xdp_umem.c 5.3 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /* XDP user-space packet buffer
  3. * Copyright(c) 2018 Intel Corporation.
  4. */
  5. #include <linux/init.h>
  6. #include <linux/sched/mm.h>
  7. #include <linux/sched/signal.h>
  8. #include <linux/sched/task.h>
  9. #include <linux/uaccess.h>
  10. #include <linux/slab.h>
  11. #include <linux/bpf.h>
  12. #include <linux/mm.h>
  13. #include <linux/netdevice.h>
  14. #include <linux/rtnetlink.h>
  15. #include <linux/idr.h>
  16. #include <linux/vmalloc.h>
  17. #include "xdp_umem.h"
  18. #include "xsk_queue.h"
  19. static DEFINE_IDA(umem_ida);
  20. static void xdp_umem_unpin_pages(struct xdp_umem *umem)
  21. {
  22. unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
  23. kvfree(umem->pgs);
  24. umem->pgs = NULL;
  25. }
  26. static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
  27. {
  28. if (umem->user) {
  29. atomic_long_sub(umem->npgs, &umem->user->locked_vm);
  30. free_uid(umem->user);
  31. }
  32. }
  33. static void xdp_umem_addr_unmap(struct xdp_umem *umem)
  34. {
  35. vunmap(umem->addrs);
  36. umem->addrs = NULL;
  37. }
  38. static int xdp_umem_addr_map(struct xdp_umem *umem, struct page **pages,
  39. u32 nr_pages)
  40. {
  41. umem->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
  42. if (!umem->addrs)
  43. return -ENOMEM;
  44. return 0;
  45. }
  46. static void xdp_umem_release(struct xdp_umem *umem)
  47. {
  48. umem->zc = false;
  49. ida_free(&umem_ida, umem->id);
  50. xdp_umem_addr_unmap(umem);
  51. xdp_umem_unpin_pages(umem);
  52. xdp_umem_unaccount_pages(umem);
  53. kfree(umem);
  54. }
  55. static void xdp_umem_release_deferred(struct work_struct *work)
  56. {
  57. struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
  58. xdp_umem_release(umem);
  59. }
  60. void xdp_get_umem(struct xdp_umem *umem)
  61. {
  62. refcount_inc(&umem->users);
  63. }
  64. void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup)
  65. {
  66. if (!umem)
  67. return;
  68. if (refcount_dec_and_test(&umem->users)) {
  69. if (defer_cleanup) {
  70. INIT_WORK(&umem->work, xdp_umem_release_deferred);
  71. schedule_work(&umem->work);
  72. } else {
  73. xdp_umem_release(umem);
  74. }
  75. }
  76. }
  77. static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
  78. {
  79. unsigned int gup_flags = FOLL_WRITE;
  80. long npgs;
  81. int err;
  82. umem->pgs = kvcalloc(umem->npgs, sizeof(*umem->pgs), GFP_KERNEL | __GFP_NOWARN);
  83. if (!umem->pgs)
  84. return -ENOMEM;
  85. mmap_read_lock(current->mm);
  86. npgs = pin_user_pages(address, umem->npgs,
  87. gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
  88. mmap_read_unlock(current->mm);
  89. if (npgs != umem->npgs) {
  90. if (npgs >= 0) {
  91. umem->npgs = npgs;
  92. err = -ENOMEM;
  93. goto out_pin;
  94. }
  95. err = npgs;
  96. goto out_pgs;
  97. }
  98. return 0;
  99. out_pin:
  100. xdp_umem_unpin_pages(umem);
  101. out_pgs:
  102. kvfree(umem->pgs);
  103. umem->pgs = NULL;
  104. return err;
  105. }
  106. static int xdp_umem_account_pages(struct xdp_umem *umem)
  107. {
  108. unsigned long lock_limit, new_npgs, old_npgs;
  109. if (capable(CAP_IPC_LOCK))
  110. return 0;
  111. lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  112. umem->user = get_uid(current_user());
  113. do {
  114. old_npgs = atomic_long_read(&umem->user->locked_vm);
  115. new_npgs = old_npgs + umem->npgs;
  116. if (new_npgs > lock_limit) {
  117. free_uid(umem->user);
  118. umem->user = NULL;
  119. return -ENOBUFS;
  120. }
  121. } while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
  122. new_npgs) != old_npgs);
  123. return 0;
  124. }
  125. static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
  126. {
  127. bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
  128. u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
  129. u64 addr = mr->addr, size = mr->len;
  130. u32 chunks_rem, npgs_rem;
  131. u64 chunks, npgs;
  132. int err;
  133. if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
  134. /* Strictly speaking we could support this, if:
  135. * - huge pages, or*
  136. * - using an IOMMU, or
  137. * - making sure the memory area is consecutive
  138. * but for now, we simply say "computer says no".
  139. */
  140. return -EINVAL;
  141. }
  142. if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
  143. return -EINVAL;
  144. if (!unaligned_chunks && !is_power_of_2(chunk_size))
  145. return -EINVAL;
  146. if (!PAGE_ALIGNED(addr)) {
  147. /* Memory area has to be page size aligned. For
  148. * simplicity, this might change.
  149. */
  150. return -EINVAL;
  151. }
  152. if ((addr + size) < addr)
  153. return -EINVAL;
  154. npgs = div_u64_rem(size, PAGE_SIZE, &npgs_rem);
  155. if (npgs_rem)
  156. npgs++;
  157. if (npgs > U32_MAX)
  158. return -EINVAL;
  159. chunks = div_u64_rem(size, chunk_size, &chunks_rem);
  160. if (!chunks || chunks > U32_MAX)
  161. return -EINVAL;
  162. if (!unaligned_chunks && chunks_rem)
  163. return -EINVAL;
  164. if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
  165. return -EINVAL;
  166. umem->size = size;
  167. umem->headroom = headroom;
  168. umem->chunk_size = chunk_size;
  169. umem->chunks = chunks;
  170. umem->npgs = npgs;
  171. umem->pgs = NULL;
  172. umem->user = NULL;
  173. umem->flags = mr->flags;
  174. INIT_LIST_HEAD(&umem->xsk_dma_list);
  175. refcount_set(&umem->users, 1);
  176. err = xdp_umem_account_pages(umem);
  177. if (err)
  178. return err;
  179. err = xdp_umem_pin_pages(umem, (unsigned long)addr);
  180. if (err)
  181. goto out_account;
  182. err = xdp_umem_addr_map(umem, umem->pgs, umem->npgs);
  183. if (err)
  184. goto out_unpin;
  185. return 0;
  186. out_unpin:
  187. xdp_umem_unpin_pages(umem);
  188. out_account:
  189. xdp_umem_unaccount_pages(umem);
  190. return err;
  191. }
  192. struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
  193. {
  194. struct xdp_umem *umem;
  195. int err;
  196. umem = kzalloc(sizeof(*umem), GFP_KERNEL);
  197. if (!umem)
  198. return ERR_PTR(-ENOMEM);
  199. err = ida_alloc(&umem_ida, GFP_KERNEL);
  200. if (err < 0) {
  201. kfree(umem);
  202. return ERR_PTR(err);
  203. }
  204. umem->id = err;
  205. err = xdp_umem_reg(umem, mr);
  206. if (err) {
  207. ida_free(&umem_ida, umem->id);
  208. kfree(umem);
  209. return ERR_PTR(err);
  210. }
  211. return umem;
  212. }