6 +409,7 @@ load_b: continue; } default: + WARN_ON(1); return 0; } } @@ -600,6 +598,24 @@ int sk_chk_filter(struct sock_filter *filter, int flen) pc + ftest->jf + 1 >= flen) return -EINVAL; break; + case BPF_S_LD_W_ABS: + case BPF_S_LD_H_ABS: + case BPF_S_LD_B_ABS: +#define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \ + code = BPF_S_ANC_##CODE; \ + break + switch (ftest->k) { + ANCILLARY(PROTOCOL); + ANCILLARY(PKTTYPE); + ANCILLARY(IFINDEX); + ANCILLARY(NLATTR); + ANCILLARY(NLATTR_NEST); + ANCILLARY(MARK); + ANCILLARY(QUEUE); + ANCILLARY(HATYPE); + ANCILLARY(RXHASH); + ANCILLARY(CPU); + } } ftest->code = code; } -- 2.7.4