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#include <linux/slab.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/capability.h>
#include <xen/xen.h>
#include <xen/page.h>
#include <xen/xenbus_dev.h>
#include "xenbus_comms.h"
MODULE_LICENSE("GPL");
static int xenbus_backend_open(struct inode *inode, struct file *filp)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return nonseekable_open(inode, filp);
}
static long xenbus_backend_ioctl(struct file *file, unsigned int cmd, unsigned long data)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
switch (cmd) {
case IOCTL_XENBUS_BACKEND_EVTCHN:
if (xen_store_evtchn > 0)
return xen_store_evtchn;
return -ENODEV;
default:
return -ENOTTY;
}
}
static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
{
size_t size = vma->vm_end - vma->vm_start;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))
return -EINVAL;
if (remap_pfn_range(vma, vma->vm_start,
virt_to_pfn(xen_store_interface),
size, vma->vm_page_prot))
return -EAGAIN;
return 0;
}
const struct file_operations xenbus_backend_fops = {
.open = xenbus_backend_open,
.mmap = xenbus_backend_mmap,
.unlocked_ioctl = xenbus_backend_ioctl,
};
static struct miscdevice xenbus_backend_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "xen/xenbus_backend",
.fops = &xenbus_backend_fops,
};
static int __init xenbus_backend_init(void)
{
int err;
if (!xen_initial_domain())
return -ENODEV;
err = misc_register(&xenbus_backend_dev);
if (err)
printk(KERN_ERR "Could not register xenbus backend device\n");
return err;
}
static void __exit xenbus_backend_exit(void)
{
misc_deregister(&xenbus_backend_dev);
}
module_init(xenbus_backend_init);
module_exit(xenbus_backend_exit);
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