added bitmap allocator
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48
include/eduos/memory.h
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48
include/eduos/memory.h
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/*
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* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* @author Steffen Vogel
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* @file include/memory.h
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* @brief Memory related functions
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*
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* This file contains platform independent memory functions
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*/
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#ifndef __MEMORY_H__
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#define __MEMORY_H__
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/** @brief Initialize the memory subsystem */
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int memory_init();
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/** @brief Request physical page frames */
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size_t get_pages(size_t npages);
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/** @brief release physical page frames */
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int put_pages(size_t phyaddr, size_t npages);
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#endif
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101
mm/memory.c
101
mm/memory.c
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@ -27,8 +27,21 @@
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#include <eduos/stddef.h>
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#include <eduos/stddef.h>
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#include <eduos/stdlib.h>
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#include <eduos/stdlib.h>
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#include <eduos/spinlock.h>
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#include <asm/atomic.h>
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#include <asm/multiboot.h>
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#include <asm/page.h>
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static char stack[MAX_TASKS-1][KERNEL_STACK_SIZE];
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static char stack[MAX_TASKS-1][KERNEL_STACK_SIZE];
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static char bitmap[BITMAP_SIZE];
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static spinlock_t bitmap_lock = SPINLOCK_INIT;
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atomic_int32_t total_pages = ATOMIC_INIT(0);
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atomic_int32_t total_allocated_pages = ATOMIC_INIT(0);
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atomic_int32_t total_available_pages = ATOMIC_INIT(0);
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void* create_stack(tid_t id)
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void* create_stack(tid_t id)
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{
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{
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@ -41,3 +54,91 @@ void* create_stack(tid_t id)
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return (void*) stack[id-1];
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return (void*) stack[id-1];
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}
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}
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inline static int page_marked(size_t i)
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{
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size_t index = i >> 3;
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size_t mod = i & 0x7;
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return (bitmap[index] & (1 << mod));
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}
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inline static void page_set_mark(size_t i)
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{
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size_t index = i >> 3;
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size_t mod = i & 0x7;
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bitmap[index] = bitmap[index] | (1 << mod);
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}
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inline static void page_clear_mark(size_t i)
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{
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size_t index = i / 8;
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size_t mod = i % 8;
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bitmap[index] = bitmap[index] & ~(1 << mod);
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}
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size_t get_pages(size_t npages)
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{
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size_t cnt, off;
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if (BUILTIN_EXPECT(!npages, 0))
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return 0;
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if (BUILTIN_EXPECT(npages > atomic_int32_read(&total_available_pages), 0))
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return 0;
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spinlock_lock(&bitmap_lock);
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off = 1;
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while (off <= BITMAP_SIZE*8 - npages) {
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for (cnt=0; cnt<npages; cnt++) {
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if (page_marked(off+cnt))
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goto next;
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}
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for (cnt=0; cnt<npages; cnt++) {
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page_set_mark(off+cnt);
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}
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spinlock_unlock(&bitmap_lock);
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atomic_int32_add(&total_allocated_pages, npages);
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atomic_int32_sub(&total_available_pages, npages);
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return off << PAGE_BITS;
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next: off += cnt+1;
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}
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spinlock_unlock(&bitmap_lock);
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return 0;
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}
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int put_pages(size_t phyaddr, size_t npages)
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{
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size_t i, ret = 0;
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size_t base = phyaddr >> PAGE_BITS;
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if (BUILTIN_EXPECT(!phyaddr, 0))
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return -EINVAL;
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if (BUILTIN_EXPECT(!npages, 0))
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return -EINVAL;
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spinlock_lock(&bitmap_lock);
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for (i=0; i<npages; i++) {
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if (page_marked(base+i)) {
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page_clear_mark(base+i);
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ret++;
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}
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}
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spinlock_unlock(&bitmap_lock);
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atomic_int32_sub(&total_allocated_pages, ret);
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atomic_int32_add(&total_available_pages, ret);
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return ret;
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}
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