1 // SPDX-License-Identifier: GPL-2.0 2 /* XDP user-space packet buffer 3 * Copyright(c) 2018 Intel Corporation. 4 */ 5 6 #include <linux/init.h> 7 #include <linux/sched/mm.h> 8 #include <linux/sched/signal.h> 9 #include <linux/sched/task.h> 10 #include <linux/uaccess.h> 11 #include <linux/slab.h> 12 #include <linux/bpf.h> 13 #include <linux/mm.h> 14 #include <linux/netdevice.h> 15 #include <linux/rtnetlink.h> 16 17 #include "xdp_umem.h" 18 #include "xsk_queue.h" 19 20 #define XDP_UMEM_MIN_CHUNK_SIZE 2048 21 22 void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) 23 { 24 unsigned long flags; 25 26 spin_lock_irqsave(&umem->xsk_list_lock, flags); 27 list_add_rcu(&xs->list, &umem->xsk_list); 28 spin_unlock_irqrestore(&umem->xsk_list_lock, flags); 29 } 30 31 void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) 32 { 33 unsigned long flags; 34 35 spin_lock_irqsave(&umem->xsk_list_lock, flags); 36 list_del_rcu(&xs->list); 37 spin_unlock_irqrestore(&umem->xsk_list_lock, flags); 38 } 39 40 /* The umem is stored both in the _rx struct and the _tx struct as we do 41 * not know if the device has more tx queues than rx, or the opposite. 42 * This might also change during run time. 43 */ 44 static void xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem, 45 u16 queue_id) 46 { 47 if (queue_id < dev->real_num_rx_queues) 48 dev->_rx[queue_id].umem = umem; 49 if (queue_id < dev->real_num_tx_queues) 50 dev->_tx[queue_id].umem = umem; 51 } 52 53 struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev, 54 u16 queue_id) 55 { 56 if (queue_id < dev->real_num_rx_queues) 57 return dev->_rx[queue_id].umem; 58 if (queue_id < dev->real_num_tx_queues) 59 return dev->_tx[queue_id].umem; 60 61 return NULL; 62 } 63 64 static void xdp_clear_umem_at_qid(struct net_device *dev, u16 queue_id) 65 { 66 if (queue_id < dev->real_num_rx_queues) 67 dev->_rx[queue_id].umem = NULL; 68 if (queue_id < dev->real_num_tx_queues) 69 dev->_tx[queue_id].umem = NULL; 70 } 71 72 int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev, 73 u16 queue_id, u16 flags) 74 { 75 bool force_zc, force_copy; 76 struct netdev_bpf bpf; 77 int err = 0; 78 79 force_zc = flags & XDP_ZEROCOPY; 80 force_copy = flags & XDP_COPY; 81 82 if (force_zc && force_copy) 83 return -EINVAL; 84 85 rtnl_lock(); 86 if (xdp_get_umem_from_qid(dev, queue_id)) { 87 err = -EBUSY; 88 goto out_rtnl_unlock; 89 } 90 91 xdp_reg_umem_at_qid(dev, umem, queue_id); 92 umem->dev = dev; 93 umem->queue_id = queue_id; 94 if (force_copy) 95 /* For copy-mode, we are done. */ 96 goto out_rtnl_unlock; 97 98 if (!dev->netdev_ops->ndo_bpf || 99 !dev->netdev_ops->ndo_xsk_async_xmit) { 100 err = -EOPNOTSUPP; 101 goto err_unreg_umem; 102 } 103 104 bpf.command = XDP_SETUP_XSK_UMEM; 105 bpf.xsk.umem = umem; 106 bpf.xsk.queue_id = queue_id; 107 108 err = dev->netdev_ops->ndo_bpf(dev, &bpf); 109 if (err) 110 goto err_unreg_umem; 111 rtnl_unlock(); 112 113 dev_hold(dev); 114 umem->zc = true; 115 return 0; 116 117 err_unreg_umem: 118 xdp_clear_umem_at_qid(dev, queue_id); 119 if (!force_zc) 120 err = 0; /* fallback to copy mode */ 121 out_rtnl_unlock: 122 rtnl_unlock(); 123 return err; 124 } 125 126 static void xdp_umem_clear_dev(struct xdp_umem *umem) 127 { 128 struct netdev_bpf bpf; 129 int err; 130 131 if (umem->zc) { 132 bpf.command = XDP_SETUP_XSK_UMEM; 133 bpf.xsk.umem = NULL; 134 bpf.xsk.queue_id = umem->queue_id; 135 136 rtnl_lock(); 137 err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf); 138 rtnl_unlock(); 139 140 if (err) 141 WARN(1, "failed to disable umem!\n"); 142 } 143 144 if (umem->dev) { 145 rtnl_lock(); 146 xdp_clear_umem_at_qid(umem->dev, umem->queue_id); 147 rtnl_unlock(); 148 } 149 150 if (umem->zc) { 151 dev_put(umem->dev); 152 umem->zc = false; 153 } 154 } 155 156 static void xdp_umem_unpin_pages(struct xdp_umem *umem) 157 { 158 unsigned int i; 159 160 for (i = 0; i < umem->npgs; i++) { 161 struct page *page = umem->pgs[i]; 162 163 set_page_dirty_lock(page); 164 put_page(page); 165 } 166 167 kfree(umem->pgs); 168 umem->pgs = NULL; 169 } 170 171 static void xdp_umem_unaccount_pages(struct xdp_umem *umem) 172 { 173 if (umem->user) { 174 atomic_long_sub(umem->npgs, &umem->user->locked_vm); 175 free_uid(umem->user); 176 } 177 } 178 179 static void xdp_umem_release(struct xdp_umem *umem) 180 { 181 struct task_struct *task; 182 struct mm_struct *mm; 183 184 xdp_umem_clear_dev(umem); 185 186 if (umem->fq) { 187 xskq_destroy(umem->fq); 188 umem->fq = NULL; 189 } 190 191 if (umem->cq) { 192 xskq_destroy(umem->cq); 193 umem->cq = NULL; 194 } 195 196 xsk_reuseq_destroy(umem); 197 198 xdp_umem_unpin_pages(umem); 199 200 task = get_pid_task(umem->pid, PIDTYPE_PID); 201 put_pid(umem->pid); 202 if (!task) 203 goto out; 204 mm = get_task_mm(task); 205 put_task_struct(task); 206 if (!mm) 207 goto out; 208 209 mmput(mm); 210 kfree(umem->pages); 211 umem->pages = NULL; 212 213 xdp_umem_unaccount_pages(umem); 214 out: 215 kfree(umem); 216 } 217 218 static void xdp_umem_release_deferred(struct work_struct *work) 219 { 220 struct xdp_umem *umem = container_of(work, struct xdp_umem, work); 221 222 xdp_umem_release(umem); 223 } 224 225 void xdp_get_umem(struct xdp_umem *umem) 226 { 227 refcount_inc(&umem->users); 228 } 229 230 void xdp_put_umem(struct xdp_umem *umem) 231 { 232 if (!umem) 233 return; 234 235 if (refcount_dec_and_test(&umem->users)) { 236 INIT_WORK(&umem->work, xdp_umem_release_deferred); 237 schedule_work(&umem->work); 238 } 239 } 240 241 static int xdp_umem_pin_pages(struct xdp_umem *umem) 242 { 243 unsigned int gup_flags = FOLL_WRITE; 244 long npgs; 245 int err; 246 247 umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs), 248 GFP_KERNEL | __GFP_NOWARN); 249 if (!umem->pgs) 250 return -ENOMEM; 251 252 down_write(¤t->mm->mmap_sem); 253 npgs = get_user_pages(umem->address, umem->npgs, 254 gup_flags, &umem->pgs[0], NULL); 255 up_write(¤t->mm->mmap_sem); 256 257 if (npgs != umem->npgs) { 258 if (npgs >= 0) { 259 umem->npgs = npgs; 260 err = -ENOMEM; 261 goto out_pin; 262 } 263 err = npgs; 264 goto out_pgs; 265 } 266 return 0; 267 268 out_pin: 269 xdp_umem_unpin_pages(umem); 270 out_pgs: 271 kfree(umem->pgs); 272 umem->pgs = NULL; 273 return err; 274 } 275 276 static int xdp_umem_account_pages(struct xdp_umem *umem) 277 { 278 unsigned long lock_limit, new_npgs, old_npgs; 279 280 if (capable(CAP_IPC_LOCK)) 281 return 0; 282 283 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; 284 umem->user = get_uid(current_user()); 285 286 do { 287 old_npgs = atomic_long_read(&umem->user->locked_vm); 288 new_npgs = old_npgs + umem->npgs; 289 if (new_npgs > lock_limit) { 290 free_uid(umem->user); 291 umem->user = NULL; 292 return -ENOBUFS; 293 } 294 } while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs, 295 new_npgs) != old_npgs); 296 return 0; 297 } 298 299 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 300 { 301 u32 chunk_size = mr->chunk_size, headroom = mr->headroom; 302 unsigned int chunks, chunks_per_page; 303 u64 addr = mr->addr, size = mr->len; 304 int size_chk, err, i; 305 306 if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { 307 /* Strictly speaking we could support this, if: 308 * - huge pages, or* 309 * - using an IOMMU, or 310 * - making sure the memory area is consecutive 311 * but for now, we simply say "computer says no". 312 */ 313 return -EINVAL; 314 } 315 316 if (!is_power_of_2(chunk_size)) 317 return -EINVAL; 318 319 if (!PAGE_ALIGNED(addr)) { 320 /* Memory area has to be page size aligned. For 321 * simplicity, this might change. 322 */ 323 return -EINVAL; 324 } 325 326 if ((addr + size) < addr) 327 return -EINVAL; 328 329 chunks = (unsigned int)div_u64(size, chunk_size); 330 if (chunks == 0) 331 return -EINVAL; 332 333 chunks_per_page = PAGE_SIZE / chunk_size; 334 if (chunks < chunks_per_page || chunks % chunks_per_page) 335 return -EINVAL; 336 337 headroom = ALIGN(headroom, 64); 338 339 size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM; 340 if (size_chk < 0) 341 return -EINVAL; 342 343 umem->pid = get_task_pid(current, PIDTYPE_PID); 344 umem->address = (unsigned long)addr; 345 umem->chunk_mask = ~((u64)chunk_size - 1); 346 umem->size = size; 347 umem->headroom = headroom; 348 umem->chunk_size_nohr = chunk_size - headroom; 349 umem->npgs = size / PAGE_SIZE; 350 umem->pgs = NULL; 351 umem->user = NULL; 352 INIT_LIST_HEAD(&umem->xsk_list); 353 spin_lock_init(&umem->xsk_list_lock); 354 355 refcount_set(&umem->users, 1); 356 357 err = xdp_umem_account_pages(umem); 358 if (err) 359 goto out; 360 361 err = xdp_umem_pin_pages(umem); 362 if (err) 363 goto out_account; 364 365 umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL); 366 if (!umem->pages) { 367 err = -ENOMEM; 368 goto out_account; 369 } 370 371 for (i = 0; i < umem->npgs; i++) 372 umem->pages[i].addr = page_address(umem->pgs[i]); 373 374 return 0; 375 376 out_account: 377 xdp_umem_unaccount_pages(umem); 378 out: 379 put_pid(umem->pid); 380 return err; 381 } 382 383 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr) 384 { 385 struct xdp_umem *umem; 386 int err; 387 388 umem = kzalloc(sizeof(*umem), GFP_KERNEL); 389 if (!umem) 390 return ERR_PTR(-ENOMEM); 391 392 err = xdp_umem_reg(umem, mr); 393 if (err) { 394 kfree(umem); 395 return ERR_PTR(err); 396 } 397 398 return umem; 399 } 400 401 bool xdp_umem_validate_queues(struct xdp_umem *umem) 402 { 403 return umem->fq && umem->cq; 404 } 405