xencomm.c

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/*
 * Copyright (C) 2006 Hollis Blanchard <[email protected]>, IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/mm.h>
#include <linux/err.h>

static unsigned long kernel_virtual_offset;
static int is_xencomm_initialized;

/* for xen early printk. It uses console io hypercall which uses xencomm.
 * However early printk may use it before xencomm initialization.
 */
int
xencomm_is_initialized(void)
{
    return is_xencomm_initialized;
}

void
xencomm_initialize(void)
{
    kernel_virtual_offset = KERNEL_START - ia64_tpa(KERNEL_START);
    is_xencomm_initialized = 1;
}

/* Translate virtual address to physical address.  */
unsigned long
xencomm_vtop(unsigned long vaddr)
{
    struct page *page;
    struct vm_area_struct *vma;

    if (vaddr == 0)
        return 0UL;

    if (REGION_NUMBER(vaddr) == 5) {
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *ptep;

        /* On ia64, TASK_SIZE refers to current.  It is not initialized
           during boot.
           Furthermore the kernel is relocatable and __pa() doesn't
           work on  addresses.  */
        if (vaddr >= KERNEL_START
            && vaddr < (KERNEL_START + KERNEL_TR_PAGE_SIZE))
            return vaddr - kernel_virtual_offset;

        /* In kernel area -- virtually mapped.  */
        pgd = pgd_offset_k(vaddr);
        if (pgd_none(*pgd) || pgd_bad(*pgd))
            return ~0UL;

        pud = pud_offset(pgd, vaddr);
        if (pud_none(*pud) || pud_bad(*pud))
            return ~0UL;

        pmd = pmd_offset(pud, vaddr);
        if (pmd_none(*pmd) || pmd_bad(*pmd))
            return ~0UL;

        ptep = pte_offset_kernel(pmd, vaddr);
        if (!ptep)
            return ~0UL;

        return (pte_val(*ptep) & _PFN_MASK) | (vaddr & ~PAGE_MASK);
    }

    if (vaddr > TASK_SIZE) {
        /* percpu variables */
        if (REGION_NUMBER(vaddr) == 7 &&
            REGION_OFFSET(vaddr) >= (1ULL << IA64_MAX_PHYS_BITS))
            ia64_tpa(vaddr);

        /* kernel address */
        return __pa(vaddr);
    }

    /* XXX double-check (lack of) locking */
    vma = find_extend_vma(current->mm, vaddr);
    if (!vma)
        return ~0UL;

    /* We assume the page is modified.  */
    page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
    if (IS_ERR_OR_NULL(page))
        return ~0UL;

    return (page_to_pfn(page) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
}