diff options
author | David S. Miller | 2018-12-15 13:23:03 -0800 |
---|---|---|
committer | David S. Miller | 2018-12-15 13:23:03 -0800 |
commit | bedf3b332034c82af4f15ff6afa90ec5aa7cfc84 (patch) | |
tree | e7a50ebb64a47a9a1f06f6ea82efe95dadf6a661 | |
parent | 35e07d23473972b8876f98bcfc631ebcf779e870 (diff) | |
parent | 4f24ed77dec9b067d08f7958a287cbf48665f35e (diff) |
Merge branch 'net-mitigate-retpoline-overhead'
Paolo Abeni says:
====================
net: mitigate retpoline overhead
The spectre v2 counter-measures, aka retpolines, are a source of measurable
overhead[1]. We can partially address that when the function pointer refers to
a builtin symbol resorting to a list of tests vs well-known builtin function and
direct calls.
Experimental results show that replacing a single indirect call via
retpoline with several branches and a direct call gives performance gains
even when multiple branches are added - 5 or more, as reported in [2].
This may lead to some uglification around the indirect calls. In netconf 2018
Eric Dumazet described a technique to hide the most relevant part of the needed
boilerplate with some macro help.
This series is a [re-]implementation of such idea, exposing the introduced
helpers in a new header file. They are later leveraged to avoid the indirect
call overhead in the GRO path, when possible.
Overall this gives > 10% performance improvement for UDP GRO benchmark and
smaller but measurable for TCP syn flood.
The added infra can be used in follow-up patches to cope with retpoline overhead
in other points of the networking stack (e.g. at the qdisc layer) and possibly
even in other subsystems.
v2 -> v3:
- fix build error with CONFIG_IPV6=m
v1 -> v2:
- list explicitly the builtin function names in INDIRECT_CALL_*(),
as suggested by Ed Cree
- expand the recipients list
rfc -> v1:
- use branch prediction hints, as suggested by Eric
[1] http://vger.kernel.org/netconf2018_files/PaoloAbeni_netconf2018.pdf
[2] https://linuxplumbersconf.org/event/2/contributions/99/attachments/98/117/lpc18_paper_af_xdp_perf-v2.pdf
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | include/linux/indirect_call_wrapper.h | 51 | ||||
-rw-r--r-- | include/net/inet_common.h | 9 | ||||
-rw-r--r-- | net/core/dev.c | 15 | ||||
-rw-r--r-- | net/ipv4/af_inet.c | 13 | ||||
-rw-r--r-- | net/ipv4/tcp_offload.c | 6 | ||||
-rw-r--r-- | net/ipv4/udp_offload.c | 15 | ||||
-rw-r--r-- | net/ipv6/ip6_offload.c | 35 | ||||
-rw-r--r-- | net/ipv6/tcpv6_offload.c | 7 | ||||
-rw-r--r-- | net/ipv6/udp_offload.c | 7 |
9 files changed, 136 insertions, 22 deletions
diff --git a/include/linux/indirect_call_wrapper.h b/include/linux/indirect_call_wrapper.h new file mode 100644 index 000000000000..7c8b7f4948af --- /dev/null +++ b/include/linux/indirect_call_wrapper.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_INDIRECT_CALL_WRAPPER_H +#define _LINUX_INDIRECT_CALL_WRAPPER_H + +#ifdef CONFIG_RETPOLINE + +/* + * INDIRECT_CALL_$NR - wrapper for indirect calls with $NR known builtin + * @f: function pointer + * @f$NR: builtin functions names, up to $NR of them + * @__VA_ARGS__: arguments for @f + * + * Avoid retpoline overhead for known builtin, checking @f vs each of them and + * eventually invoking directly the builtin function. The functions are check + * in the given order. Fallback to the indirect call. + */ +#define INDIRECT_CALL_1(f, f1, ...) \ + ({ \ + likely(f == f1) ? f1(__VA_ARGS__) : f(__VA_ARGS__); \ + }) +#define INDIRECT_CALL_2(f, f2, f1, ...) \ + ({ \ + likely(f == f2) ? f2(__VA_ARGS__) : \ + INDIRECT_CALL_1(f, f1, __VA_ARGS__); \ + }) + +#define INDIRECT_CALLABLE_DECLARE(f) f +#define INDIRECT_CALLABLE_SCOPE + +#else +#define INDIRECT_CALL_1(f, name, ...) f(__VA_ARGS__) +#define INDIRECT_CALL_2(f, name, ...) f(__VA_ARGS__) +#define INDIRECT_CALLABLE_DECLARE(f) +#define INDIRECT_CALLABLE_SCOPE static +#endif + +/* + * We can use INDIRECT_CALL_$NR for ipv6 related functions only if ipv6 is + * builtin, this macro simplify dealing with indirect calls with only ipv4/ipv6 + * alternatives + */ +#if IS_BUILTIN(CONFIG_IPV6) +#define INDIRECT_CALL_INET(f, f2, f1, ...) \ + INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__) +#elif IS_ENABLED(CONFIG_INET) +#define INDIRECT_CALL_INET(f, f2, f1, ...) INDIRECT_CALL_1(f, f1, __VA_ARGS__) +#else +#define INDIRECT_CALL_INET(f, f2, f1, ...) f(__VA_ARGS__) +#endif + +#endif diff --git a/include/net/inet_common.h b/include/net/inet_common.h index 3ca969cbd161..975901a95c0f 100644 --- a/include/net/inet_common.h +++ b/include/net/inet_common.h @@ -2,6 +2,8 @@ #ifndef _INET_COMMON_H #define _INET_COMMON_H +#include <linux/indirect_call_wrapper.h> + extern const struct proto_ops inet_stream_ops; extern const struct proto_ops inet_dgram_ops; @@ -54,4 +56,11 @@ static inline void inet_ctl_sock_destroy(struct sock *sk) sock_release(sk->sk_socket); } +#define indirect_call_gro_receive(f2, f1, cb, head, skb) \ +({ \ + unlikely(gro_recursion_inc_test(skb)) ? \ + NAPI_GRO_CB(skb)->flush |= 1, NULL : \ + INDIRECT_CALL_2(cb, f2, f1, head, skb); \ +}) + #endif diff --git a/net/core/dev.c b/net/core/dev.c index ed9aa4a91f1f..1b5a4410be0e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -145,6 +145,7 @@ #include <linux/sctp.h> #include <net/udp_tunnel.h> #include <linux/net_namespace.h> +#include <linux/indirect_call_wrapper.h> #include "net-sysfs.h" @@ -5338,6 +5339,8 @@ static void flush_all_backlogs(void) put_online_cpus(); } +INDIRECT_CALLABLE_DECLARE(int inet_gro_complete(struct sk_buff *, int)); +INDIRECT_CALLABLE_DECLARE(int ipv6_gro_complete(struct sk_buff *, int)); static int napi_gro_complete(struct sk_buff *skb) { struct packet_offload *ptype; @@ -5357,7 +5360,9 @@ static int napi_gro_complete(struct sk_buff *skb) if (ptype->type != type || !ptype->callbacks.gro_complete) continue; - err = ptype->callbacks.gro_complete(skb, 0); + err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete, + ipv6_gro_complete, inet_gro_complete, + skb, 0); break; } rcu_read_unlock(); @@ -5504,6 +5509,10 @@ static void gro_flush_oldest(struct list_head *head) napi_gro_complete(oldest); } +INDIRECT_CALLABLE_DECLARE(struct sk_buff *inet_gro_receive(struct list_head *, + struct sk_buff *)); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *ipv6_gro_receive(struct list_head *, + struct sk_buff *)); static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb) { u32 hash = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1); @@ -5553,7 +5562,9 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff NAPI_GRO_CB(skb)->csum_valid = 0; } - pp = ptype->callbacks.gro_receive(gro_head, skb); + pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive, + ipv6_gro_receive, inet_gro_receive, + gro_head, skb); break; } rcu_read_unlock(); diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 326c422c22f8..0dfb72c46671 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1385,6 +1385,10 @@ out: } EXPORT_SYMBOL(inet_gso_segment); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *, + struct sk_buff *)); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp4_gro_receive(struct list_head *, + struct sk_buff *)); struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) { const struct net_offload *ops; @@ -1494,7 +1498,8 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) skb_gro_pull(skb, sizeof(*iph)); skb_set_transport_header(skb, skb_gro_offset(skb)); - pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); + pp = indirect_call_gro_receive(tcp4_gro_receive, udp4_gro_receive, + ops->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); @@ -1556,6 +1561,8 @@ int inet_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len) return -EINVAL; } +INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *, int)); +INDIRECT_CALLABLE_DECLARE(int udp4_gro_complete(struct sk_buff *, int)); int inet_gro_complete(struct sk_buff *skb, int nhoff) { __be16 newlen = htons(skb->len - nhoff); @@ -1581,7 +1588,9 @@ int inet_gro_complete(struct sk_buff *skb, int nhoff) * because any hdr with option will have been flushed in * inet_gro_receive(). */ - err = ops->callbacks.gro_complete(skb, nhoff + sizeof(*iph)); + err = INDIRECT_CALL_2(ops->callbacks.gro_complete, + tcp4_gro_complete, udp4_gro_complete, + skb, nhoff + sizeof(*iph)); out_unlock: rcu_read_unlock(); diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 870b0a335061..0fbf7d4df9da 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -10,6 +10,7 @@ * TCPv4 GSO/GRO support */ +#include <linux/indirect_call_wrapper.h> #include <linux/skbuff.h> #include <net/tcp.h> #include <net/protocol.h> @@ -305,7 +306,8 @@ int tcp_gro_complete(struct sk_buff *skb) } EXPORT_SYMBOL(tcp_gro_complete); -static struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) +INDIRECT_CALLABLE_SCOPE +struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) { /* Don't bother verifying checksum if we're going to flush anyway. */ if (!NAPI_GRO_CB(skb)->flush && @@ -318,7 +320,7 @@ static struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff * return tcp_gro_receive(head, skb); } -static int tcp4_gro_complete(struct sk_buff *skb, int thoff) +INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) { const struct iphdr *iph = ip_hdr(skb); struct tcphdr *th = tcp_hdr(skb); diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 0646d61f4fa8..64f9715173ac 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -13,6 +13,7 @@ #include <linux/skbuff.h> #include <net/udp.h> #include <net/protocol.h> +#include <net/inet_common.h> static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, netdev_features_t features, @@ -391,6 +392,8 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head, return NULL; } +INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb, + __be16 sport, __be16 dport)); struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, struct udphdr *uh, udp_lookup_t lookup) { @@ -402,7 +405,8 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, struct sock *sk; rcu_read_lock(); - sk = (*lookup)(skb, uh->source, uh->dest); + sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, + udp4_lib_lookup_skb, skb, uh->source, uh->dest); if (!sk) goto out_unlock; @@ -451,8 +455,8 @@ out_unlock: } EXPORT_SYMBOL(udp_gro_receive); -static struct sk_buff *udp4_gro_receive(struct list_head *head, - struct sk_buff *skb) +INDIRECT_CALLABLE_SCOPE +struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb) { struct udphdr *uh = udp_gro_udphdr(skb); @@ -502,7 +506,8 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff, uh->len = newlen; rcu_read_lock(); - sk = (*lookup)(skb, uh->source, uh->dest); + sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, + udp4_lib_lookup_skb, skb, uh->source, uh->dest); if (sk && udp_sk(sk)->gro_enabled) { err = udp_gro_complete_segment(skb); } else if (sk && udp_sk(sk)->gro_complete) { @@ -525,7 +530,7 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff, } EXPORT_SYMBOL(udp_gro_complete); -static int udp4_gro_complete(struct sk_buff *skb, int nhoff) +INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff) { const struct iphdr *iph = ip_hdr(skb); struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index 70f525c33cb6..5c045691c302 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -20,6 +20,23 @@ #include "ip6_offload.h" +/* All GRO functions are always builtin, except UDP over ipv6, which lays in + * ipv6 module, as it depends on UDPv6 lookup function, so we need special care + * when ipv6 is built as a module + */ +#if IS_BUILTIN(CONFIG_IPV6) +#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__) +#else +#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_1(f, f2, __VA_ARGS__) +#endif + +#define indirect_call_gro_receive_l4(f2, f1, cb, head, skb) \ +({ \ + unlikely(gro_recursion_inc_test(skb)) ? \ + NAPI_GRO_CB(skb)->flush |= 1, NULL : \ + INDIRECT_CALL_L4(cb, f2, f1, head, skb); \ +}) + static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto) { const struct net_offload *ops = NULL; @@ -164,8 +181,12 @@ static int ipv6_exthdrs_len(struct ipv6hdr *iph, return len; } -static struct sk_buff *ipv6_gro_receive(struct list_head *head, - struct sk_buff *skb) +INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *, + struct sk_buff *)); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp6_gro_receive(struct list_head *, + struct sk_buff *)); +INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head, + struct sk_buff *skb) { const struct net_offload *ops; struct sk_buff *pp = NULL; @@ -260,7 +281,8 @@ not_same_flow: skb_gro_postpull_rcsum(skb, iph, nlen); - pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); + pp = indirect_call_gro_receive_l4(tcp6_gro_receive, udp6_gro_receive, + ops->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); @@ -301,7 +323,9 @@ static struct sk_buff *ip4ip6_gro_receive(struct list_head *head, return inet_gro_receive(head, skb); } -static int ipv6_gro_complete(struct sk_buff *skb, int nhoff) +INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *, int)); +INDIRECT_CALLABLE_DECLARE(int udp6_gro_complete(struct sk_buff *, int)); +INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff) { const struct net_offload *ops; struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff); @@ -320,7 +344,8 @@ static int ipv6_gro_complete(struct sk_buff *skb, int nhoff) if (WARN_ON(!ops || !ops->callbacks.gro_complete)) goto out_unlock; - err = ops->callbacks.gro_complete(skb, nhoff); + err = INDIRECT_CALL_L4(ops->callbacks.gro_complete, tcp6_gro_complete, + udp6_gro_complete, skb, nhoff); out_unlock: rcu_read_unlock(); diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c index e72947c99454..3179c425d7ff 100644 --- a/net/ipv6/tcpv6_offload.c +++ b/net/ipv6/tcpv6_offload.c @@ -9,14 +9,15 @@ * * TCPv6 GSO/GRO support */ +#include <linux/indirect_call_wrapper.h> #include <linux/skbuff.h> #include <net/protocol.h> #include <net/tcp.h> #include <net/ip6_checksum.h> #include "ip6_offload.h" -static struct sk_buff *tcp6_gro_receive(struct list_head *head, - struct sk_buff *skb) +INDIRECT_CALLABLE_SCOPE +struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb) { /* Don't bother verifying checksum if we're going to flush anyway. */ if (!NAPI_GRO_CB(skb)->flush && @@ -29,7 +30,7 @@ static struct sk_buff *tcp6_gro_receive(struct list_head *head, return tcp_gro_receive(head, skb); } -static int tcp6_gro_complete(struct sk_buff *skb, int thoff) +INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff) { const struct ipv6hdr *iph = ipv6_hdr(skb); struct tcphdr *th = tcp_hdr(skb); diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c index 828b2457f97b..83b11d0ac091 100644 --- a/net/ipv6/udp_offload.c +++ b/net/ipv6/udp_offload.c @@ -11,6 +11,7 @@ */ #include <linux/skbuff.h> #include <linux/netdevice.h> +#include <linux/indirect_call_wrapper.h> #include <net/protocol.h> #include <net/ipv6.h> #include <net/udp.h> @@ -114,8 +115,8 @@ out: return segs; } -static struct sk_buff *udp6_gro_receive(struct list_head *head, - struct sk_buff *skb) +INDIRECT_CALLABLE_SCOPE +struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb) { struct udphdr *uh = udp_gro_udphdr(skb); @@ -142,7 +143,7 @@ flush: return NULL; } -static int udp6_gro_complete(struct sk_buff *skb, int nhoff) +INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff) { const struct ipv6hdr *ipv6h = ipv6_hdr(skb); struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); |