Convert the get_user() and __put_user() code to the fast masked_user_access_begin()/unsafe_{get|put}_user() variant. This patch increases the performance of an UDP recvfrom() receiver (netserver) on 120 bytes messages by 7 % on an AMD EPYC 7B12 64-Core Processor platform. Presence of audit_sockaddr() makes difficult to avoid the stac/clac pair in the copy_to_user() call, this is left for a future patch. Signed-off-by: Eric Dumazet --- net/socket.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/net/socket.c b/net/socket.c index 682969deaed35df05666cc7711e5e29f7a445c07..5bc4ee0bb75d64039a2259ef01ab811b1d20034b 100644 --- a/net/socket.c +++ b/net/socket.c @@ -276,28 +276,41 @@ int move_addr_to_kernel(void __user *uaddr, int ulen, struct sockaddr_storage *k static int move_addr_to_user(struct sockaddr_storage *kaddr, int klen, void __user *uaddr, int __user *ulen) { - int err; int len; BUG_ON(klen > sizeof(struct sockaddr_storage)); - err = get_user(len, ulen); - if (err) - return err; + + if (can_do_masked_user_access()) + ulen = masked_user_access_begin(ulen); + else if (!user_access_begin(ulen, 4)) + return -EFAULT; + + unsafe_get_user(len, ulen, efault_end); + if (len > klen) len = klen; - if (len < 0) - return -EINVAL; + /* + * "fromlen shall refer to the value before truncation.." + * 1003.1g + */ + if (len >= 0) + unsafe_put_user(klen, ulen, efault_end); + + user_access_end(); + if (len) { + if (len < 0) + return -EINVAL; if (audit_sockaddr(klen, kaddr)) return -ENOMEM; if (copy_to_user(uaddr, kaddr, len)) return -EFAULT; } - /* - * "fromlen shall refer to the value before truncation.." - * 1003.1g - */ - return __put_user(klen, ulen); + return 0; + +efault_end: + user_access_end(); + return -EFAULT; } static struct kmem_cache *sock_inode_cachep __ro_after_init; -- 2.51.0.536.g15c5d4f767-goog