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
  21static unsigned long kernel_virtual_offset;
  22static 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 */
  27int
  28xencomm_is_initialized(void)
  29{
  30        return is_xencomm_initialized;
  31}
  32
  33void
  34xencomm_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.  */
  41unsigned long
  42xencomm_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}
 106