OpenCloudOS-Kernel/io_uring/kbuf.c

739 lines
18 KiB
C

// 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))
/* 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)
{
return xa_load(&ctx->io_bl_xa, bgid);
}
struct io_buf_free {
struct hlist_node list;
void *mem;
size_t size;
int inuse;
};
static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
unsigned int bgid)
{
lockdep_assert_held(&ctx->uring_lock);
return __io_buffer_get_list(ctx, bgid);
}
static int io_buffer_add_list(struct io_ring_ctx *ctx,
struct io_buffer_list *bl, unsigned int bgid)
{
/*
* Store buffer group ID and finally mark the list as visible.
* The normal lookup doesn't care about the visibility as we're
* always under the ->uring_lock, but the RCU lookup from mmap does.
*/
bl->bgid = bgid;
atomic_set(&bl->refs, 1);
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;
/* mmaped buffers are always contig */
if (bl->is_mmap || 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 ||
(req->file && !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->is_mapped)
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;
}
/*
* Mark the given mapped range as free for reuse
*/
static void io_kbuf_mark_free(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
{
struct io_buf_free *ibf;
hlist_for_each_entry(ibf, &ctx->io_buf_list, list) {
if (bl->buf_ring == ibf->mem) {
ibf->inuse = 0;
return;
}
}
/* can't happen... */
WARN_ON_ONCE(1);
}
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->is_mapped) {
i = bl->buf_ring->tail - bl->head;
if (bl->is_mmap) {
/*
* io_kbuf_list_free() will free the page(s) at
* ->release() time.
*/
io_kbuf_mark_free(ctx, bl);
bl->buf_ring = NULL;
bl->is_mmap = 0;
} else if (bl->buf_nr_pages) {
int j;
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);
bl->is_mapped = 0;
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_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
{
if (atomic_dec_and_test(&bl->refs)) {
__io_remove_buffers(ctx, bl, -1U);
kfree_rcu(bl, rcu);
}
}
void io_destroy_buffers(struct io_ring_ctx *ctx)
{
struct io_buffer_list *bl;
unsigned long index;
xa_for_each(&ctx->io_bl_xa, index, bl) {
xa_erase(&ctx->io_bl_xa, bl->bgid);
io_put_bl(ctx, 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->is_mapped)
ret = __io_remove_buffers(ctx, bl, p->nbufs);
}
io_ring_submit_unlock(ctx, issue_flags);
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}
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);
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) {
/*
* Doesn't need rcu free as it was never visible, but
* let's keep it consistent throughout.
*/
kfree_rcu(bl, rcu);
goto err;
}
}
/* can't add buffers via this command for a mapped buffer ring */
if (bl->is_mapped) {
ret = -EINVAL;
goto err;
}
ret = io_add_buffers(ctx, p, bl);
err:
io_ring_submit_unlock(ctx, issue_flags);
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}
static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
struct io_buffer_list *bl)
{
struct io_uring_buf_ring *br;
struct page **pages;
int i, nr_pages;
pages = io_pin_pages(reg->ring_addr,
flex_array_size(br, bufs, reg->ring_entries),
&nr_pages);
if (IS_ERR(pages))
return PTR_ERR(pages);
/*
* Apparently some 32-bit boxes (ARM) will return highmem pages,
* which then need to be mapped. We could support that, but it'd
* complicate the code and slowdown the common cases quite a bit.
* So just error out, returning -EINVAL just like we did on kernels
* that didn't support mapped buffer rings.
*/
for (i = 0; i < nr_pages; i++)
if (PageHighMem(pages[i]))
goto error_unpin;
br = page_address(pages[0]);
#ifdef SHM_COLOUR
/*
* On platforms that have specific aliasing requirements, SHM_COLOUR
* is set and we must guarantee that the kernel and user side align
* nicely. We cannot do that if IOU_PBUF_RING_MMAP isn't set and
* the application mmap's the provided ring buffer. Fail the request
* if we, by chance, don't end up with aligned addresses. The app
* should use IOU_PBUF_RING_MMAP instead, and liburing will handle
* this transparently.
*/
if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1))
goto error_unpin;
#endif
bl->buf_pages = pages;
bl->buf_nr_pages = nr_pages;
bl->buf_ring = br;
bl->is_mapped = 1;
bl->is_mmap = 0;
return 0;
error_unpin:
for (i = 0; i < nr_pages; i++)
unpin_user_page(pages[i]);
kvfree(pages);
return -EINVAL;
}
/*
* See if we have a suitable region that we can reuse, rather than allocate
* both a new io_buf_free and mem region again. We leave it on the list as
* even a reused entry will need freeing at ring release.
*/
static struct io_buf_free *io_lookup_buf_free_entry(struct io_ring_ctx *ctx,
size_t ring_size)
{
struct io_buf_free *ibf, *best = NULL;
size_t best_dist;
hlist_for_each_entry(ibf, &ctx->io_buf_list, list) {
size_t dist;
if (ibf->inuse || ibf->size < ring_size)
continue;
dist = ibf->size - ring_size;
if (!best || dist < best_dist) {
best = ibf;
if (!dist)
break;
best_dist = dist;
}
}
return best;
}
static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx,
struct io_uring_buf_reg *reg,
struct io_buffer_list *bl)
{
struct io_buf_free *ibf;
size_t ring_size;
void *ptr;
ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);
/* Reuse existing entry, if we can */
ibf = io_lookup_buf_free_entry(ctx, ring_size);
if (!ibf) {
ptr = io_mem_alloc(ring_size);
if (IS_ERR(ptr))
return PTR_ERR(ptr);
/* Allocate and store deferred free entry */
ibf = kmalloc(sizeof(*ibf), GFP_KERNEL_ACCOUNT);
if (!ibf) {
io_mem_free(ptr);
return -ENOMEM;
}
ibf->mem = ptr;
ibf->size = ring_size;
hlist_add_head(&ibf->list, &ctx->io_buf_list);
}
ibf->inuse = 1;
bl->buf_ring = ibf->mem;
bl->is_mapped = 1;
bl->is_mmap = 1;
return 0;
}
int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
{
struct io_uring_buf_reg reg;
struct io_buffer_list *bl, *free_bl = NULL;
int ret;
lockdep_assert_held(&ctx->uring_lock);
if (copy_from_user(&reg, arg, sizeof(reg)))
return -EFAULT;
if (reg.resv[0] || reg.resv[1] || reg.resv[2])
return -EINVAL;
if (reg.flags & ~IOU_PBUF_RING_MMAP)
return -EINVAL;
if (!(reg.flags & IOU_PBUF_RING_MMAP)) {
if (!reg.ring_addr)
return -EFAULT;
if (reg.ring_addr & ~PAGE_MASK)
return -EINVAL;
} else {
if (reg.ring_addr)
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;
bl = io_buffer_get_list(ctx, reg.bgid);
if (bl) {
/* if mapped buffer ring OR classic exists, don't allow */
if (bl->is_mapped || !list_empty(&bl->buf_list))
return -EEXIST;
} else {
free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
if (!bl)
return -ENOMEM;
}
if (!(reg.flags & IOU_PBUF_RING_MMAP))
ret = io_pin_pbuf_ring(&reg, bl);
else
ret = io_alloc_pbuf_ring(ctx, &reg, bl);
if (!ret) {
bl->nr_entries = reg.ring_entries;
bl->mask = reg.ring_entries - 1;
io_buffer_add_list(ctx, bl, reg.bgid);
return 0;
}
kfree_rcu(free_bl, rcu);
return ret;
}
int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
{
struct io_uring_buf_reg reg;
struct io_buffer_list *bl;
lockdep_assert_held(&ctx->uring_lock);
if (copy_from_user(&reg, arg, sizeof(reg)))
return -EFAULT;
if (reg.resv[0] || reg.resv[1] || reg.resv[2])
return -EINVAL;
if (reg.flags)
return -EINVAL;
bl = io_buffer_get_list(ctx, reg.bgid);
if (!bl)
return -ENOENT;
if (!bl->is_mapped)
return -EINVAL;
xa_erase(&ctx->io_bl_xa, bl->bgid);
io_put_bl(ctx, bl);
return 0;
}
struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx,
unsigned long bgid)
{
struct io_buffer_list *bl;
bool ret;
/*
* We have to be a bit careful here - we're inside mmap and cannot grab
* the uring_lock. This means the buffer_list could be simultaneously
* going away, if someone is trying to be sneaky. Look it up under rcu
* so we know it's not going away, and attempt to grab a reference to
* it. If the ref is already zero, then fail the mapping. If successful,
* the caller will call io_put_bl() to drop the the reference at at the
* end. This may then safely free the buffer_list (and drop the pages)
* at that point, vm_insert_pages() would've already grabbed the
* necessary vma references.
*/
rcu_read_lock();
bl = xa_load(&ctx->io_bl_xa, bgid);
/* must be a mmap'able buffer ring and have pages */
ret = false;
if (bl && bl->is_mmap)
ret = atomic_inc_not_zero(&bl->refs);
rcu_read_unlock();
if (ret)
return bl;
return ERR_PTR(-EINVAL);
}
/*
* Called at or after ->release(), free the mmap'ed buffers that we used
* for memory mapped provided buffer rings.
*/
void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx)
{
struct io_buf_free *ibf;
struct hlist_node *tmp;
hlist_for_each_entry_safe(ibf, tmp, &ctx->io_buf_list, list) {
hlist_del(&ibf->list);
io_mem_free(ibf->mem);
kfree(ibf);
}
}