net/core/xdp.c

   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/bpf.h>
   7 #include <linux/filter.h>
   8 #include <linux/types.h>
   9 #include <linux/mm.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/slab.h>
  12 #include <linux/idr.h>
  13 #include <linux/rhashtable.h>
  14 #include <net/page_pool.h>
  15
  16 #include <net/xdp.h>
  17
  18 #define REG_STATE_NEW           0x0
  19 #define REG_STATE_REGISTERED    0x1
  20 #define REG_STATE_UNREGISTERED  0x2
  21 #define REG_STATE_UNUSED        0x3
  22
  23 static DEFINE_IDA(mem_id_pool);
  24 static DEFINE_MUTEX(mem_id_lock);
  25 #define MEM_ID_MAX 0xFFFE
  26 #define MEM_ID_MIN 1
  27 static int mem_id_next = MEM_ID_MIN;
  28
  29 static bool mem_id_init; /* false */
  30 static struct rhashtable *mem_id_ht;
  31
  32 struct xdp_mem_allocator {
  33         struct xdp_mem_info mem;
  34         union {
  35                 void *allocator;
  36                 struct page_pool *page_pool;
  37                 struct zero_copy_allocator *zc_alloc;
  38         };
  39         struct rhash_head node;
  40         struct rcu_head rcu;
  41 };
  42
  43 static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
  44 {
  45         const u32 *k = data;
  46         const u32 key = *k;
  47
  48         BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_mem_allocator, mem.id)
  49                      != sizeof(u32));
  50
  51         /* Use cyclic increasing ID as direct hash key */
  52         return key;
  53 }
  54
  55 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
  56                           const void *ptr)
  57 {
  58         const struct xdp_mem_allocator *xa = ptr;
  59         u32 mem_id = *(u32 *)arg->key;
  60
  61         return xa->mem.id != mem_id;
  62 }
  63
  64 static const struct rhashtable_params mem_id_rht_params = {
  65         .nelem_hint = 64,
  66         .head_offset = offsetof(struct xdp_mem_allocator, node),
  67         .key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
  68         .key_len = FIELD_SIZEOF(struct xdp_mem_allocator, mem.id),
  69         .max_size = MEM_ID_MAX,
  70         .min_size = 8,
  71         .automatic_shrinking = true,
  72         .hashfn    = xdp_mem_id_hashfn,
  73         .obj_cmpfn = xdp_mem_id_cmp,
  74 };
  75
  76 static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
  77 {
  78         struct xdp_mem_allocator *xa;
  79
  80         xa = container_of(rcu, struct xdp_mem_allocator, rcu);
  81
  82         /* Allow this ID to be reused */
  83         ida_simple_remove(&mem_id_pool, xa->mem.id);
  84
  85         /* Notice, driver is expected to free the *allocator,
  86          * e.g. page_pool, and MUST also use RCU free.
  87          */
  88
  89         /* Poison memory */
  90         xa->mem.id = 0xFFFF;
  91         xa->mem.type = 0xF0F0;
  92         xa->allocator = (void *)0xDEAD9001;
  93
  94         kfree(xa);
  95 }
  96
  97 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
  98 {
  99         struct xdp_mem_allocator *xa;
 100         int id = xdp_rxq->mem.id;
 101
 102         if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 103                 WARN(1, "Missing register, driver bug");
 104                 return;
 105         }
 106
 107         if (xdp_rxq->mem.type != MEM_TYPE_PAGE_POOL &&
 108             xdp_rxq->mem.type != MEM_TYPE_ZERO_COPY) {
 109                 return;
 110         }
 111
 112         if (id == 0)
 113                 return;
 114
 115         mutex_lock(&mem_id_lock);
 116
 117         xa = rhashtable_lookup_fast(mem_id_ht, &id, mem_id_rht_params);
 118         if (xa && !rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
 119                 call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
 120
 121         mutex_unlock(&mem_id_lock);
 122 }
 123 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
 124
 125 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
 126 {
 127         /* Simplify driver cleanup code paths, allow unreg "unused" */
 128         if (xdp_rxq->reg_state == REG_STATE_UNUSED)
 129                 return;
 130
 131         WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
 132
 133         xdp_rxq_info_unreg_mem_model(xdp_rxq);
 134
 135         xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
 136         xdp_rxq->dev = NULL;
 137
 138         /* Reset mem info to defaults */
 139         xdp_rxq->mem.id = 0;
 140         xdp_rxq->mem.type = 0;
 141 }
 142 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
 143
 144 static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
 145 {
 146         memset(xdp_rxq, 0, sizeof(*xdp_rxq));
 147 }
 148
 149 /* Returns 0 on success, negative on failure */
 150 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 151                      struct net_device *dev, u32 queue_index)
 152 {
 153         if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
 154                 WARN(1, "Driver promised not to register this");
 155                 return -EINVAL;
 156         }
 157
 158         if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
 159                 WARN(1, "Missing unregister, handled but fix driver");
 160                 xdp_rxq_info_unreg(xdp_rxq);
 161         }
 162
 163         if (!dev) {
 164                 WARN(1, "Missing net_device from driver");
 165                 return -ENODEV;
 166         }
 167
 168         /* State either UNREGISTERED or NEW */
 169         xdp_rxq_info_init(xdp_rxq);
 170         xdp_rxq->dev = dev;
 171         xdp_rxq->queue_index = queue_index;
 172
 173         xdp_rxq->reg_state = REG_STATE_REGISTERED;
 174         return 0;
 175 }
 176 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
 177
 178 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
 179 {
 180         xdp_rxq->reg_state = REG_STATE_UNUSED;
 181 }
 182 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
 183
 184 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
 185 {
 186         return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
 187 }
 188 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
 189
 190 static int __mem_id_init_hash_table(void)
 191 {
 192         struct rhashtable *rht;
 193         int ret;
 194
 195         if (unlikely(mem_id_init))
 196                 return 0;
 197
 198         rht = kzalloc(sizeof(*rht), GFP_KERNEL);
 199         if (!rht)
 200                 return -ENOMEM;
 201
 202         ret = rhashtable_init(rht, &mem_id_rht_params);
 203         if (ret < 0) {
 204                 kfree(rht);
 205                 return ret;
 206         }
 207         mem_id_ht = rht;
 208         smp_mb(); /* mutex lock should provide enough pairing */
 209         mem_id_init = true;
 210
 211         return 0;
 212 }
 213
 214 /* Allocate a cyclic ID that maps to allocator pointer.
 215  * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
 216  *
 217  * Caller must lock mem_id_lock.
 218  */
 219 static int __mem_id_cyclic_get(gfp_t gfp)
 220 {
 221         int retries = 1;
 222         int id;
 223
 224 again:
 225         id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
 226         if (id < 0) {
 227                 if (id == -ENOSPC) {
 228                         /* Cyclic allocator, reset next id */
 229                         if (retries--) {
 230                                 mem_id_next = MEM_ID_MIN;
 231                                 goto again;
 232                         }
 233                 }
 234                 return id; /* errno */
 235         }
 236         mem_id_next = id + 1;
 237
 238         return id;
 239 }
 240
 241 static bool __is_supported_mem_type(enum xdp_mem_type type)
 242 {
 243         if (type == MEM_TYPE_PAGE_POOL)
 244                 return is_page_pool_compiled_in();
 245
 246         if (type >= MEM_TYPE_MAX)
 247                 return false;
 248
 249         return true;
 250 }
 251
 252 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 253                                enum xdp_mem_type type, void *allocator)
 254 {
 255         struct xdp_mem_allocator *xdp_alloc;
 256         gfp_t gfp = GFP_KERNEL;
 257         int id, errno, ret;
 258         void *ptr;
 259
 260         if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 261                 WARN(1, "Missing register, driver bug");
 262                 return -EFAULT;
 263         }
 264
 265         if (!__is_supported_mem_type(type))
 266                 return -EOPNOTSUPP;
 267
 268         xdp_rxq->mem.type = type;
 269
 270         if (!allocator) {
 271                 if (type == MEM_TYPE_PAGE_POOL || type == MEM_TYPE_ZERO_COPY)
 272                         return -EINVAL; /* Setup time check page_pool req */
 273                 return 0;
 274         }
 275
 276         /* Delay init of rhashtable to save memory if feature isn't used */
 277         if (!mem_id_init) {
 278                 mutex_lock(&mem_id_lock);
 279                 ret = __mem_id_init_hash_table();
 280                 mutex_unlock(&mem_id_lock);
 281                 if (ret < 0) {
 282                         WARN_ON(1);
 283                         return ret;
 284                 }
 285         }
 286
 287         xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
 288         if (!xdp_alloc)
 289                 return -ENOMEM;
 290
 291         mutex_lock(&mem_id_lock);
 292         id = __mem_id_cyclic_get(gfp);
 293         if (id < 0) {
 294                 errno = id;
 295                 goto err;
 296         }
 297         xdp_rxq->mem.id = id;
 298         xdp_alloc->mem  = xdp_rxq->mem;
 299         xdp_alloc->allocator = allocator;
 300
 301         /* Insert allocator into ID lookup table */
 302         ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
 303         if (IS_ERR(ptr)) {
 304                 errno = PTR_ERR(ptr);
 305                 goto err;
 306         }
 307
 308         mutex_unlock(&mem_id_lock);
 309
 310         return 0;
 311 err:
 312         mutex_unlock(&mem_id_lock);
 313         kfree(xdp_alloc);
 314         return errno;
 315 }
 316 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
 317
 318 /* XDP RX runs under NAPI protection, and in different delivery error
 319  * scenarios (e.g. queue full), it is possible to return the xdp_frame
 320  * while still leveraging this protection.  The @napi_direct boolian
 321  * is used for those calls sites.  Thus, allowing for faster recycling
 322  * of xdp_frames/pages in those cases.
 323  */
 324 static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 325                          unsigned long handle)
 326 {
 327         struct xdp_mem_allocator *xa;
 328         struct page *page;
 329
 330         switch (mem->type) {
 331         case MEM_TYPE_PAGE_POOL:
 332                 rcu_read_lock();
 333                 /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
 334                 xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 335                 page = virt_to_head_page(data);
 336                 if (xa) {
 337                         napi_direct &= !xdp_return_frame_no_direct();
 338                         page_pool_put_page(xa->page_pool, page, napi_direct);
 339                 } else {
 340                         put_page(page);
 341                 }
 342                 rcu_read_unlock();
 343                 break;
 344         case MEM_TYPE_PAGE_SHARED:
 345                 page_frag_free(data);
 346                 break;
 347         case MEM_TYPE_PAGE_ORDER0:
 348                 page = virt_to_page(data); /* Assumes order0 page*/
 349                 put_page(page);
 350                 break;
 351         case MEM_TYPE_ZERO_COPY:
 352                 /* NB! Only valid from an xdp_buff! */
 353                 rcu_read_lock();
 354                 /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
 355                 xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 356                 xa->zc_alloc->free(xa->zc_alloc, handle);
 357                 rcu_read_unlock();
 358         default:
 359                 /* Not possible, checked in xdp_rxq_info_reg_mem_model() */
 360                 break;
 361         }
 362 }
 363
 364 void xdp_return_frame(struct xdp_frame *xdpf)
 365 {
 366         __xdp_return(xdpf->data, &xdpf->mem, false, 0);
 367 }
 368 EXPORT_SYMBOL_GPL(xdp_return_frame);
 369
 370 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 371 {
 372         __xdp_return(xdpf->data, &xdpf->mem, true, 0);
 373 }
 374 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
 375
 376 void xdp_return_buff(struct xdp_buff *xdp)
 377 {
 378         __xdp_return(xdp->data, &xdp->rxq->mem, true, xdp->handle);
 379 }
 380 EXPORT_SYMBOL_GPL(xdp_return_buff);
 381
 382 int xdp_attachment_query(struct xdp_attachment_info *info,
 383                          struct netdev_bpf *bpf)
 384 {
 385         bpf->prog_id = info->prog ? info->prog->aux->id : 0;
 386         bpf->prog_flags = info->prog ? info->flags : 0;
 387         return 0;
 388 }
 389 EXPORT_SYMBOL_GPL(xdp_attachment_query);
 390
 391 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 392                              struct netdev_bpf *bpf)
 393 {
 394         if (info->prog && (bpf->flags ^ info->flags) & XDP_FLAGS_MODES) {
 395                 NL_SET_ERR_MSG(bpf->extack,
 396                                "program loaded with different flags");
 397                 return false;
 398         }
 399         return true;
 400 }
 401 EXPORT_SYMBOL_GPL(xdp_attachment_flags_ok);
 402
 403 void xdp_attachment_setup(struct xdp_attachment_info *info,
 404                           struct netdev_bpf *bpf)
 405 {
 406         if (info->prog)
 407                 bpf_prog_put(info->prog);
 408         info->prog = bpf->prog;
 409         info->flags = bpf->flags;
 410 }
 411 EXPORT_SYMBOL_GPL(xdp_attachment_setup);
 412
 413 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
 414 {
 415         unsigned int metasize, totsize;
 416         void *addr, *data_to_copy;
 417         struct xdp_frame *xdpf;
 418         struct page *page;
 419
 420         /* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
 421         metasize = xdp_data_meta_unsupported(xdp) ? 0 :
 422                    xdp->data - xdp->data_meta;
 423         totsize = xdp->data_end - xdp->data + metasize;
 424
 425         if (sizeof(*xdpf) + totsize > PAGE_SIZE)
 426                 return NULL;
 427
 428         page = dev_alloc_page();
 429         if (!page)
 430                 return NULL;
 431
 432         addr = page_to_virt(page);
 433         xdpf = addr;
 434         memset(xdpf, 0, sizeof(*xdpf));
 435
 436         addr += sizeof(*xdpf);
 437         data_to_copy = metasize ? xdp->data_meta : xdp->data;
 438         memcpy(addr, data_to_copy, totsize);
 439
 440         xdpf->data = addr + metasize;
 441         xdpf->len = totsize - metasize;
 442         xdpf->headroom = 0;
 443         xdpf->metasize = metasize;
 444         xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
 445
 446         xdp_return_buff(xdp);
 447         return xdpf;
 448 }
 449 EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);