mirror of https://gitee.com/openkylin/linux.git
211 lines
4.6 KiB
C
211 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR MIT
|
|
|
|
/******************************************************************************
|
|
* privcmd-buf.c
|
|
*
|
|
* Mmap of hypercall buffers.
|
|
*
|
|
* Copyright (c) 2018 Juergen Gross
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/list.h>
|
|
#include <linux/miscdevice.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/slab.h>
|
|
|
|
#include "privcmd.h"
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
static unsigned int limit = 64;
|
|
module_param(limit, uint, 0644);
|
|
MODULE_PARM_DESC(limit, "Maximum number of pages that may be allocated by "
|
|
"the privcmd-buf device per open file");
|
|
|
|
struct privcmd_buf_private {
|
|
struct mutex lock;
|
|
struct list_head list;
|
|
unsigned int allocated;
|
|
};
|
|
|
|
struct privcmd_buf_vma_private {
|
|
struct privcmd_buf_private *file_priv;
|
|
struct list_head list;
|
|
unsigned int users;
|
|
unsigned int n_pages;
|
|
struct page *pages[];
|
|
};
|
|
|
|
static int privcmd_buf_open(struct inode *ino, struct file *file)
|
|
{
|
|
struct privcmd_buf_private *file_priv;
|
|
|
|
file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
|
|
if (!file_priv)
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&file_priv->lock);
|
|
INIT_LIST_HEAD(&file_priv->list);
|
|
|
|
file->private_data = file_priv;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void privcmd_buf_vmapriv_free(struct privcmd_buf_vma_private *vma_priv)
|
|
{
|
|
unsigned int i;
|
|
|
|
vma_priv->file_priv->allocated -= vma_priv->n_pages;
|
|
|
|
list_del(&vma_priv->list);
|
|
|
|
for (i = 0; i < vma_priv->n_pages; i++)
|
|
if (vma_priv->pages[i])
|
|
__free_page(vma_priv->pages[i]);
|
|
|
|
kfree(vma_priv);
|
|
}
|
|
|
|
static int privcmd_buf_release(struct inode *ino, struct file *file)
|
|
{
|
|
struct privcmd_buf_private *file_priv = file->private_data;
|
|
struct privcmd_buf_vma_private *vma_priv;
|
|
|
|
mutex_lock(&file_priv->lock);
|
|
|
|
while (!list_empty(&file_priv->list)) {
|
|
vma_priv = list_first_entry(&file_priv->list,
|
|
struct privcmd_buf_vma_private,
|
|
list);
|
|
privcmd_buf_vmapriv_free(vma_priv);
|
|
}
|
|
|
|
mutex_unlock(&file_priv->lock);
|
|
|
|
kfree(file_priv);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void privcmd_buf_vma_open(struct vm_area_struct *vma)
|
|
{
|
|
struct privcmd_buf_vma_private *vma_priv = vma->vm_private_data;
|
|
|
|
if (!vma_priv)
|
|
return;
|
|
|
|
mutex_lock(&vma_priv->file_priv->lock);
|
|
vma_priv->users++;
|
|
mutex_unlock(&vma_priv->file_priv->lock);
|
|
}
|
|
|
|
static void privcmd_buf_vma_close(struct vm_area_struct *vma)
|
|
{
|
|
struct privcmd_buf_vma_private *vma_priv = vma->vm_private_data;
|
|
struct privcmd_buf_private *file_priv;
|
|
|
|
if (!vma_priv)
|
|
return;
|
|
|
|
file_priv = vma_priv->file_priv;
|
|
|
|
mutex_lock(&file_priv->lock);
|
|
|
|
vma_priv->users--;
|
|
if (!vma_priv->users)
|
|
privcmd_buf_vmapriv_free(vma_priv);
|
|
|
|
mutex_unlock(&file_priv->lock);
|
|
}
|
|
|
|
static vm_fault_t privcmd_buf_vma_fault(struct vm_fault *vmf)
|
|
{
|
|
pr_debug("fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
|
|
vmf->vma, vmf->vma->vm_start, vmf->vma->vm_end,
|
|
vmf->pgoff, (void *)vmf->address);
|
|
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
static const struct vm_operations_struct privcmd_buf_vm_ops = {
|
|
.open = privcmd_buf_vma_open,
|
|
.close = privcmd_buf_vma_close,
|
|
.fault = privcmd_buf_vma_fault,
|
|
};
|
|
|
|
static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
struct privcmd_buf_private *file_priv = file->private_data;
|
|
struct privcmd_buf_vma_private *vma_priv;
|
|
unsigned long count = vma_pages(vma);
|
|
unsigned int i;
|
|
int ret = 0;
|
|
|
|
if (!(vma->vm_flags & VM_SHARED) || count > limit ||
|
|
file_priv->allocated + count > limit)
|
|
return -EINVAL;
|
|
|
|
vma_priv = kzalloc(sizeof(*vma_priv) + count * sizeof(void *),
|
|
GFP_KERNEL);
|
|
if (!vma_priv)
|
|
return -ENOMEM;
|
|
|
|
vma_priv->n_pages = count;
|
|
count = 0;
|
|
for (i = 0; i < vma_priv->n_pages; i++) {
|
|
vma_priv->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
|
|
if (!vma_priv->pages[i])
|
|
break;
|
|
count++;
|
|
}
|
|
|
|
mutex_lock(&file_priv->lock);
|
|
|
|
file_priv->allocated += count;
|
|
|
|
vma_priv->file_priv = file_priv;
|
|
vma_priv->users = 1;
|
|
|
|
vma->vm_flags |= VM_IO | VM_DONTEXPAND;
|
|
vma->vm_ops = &privcmd_buf_vm_ops;
|
|
vma->vm_private_data = vma_priv;
|
|
|
|
list_add(&vma_priv->list, &file_priv->list);
|
|
|
|
if (vma_priv->n_pages != count)
|
|
ret = -ENOMEM;
|
|
else
|
|
for (i = 0; i < vma_priv->n_pages; i++) {
|
|
ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE,
|
|
vma_priv->pages[i]);
|
|
if (ret)
|
|
break;
|
|
}
|
|
|
|
if (ret)
|
|
privcmd_buf_vmapriv_free(vma_priv);
|
|
|
|
mutex_unlock(&file_priv->lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
const struct file_operations xen_privcmdbuf_fops = {
|
|
.owner = THIS_MODULE,
|
|
.open = privcmd_buf_open,
|
|
.release = privcmd_buf_release,
|
|
.mmap = privcmd_buf_mmap,
|
|
};
|
|
EXPORT_SYMBOL_GPL(xen_privcmdbuf_fops);
|
|
|
|
struct miscdevice xen_privcmdbuf_dev = {
|
|
.minor = MISC_DYNAMIC_MINOR,
|
|
.name = "xen/hypercall",
|
|
.fops = &xen_privcmdbuf_fops,
|
|
};
|