1 /* include/net/xdp.h 2 * 3 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. 4 * Released under terms in GPL version 2. See COPYING. 5 */ 6 #ifndef __LINUX_NET_XDP_H__ 7 #define __LINUX_NET_XDP_H__ 8 9 /** 10 * DOC: XDP RX-queue information 11 * 12 * The XDP RX-queue info (xdp_rxq_info) is associated with the driver 13 * level RX-ring queues. It is information that is specific to how 14 * the driver have configured a given RX-ring queue. 15 * 16 * Each xdp_buff frame received in the driver carry a (pointer) 17 * reference to this xdp_rxq_info structure. This provides the XDP 18 * data-path read-access to RX-info for both kernel and bpf-side 19 * (limited subset). 20 * 21 * For now, direct access is only safe while running in NAPI/softirq 22 * context. Contents is read-mostly and must not be updated during 23 * driver NAPI/softirq poll. 24 * 25 * The driver usage API is a register and unregister API. 26 * 27 * The struct is not directly tied to the XDP prog. A new XDP prog 28 * can be attached as long as it doesn't change the underlying 29 * RX-ring. If the RX-ring does change significantly, the NIC driver 30 * naturally need to stop the RX-ring before purging and reallocating 31 * memory. In that process the driver MUST call unregistor (which 32 * also apply for driver shutdown and unload). The register API is 33 * also mandatory during RX-ring setup. 34 */ 35 36 enum xdp_mem_type { 37 MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */ 38 MEM_TYPE_PAGE_ORDER0, /* Orig XDP full page model */ 39 MEM_TYPE_MAX, 40 }; 41 42 struct xdp_mem_info { 43 u32 type; /* enum xdp_mem_type, but known size type */ 44 }; 45 46 struct xdp_rxq_info { 47 struct net_device *dev; 48 u32 queue_index; 49 u32 reg_state; 50 struct xdp_mem_info mem; 51 } ____cacheline_aligned; /* perf critical, avoid false-sharing */ 52 53 struct xdp_buff { 54 void *data; 55 void *data_end; 56 void *data_meta; 57 void *data_hard_start; 58 struct xdp_rxq_info *rxq; 59 }; 60 61 struct xdp_frame { 62 void *data; 63 u16 len; 64 u16 headroom; 65 u16 metasize; 66 /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time, 67 * while mem info is valid on remote CPU. 68 */ 69 struct xdp_mem_info mem; 70 }; 71 72 /* Convert xdp_buff to xdp_frame */ 73 static inline 74 struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) 75 { 76 struct xdp_frame *xdp_frame; 77 int metasize; 78 int headroom; 79 80 /* Assure headroom is available for storing info */ 81 headroom = xdp->data - xdp->data_hard_start; 82 metasize = xdp->data - xdp->data_meta; 83 metasize = metasize > 0 ? metasize : 0; 84 if (unlikely((headroom - metasize) < sizeof(*xdp_frame))) 85 return NULL; 86 87 /* Store info in top of packet */ 88 xdp_frame = xdp->data_hard_start; 89 90 xdp_frame->data = xdp->data; 91 xdp_frame->len = xdp->data_end - xdp->data; 92 xdp_frame->headroom = headroom - sizeof(*xdp_frame); 93 xdp_frame->metasize = metasize; 94 95 /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */ 96 xdp_frame->mem = xdp->rxq->mem; 97 98 return xdp_frame; 99 } 100 101 static inline 102 void xdp_return_frame(void *data, struct xdp_mem_info *mem) 103 { 104 if (mem->type == MEM_TYPE_PAGE_SHARED) 105 page_frag_free(data); 106 107 if (mem->type == MEM_TYPE_PAGE_ORDER0) { 108 struct page *page = virt_to_page(data); /* Assumes order0 page*/ 109 110 put_page(page); 111 } 112 } 113 114 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq, 115 struct net_device *dev, u32 queue_index); 116 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq); 117 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq); 118 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq); 119 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, 120 enum xdp_mem_type type, void *allocator); 121 122 /* Drivers not supporting XDP metadata can use this helper, which 123 * rejects any room expansion for metadata as a result. 124 */ 125 static __always_inline void 126 xdp_set_data_meta_invalid(struct xdp_buff *xdp) 127 { 128 xdp->data_meta = xdp->data + 1; 129 } 130 131 static __always_inline bool 132 xdp_data_meta_unsupported(const struct xdp_buff *xdp) 133 { 134 return unlikely(xdp->data_meta > xdp->data); 135 } 136 137 #endif /* __LINUX_NET_XDP_H__ */ 138