net/xdp/xdp_umem.c

   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 #include <linux/idr.h>
  17 #include <linux/vmalloc.h>
  18
  19 #include "xdp_umem.h"
  20 #include "xsk_queue.h"
  21
  22 static DEFINE_IDA(umem_ida);
  23
  24 static void xdp_umem_unpin_pages(struct xdp_umem *umem)
  25 {
  26         unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
  27
  28         kvfree(umem->pgs);
  29         umem->pgs = NULL;
  30 }
  31
  32 static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
  33 {
  34         if (umem->user) {
  35                 atomic_long_sub(umem->npgs, &umem->user->locked_vm);
  36                 free_uid(umem->user);
  37         }
  38 }
  39
  40 static void xdp_umem_addr_unmap(struct xdp_umem *umem)
  41 {
  42         vunmap(umem->addrs);
  43         umem->addrs = NULL;
  44 }
  45
  46 static int xdp_umem_addr_map(struct xdp_umem *umem, struct page **pages,
  47                              u32 nr_pages)
  48 {
  49         umem->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
  50         if (!umem->addrs)
  51                 return -ENOMEM;
  52         return 0;
  53 }
  54
  55 static void xdp_umem_release(struct xdp_umem *umem)
  56 {
  57         umem->zc = false;
  58         ida_free(&umem_ida, umem->id);
  59
  60         xdp_umem_addr_unmap(umem);
  61         xdp_umem_unpin_pages(umem);
  62
  63         xdp_umem_unaccount_pages(umem);
  64         kfree(umem);
  65 }
  66
  67 static void xdp_umem_release_deferred(struct work_struct *work)
  68 {
  69         struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
  70
  71         xdp_umem_release(umem);
  72 }
  73
  74 void xdp_get_umem(struct xdp_umem *umem)
  75 {
  76         refcount_inc(&umem->users);
  77 }
  78
  79 void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup)
  80 {
  81         if (!umem)
  82                 return;
  83
  84         if (refcount_dec_and_test(&umem->users)) {
  85                 if (defer_cleanup) {
  86                         INIT_WORK(&umem->work, xdp_umem_release_deferred);
  87                         schedule_work(&umem->work);
  88                 } else {
  89                         xdp_umem_release(umem);
  90                 }
  91         }
  92 }
  93
  94 static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
  95 {
  96         unsigned int gup_flags = FOLL_WRITE;
  97         long npgs;
  98         int err;
  99
 100         umem->pgs = kvcalloc(umem->npgs, sizeof(*umem->pgs), GFP_KERNEL | __GFP_NOWARN);
 101         if (!umem->pgs)
 102                 return -ENOMEM;
 103
 104         mmap_read_lock(current->mm);
 105         npgs = pin_user_pages(address, umem->npgs,
 106                               gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
 107         mmap_read_unlock(current->mm);
 108
 109         if (npgs != umem->npgs) {
 110                 if (npgs >= 0) {
 111                         umem->npgs = npgs;
 112                         err = -ENOMEM;
 113                         goto out_pin;
 114                 }
 115                 err = npgs;
 116                 goto out_pgs;
 117         }
 118         return 0;
 119
 120 out_pin:
 121         xdp_umem_unpin_pages(umem);
 122 out_pgs:
 123         kvfree(umem->pgs);
 124         umem->pgs = NULL;
 125         return err;
 126 }
 127
 128 static int xdp_umem_account_pages(struct xdp_umem *umem)
 129 {
 130         unsigned long lock_limit, new_npgs, old_npgs;
 131
 132         if (capable(CAP_IPC_LOCK))
 133                 return 0;
 134
 135         lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 136         umem->user = get_uid(current_user());
 137
 138         do {
 139                 old_npgs = atomic_long_read(&umem->user->locked_vm);
 140                 new_npgs = old_npgs + umem->npgs;
 141                 if (new_npgs > lock_limit) {
 142                         free_uid(umem->user);
 143                         umem->user = NULL;
 144                         return -ENOBUFS;
 145                 }
 146         } while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
 147                                      new_npgs) != old_npgs);
 148         return 0;
 149 }
 150
 151 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 152 {
 153         u32 npgs_rem, chunk_size = mr->chunk_size, headroom = mr->headroom;
 154         bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
 155         u64 npgs, addr = mr->addr, size = mr->len;
 156         unsigned int chunks, chunks_rem;
 157         int err;
 158
 159         if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
 160                 /* Strictly speaking we could support this, if:
 161                  * - huge pages, or*
 162                  * - using an IOMMU, or
 163                  * - making sure the memory area is consecutive
 164                  * but for now, we simply say "computer says no".
 165                  */
 166                 return -EINVAL;
 167         }
 168
 169         if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
 170                 return -EINVAL;
 171
 172         if (!unaligned_chunks && !is_power_of_2(chunk_size))
 173                 return -EINVAL;
 174
 175         if (!PAGE_ALIGNED(addr)) {
 176                 /* Memory area has to be page size aligned. For
 177                  * simplicity, this might change.
 178                  */
 179                 return -EINVAL;
 180         }
 181
 182         if ((addr + size) < addr)
 183                 return -EINVAL;
 184
 185         npgs = div_u64_rem(size, PAGE_SIZE, &npgs_rem);
 186         if (npgs_rem)
 187                 npgs++;
 188         if (npgs > U32_MAX)
 189                 return -EINVAL;
 190
 191         chunks = (unsigned int)div_u64_rem(size, chunk_size, &chunks_rem);
 192         if (chunks == 0)
 193                 return -EINVAL;
 194
 195         if (!unaligned_chunks && chunks_rem)
 196                 return -EINVAL;
 197
 198         if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
 199                 return -EINVAL;
 200
 201         umem->size = size;
 202         umem->headroom = headroom;
 203         umem->chunk_size = chunk_size;
 204         umem->chunks = chunks;
 205         umem->npgs = (u32)npgs;
 206         umem->pgs = NULL;
 207         umem->user = NULL;
 208         umem->flags = mr->flags;
 209
 210         INIT_LIST_HEAD(&umem->xsk_dma_list);
 211         refcount_set(&umem->users, 1);
 212
 213         err = xdp_umem_account_pages(umem);
 214         if (err)
 215                 return err;
 216
 217         err = xdp_umem_pin_pages(umem, (unsigned long)addr);
 218         if (err)
 219                 goto out_account;
 220
 221         err = xdp_umem_addr_map(umem, umem->pgs, umem->npgs);
 222         if (err)
 223                 goto out_unpin;
 224
 225         return 0;
 226
 227 out_unpin:
 228         xdp_umem_unpin_pages(umem);
 229 out_account:
 230         xdp_umem_unaccount_pages(umem);
 231         return err;
 232 }
 233
 234 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
 235 {
 236         struct xdp_umem *umem;
 237         int err;
 238
 239         umem = kzalloc(sizeof(*umem), GFP_KERNEL);
 240         if (!umem)
 241                 return ERR_PTR(-ENOMEM);
 242
 243         err = ida_alloc(&umem_ida, GFP_KERNEL);
 244         if (err < 0) {
 245                 kfree(umem);
 246                 return ERR_PTR(err);
 247         }
 248         umem->id = err;
 249
 250         err = xdp_umem_reg(umem, mr);
 251         if (err) {
 252                 ida_free(&umem_ida, umem->id);
 253                 kfree(umem);
 254                 return ERR_PTR(err);
 255         }
 256
 257         return umem;
 258 }