text: /* SPDX-License-Identifier: GPL-2.0-only */
  /* include/net/xdp.h
   *
   * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   */
  #ifndef __LINUX_NET_XDP_H__
  #define __LINUX_NET_XDP_H__
  
  #include <linux/skbuff.h> /* skb_shared_info */
  
  /**
   * DOC: XDP RX-queue information
   *
   * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
   * level RX-ring queues.  It is information that is specific to how
   * the driver have configured a given RX-ring queue.
   *
   * Each xdp_buff frame received in the driver carries a (pointer)
   * reference to this xdp_rxq_info structure.  This provides the XDP
   * data-path read-access to RX-info for both kernel and bpf-side
   * (limited subset).
   *
   * For now, direct access is only safe while running in NAPI/softirq
   * context.  Contents are read-mostly and must not be updated during
   * driver NAPI/softirq poll.
   *
   * The driver usage API is a register and unregister API.
   *
   * The struct is not directly tied to the XDP prog.  A new XDP prog
   * can be attached as long as it doesn't change the underlying
   * RX-ring.  If the RX-ring does change significantly, the NIC driver
   * naturally need to stop the RX-ring before purging and reallocating
   * memory.  In that process the driver MUST call unregister (which
   * also applies for driver shutdown and unload).  The register API is
   * also mandatory during RX-ring setup.
   */
  
  enum xdp_mem_type {
  	MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
  	MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
  	MEM_TYPE_PAGE_POOL,
  	MEM_TYPE_XSK_BUFF_POOL,
  	MEM_TYPE_MAX,
  };
  
  /* XDP flags for ndo_xdp_xmit */
  #define XDP_XMIT_FLUSH		(1U << 0)	/* doorbell signal consumer */
  #define XDP_XMIT_FLAGS_MASK	XDP_XMIT_FLUSH
  
  struct xdp_mem_info {
  	u32 type; /* enum xdp_mem_type, but known size type */
  	u32 id;
  };
  
  struct page_pool;
  
  struct xdp_rxq_info {
  	struct net_device *dev;
  	u32 queue_index;
  	u32 reg_state;
  	struct xdp_mem_info mem;
  	unsigned int napi_id;
  } ____cacheline_aligned; /* perf critical, avoid false-sharing */
  
  struct xdp_txq_info {
  	struct net_device *dev;
  };
  
  struct xdp_buff {
  	void *data;
  	void *data_end;
  	void *data_meta;
  	void *data_hard_start;
  	struct xdp_rxq_info *rxq;
  	struct xdp_txq_info *txq;
  	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
  };
  
  static __always_inline void
  xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)
  {
  	xdp->frame_sz = frame_sz;
  	xdp->rxq = rxq;
  }
  
  static __always_inline void
  xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,
  		 int headroom, int data_len, const bool meta_valid)
  {
  	unsigned char *data = hard_start + headroom;
  
  	xdp->data_hard_start = hard_start;
  	xdp->data = data;
  	xdp->data_end = data + data_len;
  	xdp->data_meta = meta_valid ? data : data + 1;
  }
  
  /* Reserve memory area at end-of data area.
   *
   * This macro reserves tailroom in the XDP buffer by limiting the
   * XDP/BPF data access to data_hard_end.  Notice same area (and size)
   * is used for XDP_PASS, when constructing the SKB via build_skb().
   */
  #define xdp_data_hard_end(xdp)				\
  	((xdp)->data_hard_start + (xdp)->frame_sz -	\
  	 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
  
  static inline struct skb_shared_info *
  xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
  {
  	return (struct skb_shared_info *)xdp_data_hard_end(xdp);
  }
  
  struct xdp_frame {
  	void *data;
  	u16 len;
  	u16 headroom;
  	u32 metasize:8;
  	u32 frame_sz:24;
  	/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
  	 * while mem info is valid on remote CPU.
  	 */
  	struct xdp_mem_info mem;
  	struct net_device *dev_rx; /* used by cpumap */
  };
  
  #define XDP_BULK_QUEUE_SIZE	16
  struct xdp_frame_bulk {
  	int count;
  	void *xa;
  	void *q[XDP_BULK_QUEUE_SIZE];
  };
  
  static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
  {
  	/* bq->count will be zero'ed when bq->xa gets updated */
  	bq->xa = NULL;
  }
  
  static inline struct skb_shared_info *
  xdp_get_shared_info_from_frame(struct xdp_frame *frame)
  {
  	void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
  
  	return (struct skb_shared_info *)(data_hard_start + frame->frame_sz -
  				SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
  }
  
  struct xdp_cpumap_stats {
  	unsigned int redirect;
  	unsigned int pass;
  	unsigned int drop;
  };
  
  /* Clear kernel pointers in xdp_frame */
  static inline void xdp_scrub_frame(struct xdp_frame *frame)
  {
  	frame->data = NULL;
  	frame->dev_rx = NULL;
  }
  
  /* Avoids inlining WARN macro in fast-path */
  void xdp_warn(const char *msg, const char *func, const int line);
  #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
  
  struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
  struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
  					   struct sk_buff *skb,
  					   struct net_device *dev);
  struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
  					 struct net_device *dev);
  int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp);
  struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
  
  static inline
  void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
  {
  	xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
  	xdp->data = frame->data;
  	xdp->data_end = frame->data + frame->len;
  	xdp->data_meta = frame->data - frame->metasize;
  	xdp->frame_sz = frame->frame_sz;
  }
  
  static inline
  int xdp_update_frame_from_buff(struct xdp_buff *xdp,
  			       struct xdp_frame *xdp_frame)
  {
  	int metasize, headroom;
  
  	/* Assure headroom is available for storing info */
  	headroom = xdp->data - xdp->data_hard_start;
  	metasize = xdp->data - xdp->data_meta;
  	metasize = metasize > 0 ? metasize : 0;
  	if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
  		return -ENOSPC;
  
  	/* Catch if driver didn't reserve tailroom for skb_shared_info */
  	if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
  		XDP_WARN("Driver BUG: missing reserved tailroom");
  		return -ENOSPC;
  	}
  
  	xdp_frame->data = xdp->data;
  	xdp_frame->len  = xdp->data_end - xdp->data;
  	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
  	xdp_frame->metasize = metasize;
  	xdp_frame->frame_sz = xdp->frame_sz;
  
  	return 0;
  }
  
  /* Convert xdp_buff to xdp_frame */
  static inline
  struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
  {
  	struct xdp_frame *xdp_frame;
  
  	if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
  		return xdp_convert_zc_to_xdp_frame(xdp);
  
  	/* Store info in top of packet */
  	xdp_frame = xdp->data_hard_start;
  	if (unlikely(xdp_update_frame_from_buff(xdp, xdp_frame) < 0))
  		return NULL;
  
  	/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
  	xdp_frame->mem = xdp->rxq->mem;
  
  	return xdp_frame;
  }
  
  void xdp_return_frame(struct xdp_frame *xdpf);
  void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
  void xdp_return_buff(struct xdp_buff *xdp);
  void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
  void xdp_return_frame_bulk(struct xdp_frame *xdpf,
  			   struct xdp_frame_bulk *bq);
  
  /* When sending xdp_frame into the network stack, then there is no
   * return point callback, which is needed to release e.g. DMA-mapping
   * resources with page_pool.  Thus, have explicit function to release
   * frame resources.
   */
  void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
  static inline void xdp_release_frame(struct xdp_frame *xdpf)
  {
  	struct xdp_mem_info *mem = &xdpf->mem;
  
  	/* Curr only page_pool needs this */
  	if (mem->type == MEM_TYPE_PAGE_POOL)
  		__xdp_release_frame(xdpf->data, mem);
  }
  
  int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
  		     struct net_device *dev, u32 queue_index, unsigned int napi_id);
  void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
  void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
  bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
  int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
  			       enum xdp_mem_type type, void *allocator);
  void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
  
  /* Drivers not supporting XDP metadata can use this helper, which
   * rejects any room expansion for metadata as a result.
   */
  static __always_inline void
  xdp_set_data_meta_invalid(struct xdp_buff *xdp)
  {
  	xdp->data_meta = xdp->data + 1;
  }
  
  static __always_inline bool
  xdp_data_meta_unsupported(const struct xdp_buff *xdp)
  {
  	return unlikely(xdp->data_meta > xdp->data);
  }
  
  static inline bool xdp_metalen_invalid(unsigned long metalen)
  {
  	return (metalen & (sizeof(__u32) - 1)) || (metalen > 32);
  }
  
  struct xdp_attachment_info {
  	struct bpf_prog *prog;
  	u32 flags;
  };
  
  struct netdev_bpf;
  void xdp_attachment_setup(struct xdp_attachment_info *info,
  			  struct netdev_bpf *bpf);
  
  #define DEV_MAP_BULK_SIZE XDP_BULK_QUEUE_SIZE
  
  #endif /* __LINUX_NET_XDP_H__ */
  