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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.
 */

/** @addtogroup sparc64proc
 * @{
 */
/** @file
 */

#include <proc/scheduler.h>
#include <proc/thread.h>
#include <arch.h>
#include <arch/asm.h>
#include <arch/regdef.h>
#include <arch/stack.h>
#include <arch/mm/tlb.h>
#include <arch/mm/page.h>
#include <config.h>
#include <align.h>
#include <macros.h>

/** Perform sparc64 specific tasks needed before the new task is run. */
void before_task_runs_arch(void)
{
}

/** Perform sparc64 specific steps before scheduling a thread.
 *
 * Ensure that thread's kernel stack, as well as userspace window buffer for
 * userspace threads, are locked in DTLB. For userspace threads, initialize
 * reserved global registers in the alternate and interrupt sets.
 */
void before_thread_runs_arch(void)
{
    uintptr_t base;
    
    base = ALIGN_DOWN(config.base, 1<<KERNEL_PAGE_WIDTH);

    if (!overlaps((uintptr_t) THREAD->kstack, PAGE_SIZE, base, (1 <<
        KERNEL_PAGE_WIDTH))) {
        /*
         * Kernel stack of this thread is not locked in DTLB.
         * First, make sure it is not mapped already.
         * If not, create a locked mapping for it.
         */
        dtlb_demap(TLB_DEMAP_PAGE, TLB_DEMAP_NUCLEUS, (uintptr_t)
            THREAD->kstack);
        dtlb_insert_mapping((uintptr_t) THREAD->kstack,
            KA2PA(THREAD->kstack), PAGESIZE_8K, true, true);
    }
    
    if ((THREAD->flags & THREAD_FLAG_USPACE)) {
        /*
         * If this thread executes also in userspace, we have to lock
         * its userspace window buffer into DTLB.
         */
        ASSERT(THREAD->arch.uspace_window_buffer);
        uintptr_t uw_buf = ALIGN_DOWN((uintptr_t)
            THREAD->arch.uspace_window_buffer, PAGE_SIZE);
        if (!overlaps(uw_buf, PAGE_SIZE, base, 1 << KERNEL_PAGE_WIDTH))
            {
            /*
             * The buffer is not covered by the 4M locked kernel
             * DTLB entry.
             */
            dtlb_demap(TLB_DEMAP_PAGE, TLB_DEMAP_NUCLEUS, uw_buf);
            dtlb_insert_mapping(uw_buf, KA2PA(uw_buf), PAGESIZE_8K,
                true, true);
        }
        
        /*
         * Write kernel stack address to %g6 of the alternate and
         * interrupt global sets.
         *
         * Write pointer to the last item in the userspace window buffer
         * to %g7 in the alternate set. Write to the interrupt %g7 is
         * not necessary because:
         * - spill traps operate only in the alternate global set,
         * - preemptible trap handler switches to alternate globals
         *   before it explicitly uses %g7.
         */
        uint64_t sp = (uintptr_t) THREAD->kstack + STACK_SIZE
            - (STACK_BIAS + ALIGN_UP(STACK_ITEM_SIZE,
            STACK_ALIGNMENT));
        write_to_ig_g6(sp);
        write_to_ag_g6(sp);
        write_to_ag_g7((uintptr_t) THREAD->arch.uspace_window_buffer);
    }
}

/** Perform sparc64 specific steps before a thread stops running.
 *
 * Demap any locked DTLB entries installed by the thread (i.e. kernel stack
 * and userspace window buffer).
 */
void after_thread_ran_arch(void)
{
    uintptr_t base;

    base = ALIGN_DOWN(config.base, 1 << KERNEL_PAGE_WIDTH);

    if (!overlaps((uintptr_t) THREAD->kstack, PAGE_SIZE, base, (1 <<
        KERNEL_PAGE_WIDTH))) {
        /*
         * Kernel stack of this thread is locked in DTLB.
         * Destroy the mapping.
         */
        dtlb_demap(TLB_DEMAP_PAGE, TLB_DEMAP_NUCLEUS, (uintptr_t)
            THREAD->kstack);
    }
    
    if ((THREAD->flags & THREAD_FLAG_USPACE)) {
        /*
         * If this thread executes also in userspace, we have to
         * demap the userspace window buffer from DTLB.
         */
        ASSERT(THREAD->arch.uspace_window_buffer);
        
        uintptr_t uw_buf = ALIGN_DOWN((uintptr_t)
            THREAD->arch.uspace_window_buffer, PAGE_SIZE);
        if (!overlaps(uw_buf, PAGE_SIZE, base, 1 << KERNEL_PAGE_WIDTH)) {
            /*
             * The buffer is not covered by the 4M locked kernel DTLB entry
             * and therefore it was given a dedicated locked DTLB entry.
             * Demap it.
             */
            dtlb_demap(TLB_DEMAP_PAGE, TLB_DEMAP_NUCLEUS, uw_buf);
        }
    
        /* sample the state of the userspace window buffer */   
        THREAD->arch.uspace_window_buffer = (uint8_t *) read_from_ag_g7();
    }
}

/** @}
 */