source: mainline/arch/ia32/src/proc/scheduler.c@ 040e4e9

/*
 * Copyright (C) 2005 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 <proc/scheduler.h>
#include <cpu.h>
#include <proc/task.h>
#include <proc/thread.h>
#include <arch.h>
#include <arch/context.h>       /* SP_DELTA */
#include <arch/debugger.h>
#include <arch/pm.h>
#include <arch/asm.h>
#include <adt/bitmap.h>

/** Perform ia32 specific tasks needed before the new task is run.
 *
 * Interrupts are disabled.
 */
void before_task_runs_arch(void)
{
        count_t bits;
        ptr_16_32_t cpugdtr;
        descriptor_t *gdt_p;

        /*
         * Switch the I/O Permission Bitmap, if necessary.
         */

        /* First, copy the I/O Permission Bitmap. */
        spinlock_lock(&TASK->lock);
        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 four bits because of the extra
                 * convenience byte in TSS_IOMAP_SIZE.
                 */
                bitmap_set_range(&iomap, TASK->arch.iomap.bits, 4);
        }
        spinlock_unlock(&TASK->lock);

        /* Second, adjust TSS segment limit. */
        gdtr_store(&cpugdtr);
        gdt_p = (descriptor_t *) cpugdtr.base;
        gdt_setlimit(&gdt_p[TSS_DES], TSS_BASIC_SIZE + BITS2BYTES(bits) - 1);
        gdtr_load(&cpugdtr);
}

/** Perform ia32 specific tasks needed before the new thread is scheduled.
 *
 * THREAD is locked and interrupts are disabled.
 */
void before_thread_runs_arch(void)
{
        CPU->arch.tss->esp0 = (__address) &THREAD->kstack[THREAD_STACK_SIZE-SP_DELTA];
        CPU->arch.tss->ss0 = selector(KDATA_DES);

        /* Set up TLS in GS register */
        set_tls_desc(THREAD->arch.tls);

#ifdef CONFIG_DEBUG_AS_WATCHPOINT
        /* Set watchpoint on AS to ensure that nobody sets it to zero */
        if (CPU->id < BKPOINTS_MAX)
                breakpoint_add(&((the_t *) THREAD->kstack)->as, 
                               BKPOINT_WRITE | BKPOINT_CHECK_ZERO,
                               CPU->id);
#endif
}

void after_thread_ran_arch(void)
{
}