include/net/xdp.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /* include/net/xdp.h
   3  *
   4  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   5  */
   6 #ifndef __LINUX_NET_XDP_H__
   7 #define __LINUX_NET_XDP_H__
   8
   9 #include <linux/skbuff.h> /* skb_shared_info */
  10
  11 /**
  12  * DOC: XDP RX-queue information
  13  *
  14  * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
  15  * level RX-ring queues.  It is information that is specific to how
  16  * the driver have configured a given RX-ring queue.
  17  *
  18  * Each xdp_buff frame received in the driver carry a (pointer)
  19  * reference to this xdp_rxq_info structure.  This provides the XDP
  20  * data-path read-access to RX-info for both kernel and bpf-side
  21  * (limited subset).
  22  *
  23  * For now, direct access is only safe while running in NAPI/softirq
  24  * context.  Contents is read-mostly and must not be updated during
  25  * driver NAPI/softirq poll.
  26  *
  27  * The driver usage API is a register and unregister API.
  28  *
  29  * The struct is not directly tied to the XDP prog.  A new XDP prog
  30  * can be attached as long as it doesn't change the underlying
  31  * RX-ring.  If the RX-ring does change significantly, the NIC driver
  32  * naturally need to stop the RX-ring before purging and reallocating
  33  * memory.  In that process the driver MUST call unregistor (which
  34  * also apply for driver shutdown and unload).  The register API is
  35  * also mandatory during RX-ring setup.
  36  */
  37
  38 enum xdp_mem_type {
  39         MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
  40         MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
  41         MEM_TYPE_PAGE_POOL,
  42         MEM_TYPE_XSK_BUFF_POOL,
  43         MEM_TYPE_MAX,
  44 };
  45
  46 /* XDP flags for ndo_xdp_xmit */
  47 #define XDP_XMIT_FLUSH          (1U << 0)       /* doorbell signal consumer */
  48 #define XDP_XMIT_FLAGS_MASK     XDP_XMIT_FLUSH
  49
  50 struct xdp_mem_info {
  51         u32 type; /* enum xdp_mem_type, but known size type */
  52         u32 id;
  53 };
  54
  55 struct page_pool;
  56
  57 struct xdp_rxq_info {
  58         struct net_device *dev;
  59         u32 queue_index;
  60         u32 reg_state;
  61         struct xdp_mem_info mem;
  62 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
  63
  64 struct xdp_txq_info {
  65         struct net_device *dev;
  66 };
  67
  68 struct xdp_buff {
  69         void *data;
  70         void *data_end;
  71         void *data_meta;
  72         void *data_hard_start;
  73         struct xdp_rxq_info *rxq;
  74         struct xdp_txq_info *txq;
  75         u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
  76 };
  77
  78 /* Reserve memory area at end-of data area.
  79  *
  80  * This macro reserves tailroom in the XDP buffer by limiting the
  81  * XDP/BPF data access to data_hard_end.  Notice same area (and size)
  82  * is used for XDP_PASS, when constructing the SKB via build_skb().
  83  */
  84 #define xdp_data_hard_end(xdp)                          \
  85         ((xdp)->data_hard_start + (xdp)->frame_sz -     \
  86          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
  87
  88 struct xdp_frame {
  89         void *data;
  90         u16 len;
  91         u16 headroom;
  92         u32 metasize:8;
  93         u32 frame_sz:24;
  94         /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
  95          * while mem info is valid on remote CPU.
  96          */
  97         struct xdp_mem_info mem;
  98         struct net_device *dev_rx; /* used by cpumap */
  99 };
 100
 101 /* Clear kernel pointers in xdp_frame */
 102 static inline void xdp_scrub_frame(struct xdp_frame *frame)
 103 {
 104         frame->data = NULL;
 105         frame->dev_rx = NULL;
 106 }
 107
 108 /* Avoids inlining WARN macro in fast-path */
 109 void xdp_warn(const char *msg, const char *func, const int line);
 110 #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
 111
 112 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
 113
 114 static inline
 115 void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
 116 {
 117         xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
 118         xdp->data = frame->data;
 119         xdp->data_end = frame->data + frame->len;
 120         xdp->data_meta = frame->data - frame->metasize;
 121         xdp->frame_sz = frame->frame_sz;
 122 }
 123
 124 /* Convert xdp_buff to xdp_frame */
 125 static inline
 126 struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
 127 {
 128         struct xdp_frame *xdp_frame;
 129         int metasize;
 130         int headroom;
 131
 132         if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
 133                 return xdp_convert_zc_to_xdp_frame(xdp);
 134
 135         /* Assure headroom is available for storing info */
 136         headroom = xdp->data - xdp->data_hard_start;
 137         metasize = xdp->data - xdp->data_meta;
 138         metasize = metasize > 0 ? metasize : 0;
 139         if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
 140                 return NULL;
 141
 142         /* Catch if driver didn't reserve tailroom for skb_shared_info */
 143         if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
 144                 XDP_WARN("Driver BUG: missing reserved tailroom");
 145                 return NULL;
 146         }
 147
 148         /* Store info in top of packet */
 149         xdp_frame = xdp->data_hard_start;
 150
 151         xdp_frame->data = xdp->data;
 152         xdp_frame->len  = xdp->data_end - xdp->data;
 153         xdp_frame->headroom = headroom - sizeof(*xdp_frame);
 154         xdp_frame->metasize = metasize;
 155         xdp_frame->frame_sz = xdp->frame_sz;
 156
 157         /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
 158         xdp_frame->mem = xdp->rxq->mem;
 159
 160         return xdp_frame;
 161 }
 162
 163 void xdp_return_frame(struct xdp_frame *xdpf);
 164 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 165 void xdp_return_buff(struct xdp_buff *xdp);
 166
 167 /* When sending xdp_frame into the network stack, then there is no
 168  * return point callback, which is needed to release e.g. DMA-mapping
 169  * resources with page_pool.  Thus, have explicit function to release
 170  * frame resources.
 171  */
 172 void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
 173 static inline void xdp_release_frame(struct xdp_frame *xdpf)
 174 {
 175         struct xdp_mem_info *mem = &xdpf->mem;
 176
 177         /* Curr only page_pool needs this */
 178         if (mem->type == MEM_TYPE_PAGE_POOL)
 179                 __xdp_release_frame(xdpf->data, mem);
 180 }
 181
 182 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 183                      struct net_device *dev, u32 queue_index);
 184 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 185 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
 186 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 187 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 188                                enum xdp_mem_type type, void *allocator);
 189 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
 190
 191 /* Drivers not supporting XDP metadata can use this helper, which
 192  * rejects any room expansion for metadata as a result.
 193  */
 194 static __always_inline void
 195 xdp_set_data_meta_invalid(struct xdp_buff *xdp)
 196 {
 197         xdp->data_meta = xdp->data + 1;
 198 }
 199
 200 static __always_inline bool
 201 xdp_data_meta_unsupported(const struct xdp_buff *xdp)
 202 {
 203         return unlikely(xdp->data_meta > xdp->data);
 204 }
 205
 206 struct xdp_attachment_info {
 207         struct bpf_prog *prog;
 208         u32 flags;
 209 };
 210
 211 struct netdev_bpf;
 212 int xdp_attachment_query(struct xdp_attachment_info *info,
 213                          struct netdev_bpf *bpf);
 214 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 215                              struct netdev_bpf *bpf);
 216 void xdp_attachment_setup(struct xdp_attachment_info *info,
 217                           struct netdev_bpf *bpf);
 218
 219 #define DEV_MAP_BULK_SIZE 16
 220
 221 #endif /* __LINUX_NET_XDP_H__ */