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-rw-r--r--io_uring/kbuf.c555
1 files changed, 555 insertions, 0 deletions
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
new file mode 100644
index 000000000..57ef6850c
--- /dev/null
+++ b/io_uring/kbuf.c
@@ -0,0 +1,555 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/poll.h>
+#include <linux/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io_uring.h"
+#include "opdef.h"
+#include "kbuf.h"
+
+#define IO_BUFFER_LIST_BUF_PER_PAGE (PAGE_SIZE / sizeof(struct io_uring_buf))
+
+#define BGID_ARRAY 64
+
+/* BIDs are addressed by a 16-bit field in a CQE */
+#define MAX_BIDS_PER_BGID (1 << 16)
+
+struct io_provide_buf {
+ struct file *file;
+ __u64 addr;
+ __u32 len;
+ __u32 bgid;
+ __u32 nbufs;
+ __u16 bid;
+};
+
+static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
+ unsigned int bgid)
+{
+ if (ctx->io_bl && bgid < BGID_ARRAY)
+ return &ctx->io_bl[bgid];
+
+ return xa_load(&ctx->io_bl_xa, bgid);
+}
+
+static int io_buffer_add_list(struct io_ring_ctx *ctx,
+ struct io_buffer_list *bl, unsigned int bgid)
+{
+ bl->bgid = bgid;
+ if (bgid < BGID_ARRAY)
+ return 0;
+
+ return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));
+}
+
+void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_buffer_list *bl;
+ struct io_buffer *buf;
+
+ /*
+ * For legacy provided buffer mode, don't recycle if we already did
+ * IO to this buffer. For ring-mapped provided buffer mode, we should
+ * increment ring->head to explicitly monopolize the buffer to avoid
+ * multiple use.
+ */
+ if (req->flags & REQ_F_PARTIAL_IO)
+ return;
+
+ io_ring_submit_lock(ctx, issue_flags);
+
+ buf = req->kbuf;
+ bl = io_buffer_get_list(ctx, buf->bgid);
+ list_add(&buf->list, &bl->buf_list);
+ req->flags &= ~REQ_F_BUFFER_SELECTED;
+ req->buf_index = buf->bgid;
+
+ io_ring_submit_unlock(ctx, issue_flags);
+ return;
+}
+
+unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags)
+{
+ unsigned int cflags;
+
+ /*
+ * We can add this buffer back to two lists:
+ *
+ * 1) The io_buffers_cache list. This one is protected by the
+ * ctx->uring_lock. If we already hold this lock, add back to this
+ * list as we can grab it from issue as well.
+ * 2) The io_buffers_comp list. This one is protected by the
+ * ctx->completion_lock.
+ *
+ * We migrate buffers from the comp_list to the issue cache list
+ * when we need one.
+ */
+ if (req->flags & REQ_F_BUFFER_RING) {
+ /* no buffers to recycle for this case */
+ cflags = __io_put_kbuf_list(req, NULL);
+ } else if (issue_flags & IO_URING_F_UNLOCKED) {
+ struct io_ring_ctx *ctx = req->ctx;
+
+ spin_lock(&ctx->completion_lock);
+ cflags = __io_put_kbuf_list(req, &ctx->io_buffers_comp);
+ spin_unlock(&ctx->completion_lock);
+ } else {
+ lockdep_assert_held(&req->ctx->uring_lock);
+
+ cflags = __io_put_kbuf_list(req, &req->ctx->io_buffers_cache);
+ }
+ return cflags;
+}
+
+static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,
+ struct io_buffer_list *bl)
+{
+ if (!list_empty(&bl->buf_list)) {
+ struct io_buffer *kbuf;
+
+ kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list);
+ list_del(&kbuf->list);
+ if (*len == 0 || *len > kbuf->len)
+ *len = kbuf->len;
+ req->flags |= REQ_F_BUFFER_SELECTED;
+ req->kbuf = kbuf;
+ req->buf_index = kbuf->bid;
+ return u64_to_user_ptr(kbuf->addr);
+ }
+ return NULL;
+}
+
+static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,
+ struct io_buffer_list *bl,
+ unsigned int issue_flags)
+{
+ struct io_uring_buf_ring *br = bl->buf_ring;
+ struct io_uring_buf *buf;
+ __u16 head = bl->head;
+
+ if (unlikely(smp_load_acquire(&br->tail) == head))
+ return NULL;
+
+ head &= bl->mask;
+ if (head < IO_BUFFER_LIST_BUF_PER_PAGE) {
+ buf = &br->bufs[head];
+ } else {
+ int off = head & (IO_BUFFER_LIST_BUF_PER_PAGE - 1);
+ int index = head / IO_BUFFER_LIST_BUF_PER_PAGE;
+ buf = page_address(bl->buf_pages[index]);
+ buf += off;
+ }
+ if (*len == 0 || *len > buf->len)
+ *len = buf->len;
+ req->flags |= REQ_F_BUFFER_RING;
+ req->buf_list = bl;
+ req->buf_index = buf->bid;
+
+ if (issue_flags & IO_URING_F_UNLOCKED || !file_can_poll(req->file)) {
+ /*
+ * If we came in unlocked, we have no choice but to consume the
+ * buffer here, otherwise nothing ensures that the buffer won't
+ * get used by others. This does mean it'll be pinned until the
+ * IO completes, coming in unlocked means we're being called from
+ * io-wq context and there may be further retries in async hybrid
+ * mode. For the locked case, the caller must call commit when
+ * the transfer completes (or if we get -EAGAIN and must poll of
+ * retry).
+ */
+ req->buf_list = NULL;
+ bl->head++;
+ }
+ return u64_to_user_ptr(buf->addr);
+}
+
+void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
+ unsigned int issue_flags)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_buffer_list *bl;
+ void __user *ret = NULL;
+
+ io_ring_submit_lock(req->ctx, issue_flags);
+
+ bl = io_buffer_get_list(ctx, req->buf_index);
+ if (likely(bl)) {
+ if (bl->buf_nr_pages)
+ ret = io_ring_buffer_select(req, len, bl, issue_flags);
+ else
+ ret = io_provided_buffer_select(req, len, bl);
+ }
+ io_ring_submit_unlock(req->ctx, issue_flags);
+ return ret;
+}
+
+static __cold int io_init_bl_list(struct io_ring_ctx *ctx)
+{
+ int i;
+
+ ctx->io_bl = kcalloc(BGID_ARRAY, sizeof(struct io_buffer_list),
+ GFP_KERNEL);
+ if (!ctx->io_bl)
+ return -ENOMEM;
+
+ for (i = 0; i < BGID_ARRAY; i++) {
+ INIT_LIST_HEAD(&ctx->io_bl[i].buf_list);
+ ctx->io_bl[i].bgid = i;
+ }
+
+ return 0;
+}
+
+static int __io_remove_buffers(struct io_ring_ctx *ctx,
+ struct io_buffer_list *bl, unsigned nbufs)
+{
+ unsigned i = 0;
+
+ /* shouldn't happen */
+ if (!nbufs)
+ return 0;
+
+ if (bl->buf_nr_pages) {
+ int j;
+
+ i = bl->buf_ring->tail - bl->head;
+ for (j = 0; j < bl->buf_nr_pages; j++)
+ unpin_user_page(bl->buf_pages[j]);
+ kvfree(bl->buf_pages);
+ bl->buf_pages = NULL;
+ bl->buf_nr_pages = 0;
+ /* make sure it's seen as empty */
+ INIT_LIST_HEAD(&bl->buf_list);
+ return i;
+ }
+
+ /* protects io_buffers_cache */
+ lockdep_assert_held(&ctx->uring_lock);
+
+ while (!list_empty(&bl->buf_list)) {
+ struct io_buffer *nxt;
+
+ nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);
+ list_move(&nxt->list, &ctx->io_buffers_cache);
+ if (++i == nbufs)
+ return i;
+ cond_resched();
+ }
+
+ return i;
+}
+
+void io_destroy_buffers(struct io_ring_ctx *ctx)
+{
+ struct io_buffer_list *bl;
+ unsigned long index;
+ int i;
+
+ for (i = 0; i < BGID_ARRAY; i++) {
+ if (!ctx->io_bl)
+ break;
+ __io_remove_buffers(ctx, &ctx->io_bl[i], -1U);
+ }
+
+ xa_for_each(&ctx->io_bl_xa, index, bl) {
+ xa_erase(&ctx->io_bl_xa, bl->bgid);
+ __io_remove_buffers(ctx, bl, -1U);
+ kfree(bl);
+ }
+
+ while (!list_empty(&ctx->io_buffers_pages)) {
+ struct page *page;
+
+ page = list_first_entry(&ctx->io_buffers_pages, struct page, lru);
+ list_del_init(&page->lru);
+ __free_page(page);
+ }
+}
+
+int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
+ u64 tmp;
+
+ if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off ||
+ sqe->splice_fd_in)
+ return -EINVAL;
+
+ tmp = READ_ONCE(sqe->fd);
+ if (!tmp || tmp > MAX_BIDS_PER_BGID)
+ return -EINVAL;
+
+ memset(p, 0, sizeof(*p));
+ p->nbufs = tmp;
+ p->bgid = READ_ONCE(sqe->buf_group);
+ return 0;
+}
+
+int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
+{
+ struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_buffer_list *bl;
+ int ret = 0;
+
+ io_ring_submit_lock(ctx, issue_flags);
+
+ ret = -ENOENT;
+ bl = io_buffer_get_list(ctx, p->bgid);
+ if (bl) {
+ ret = -EINVAL;
+ /* can't use provide/remove buffers command on mapped buffers */
+ if (!bl->buf_nr_pages)
+ ret = __io_remove_buffers(ctx, bl, p->nbufs);
+ }
+ if (ret < 0)
+ req_set_fail(req);
+
+ /* complete before unlock, IOPOLL may need the lock */
+ io_req_set_res(req, ret, 0);
+ __io_req_complete(req, issue_flags);
+ io_ring_submit_unlock(ctx, issue_flags);
+ return IOU_ISSUE_SKIP_COMPLETE;
+}
+
+int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ unsigned long size, tmp_check;
+ struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
+ u64 tmp;
+
+ if (sqe->rw_flags || sqe->splice_fd_in)
+ return -EINVAL;
+
+ tmp = READ_ONCE(sqe->fd);
+ if (!tmp || tmp > MAX_BIDS_PER_BGID)
+ return -E2BIG;
+ p->nbufs = tmp;
+ p->addr = READ_ONCE(sqe->addr);
+ p->len = READ_ONCE(sqe->len);
+
+ if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs,
+ &size))
+ return -EOVERFLOW;
+ if (check_add_overflow((unsigned long)p->addr, size, &tmp_check))
+ return -EOVERFLOW;
+
+ size = (unsigned long)p->len * p->nbufs;
+ if (!access_ok(u64_to_user_ptr(p->addr), size))
+ return -EFAULT;
+
+ p->bgid = READ_ONCE(sqe->buf_group);
+ tmp = READ_ONCE(sqe->off);
+ if (tmp > USHRT_MAX)
+ return -E2BIG;
+ if (tmp + p->nbufs > MAX_BIDS_PER_BGID)
+ return -EINVAL;
+ p->bid = tmp;
+ return 0;
+}
+
+static int io_refill_buffer_cache(struct io_ring_ctx *ctx)
+{
+ struct io_buffer *buf;
+ struct page *page;
+ int bufs_in_page;
+
+ /*
+ * Completions that don't happen inline (eg not under uring_lock) will
+ * add to ->io_buffers_comp. If we don't have any free buffers, check
+ * the completion list and splice those entries first.
+ */
+ if (!list_empty_careful(&ctx->io_buffers_comp)) {
+ spin_lock(&ctx->completion_lock);
+ if (!list_empty(&ctx->io_buffers_comp)) {
+ list_splice_init(&ctx->io_buffers_comp,
+ &ctx->io_buffers_cache);
+ spin_unlock(&ctx->completion_lock);
+ return 0;
+ }
+ spin_unlock(&ctx->completion_lock);
+ }
+
+ /*
+ * No free buffers and no completion entries either. Allocate a new
+ * page worth of buffer entries and add those to our freelist.
+ */
+ page = alloc_page(GFP_KERNEL_ACCOUNT);
+ if (!page)
+ return -ENOMEM;
+
+ list_add(&page->lru, &ctx->io_buffers_pages);
+
+ buf = page_address(page);
+ bufs_in_page = PAGE_SIZE / sizeof(*buf);
+ while (bufs_in_page) {
+ list_add_tail(&buf->list, &ctx->io_buffers_cache);
+ buf++;
+ bufs_in_page--;
+ }
+
+ return 0;
+}
+
+static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf,
+ struct io_buffer_list *bl)
+{
+ struct io_buffer *buf;
+ u64 addr = pbuf->addr;
+ int i, bid = pbuf->bid;
+
+ for (i = 0; i < pbuf->nbufs; i++) {
+ if (list_empty(&ctx->io_buffers_cache) &&
+ io_refill_buffer_cache(ctx))
+ break;
+ buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer,
+ list);
+ list_move_tail(&buf->list, &bl->buf_list);
+ buf->addr = addr;
+ buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);
+ buf->bid = bid;
+ buf->bgid = pbuf->bgid;
+ addr += pbuf->len;
+ bid++;
+ cond_resched();
+ }
+
+ return i ? 0 : -ENOMEM;
+}
+
+int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
+{
+ struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_buffer_list *bl;
+ int ret = 0;
+
+ io_ring_submit_lock(ctx, issue_flags);
+
+ if (unlikely(p->bgid < BGID_ARRAY && !ctx->io_bl)) {
+ ret = io_init_bl_list(ctx);
+ if (ret)
+ goto err;
+ }
+
+ bl = io_buffer_get_list(ctx, p->bgid);
+ if (unlikely(!bl)) {
+ bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT);
+ if (!bl) {
+ ret = -ENOMEM;
+ goto err;
+ }
+ INIT_LIST_HEAD(&bl->buf_list);
+ ret = io_buffer_add_list(ctx, bl, p->bgid);
+ if (ret) {
+ kfree(bl);
+ goto err;
+ }
+ }
+ /* can't add buffers via this command for a mapped buffer ring */
+ if (bl->buf_nr_pages) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ret = io_add_buffers(ctx, p, bl);
+err:
+ if (ret < 0)
+ req_set_fail(req);
+ /* complete before unlock, IOPOLL may need the lock */
+ io_req_set_res(req, ret, 0);
+ __io_req_complete(req, issue_flags);
+ io_ring_submit_unlock(ctx, issue_flags);
+ return IOU_ISSUE_SKIP_COMPLETE;
+}
+
+int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
+{
+ struct io_uring_buf_ring *br;
+ struct io_uring_buf_reg reg;
+ struct io_buffer_list *bl, *free_bl = NULL;
+ struct page **pages;
+ int nr_pages;
+
+ if (copy_from_user(&reg, arg, sizeof(reg)))
+ return -EFAULT;
+
+ if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
+ return -EINVAL;
+ if (!reg.ring_addr)
+ return -EFAULT;
+ if (reg.ring_addr & ~PAGE_MASK)
+ return -EINVAL;
+ if (!is_power_of_2(reg.ring_entries))
+ return -EINVAL;
+
+ /* cannot disambiguate full vs empty due to head/tail size */
+ if (reg.ring_entries >= 65536)
+ return -EINVAL;
+
+ if (unlikely(reg.bgid < BGID_ARRAY && !ctx->io_bl)) {
+ int ret = io_init_bl_list(ctx);
+ if (ret)
+ return ret;
+ }
+
+ bl = io_buffer_get_list(ctx, reg.bgid);
+ if (bl) {
+ /* if mapped buffer ring OR classic exists, don't allow */
+ if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
+ return -EEXIST;
+ } else {
+ free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+ if (!bl)
+ return -ENOMEM;
+ }
+
+ pages = io_pin_pages(reg.ring_addr,
+ flex_array_size(br, bufs, reg.ring_entries),
+ &nr_pages);
+ if (IS_ERR(pages)) {
+ kfree(free_bl);
+ return PTR_ERR(pages);
+ }
+
+ br = page_address(pages[0]);
+ bl->buf_pages = pages;
+ bl->buf_nr_pages = nr_pages;
+ bl->nr_entries = reg.ring_entries;
+ bl->buf_ring = br;
+ bl->mask = reg.ring_entries - 1;
+ io_buffer_add_list(ctx, bl, reg.bgid);
+ return 0;
+}
+
+int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
+{
+ struct io_uring_buf_reg reg;
+ struct io_buffer_list *bl;
+
+ if (copy_from_user(&reg, arg, sizeof(reg)))
+ return -EFAULT;
+ if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
+ return -EINVAL;
+
+ bl = io_buffer_get_list(ctx, reg.bgid);
+ if (!bl)
+ return -ENOENT;
+ if (!bl->buf_nr_pages)
+ return -EINVAL;
+
+ __io_remove_buffers(ctx, bl, -1U);
+ if (bl->bgid >= BGID_ARRAY) {
+ xa_erase(&ctx->io_bl_xa, bl->bgid);
+ kfree(bl);
+ }
+ return 0;
+}