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1// SPDX-License-Identifier: GPL-2.02#include <linux/kernel.h>3#include <linux/errno.h>4#include <linux/fs.h>5#include <linux/file.h>6#include <linux/mm.h>7#include <linux/slab.h>8#include <linux/namei.h>9#include <linux/poll.h>10#include <linux/vmalloc.h>11#include <linux/io_uring.h>12 13#include <uapi/linux/io_uring.h>14 15#include "io_uring.h"16#include "opdef.h"17#include "kbuf.h"18#include "memmap.h"19 20/* BIDs are addressed by a 16-bit field in a CQE */21#define MAX_BIDS_PER_BGID (1 << 16)22 23struct kmem_cache *io_buf_cachep;24 25struct io_provide_buf {26 struct file *file;27 __u64 addr;28 __u32 len;29 __u32 bgid;30 __u32 nbufs;31 __u16 bid;32};33 34static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,35 unsigned int bgid)36{37 lockdep_assert_held(&ctx->uring_lock);38 39 return xa_load(&ctx->io_bl_xa, bgid);40}41 42static int io_buffer_add_list(struct io_ring_ctx *ctx,43 struct io_buffer_list *bl, unsigned int bgid)44{45 /*46 * Store buffer group ID and finally mark the list as visible.47 * The normal lookup doesn't care about the visibility as we're48 * always under the ->uring_lock, but the RCU lookup from mmap does.49 */50 bl->bgid = bgid;51 atomic_set(&bl->refs, 1);52 return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));53}54 55bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags)56{57 struct io_ring_ctx *ctx = req->ctx;58 struct io_buffer_list *bl;59 struct io_buffer *buf;60 61 io_ring_submit_lock(ctx, issue_flags);62 63 buf = req->kbuf;64 bl = io_buffer_get_list(ctx, buf->bgid);65 list_add(&buf->list, &bl->buf_list);66 req->flags &= ~REQ_F_BUFFER_SELECTED;67 req->buf_index = buf->bgid;68 69 io_ring_submit_unlock(ctx, issue_flags);70 return true;71}72 73void __io_put_kbuf(struct io_kiocb *req, int len, unsigned issue_flags)74{75 /*76 * We can add this buffer back to two lists:77 *78 * 1) The io_buffers_cache list. This one is protected by the79 * ctx->uring_lock. If we already hold this lock, add back to this80 * list as we can grab it from issue as well.81 * 2) The io_buffers_comp list. This one is protected by the82 * ctx->completion_lock.83 *84 * We migrate buffers from the comp_list to the issue cache list85 * when we need one.86 */87 if (issue_flags & IO_URING_F_UNLOCKED) {88 struct io_ring_ctx *ctx = req->ctx;89 90 spin_lock(&ctx->completion_lock);91 __io_put_kbuf_list(req, len, &ctx->io_buffers_comp);92 spin_unlock(&ctx->completion_lock);93 } else {94 lockdep_assert_held(&req->ctx->uring_lock);95 96 __io_put_kbuf_list(req, len, &req->ctx->io_buffers_cache);97 }98}99 100static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,101 struct io_buffer_list *bl)102{103 if (!list_empty(&bl->buf_list)) {104 struct io_buffer *kbuf;105 106 kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list);107 list_del(&kbuf->list);108 if (*len == 0 || *len > kbuf->len)109 *len = kbuf->len;110 if (list_empty(&bl->buf_list))111 req->flags |= REQ_F_BL_EMPTY;112 req->flags |= REQ_F_BUFFER_SELECTED;113 req->kbuf = kbuf;114 req->buf_index = kbuf->bid;115 return u64_to_user_ptr(kbuf->addr);116 }117 return NULL;118}119 120static int io_provided_buffers_select(struct io_kiocb *req, size_t *len,121 struct io_buffer_list *bl,122 struct iovec *iov)123{124 void __user *buf;125 126 buf = io_provided_buffer_select(req, len, bl);127 if (unlikely(!buf))128 return -ENOBUFS;129 130 iov[0].iov_base = buf;131 iov[0].iov_len = *len;132 return 1;133}134 135static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,136 struct io_buffer_list *bl,137 unsigned int issue_flags)138{139 struct io_uring_buf_ring *br = bl->buf_ring;140 __u16 tail, head = bl->head;141 struct io_uring_buf *buf;142 143 tail = smp_load_acquire(&br->tail);144 if (unlikely(tail == head))145 return NULL;146 147 if (head + 1 == tail)148 req->flags |= REQ_F_BL_EMPTY;149 150 buf = io_ring_head_to_buf(br, head, bl->mask);151 if (*len == 0 || *len > buf->len)152 *len = buf->len;153 req->flags |= REQ_F_BUFFER_RING | REQ_F_BUFFERS_COMMIT;154 req->buf_list = bl;155 req->buf_index = buf->bid;156 157 if (issue_flags & IO_URING_F_UNLOCKED || !io_file_can_poll(req)) {158 /*159 * If we came in unlocked, we have no choice but to consume the160 * buffer here, otherwise nothing ensures that the buffer won't161 * get used by others. This does mean it'll be pinned until the162 * IO completes, coming in unlocked means we're being called from163 * io-wq context and there may be further retries in async hybrid164 * mode. For the locked case, the caller must call commit when165 * the transfer completes (or if we get -EAGAIN and must poll of166 * retry).167 */168 io_kbuf_commit(req, bl, *len, 1);169 req->buf_list = NULL;170 }171 return u64_to_user_ptr(buf->addr);172}173 174void __user *io_buffer_select(struct io_kiocb *req, size_t *len,175 unsigned int issue_flags)176{177 struct io_ring_ctx *ctx = req->ctx;178 struct io_buffer_list *bl;179 void __user *ret = NULL;180 181 io_ring_submit_lock(req->ctx, issue_flags);182 183 bl = io_buffer_get_list(ctx, req->buf_index);184 if (likely(bl)) {185 if (bl->flags & IOBL_BUF_RING)186 ret = io_ring_buffer_select(req, len, bl, issue_flags);187 else188 ret = io_provided_buffer_select(req, len, bl);189 }190 io_ring_submit_unlock(req->ctx, issue_flags);191 return ret;192}193 194/* cap it at a reasonable 256, will be one page even for 4K */195#define PEEK_MAX_IMPORT 256196 197static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,198 struct io_buffer_list *bl)199{200 struct io_uring_buf_ring *br = bl->buf_ring;201 struct iovec *iov = arg->iovs;202 int nr_iovs = arg->nr_iovs;203 __u16 nr_avail, tail, head;204 struct io_uring_buf *buf;205 206 tail = smp_load_acquire(&br->tail);207 head = bl->head;208 nr_avail = min_t(__u16, tail - head, UIO_MAXIOV);209 if (unlikely(!nr_avail))210 return -ENOBUFS;211 212 buf = io_ring_head_to_buf(br, head, bl->mask);213 if (arg->max_len) {214 u32 len = READ_ONCE(buf->len);215 216 if (unlikely(!len))217 return -ENOBUFS;218 /*219 * Limit incremental buffers to 1 segment. No point trying220 * to peek ahead and map more than we need, when the buffers221 * themselves should be large when setup with222 * IOU_PBUF_RING_INC.223 */224 if (bl->flags & IOBL_INC) {225 nr_avail = 1;226 } else {227 size_t needed;228 229 needed = (arg->max_len + len - 1) / len;230 needed = min_not_zero(needed, (size_t) PEEK_MAX_IMPORT);231 if (nr_avail > needed)232 nr_avail = needed;233 }234 }235 236 /*237 * only alloc a bigger array if we know we have data to map, eg not238 * a speculative peek operation.239 */240 if (arg->mode & KBUF_MODE_EXPAND && nr_avail > nr_iovs && arg->max_len) {241 iov = kmalloc_array(nr_avail, sizeof(struct iovec), GFP_KERNEL);242 if (unlikely(!iov))243 return -ENOMEM;244 if (arg->mode & KBUF_MODE_FREE)245 kfree(arg->iovs);246 arg->iovs = iov;247 nr_iovs = nr_avail;248 } else if (nr_avail < nr_iovs) {249 nr_iovs = nr_avail;250 }251 252 /* set it to max, if not set, so we can use it unconditionally */253 if (!arg->max_len)254 arg->max_len = INT_MAX;255 256 req->buf_index = buf->bid;257 do {258 u32 len = buf->len;259 260 /* truncate end piece, if needed, for non partial buffers */261 if (len > arg->max_len) {262 len = arg->max_len;263 if (!(bl->flags & IOBL_INC))264 buf->len = len;265 }266 267 iov->iov_base = u64_to_user_ptr(buf->addr);268 iov->iov_len = len;269 iov++;270 271 arg->out_len += len;272 arg->max_len -= len;273 if (!arg->max_len)274 break;275 276 buf = io_ring_head_to_buf(br, ++head, bl->mask);277 } while (--nr_iovs);278 279 if (head == tail)280 req->flags |= REQ_F_BL_EMPTY;281 282 req->flags |= REQ_F_BUFFER_RING;283 req->buf_list = bl;284 return iov - arg->iovs;285}286 287int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg,288 unsigned int issue_flags)289{290 struct io_ring_ctx *ctx = req->ctx;291 struct io_buffer_list *bl;292 int ret = -ENOENT;293 294 io_ring_submit_lock(ctx, issue_flags);295 bl = io_buffer_get_list(ctx, req->buf_index);296 if (unlikely(!bl))297 goto out_unlock;298 299 if (bl->flags & IOBL_BUF_RING) {300 ret = io_ring_buffers_peek(req, arg, bl);301 /*302 * Don't recycle these buffers if we need to go through poll.303 * Nobody else can use them anyway, and holding on to provided304 * buffers for a send/write operation would happen on the app305 * side anyway with normal buffers. Besides, we already306 * committed them, they cannot be put back in the queue.307 */308 if (ret > 0) {309 req->flags |= REQ_F_BUFFERS_COMMIT | REQ_F_BL_NO_RECYCLE;310 io_kbuf_commit(req, bl, arg->out_len, ret);311 }312 } else {313 ret = io_provided_buffers_select(req, &arg->out_len, bl, arg->iovs);314 }315out_unlock:316 io_ring_submit_unlock(ctx, issue_flags);317 return ret;318}319 320int io_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg)321{322 struct io_ring_ctx *ctx = req->ctx;323 struct io_buffer_list *bl;324 int ret;325 326 lockdep_assert_held(&ctx->uring_lock);327 328 bl = io_buffer_get_list(ctx, req->buf_index);329 if (unlikely(!bl))330 return -ENOENT;331 332 if (bl->flags & IOBL_BUF_RING) {333 ret = io_ring_buffers_peek(req, arg, bl);334 if (ret > 0)335 req->flags |= REQ_F_BUFFERS_COMMIT;336 return ret;337 }338 339 /* don't support multiple buffer selections for legacy */340 return io_provided_buffers_select(req, &arg->max_len, bl, arg->iovs);341}342 343static HWJS_SUSPENDS int __io_remove_buffers(struct io_ring_ctx *ctx,344 struct io_buffer_list *bl, unsigned nbufs)345{346 unsigned i = 0;347 348 /* shouldn't happen */349 if (!nbufs)350 return 0;351 352 if (bl->flags & IOBL_BUF_RING) {353 i = bl->buf_ring->tail - bl->head;354 if (bl->buf_nr_pages) {355 int j;356 357 if (!(bl->flags & IOBL_MMAP)) {358 for (j = 0; j < bl->buf_nr_pages; j++)359 unpin_user_page(bl->buf_pages[j]);360 }361 io_pages_unmap(bl->buf_ring, &bl->buf_pages,362 &bl->buf_nr_pages, bl->flags & IOBL_MMAP);363 bl->flags &= ~IOBL_MMAP;364 }365 /* make sure it's seen as empty */366 INIT_LIST_HEAD(&bl->buf_list);367 bl->flags &= ~IOBL_BUF_RING;368 return i;369 }370 371 /* protects io_buffers_cache */372 lockdep_assert_held(&ctx->uring_lock);373 374 while (!list_empty(&bl->buf_list)) {375 struct io_buffer *nxt;376 377 nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);378 list_move(&nxt->list, &ctx->io_buffers_cache);379 if (++i == nbufs)380 return i;381 cond_resched();382 }383 384 return i;385}386 387void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)388{389 if (atomic_dec_and_test(&bl->refs)) {390 __io_remove_buffers(ctx, bl, -1U);391 kfree_rcu(bl, rcu);392 }393}394 395void io_destroy_buffers(struct io_ring_ctx *ctx)396{397 struct io_buffer_list *bl;398 struct list_head *item, *tmp;399 struct io_buffer *buf;400 unsigned long index;401 402 xa_for_each(&ctx->io_bl_xa, index, bl) {403 xa_erase(&ctx->io_bl_xa, bl->bgid);404 io_put_bl(ctx, bl);405 }406 407 /*408 * Move deferred locked entries to cache before pruning409 */410 spin_lock(&ctx->completion_lock);411 if (!list_empty(&ctx->io_buffers_comp))412 list_splice_init(&ctx->io_buffers_comp, &ctx->io_buffers_cache);413 spin_unlock(&ctx->completion_lock);414 415 list_for_each_safe(item, tmp, &ctx->io_buffers_cache) {416 buf = list_entry(item, struct io_buffer, list);417 kmem_cache_free(io_buf_cachep, buf);418 }419}420 421int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)422{423 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);424 u64 tmp;425 426 if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off ||427 sqe->splice_fd_in)428 return -EINVAL;429 430 tmp = READ_ONCE(sqe->fd);431 if (!tmp || tmp > MAX_BIDS_PER_BGID)432 return -EINVAL;433 434 memset(p, 0, sizeof(*p));435 p->nbufs = tmp;436 p->bgid = READ_ONCE(sqe->buf_group);437 return 0;438}439 440int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)441{442 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);443 struct io_ring_ctx *ctx = req->ctx;444 struct io_buffer_list *bl;445 int ret = 0;446 447 io_ring_submit_lock(ctx, issue_flags);448 449 ret = -ENOENT;450 bl = io_buffer_get_list(ctx, p->bgid);451 if (bl) {452 ret = -EINVAL;453 /* can't use provide/remove buffers command on mapped buffers */454 if (!(bl->flags & IOBL_BUF_RING))455 ret = __io_remove_buffers(ctx, bl, p->nbufs);456 }457 io_ring_submit_unlock(ctx, issue_flags);458 if (ret < 0)459 req_set_fail(req);460 io_req_set_res(req, ret, 0);461 return IOU_OK;462}463 464int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)465{466 unsigned long size, tmp_check;467 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);468 u64 tmp;469 470 if (sqe->rw_flags || sqe->splice_fd_in)471 return -EINVAL;472 473 tmp = READ_ONCE(sqe->fd);474 if (!tmp || tmp > MAX_BIDS_PER_BGID)475 return -E2BIG;476 p->nbufs = tmp;477 p->addr = READ_ONCE(sqe->addr);478 p->len = READ_ONCE(sqe->len);479 480 if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs,481 &size))482 return -EOVERFLOW;483 if (check_add_overflow((unsigned long)p->addr, size, &tmp_check))484 return -EOVERFLOW;485 486 size = (unsigned long)p->len * p->nbufs;487 if (!access_ok(u64_to_user_ptr(p->addr), size))488 return -EFAULT;489 490 p->bgid = READ_ONCE(sqe->buf_group);491 tmp = READ_ONCE(sqe->off);492 if (tmp > USHRT_MAX)493 return -E2BIG;494 if (tmp + p->nbufs > MAX_BIDS_PER_BGID)495 return -EINVAL;496 p->bid = tmp;497 return 0;498}499 500#define IO_BUFFER_ALLOC_BATCH 64501 502static int io_refill_buffer_cache(struct io_ring_ctx *ctx)503{504 struct io_buffer *bufs[IO_BUFFER_ALLOC_BATCH];505 int allocated;506 507 /*508 * Completions that don't happen inline (eg not under uring_lock) will509 * add to ->io_buffers_comp. If we don't have any free buffers, check510 * the completion list and splice those entries first.511 */512 if (!list_empty_careful(&ctx->io_buffers_comp)) {513 spin_lock(&ctx->completion_lock);514 if (!list_empty(&ctx->io_buffers_comp)) {515 list_splice_init(&ctx->io_buffers_comp,516 &ctx->io_buffers_cache);517 spin_unlock(&ctx->completion_lock);518 return 0;519 }520 spin_unlock(&ctx->completion_lock);521 }522 523 /*524 * No free buffers and no completion entries either. Allocate a new525 * batch of buffer entries and add those to our freelist.526 */527 528 allocated = kmem_cache_alloc_bulk(io_buf_cachep, GFP_KERNEL_ACCOUNT,529 ARRAY_SIZE(bufs), (void **) bufs);530 if (unlikely(!allocated)) {531 /*532 * Bulk alloc is all-or-nothing. If we fail to get a batch,533 * retry single alloc to be on the safe side.534 */535 bufs[0] = kmem_cache_alloc(io_buf_cachep, GFP_KERNEL);536 if (!bufs[0])537 return -ENOMEM;538 allocated = 1;539 }540 541 while (allocated)542 list_add_tail(&bufs[--allocated]->list, &ctx->io_buffers_cache);543 544 return 0;545}546 547static HWJS_SUSPENDS int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf,548 struct io_buffer_list *bl)549{550 struct io_buffer *buf;551 u64 addr = pbuf->addr;552 int i, bid = pbuf->bid;553 554 for (i = 0; i < pbuf->nbufs; i++) {555 if (list_empty(&ctx->io_buffers_cache) &&556 io_refill_buffer_cache(ctx))557 break;558 buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer,559 list);560 list_move_tail(&buf->list, &bl->buf_list);561 buf->addr = addr;562 buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);563 buf->bid = bid;564 buf->bgid = pbuf->bgid;565 addr += pbuf->len;566 bid++;567 cond_resched();568 }569 570 return i ? 0 : -ENOMEM;571}572 573int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)574{575 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);576 struct io_ring_ctx *ctx = req->ctx;577 struct io_buffer_list *bl;578 int ret = 0;579 580 io_ring_submit_lock(ctx, issue_flags);581 582 bl = io_buffer_get_list(ctx, p->bgid);583 if (unlikely(!bl)) {584 bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT);585 if (!bl) {586 ret = -ENOMEM;587 goto err;588 }589 INIT_LIST_HEAD(&bl->buf_list);590 ret = io_buffer_add_list(ctx, bl, p->bgid);591 if (ret) {592 /*593 * Doesn't need rcu free as it was never visible, but594 * let's keep it consistent throughout.595 */596 kfree_rcu(bl, rcu);597 goto err;598 }599 }600 /* can't add buffers via this command for a mapped buffer ring */601 if (bl->flags & IOBL_BUF_RING) {602 ret = -EINVAL;603 goto err;604 }605 606 ret = io_add_buffers(ctx, p, bl);607err:608 io_ring_submit_unlock(ctx, issue_flags);609 610 if (ret < 0)611 req_set_fail(req);612 io_req_set_res(req, ret, 0);613 return IOU_OK;614}615 616static HWJS_SUSPENDS int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,617 struct io_buffer_list *bl)618{619 struct io_uring_buf_ring *br = NULL;620 struct page **pages;621 int nr_pages, ret;622 623 pages = io_pin_pages(reg->ring_addr,624 flex_array_size(br, bufs, reg->ring_entries),625 &nr_pages);626 if (IS_ERR(pages))627 return PTR_ERR(pages);628 629 br = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);630 if (!br) {631 ret = -ENOMEM;632 goto error_unpin;633 }634 635#ifdef SHM_COLOUR636 /*637 * On platforms that have specific aliasing requirements, SHM_COLOUR638 * is set and we must guarantee that the kernel and user side align639 * nicely. We cannot do that if IOU_PBUF_RING_MMAP isn't set and640 * the application mmap's the provided ring buffer. Fail the request641 * if we, by chance, don't end up with aligned addresses. The app642 * should use IOU_PBUF_RING_MMAP instead, and liburing will handle643 * this transparently.644 */645 if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1)) {646 ret = -EINVAL;647 goto error_unpin;648 }649#endif650 bl->buf_pages = pages;651 bl->buf_nr_pages = nr_pages;652 bl->buf_ring = br;653 bl->flags |= IOBL_BUF_RING;654 bl->flags &= ~IOBL_MMAP;655 return 0;656error_unpin:657 unpin_user_pages(pages, nr_pages);658 kvfree(pages);659 vunmap(br);660 return ret;661}662 663static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx,664 struct io_uring_buf_reg *reg,665 struct io_buffer_list *bl)666{667 size_t ring_size;668 669 ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);670 671 bl->buf_ring = io_pages_map(&bl->buf_pages, &bl->buf_nr_pages, ring_size);672 if (IS_ERR(bl->buf_ring)) {673 bl->buf_ring = NULL;674 return -ENOMEM;675 }676 677 bl->flags |= (IOBL_BUF_RING | IOBL_MMAP);678 return 0;679}680 681int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)682{683 struct io_uring_buf_reg reg;684 struct io_buffer_list *bl, *free_bl = NULL;685 int ret;686 687 lockdep_assert_held(&ctx->uring_lock);688 689 if (copy_from_user(®, arg, sizeof(reg)))690 return -EFAULT;691 692 if (reg.resv[0] || reg.resv[1] || reg.resv[2])693 return -EINVAL;694 if (reg.flags & ~(IOU_PBUF_RING_MMAP | IOU_PBUF_RING_INC))695 return -EINVAL;696 if (!(reg.flags & IOU_PBUF_RING_MMAP)) {697 if (!reg.ring_addr)698 return -EFAULT;699 if (reg.ring_addr & ~PAGE_MASK)700 return -EINVAL;701 } else {702 if (reg.ring_addr)703 return -EINVAL;704 }705 706 if (!is_power_of_2(reg.ring_entries))707 return -EINVAL;708 709 /* cannot disambiguate full vs empty due to head/tail size */710 if (reg.ring_entries >= 65536)711 return -EINVAL;712 713 bl = io_buffer_get_list(ctx, reg.bgid);714 if (bl) {715 /* if mapped buffer ring OR classic exists, don't allow */716 if (bl->flags & IOBL_BUF_RING || !list_empty(&bl->buf_list))717 return -EEXIST;718 } else {719 free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);720 if (!bl)721 return -ENOMEM;722 }723 724 if (!(reg.flags & IOU_PBUF_RING_MMAP))725 ret = io_pin_pbuf_ring(®, bl);726 else727 ret = io_alloc_pbuf_ring(ctx, ®, bl);728 729 if (!ret) {730 bl->nr_entries = reg.ring_entries;731 bl->mask = reg.ring_entries - 1;732 if (reg.flags & IOU_PBUF_RING_INC)733 bl->flags |= IOBL_INC;734 735 io_buffer_add_list(ctx, bl, reg.bgid);736 return 0;737 }738 739 kfree_rcu(free_bl, rcu);740 return ret;741}742 743int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)744{745 struct io_uring_buf_reg reg;746 struct io_buffer_list *bl;747 748 lockdep_assert_held(&ctx->uring_lock);749 750 if (copy_from_user(®, arg, sizeof(reg)))751 return -EFAULT;752 if (reg.resv[0] || reg.resv[1] || reg.resv[2])753 return -EINVAL;754 if (reg.flags)755 return -EINVAL;756 757 bl = io_buffer_get_list(ctx, reg.bgid);758 if (!bl)759 return -ENOENT;760 if (!(bl->flags & IOBL_BUF_RING))761 return -EINVAL;762 763 xa_erase(&ctx->io_bl_xa, bl->bgid);764 io_put_bl(ctx, bl);765 return 0;766}767 768int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg)769{770 struct io_uring_buf_status buf_status;771 struct io_buffer_list *bl;772 int i;773 774 if (copy_from_user(&buf_status, arg, sizeof(buf_status)))775 return -EFAULT;776 777 for (i = 0; i < ARRAY_SIZE(buf_status.resv); i++)778 if (buf_status.resv[i])779 return -EINVAL;780 781 bl = io_buffer_get_list(ctx, buf_status.buf_group);782 if (!bl)783 return -ENOENT;784 if (!(bl->flags & IOBL_BUF_RING))785 return -EINVAL;786 787 buf_status.head = bl->head;788 if (copy_to_user(arg, &buf_status, sizeof(buf_status)))789 return -EFAULT;790 791 return 0;792}793 794struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx,795 unsigned long bgid)796{797 struct io_buffer_list *bl;798 bool ret;799 800 /*801 * We have to be a bit careful here - we're inside mmap and cannot grab802 * the uring_lock. This means the buffer_list could be simultaneously803 * going away, if someone is trying to be sneaky. Look it up under rcu804 * so we know it's not going away, and attempt to grab a reference to805 * it. If the ref is already zero, then fail the mapping. If successful,806 * the caller will call io_put_bl() to drop the the reference at at the807 * end. This may then safely free the buffer_list (and drop the pages)808 * at that point, vm_insert_pages() would've already grabbed the809 * necessary vma references.810 */811 rcu_read_lock();812 bl = xa_load(&ctx->io_bl_xa, bgid);813 /* must be a mmap'able buffer ring and have pages */814 ret = false;815 if (bl && bl->flags & IOBL_MMAP)816 ret = atomic_inc_not_zero(&bl->refs);817 rcu_read_unlock();818 819 if (ret)820 return bl;821 822 return ERR_PTR(-EINVAL);823}824 825int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma)826{827 struct io_ring_ctx *ctx = file->private_data;828 loff_t pgoff = vma->vm_pgoff << PAGE_SHIFT;829 struct io_buffer_list *bl;830 int bgid, ret;831 832 bgid = (pgoff & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;833 bl = io_pbuf_get_bl(ctx, bgid);834 if (IS_ERR(bl))835 return PTR_ERR(bl);836 837 ret = io_uring_mmap_pages(ctx, vma, bl->buf_pages, bl->buf_nr_pages);838 io_put_bl(ctx, bl);839 return ret;840}841