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bpf, xdp: Restructure redirect actions

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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 <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel 2021-03-08 12:29:07 +01:00 • committed by Daniel Borkmann
parent e6a4750ffe
commit ee75aef23a
6 changed files with 115 additions and 128 deletions
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62
include/trace/events/xdp.h
View file

@ -86,19 +86,15 @@ struct _bpf_dtab_netdev {
};
#endif /* __DEVMAP_OBJ_TYPE */
#define devmap_ifindex(tgt, map) \
(((map->map_type == BPF_MAP_TYPE_DEVMAP || \
map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)) ? \
((struct _bpf_dtab_netdev *)tgt)->dev->ifindex : 0)
DECLARE_EVENT_CLASS(xdp_redirect_template,
TP_PROTO(const struct net_device *dev,
const struct bpf_prog *xdp,
const void *tgt, int err,
const struct bpf_map *map, u32 index),
enum bpf_map_type map_type,
u32 map_id, u32 index),
TP_ARGS(dev, xdp, tgt, err, map, index),
TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index),
TP_STRUCT__entry(
__field(int, prog_id)
@ -111,14 +107,22 @@ DECLARE_EVENT_CLASS(xdp_redirect_template,
),
TP_fast_assign(
u32 ifindex = 0, map_index = index;
if (map_type == BPF_MAP_TYPE_DEVMAP || map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
ifindex = ((struct _bpf_dtab_netdev *)tgt)->dev->ifindex;
} else if (map_type == BPF_MAP_TYPE_UNSPEC && map_id == INT_MAX) {
ifindex = index;
map_index = 0;
}
__entry->prog_id = xdp->aux->id;
__entry->act = XDP_REDIRECT;
__entry->ifindex = dev->ifindex;
__entry->err = err;
__entry->to_ifindex = map ? devmap_ifindex(tgt, map) :
index;
__entry->map_id = map ? map->id : 0;
__entry->map_index = map ? index : 0;
__entry->to_ifindex = ifindex;
__entry->map_id = map_id;
__entry->map_index = map_index;
),
TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d"
@ -133,45 +137,49 @@ DEFINE_EVENT(xdp_redirect_template, xdp_redirect,
TP_PROTO(const struct net_device *dev,
const struct bpf_prog *xdp,
const void *tgt, int err,
const struct bpf_map *map, u32 index),
TP_ARGS(dev, xdp, tgt, err, map, index)
enum bpf_map_type map_type,
u32 map_id, u32 index),
TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index)
);
DEFINE_EVENT(xdp_redirect_template, xdp_redirect_err,
TP_PROTO(const struct net_device *dev,
const struct bpf_prog *xdp,
const void *tgt, int err,
const struct bpf_map *map, u32 index),
TP_ARGS(dev, xdp, tgt, err, map, index)
enum bpf_map_type map_type,
u32 map_id, u32 index),
TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index)
);
#define _trace_xdp_redirect(dev, xdp, to) \
trace_xdp_redirect(dev, xdp, NULL, 0, NULL, to)
#define _trace_xdp_redirect(dev, xdp, to) \
trace_xdp_redirect(dev, xdp, NULL, 0, BPF_MAP_TYPE_UNSPEC, INT_MAX, to)
#define _trace_xdp_redirect_err(dev, xdp, to, err) \
trace_xdp_redirect_err(dev, xdp, NULL, err, NULL, to)
#define _trace_xdp_redirect_err(dev, xdp, to, err) \
trace_xdp_redirect_err(dev, xdp, NULL, err, BPF_MAP_TYPE_UNSPEC, INT_MAX, to)
#define _trace_xdp_redirect_map(dev, xdp, to, map, index) \
trace_xdp_redirect(dev, xdp, to, 0, map, index)
#define _trace_xdp_redirect_map(dev, xdp, to, map_type, map_id, index) \
trace_xdp_redirect(dev, xdp, to, 0, map_type, map_id, index)
#define _trace_xdp_redirect_map_err(dev, xdp, to, map, index, err) \
trace_xdp_redirect_err(dev, xdp, to, err, map, index)
#define _trace_xdp_redirect_map_err(dev, xdp, to, map_type, map_id, index, err) \
trace_xdp_redirect_err(dev, xdp, to, err, map_type, map_id, index)
/* not used anymore, but kept around so as not to break old programs */
DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map,
TP_PROTO(const struct net_device *dev,
const struct bpf_prog *xdp,
const void *tgt, int err,
const struct bpf_map *map, u32 index),
TP_ARGS(dev, xdp, tgt, err, map, index)
enum bpf_map_type map_type,
u32 map_id, u32 index),
TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index)
);
DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map_err,
TP_PROTO(const struct net_device *dev,
const struct bpf_prog *xdp,
const void *tgt, int err,
const struct bpf_map *map, u32 index),
TP_ARGS(dev, xdp, tgt, err, map, index)
enum bpf_map_type map_type,
u32 map_id, u32 index),
TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index)
);
TRACE_EVENT(xdp_cpumap_kthread,