1 /* net/core/xdp.c 2 * 3 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. 4 * Released under terms in GPL version 2. See COPYING. 5 */ 6 #include <linux/types.h> 7 #include <linux/mm.h> 8 #include <linux/slab.h> 9 #include <linux/idr.h> 10 #include <linux/rhashtable.h> 11 #include <net/page_pool.h> 12 13 #include <net/xdp.h> 14 15 #define REG_STATE_NEW 0x0 16 #define REG_STATE_REGISTERED 0x1 17 #define REG_STATE_UNREGISTERED 0x2 18 #define REG_STATE_UNUSED 0x3 19 20 static DEFINE_IDA(mem_id_pool); 21 static DEFINE_MUTEX(mem_id_lock); 22 #define MEM_ID_MAX 0xFFFE 23 #define MEM_ID_MIN 1 24 static int mem_id_next = MEM_ID_MIN; 25 26 static bool mem_id_init; /* false */ 27 static struct rhashtable *mem_id_ht; 28 29 struct xdp_mem_allocator { 30 struct xdp_mem_info mem; 31 union { 32 void *allocator; 33 struct page_pool *page_pool; 34 }; 35 struct rhash_head node; 36 struct rcu_head rcu; 37 }; 38 39 static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed) 40 { 41 const u32 *k = data; 42 const u32 key = *k; 43 44 BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_mem_allocator, mem.id) 45 != sizeof(u32)); 46 47 /* Use cyclic increasing ID as direct hash key, see rht_bucket_index */ 48 return key << RHT_HASH_RESERVED_SPACE; 49 } 50 51 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg, 52 const void *ptr) 53 { 54 const struct xdp_mem_allocator *xa = ptr; 55 u32 mem_id = *(u32 *)arg->key; 56 57 return xa->mem.id != mem_id; 58 } 59 60 static const struct rhashtable_params mem_id_rht_params = { 61 .nelem_hint = 64, 62 .head_offset = offsetof(struct xdp_mem_allocator, node), 63 .key_offset = offsetof(struct xdp_mem_allocator, mem.id), 64 .key_len = FIELD_SIZEOF(struct xdp_mem_allocator, mem.id), 65 .max_size = MEM_ID_MAX, 66 .min_size = 8, 67 .automatic_shrinking = true, 68 .hashfn = xdp_mem_id_hashfn, 69 .obj_cmpfn = xdp_mem_id_cmp, 70 }; 71 72 static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu) 73 { 74 struct xdp_mem_allocator *xa; 75 76 xa = container_of(rcu, struct xdp_mem_allocator, rcu); 77 78 /* Allow this ID to be reused */ 79 ida_simple_remove(&mem_id_pool, xa->mem.id); 80 81 /* Notice, driver is expected to free the *allocator, 82 * e.g. page_pool, and MUST also use RCU free. 83 */ 84 85 /* Poison memory */ 86 xa->mem.id = 0xFFFF; 87 xa->mem.type = 0xF0F0; 88 xa->allocator = (void *)0xDEAD9001; 89 90 kfree(xa); 91 } 92 93 static void __xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq) 94 { 95 struct xdp_mem_allocator *xa; 96 int id = xdp_rxq->mem.id; 97 int err; 98 99 if (id == 0) 100 return; 101 102 mutex_lock(&mem_id_lock); 103 104 xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params); 105 if (!xa) { 106 mutex_unlock(&mem_id_lock); 107 return; 108 } 109 110 err = rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params); 111 WARN_ON(err); 112 113 call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free); 114 115 mutex_unlock(&mem_id_lock); 116 } 117 118 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq) 119 { 120 /* Simplify driver cleanup code paths, allow unreg "unused" */ 121 if (xdp_rxq->reg_state == REG_STATE_UNUSED) 122 return; 123 124 WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG"); 125 126 __xdp_rxq_info_unreg_mem_model(xdp_rxq); 127 128 xdp_rxq->reg_state = REG_STATE_UNREGISTERED; 129 xdp_rxq->dev = NULL; 130 131 /* Reset mem info to defaults */ 132 xdp_rxq->mem.id = 0; 133 xdp_rxq->mem.type = 0; 134 } 135 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg); 136 137 static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq) 138 { 139 memset(xdp_rxq, 0, sizeof(*xdp_rxq)); 140 } 141 142 /* Returns 0 on success, negative on failure */ 143 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq, 144 struct net_device *dev, u32 queue_index) 145 { 146 if (xdp_rxq->reg_state == REG_STATE_UNUSED) { 147 WARN(1, "Driver promised not to register this"); 148 return -EINVAL; 149 } 150 151 if (xdp_rxq->reg_state == REG_STATE_REGISTERED) { 152 WARN(1, "Missing unregister, handled but fix driver"); 153 xdp_rxq_info_unreg(xdp_rxq); 154 } 155 156 if (!dev) { 157 WARN(1, "Missing net_device from driver"); 158 return -ENODEV; 159 } 160 161 /* State either UNREGISTERED or NEW */ 162 xdp_rxq_info_init(xdp_rxq); 163 xdp_rxq->dev = dev; 164 xdp_rxq->queue_index = queue_index; 165 166 xdp_rxq->reg_state = REG_STATE_REGISTERED; 167 return 0; 168 } 169 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg); 170 171 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq) 172 { 173 xdp_rxq->reg_state = REG_STATE_UNUSED; 174 } 175 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused); 176 177 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq) 178 { 179 return (xdp_rxq->reg_state == REG_STATE_REGISTERED); 180 } 181 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg); 182 183 static int __mem_id_init_hash_table(void) 184 { 185 struct rhashtable *rht; 186 int ret; 187 188 if (unlikely(mem_id_init)) 189 return 0; 190 191 rht = kzalloc(sizeof(*rht), GFP_KERNEL); 192 if (!rht) 193 return -ENOMEM; 194 195 ret = rhashtable_init(rht, &mem_id_rht_params); 196 if (ret < 0) { 197 kfree(rht); 198 return ret; 199 } 200 mem_id_ht = rht; 201 smp_mb(); /* mutex lock should provide enough pairing */ 202 mem_id_init = true; 203 204 return 0; 205 } 206 207 /* Allocate a cyclic ID that maps to allocator pointer. 208 * See: https://www.kernel.org/doc/html/latest/core-api/idr.html 209 * 210 * Caller must lock mem_id_lock. 211 */ 212 static int __mem_id_cyclic_get(gfp_t gfp) 213 { 214 int retries = 1; 215 int id; 216 217 again: 218 id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp); 219 if (id < 0) { 220 if (id == -ENOSPC) { 221 /* Cyclic allocator, reset next id */ 222 if (retries--) { 223 mem_id_next = MEM_ID_MIN; 224 goto again; 225 } 226 } 227 return id; /* errno */ 228 } 229 mem_id_next = id + 1; 230 231 return id; 232 } 233 234 static bool __is_supported_mem_type(enum xdp_mem_type type) 235 { 236 if (type == MEM_TYPE_PAGE_POOL) 237 return is_page_pool_compiled_in(); 238 239 if (type >= MEM_TYPE_MAX) 240 return false; 241 242 return true; 243 } 244 245 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, 246 enum xdp_mem_type type, void *allocator) 247 { 248 struct xdp_mem_allocator *xdp_alloc; 249 gfp_t gfp = GFP_KERNEL; 250 int id, errno, ret; 251 void *ptr; 252 253 if (xdp_rxq->reg_state != REG_STATE_REGISTERED) { 254 WARN(1, "Missing register, driver bug"); 255 return -EFAULT; 256 } 257 258 if (!__is_supported_mem_type(type)) 259 return -EOPNOTSUPP; 260 261 xdp_rxq->mem.type = type; 262 263 if (!allocator) { 264 if (type == MEM_TYPE_PAGE_POOL) 265 return -EINVAL; /* Setup time check page_pool req */ 266 return 0; 267 } 268 269 /* Delay init of rhashtable to save memory if feature isn't used */ 270 if (!mem_id_init) { 271 mutex_lock(&mem_id_lock); 272 ret = __mem_id_init_hash_table(); 273 mutex_unlock(&mem_id_lock); 274 if (ret < 0) { 275 WARN_ON(1); 276 return ret; 277 } 278 } 279 280 xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp); 281 if (!xdp_alloc) 282 return -ENOMEM; 283 284 mutex_lock(&mem_id_lock); 285 id = __mem_id_cyclic_get(gfp); 286 if (id < 0) { 287 errno = id; 288 goto err; 289 } 290 xdp_rxq->mem.id = id; 291 xdp_alloc->mem = xdp_rxq->mem; 292 xdp_alloc->allocator = allocator; 293 294 /* Insert allocator into ID lookup table */ 295 ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node); 296 if (IS_ERR(ptr)) { 297 errno = PTR_ERR(ptr); 298 goto err; 299 } 300 301 mutex_unlock(&mem_id_lock); 302 303 return 0; 304 err: 305 mutex_unlock(&mem_id_lock); 306 kfree(xdp_alloc); 307 return errno; 308 } 309 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model); 310 311 static void xdp_return(void *data, struct xdp_mem_info *mem) 312 { 313 struct xdp_mem_allocator *xa; 314 struct page *page; 315 316 switch (mem->type) { 317 case MEM_TYPE_PAGE_POOL: 318 rcu_read_lock(); 319 /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */ 320 xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params); 321 page = virt_to_head_page(data); 322 if (xa) 323 page_pool_put_page(xa->page_pool, page); 324 else 325 put_page(page); 326 rcu_read_unlock(); 327 break; 328 case MEM_TYPE_PAGE_SHARED: 329 page_frag_free(data); 330 break; 331 case MEM_TYPE_PAGE_ORDER0: 332 page = virt_to_page(data); /* Assumes order0 page*/ 333 put_page(page); 334 break; 335 default: 336 /* Not possible, checked in xdp_rxq_info_reg_mem_model() */ 337 break; 338 } 339 } 340 341 void xdp_return_frame(struct xdp_frame *xdpf) 342 { 343 xdp_return(xdpf->data, &xdpf->mem); 344 } 345 EXPORT_SYMBOL_GPL(xdp_return_frame); 346 347 void xdp_return_buff(struct xdp_buff *xdp) 348 { 349 xdp_return(xdp->data, &xdp->rxq->mem); 350 } 351 EXPORT_SYMBOL_GPL(xdp_return_buff); 352