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
  22 static unsigned long kernel_virtual_offset;
  23 static 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  */
  28 int
  29 xencomm_is_initialized(void)
  30 {
  31         return is_xencomm_initialized;
  32 }
  33
  34 void
  35 xencomm_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.  */
  42 unsigned long
  43 xencomm_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 }