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 if (xs->dev) { 36 spin_lock_irqsave(&umem->xsk_list_lock, flags); 37 list_del_rcu(&xs->list); 38 spin_unlock_irqrestore(&umem->xsk_list_lock, flags); 39 40 if (umem->zc) 41 synchronize_net(); 42 } 43 } 44 45 int xdp_umem_query(struct net_device *dev, u16 queue_id) 46 { 47 struct netdev_bpf bpf; 48 49 ASSERT_RTNL(); 50 51 memset(&bpf, 0, sizeof(bpf)); 52 bpf.command = XDP_QUERY_XSK_UMEM; 53 bpf.xsk.queue_id = queue_id; 54 55 if (!dev->netdev_ops->ndo_bpf) 56 return 0; 57 return dev->netdev_ops->ndo_bpf(dev, &bpf) ?: !!bpf.xsk.umem; 58 } 59 60 int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev, 61 u32 queue_id, u16 flags) 62 { 63 bool force_zc, force_copy; 64 struct netdev_bpf bpf; 65 int err; 66 67 force_zc = flags & XDP_ZEROCOPY; 68 force_copy = flags & XDP_COPY; 69 70 if (force_zc && force_copy) 71 return -EINVAL; 72 73 if (force_copy) 74 return 0; 75 76 if (!dev->netdev_ops->ndo_bpf || !dev->netdev_ops->ndo_xsk_async_xmit) 77 return force_zc ? -EOPNOTSUPP : 0; /* fail or fallback */ 78 79 bpf.command = XDP_QUERY_XSK_UMEM; 80 81 rtnl_lock(); 82 err = xdp_umem_query(dev, queue_id); 83 if (err) { 84 err = err < 0 ? -EOPNOTSUPP : -EBUSY; 85 goto err_rtnl_unlock; 86 } 87 88 bpf.command = XDP_SETUP_XSK_UMEM; 89 bpf.xsk.umem = umem; 90 bpf.xsk.queue_id = queue_id; 91 92 err = dev->netdev_ops->ndo_bpf(dev, &bpf); 93 if (err) 94 goto err_rtnl_unlock; 95 rtnl_unlock(); 96 97 dev_hold(dev); 98 umem->dev = dev; 99 umem->queue_id = queue_id; 100 umem->zc = true; 101 return 0; 102 103 err_rtnl_unlock: 104 rtnl_unlock(); 105 return force_zc ? err : 0; /* fail or fallback */ 106 } 107 108 static void xdp_umem_clear_dev(struct xdp_umem *umem) 109 { 110 struct netdev_bpf bpf; 111 int err; 112 113 if (umem->dev) { 114 bpf.command = XDP_SETUP_XSK_UMEM; 115 bpf.xsk.umem = NULL; 116 bpf.xsk.queue_id = umem->queue_id; 117 118 rtnl_lock(); 119 err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf); 120 rtnl_unlock(); 121 122 if (err) 123 WARN(1, "failed to disable umem!\n"); 124 125 dev_put(umem->dev); 126 umem->dev = NULL; 127 } 128 } 129 130 static void xdp_umem_unpin_pages(struct xdp_umem *umem) 131 { 132 unsigned int i; 133 134 for (i = 0; i < umem->npgs; i++) { 135 struct page *page = umem->pgs[i]; 136 137 set_page_dirty_lock(page); 138 put_page(page); 139 } 140 141 kfree(umem->pgs); 142 umem->pgs = NULL; 143 } 144 145 static void xdp_umem_unaccount_pages(struct xdp_umem *umem) 146 { 147 if (umem->user) { 148 atomic_long_sub(umem->npgs, &umem->user->locked_vm); 149 free_uid(umem->user); 150 } 151 } 152 153 static void xdp_umem_release(struct xdp_umem *umem) 154 { 155 struct task_struct *task; 156 struct mm_struct *mm; 157 158 xdp_umem_clear_dev(umem); 159 160 if (umem->fq) { 161 xskq_destroy(umem->fq); 162 umem->fq = NULL; 163 } 164 165 if (umem->cq) { 166 xskq_destroy(umem->cq); 167 umem->cq = NULL; 168 } 169 170 xdp_umem_unpin_pages(umem); 171 172 task = get_pid_task(umem->pid, PIDTYPE_PID); 173 put_pid(umem->pid); 174 if (!task) 175 goto out; 176 mm = get_task_mm(task); 177 put_task_struct(task); 178 if (!mm) 179 goto out; 180 181 mmput(mm); 182 kfree(umem->pages); 183 umem->pages = NULL; 184 185 xdp_umem_unaccount_pages(umem); 186 out: 187 kfree(umem); 188 } 189 190 static void xdp_umem_release_deferred(struct work_struct *work) 191 { 192 struct xdp_umem *umem = container_of(work, struct xdp_umem, work); 193 194 xdp_umem_release(umem); 195 } 196 197 void xdp_get_umem(struct xdp_umem *umem) 198 { 199 refcount_inc(&umem->users); 200 } 201 202 void xdp_put_umem(struct xdp_umem *umem) 203 { 204 if (!umem) 205 return; 206 207 if (refcount_dec_and_test(&umem->users)) { 208 INIT_WORK(&umem->work, xdp_umem_release_deferred); 209 schedule_work(&umem->work); 210 } 211 } 212 213 static int xdp_umem_pin_pages(struct xdp_umem *umem) 214 { 215 unsigned int gup_flags = FOLL_WRITE; 216 long npgs; 217 int err; 218 219 umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs), 220 GFP_KERNEL | __GFP_NOWARN); 221 if (!umem->pgs) 222 return -ENOMEM; 223 224 down_write(¤t->mm->mmap_sem); 225 npgs = get_user_pages(umem->address, umem->npgs, 226 gup_flags, &umem->pgs[0], NULL); 227 up_write(¤t->mm->mmap_sem); 228 229 if (npgs != umem->npgs) { 230 if (npgs >= 0) { 231 umem->npgs = npgs; 232 err = -ENOMEM; 233 goto out_pin; 234 } 235 err = npgs; 236 goto out_pgs; 237 } 238 return 0; 239 240 out_pin: 241 xdp_umem_unpin_pages(umem); 242 out_pgs: 243 kfree(umem->pgs); 244 umem->pgs = NULL; 245 return err; 246 } 247 248 static int xdp_umem_account_pages(struct xdp_umem *umem) 249 { 250 unsigned long lock_limit, new_npgs, old_npgs; 251 252 if (capable(CAP_IPC_LOCK)) 253 return 0; 254 255 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; 256 umem->user = get_uid(current_user()); 257 258 do { 259 old_npgs = atomic_long_read(&umem->user->locked_vm); 260 new_npgs = old_npgs + umem->npgs; 261 if (new_npgs > lock_limit) { 262 free_uid(umem->user); 263 umem->user = NULL; 264 return -ENOBUFS; 265 } 266 } while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs, 267 new_npgs) != old_npgs); 268 return 0; 269 } 270 271 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 272 { 273 u32 chunk_size = mr->chunk_size, headroom = mr->headroom; 274 unsigned int chunks, chunks_per_page; 275 u64 addr = mr->addr, size = mr->len; 276 int size_chk, err, i; 277 278 if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { 279 /* Strictly speaking we could support this, if: 280 * - huge pages, or* 281 * - using an IOMMU, or 282 * - making sure the memory area is consecutive 283 * but for now, we simply say "computer says no". 284 */ 285 return -EINVAL; 286 } 287 288 if (!is_power_of_2(chunk_size)) 289 return -EINVAL; 290 291 if (!PAGE_ALIGNED(addr)) { 292 /* Memory area has to be page size aligned. For 293 * simplicity, this might change. 294 */ 295 return -EINVAL; 296 } 297 298 if ((addr + size) < addr) 299 return -EINVAL; 300 301 chunks = (unsigned int)div_u64(size, chunk_size); 302 if (chunks == 0) 303 return -EINVAL; 304 305 chunks_per_page = PAGE_SIZE / chunk_size; 306 if (chunks < chunks_per_page || chunks % chunks_per_page) 307 return -EINVAL; 308 309 headroom = ALIGN(headroom, 64); 310 311 size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM; 312 if (size_chk < 0) 313 return -EINVAL; 314 315 umem->pid = get_task_pid(current, PIDTYPE_PID); 316 umem->address = (unsigned long)addr; 317 umem->props.chunk_mask = ~((u64)chunk_size - 1); 318 umem->props.size = size; 319 umem->headroom = headroom; 320 umem->chunk_size_nohr = chunk_size - headroom; 321 umem->npgs = size / PAGE_SIZE; 322 umem->pgs = NULL; 323 umem->user = NULL; 324 INIT_LIST_HEAD(&umem->xsk_list); 325 spin_lock_init(&umem->xsk_list_lock); 326 327 refcount_set(&umem->users, 1); 328 329 err = xdp_umem_account_pages(umem); 330 if (err) 331 goto out; 332 333 err = xdp_umem_pin_pages(umem); 334 if (err) 335 goto out_account; 336 337 umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL); 338 if (!umem->pages) { 339 err = -ENOMEM; 340 goto out_account; 341 } 342 343 for (i = 0; i < umem->npgs; i++) 344 umem->pages[i].addr = page_address(umem->pgs[i]); 345 346 return 0; 347 348 out_account: 349 xdp_umem_unaccount_pages(umem); 350 out: 351 put_pid(umem->pid); 352 return err; 353 } 354 355 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr) 356 { 357 struct xdp_umem *umem; 358 int err; 359 360 umem = kzalloc(sizeof(*umem), GFP_KERNEL); 361 if (!umem) 362 return ERR_PTR(-ENOMEM); 363 364 err = xdp_umem_reg(umem, mr); 365 if (err) { 366 kfree(umem); 367 return ERR_PTR(err); 368 } 369 370 return umem; 371 } 372 373 bool xdp_umem_validate_queues(struct xdp_umem *umem) 374 { 375 return umem->fq && umem->cq; 376 } 377