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;
+}