ddi.c

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/*
 * Copyright (C) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <ddi/ddi.h>
#include <arch/ddi/ddi.h>
#include <proc/task.h>
#include <arch/types.h>
#include <typedefs.h>
#include <adt/bitmap.h>
#include <mm/slab.h>
#include <arch/pm.h>
#include <errno.h>
#include <arch/cpu.h>
#include <cpu.h>
#include <arch.h>
#include <align.h>

int ddi_iospace_enable_arch(task_t *task, __address ioaddr, size_t size)
{
        count_t bits;

        bits = ioaddr + size;
        if (bits > IO_PORTS)
                return ENOENT;

        if (task->arch.iomap.bits < bits) {
                bitmap_t oldiomap;
                __u8 *newmap;
        
                /*
                 * The I/O permission bitmap is too small and needs to be grown.
                 */
                
                newmap = (__u8 *) malloc(BITS2BYTES(bits), FRAME_ATOMIC);
                if (!newmap)
                        return ENOMEM;
                
                bitmap_initialize(&oldiomap, task->arch.iomap.map, task->arch.iomap.bits);
                bitmap_initialize(&task->arch.iomap, newmap, bits);

                /*
                 * Mark the new range inaccessible.
                 */
                bitmap_set_range(&task->arch.iomap, oldiomap.bits, bits - oldiomap.bits);

                /*
                 * In case there really existed smaller iomap,
                 * copy its contents and deallocate it.
                 */             
                if (oldiomap.bits) {
                        bitmap_copy(&task->arch.iomap, &oldiomap, oldiomap.bits);
                        free(oldiomap.map);
                }
        }

        /*
         * Enable the range and we are done.
         */
        bitmap_clear_range(&task->arch.iomap, (index_t) ioaddr, (count_t) size);

        /*
         * Increment I/O Permission bitmap generation counter.
         */
        task->arch.iomapver++;

        return 0;
}

void io_perm_bitmap_install(void)
{
        count_t bits;
        ptr_16_32_t cpugdtr;
        descriptor_t *gdt_p;
        count_t ver;

        /* First, copy the I/O Permission Bitmap. */
        spinlock_lock(&TASK->lock);
        ver = TASK->arch.iomapver;
        if ((bits = TASK->arch.iomap.bits)) {
                bitmap_t iomap;
        
                ASSERT(TASK->arch.iomap.map);
                bitmap_initialize(&iomap, CPU->arch.tss->iomap, TSS_IOMAP_SIZE * 8);
                bitmap_copy(&iomap, &TASK->arch.iomap, TASK->arch.iomap.bits);
                /*
                 * It is safe to set the trailing eight bits because of the extra
                 * convenience byte in TSS_IOMAP_SIZE.
                 */
                bitmap_set_range(&iomap, ALIGN_UP(TASK->arch.iomap.bits, 8), 8);
        }
        spinlock_unlock(&TASK->lock);

        /*
         * Second, adjust TSS segment limit.
         * Take the extra ending byte with all bits set into account.
         */
        gdtr_store(&cpugdtr);
        gdt_p = (descriptor_t *) cpugdtr.base;
        gdt_setlimit(&gdt_p[TSS_DES], TSS_BASIC_SIZE + BITS2BYTES(bits));
        gdtr_load(&cpugdtr);

        /*
         * Before we load new TSS limit, the current TSS descriptor
         * type must be changed to describe inactive TSS.
         */
        gdt_p[TSS_DES].access = AR_PRESENT | AR_TSS | DPL_KERNEL;
        tr_load(selector(TSS_DES));
        
        /*
         * Update the generation count so that faults caused by
         * early accesses can be serviced.
         */
        CPU->arch.iomapver_copy = ver;
}

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