From e6a4750ffe9d701c4d55212b14b615e63571d235 Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Mon, 8 Mar 2021 12:29:06 +0100 Subject: bpf, xdp: Make bpf_redirect_map() a map operation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently the bpf_redirect_map() implementation dispatches to the correct map-lookup function via a switch-statement. To avoid the dispatching, this change adds bpf_redirect_map() as a map operation. Each map provides its bpf_redirect_map() version, and correct function is automatically selected by the BPF verifier. A nice side-effect of the code movement is that the map lookup functions are now local to the map implementation files, which removes one additional function call. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Acked-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com --- kernel/bpf/devmap.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 85d9d1b72a33..f7f42448259f 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -258,7 +258,7 @@ static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key) return 0; } -struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key) +static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); struct hlist_head *head = dev_map_index_hash(dtab, key); @@ -392,7 +392,7 @@ void __dev_flush(void) * update happens in parallel here a dev_put wont happen until after reading the * ifindex. */ -struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key) +static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); struct bpf_dtab_netdev *obj; @@ -735,6 +735,16 @@ static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value, map, key, value, map_flags); } +static int dev_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags) +{ + return __bpf_xdp_redirect_map(map, ifindex, flags, __dev_map_lookup_elem); +} + +static int dev_hash_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags) +{ + return __bpf_xdp_redirect_map(map, ifindex, flags, __dev_map_hash_lookup_elem); +} + static int dev_map_btf_id; const struct bpf_map_ops dev_map_ops = { .map_meta_equal = bpf_map_meta_equal, @@ -747,6 +757,7 @@ const struct bpf_map_ops dev_map_ops = { .map_check_btf = map_check_no_btf, .map_btf_name = "bpf_dtab", .map_btf_id = &dev_map_btf_id, + .map_redirect = dev_map_redirect, }; static int dev_map_hash_map_btf_id; @@ -761,6 +772,7 @@ const struct bpf_map_ops dev_map_hash_ops = { .map_check_btf = map_check_no_btf, .map_btf_name = "bpf_dtab", .map_btf_id = &dev_map_hash_map_btf_id, + .map_redirect = dev_hash_map_redirect, }; static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab, -- cgit From ee75aef23afe6e88497151c127c13ed69f41aaa2 Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Mon, 8 Mar 2021 12:29:07 +0100 Subject: bpf, xdp: Restructure redirect actions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The XDP_REDIRECT implementations for maps and non-maps are fairly similar, but obviously need to take different code paths depending on if the target is using a map or not. Today, the redirect targets for XDP either uses a map, or is based on ifindex. Here, the map type and id are added to bpf_redirect_info, instead of the actual map. Map type, map item/ifindex, and the map_id (if any) is passed to xdp_do_redirect(). For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper, a special map type/id are used. Map type of UNSPEC together with map id equal to INT_MAX has the special meaning of an ifindex based redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive ([1,INT_MAX[). In addition to making the code easier to follow, using explicit type and id in bpf_redirect_info has a slight positive performance impact by avoiding a pointer indirection for the map type lookup, and instead use the cacheline for bpf_redirect_info. Since the actual map is not passed via bpf_redirect_info anymore, the map lookup is only done in the BPF helper. This means that the bpf_clear_redirect_map() function can be removed. The actual map item is RCU protected. The bpf_redirect_info flags member is not used by XDP, and not read/written any more. The map member is only written to when required/used, and not unconditionally. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Maciej Fijalkowski Acked-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com --- kernel/bpf/devmap.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index f7f42448259f..7a5ad7331c3b 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -197,7 +197,6 @@ static void dev_map_free(struct bpf_map *map) list_del_rcu(&dtab->list); spin_unlock(&dev_map_lock); - bpf_clear_redirect_map(map); synchronize_rcu(); /* Make sure prior __dev_map_entry_free() have completed. */ -- cgit