f14637a615
Before this commit u2mfn got the address via kmap(get_user_pages(...)). This has the problem that get_user_pages() does not work in some cases. For example when qemu in a stubdom tries to get the mfn for a page which is mapped from the target domain u2mfn fails because get_user_pages() cannot be used for such mappings. So get the address from the pte with apply_to_page_range(). Since we are only interested in one page get_locked_pte() would be simpler but it's not available to modules.
173 lines
4.1 KiB
C
173 lines
4.1 KiB
C
/*
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* The Qubes OS Project, http://www.qubes-os.org
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*
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* Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include <linux/module.h>
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#include <linux/version.h>
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#include <linux/proc_fs.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#ifndef FOREIGN_FRAME_BIT
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#include <xen/page.h>
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#endif
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#include <linux/highmem.h>
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/* copy of /usr/include/u2mfn-kernel.h, to reduce requirements */
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#include <linux/ioctl.h>
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#define U2MFN_MAGIC 0xf5
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#define U2MFN_GET_MFN_FOR_PAGE _IOW(U2MFN_MAGIC, 1, int)
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#define U2MFN_GET_LAST_MFN _IO(U2MFN_MAGIC, 2)
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#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
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static inline unsigned long virt_to_phys(volatile void *address)
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{
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return __pa((unsigned long) address);
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}
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#endif
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#ifdef virt_to_mfn
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#define VIRT_TO_MFN virt_to_mfn
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#else
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extern unsigned long *phys_to_machine_mapping;
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static inline unsigned long VIRT_TO_MFN(void *addr)
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{
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return phys_to_machine_mapping[virt_to_phys(addr) >> PAGE_SHIFT] & ~FOREIGN_FRAME_BIT;
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}
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#endif
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static int u2mfn_get_mfn(pte_t *pte, pgtable_t token, unsigned long addr, void *data) {
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*((unsigned long *) data) = pfn_to_mfn(pte_pfn(*pte));
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return 0;
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}
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/// User virtual address to mfn translator
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/**
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\param cmd ignored
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\param data the user-specified address
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\return mfn corresponding to "data" argument, or -1 on error
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*/
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static long u2mfn_ioctl(struct file *f, unsigned int cmd,
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unsigned long data)
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{
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long ret;
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unsigned long mfn;
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if (_IOC_TYPE(cmd) != U2MFN_MAGIC) {
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printk("Qubes u2mfn: wrong IOCTL magic");
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return -ENOTTY;
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}
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switch (cmd) {
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case U2MFN_GET_MFN_FOR_PAGE:
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ret = apply_to_page_range(current->mm, data, PAGE_SIZE, u2mfn_get_mfn, &mfn);
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if (ret < 0 || mfn == INVALID_P2M_ENTRY) {
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printk("U2MFN_GET_MFN_FOR_PAGE: failed to get mfn, "
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"addr=0x%lx ret=0x%lx\n", data, ret);
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return -1;
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}
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ret = mfn;
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break;
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case U2MFN_GET_LAST_MFN:
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if (f->private_data)
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ret = VIRT_TO_MFN(f->private_data);
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else
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ret = 0;
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break;
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default:
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printk("Qubes u2mfn: wrong ioctl passed!\n");
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return -ENOTTY;
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}
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return ret;
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}
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static int u2mfn_mmap(struct file *f, struct vm_area_struct *vma)
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{
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int ret;
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char *kbuf;
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long length = vma->vm_end - vma->vm_start;
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printk("u2mfn_mmap: entering, private=%p\n", f->private_data);
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if (f->private_data)
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return -EBUSY;
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if (length != PAGE_SIZE)
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return -EINVAL;
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kbuf = (char *) __get_free_page(GFP_KERNEL);
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if (!kbuf)
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return -ENOMEM;
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f->private_data = kbuf;
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ret = remap_pfn_range(vma, vma->vm_start,
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virt_to_phys(kbuf) >> PAGE_SHIFT,
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length, vma->vm_page_prot);
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printk("u2mfn_mmap: calling remap return %d\n", ret);
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if (ret)
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return ret;
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return 0;
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}
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static int u2mfn_release(struct inode *i, struct file *f)
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{
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printk("u2mfn_release, priv=%p\n", f->private_data);
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if (f->private_data)
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__free_page(f->private_data);
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f->private_data = NULL;
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return 0;
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}
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static struct file_operations u2mfn_fops = {
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.unlocked_ioctl = u2mfn_ioctl,
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.mmap = u2mfn_mmap,
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.release = u2mfn_release
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};
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/// u2mfn module registration
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/**
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tries to register "/proc/u2mfn" pseudofile
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*/
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static int u2mfn_init(void)
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{
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struct proc_dir_entry *u2mfn_node =
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proc_create_data("u2mfn", 0666, NULL,
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&u2mfn_fops, 0);
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if (!u2mfn_node)
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return -1;
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return 0;
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}
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static void u2mfn_exit(void)
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{
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remove_proc_entry("u2mfn", 0);
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}
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module_init(u2mfn_init);
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module_exit(u2mfn_exit);
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MODULE_LICENSE("GPL");
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