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 static unsigned long kernel_virtual_offset;
  22 static int is_xencomm_initialized;
  23
  24 /* for xen early printk. It uses console io hypercall which uses xencomm.
  25  * However early printk may use it before xencomm initialization.
  26  */
  27 int
  28 xencomm_is_initialized(void)
  29 {
  30         return is_xencomm_initialized;
  31 }
  32
  33 void
  34 xencomm_initialize(void)
  35 {
  36         kernel_virtual_offset = KERNEL_START - ia64_tpa(KERNEL_START);
  37         is_xencomm_initialized = 1;
  38 }
  39
  40 /* Translate virtual address to physical address.  */
  41 unsigned long
  42 xencomm_vtop(unsigned long vaddr)
  43 {
  44         struct page *page;
  45         struct vm_area_struct *vma;
  46
  47         if (vaddr == 0)
  48                 return 0UL;
  49
  50         if (REGION_NUMBER(vaddr) == 5) {
  51                 pgd_t *pgd;
  52                 pud_t *pud;
  53                 pmd_t *pmd;
  54                 pte_t *ptep;
  55
  56                 /* On ia64, TASK_SIZE refers to current.  It is not initialized
  57                    during boot.
  58                    Furthermore the kernel is relocatable and __pa() doesn't
  59                    work on  addresses.  */
  60                 if (vaddr >= KERNEL_START
  61                     && vaddr < (KERNEL_START + KERNEL_TR_PAGE_SIZE))
  62                         return vaddr - kernel_virtual_offset;
  63
  64                 /* In kernel area -- virtually mapped.  */
  65                 pgd = pgd_offset_k(vaddr);
  66                 if (pgd_none(*pgd) || pgd_bad(*pgd))
  67                         return ~0UL;
  68
  69                 pud = pud_offset(pgd, vaddr);
  70                 if (pud_none(*pud) || pud_bad(*pud))
  71                         return ~0UL;
  72
  73                 pmd = pmd_offset(pud, vaddr);
  74                 if (pmd_none(*pmd) || pmd_bad(*pmd))
  75                         return ~0UL;
  76
  77                 ptep = pte_offset_kernel(pmd, vaddr);
  78                 if (!ptep)
  79                         return ~0UL;
  80
  81                 return (pte_val(*ptep) & _PFN_MASK) | (vaddr & ~PAGE_MASK);
  82         }
  83
  84         if (vaddr > TASK_SIZE) {
  85                 /* percpu variables */
  86                 if (REGION_NUMBER(vaddr) == 7 &&
  87                     REGION_OFFSET(vaddr) >= (1ULL << IA64_MAX_PHYS_BITS))
  88                         ia64_tpa(vaddr);
  89
  90                 /* kernel address */
  91                 return __pa(vaddr);
  92         }
  93
  94         /* XXX double-check (lack of) locking */
  95         vma = find_extend_vma(current->mm, vaddr);
  96         if (!vma)
  97                 return ~0UL;
  98
  99         /* We assume the page is modified.  */
 100         page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
 101         if (!page)
 102                 return ~0UL;
 103
 104         return (page_to_pfn(page) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
 105 }