LXR linux/arch/ia64/xen/xencomm.c

   1/*
   2 * Copyright (C) 2006 Hollis Blanchard <hollisb@us.ibm.com>, IBM Corporation
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation; either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  17 */
  18
  19#include <linux/mm.h>
  20#include <linux/err.h>
  21
  22static unsigned long kernel_virtual_offset;
  23static int is_xencomm_initialized;
  24
  25/* for xen early printk. It uses console io hypercall which uses xencomm.
  26 * However early printk may use it before xencomm initialization.
  27 */
  28int
  29xencomm_is_initialized(void)
  30{
  31        return is_xencomm_initialized;
  32}
  33
  34void
  35xencomm_initialize(void)
  36{
  37        kernel_virtual_offset = KERNEL_START - ia64_tpa(KERNEL_START);
  38        is_xencomm_initialized = 1;
  39}
  40
  41/* Translate virtual address to physical address.  */
  42unsigned long
  43xencomm_vtop(unsigned long vaddr)
  44{
  45        struct page *page;
  46        struct vm_area_struct *vma;
  47
  48        if (vaddr == 0)
  49                return 0UL;
  50
  51        if (REGION_NUMBER(vaddr) == 5) {
  52                pgd_t *pgd;
  53                pud_t *pud;
  54                pmd_t *pmd;
  55                pte_t *ptep;
  56
  57                /* On ia64, TASK_SIZE refers to current.  It is not initialized
  58                   during boot.
  59                   Furthermore the kernel is relocatable and __pa() doesn't
  60                   work on  addresses.  */
  61                if (vaddr >= KERNEL_START
  62                    && vaddr < (KERNEL_START + KERNEL_TR_PAGE_SIZE))
  63                        return vaddr - kernel_virtual_offset;
  64
  65                /* In kernel area -- virtually mapped.  */
  66                pgd = pgd_offset_k(vaddr);
  67                if (pgd_none(*pgd) || pgd_bad(*pgd))
  68                        return ~0UL;
  69
  70                pud = pud_offset(pgd, vaddr);
  71                if (pud_none(*pud) || pud_bad(*pud))
  72                        return ~0UL;
  73
  74                pmd = pmd_offset(pud, vaddr);
  75                if (pmd_none(*pmd) || pmd_bad(*pmd))
  76                        return ~0UL;
  77
  78                ptep = pte_offset_kernel(pmd, vaddr);
  79                if (!ptep)
  80                        return ~0UL;
  81
  82                return (pte_val(*ptep) & _PFN_MASK) | (vaddr & ~PAGE_MASK);
  83        }
  84
  85        if (vaddr > TASK_SIZE) {
  86                /* percpu variables */
  87                if (REGION_NUMBER(vaddr) == 7 &&
  88                    REGION_OFFSET(vaddr) >= (1ULL << IA64_MAX_PHYS_BITS))
  89                        ia64_tpa(vaddr);
  90
  91                /* kernel address */
  92                return __pa(vaddr);
  93        }
  94
  95        /* XXX double-check (lack of) locking */
  96        vma = find_extend_vma(current->mm, vaddr);
  97        if (!vma)
  98                return ~0UL;
  99
 100        /* We assume the page is modified.  */
 101        page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
 102        if (IS_ERR_OR_NULL(page))
 103                return ~0UL;
 104
 105        return (page_to_pfn(page) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
 106}
 107