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
  21 #ifdef HAVE_XEN_PLATFORM_COMPAT_H
  22 #include <xen/platform-compat.h>
  23 #endif
  24
  25 static unsigned long kernel_start_pa;
  26
  27 void
  28 xencomm_initialize(void)
  29 {
  30         kernel_start_pa = KERNEL_START - ia64_tpa(KERNEL_START);
  31 }
  32
  33 /* Translate virtual address to physical address.  */
  34 unsigned long
  35 xencomm_vtop(unsigned long vaddr)
  36 {
  37         struct page *page;
  38         struct vm_area_struct *vma;
  39
  40         if (vaddr == 0)
  41                 return 0;
  42
  43 #ifdef __ia64__
  44         if (REGION_NUMBER(vaddr) == 5) {
  45                 pgd_t *pgd;
  46                 pud_t *pud;
  47                 pmd_t *pmd;
  48                 pte_t *ptep;
  49
  50                 /* On ia64, TASK_SIZE refers to current.  It is not initialized
  51                    during boot.
  52                    Furthermore the kernel is relocatable and __pa() doesn't
  53                    work on  addresses.  */
  54                 if (vaddr >= KERNEL_START
  55                     && vaddr < (KERNEL_START + KERNEL_TR_PAGE_SIZE))
  56                         return vaddr - kernel_start_pa;
  57
  58                 /* In kernel area -- virtually mapped.  */
  59                 pgd = pgd_offset_k(vaddr);
  60                 if (pgd_none(*pgd) || pgd_bad(*pgd))
  61                         return ~0UL;
  62
  63                 pud = pud_offset(pgd, vaddr);
  64                 if (pud_none(*pud) || pud_bad(*pud))
  65                         return ~0UL;
  66
  67                 pmd = pmd_offset(pud, vaddr);
  68                 if (pmd_none(*pmd) || pmd_bad(*pmd))
  69                         return ~0UL;
  70
  71                 ptep = pte_offset_kernel(pmd, vaddr);
  72                 if (!ptep)
  73                         return ~0UL;
  74
  75                 return (pte_val(*ptep) & _PFN_MASK) | (vaddr & ~PAGE_MASK);
  76         }
  77 #endif
  78
  79         if (vaddr > TASK_SIZE) {
  80                 /* kernel address */
  81                 return __pa(vaddr);
  82         }
  83
  84         /* XXX double-check (lack of) locking */
  85         vma = find_extend_vma(current->mm, vaddr);
  86         if (!vma)
  87                 return ~0UL;
  88
  89         /* We assume the page is modified.  */
  90         page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
  91         if (!page)
  92                 return ~0UL;
  93
  94         return (page_to_pfn(page) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
  95 }