/******************************************************************************
 * xencomm.c
 *
 * 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, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (C) IBM Corp. 2006
 *
 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
 *          Tristan Gingold <tristan.gingold@bull.net>
 *          Isaku Yamahata <yamahata@valinux.co.jp> multiple page support
 */

#include <xen/config.h>
#include <xen/mm.h>
#include <xen/sched.h>
#include <xen/xencomm.h>
#include <public/xen.h>
#include <public/xencomm.h>

#undef DEBUG
#ifdef DEBUG
#define xc_dprintk(f, a...) printk("[xencomm]" f , ## a)
#else
#define xc_dprintk(f, a...) ((void)0)
#endif

static void *
xencomm_vaddr(unsigned long paddr, struct page_info *page)
{
    return (void*)((paddr & ~PAGE_MASK) | (unsigned long)page_to_virt(page));
}

/* get_page() to prevent another vcpu freeing the page. */
static int
xencomm_get_page(unsigned long paddr, struct page_info **page)
{
    unsigned long maddr = paddr_to_maddr(paddr);
    if ( maddr == 0 )
        return -EFAULT;
        
    *page = maddr_to_page(maddr);
    if ( get_page(*page, current->domain) == 0 )
    {
        if ( page_get_owner(*page) != current->domain )
        {
            /*
             * This page might be a page granted by another domain, or
             * this page is freed with decrease reservation hypercall at
             * the same time.
             */
            gdprintk(XENLOG_WARNING,
                     "bad page is passed. paddr 0x%lx maddr 0x%lx\n",
                     paddr, maddr);
            return -EFAULT;
        }

        /* Try again. */
        cpu_relax();
        return -EAGAIN;
    }

    return 0;
}

/* check if struct desc doesn't cross page boundry */
static int
xencomm_desc_cross_page_boundary(unsigned long paddr)
{
    unsigned long offset = paddr & ~PAGE_MASK;
    if ( offset > PAGE_SIZE - sizeof(struct xencomm_desc) )
        return 1;
    return 0;
}

struct xencomm_ctxt {
    struct xencomm_desc __user *desc_in_paddr;
    uint32_t nr_addrs;

    struct page_info *page;
    unsigned long *address;
};

static uint32_t
xencomm_ctxt_nr_addrs(const struct xencomm_ctxt *ctxt)
{
    return ctxt->nr_addrs;
}

static unsigned long*
xencomm_ctxt_address(struct xencomm_ctxt *ctxt)
{
    return ctxt->address;
}

static int
xencomm_ctxt_init(const void *handle, struct xencomm_ctxt *ctxt)
{
    struct page_info *page;
    struct xencomm_desc *desc;
    int ret;

    /* Avoid unaligned access. */
    if ( ((unsigned long)handle % __alignof__(*desc)) != 0 )
        return -EINVAL;
    if ( xencomm_desc_cross_page_boundary((unsigned long)handle) )
        return -EINVAL;

    /* First we need to access the descriptor. */
    ret = xencomm_get_page((unsigned long)handle, &page);
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