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