blob: 5b44ef226904f9be2530b992c3d06ed338dca53c [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
#include <linux/cred.h>
#include <linux/device.h>
#include <linux/dma-buf.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/memfd.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/udmabuf.h>
static const u32 list_limit = 1024; /* udmabuf_create_list->count limit */
static const size_t size_limit_mb = 64; /* total dmabuf size, in megabytes */
struct udmabuf {
pgoff_t pagecount;
struct page **pages;
};
static int udmabuf_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
struct udmabuf *ubuf = vma->vm_private_data;
vmf->page = ubuf->pages[vmf->pgoff];
get_page(vmf->page);
return 0;
}
static const struct vm_operations_struct udmabuf_vm_ops = {
.fault = udmabuf_vm_fault,
};
static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
{
struct udmabuf *ubuf = buf->priv;
if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
return -EINVAL;
vma->vm_ops = &udmabuf_vm_ops;
vma->vm_private_data = ubuf;
return 0;
}
static struct sg_table *map_udmabuf(struct dma_buf_attachment *at,
enum dma_data_direction direction)
{
struct udmabuf *ubuf = at->dmabuf->priv;
struct sg_table *sg;
int ret;
sg = kzalloc(sizeof(*sg), GFP_KERNEL);
if (!sg)
return ERR_PTR(-ENOMEM);
ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount,
0, ubuf->pagecount << PAGE_SHIFT,
GFP_KERNEL);
if (ret < 0)
goto err;
if (!dma_map_sg(at->dev, sg->sgl, sg->nents, direction)) {
ret = -EINVAL;
goto err;
}
return sg;
err:
sg_free_table(sg);
kfree(sg);
return ERR_PTR(ret);
}
static void unmap_udmabuf(struct dma_buf_attachment *at,
struct sg_table *sg,
enum dma_data_direction direction)
{
sg_free_table(sg);
kfree(sg);
}
static void release_udmabuf(struct dma_buf *buf)
{
struct udmabuf *ubuf = buf->priv;
pgoff_t pg;
for (pg = 0; pg < ubuf->pagecount; pg++)
put_page(ubuf->pages[pg]);
kfree(ubuf->pages);
kfree(ubuf);
}
static void *kmap_udmabuf(struct dma_buf *buf, unsigned long page_num)
{
struct udmabuf *ubuf = buf->priv;
struct page *page = ubuf->pages[page_num];
return kmap(page);
}
static void kunmap_udmabuf(struct dma_buf *buf, unsigned long page_num,
void *vaddr)
{
kunmap(vaddr);
}
static const struct dma_buf_ops udmabuf_ops = {
.map_dma_buf = map_udmabuf,
.unmap_dma_buf = unmap_udmabuf,
.release = release_udmabuf,
.map = kmap_udmabuf,
.unmap = kunmap_udmabuf,
.mmap = mmap_udmabuf,
};
#define SEALS_WANTED (F_SEAL_SHRINK)
#define SEALS_DENIED (F_SEAL_WRITE)
static long udmabuf_create(const struct udmabuf_create_list *head,
const struct udmabuf_create_item *list)
{
DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
struct file *memfd = NULL;
struct udmabuf *ubuf;
struct dma_buf *buf;
pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
struct page *page;
int seals, ret = -EINVAL;
u32 i, flags;
ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
if (!ubuf)
return -ENOMEM;
pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
for (i = 0; i < head->count; i++) {
if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
goto err;
if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
goto err;
ubuf->pagecount += list[i].size >> PAGE_SHIFT;
if (ubuf->pagecount > pglimit)
goto err;
}
ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
GFP_KERNEL);
if (!ubuf->pages) {
ret = -ENOMEM;
goto err;
}
pgbuf = 0;
for (i = 0; i < head->count; i++) {
ret = -EBADFD;
memfd = fget(list[i].memfd);
if (!memfd)
goto err;
if (!shmem_mapping(file_inode(memfd)->i_mapping))
goto err;
seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
if (seals == -EINVAL)
goto err;
ret = -EINVAL;
if ((seals & SEALS_WANTED) != SEALS_WANTED ||
(seals & SEALS_DENIED) != 0)
goto err;
pgoff = list[i].offset >> PAGE_SHIFT;
pgcnt = list[i].size >> PAGE_SHIFT;
for (pgidx = 0; pgidx < pgcnt; pgidx++) {
page = shmem_read_mapping_page(
file_inode(memfd)->i_mapping, pgoff + pgidx);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
goto err;
}
ubuf->pages[pgbuf++] = page;
}
fput(memfd);
memfd = NULL;
}
exp_info.ops = &udmabuf_ops;
exp_info.size = ubuf->pagecount << PAGE_SHIFT;
exp_info.priv = ubuf;
buf = dma_buf_export(&exp_info);
if (IS_ERR(buf)) {
ret = PTR_ERR(buf);
goto err;
}
flags = 0;
if (head->flags & UDMABUF_FLAGS_CLOEXEC)
flags |= O_CLOEXEC;
return dma_buf_fd(buf, flags);
err:
while (pgbuf > 0)
put_page(ubuf->pages[--pgbuf]);
if (memfd)
fput(memfd);
kfree(ubuf->pages);
kfree(ubuf);
return ret;
}
static long udmabuf_ioctl_create(struct file *filp, unsigned long arg)
{
struct udmabuf_create create;
struct udmabuf_create_list head;
struct udmabuf_create_item list;
if (copy_from_user(&create, (void __user *)arg,
sizeof(create)))
return -EFAULT;
head.flags = create.flags;
head.count = 1;
list.memfd = create.memfd;
list.offset = create.offset;
list.size = create.size;
return udmabuf_create(&head, &list);
}
static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
{
struct udmabuf_create_list head;
struct udmabuf_create_item *list;
int ret = -EINVAL;
u32 lsize;
if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
return -EFAULT;
if (head.count > list_limit)
return -EINVAL;
lsize = sizeof(struct udmabuf_create_item) * head.count;
list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
if (IS_ERR(list))
return PTR_ERR(list);
ret = udmabuf_create(&head, list);
kfree(list);
return ret;
}
static long udmabuf_ioctl(struct file *filp, unsigned int ioctl,
unsigned long arg)
{
long ret;
switch (ioctl) {
case UDMABUF_CREATE:
ret = udmabuf_ioctl_create(filp, arg);
break;
case UDMABUF_CREATE_LIST:
ret = udmabuf_ioctl_create_list(filp, arg);
break;
default:
ret = -ENOTTY;
break;
}
return ret;
}
static const struct file_operations udmabuf_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = udmabuf_ioctl,
};
static struct miscdevice udmabuf_misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = "udmabuf",
.fops = &udmabuf_fops,
};
static int __init udmabuf_dev_init(void)
{
return misc_register(&udmabuf_misc);
}
static void __exit udmabuf_dev_exit(void)
{
misc_deregister(&udmabuf_misc);
}
module_init(udmabuf_dev_init)
module_exit(udmabuf_dev_exit)
MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");
MODULE_LICENSE("GPL v2");