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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <mm/heap.h>
  30. #include <synch/spinlock.h>
  31. #include <func.h>
  32. #include <memstr.h>
  33. #include <panic.h>
  34. #include <arch/types.h>
  35. #include <arch/asm.h>
  36. #include <arch.h>
  37.  
  38. /*
  39.  * First-fit algorithm.
  40.  * Simple, but hopefully correct.
  41.  * Chunks being freed are tested for mergability with their neighbours.
  42.  */
  43.  
  44. static chunk_t *chunk0;
  45. static spinlock_t heaplock;
  46.  
  47. void early_heap_init(__address heap, size_t size)
  48. {
  49.     spinlock_initialize(&heaplock);
  50.     memsetb(heap, size, 0);
  51.     chunk0 = (chunk_t *) heap;
  52.     chunk0->used = 0;
  53.     chunk0->size = size - sizeof(chunk_t);
  54.     chunk0->next = NULL;
  55.     chunk0->prev = NULL;
  56. }
  57.  
  58. /*
  59.  * Uses first-fit algorithm.
  60.  */
  61. void *early_malloc(size_t size)
  62. {
  63.     ipl_t ipl;
  64.     chunk_t *x, *y, *z;
  65.  
  66.     if (size == 0)
  67.         panic("zero-size allocation request");
  68.        
  69.     x = chunk0;
  70.     ipl = interrupts_disable();
  71.     spinlock_lock(&heaplock);      
  72.     while (x) {
  73.         if (x->used || x->size < size) {
  74.             x = x->next;
  75.             continue;
  76.         }
  77.        
  78.         x->used = 1;
  79.    
  80.         /*
  81.          * If the chunk exactly matches required size or if truncating
  82.          * it would not provide enough space for storing a new chunk
  83.          * header plus at least one byte of data, we are finished.
  84.          */
  85.         if (x->size < size + sizeof(chunk_t) + 1) {
  86.             spinlock_unlock(&heaplock);
  87.             interrupts_restore(ipl);
  88.             return &x->data[0];
  89.         }
  90.  
  91.         /*
  92.          * Truncate x and create a new chunk.
  93.          */
  94.         y = (chunk_t *) (((__address) x) + size + sizeof(chunk_t));
  95.         y->used = 0;
  96.         y->size = x->size - size - sizeof(chunk_t);
  97.         y->prev = x;
  98.         y->next = NULL;
  99.        
  100.         if (z = x->next) {
  101.             z->prev = y;
  102.             y->next = z;
  103.         }
  104.        
  105.         x->size = size;
  106.         x->next = y;
  107.         spinlock_unlock(&heaplock);
  108.         interrupts_restore(ipl);
  109.  
  110.         return &x->data[0];
  111.     }
  112.     spinlock_unlock(&heaplock);
  113.     interrupts_restore(ipl);
  114.     return NULL;
  115. }
  116.  
  117. void early_free(void *ptr)
  118. {
  119.     ipl_t ipl;
  120.     chunk_t *x, *y, *z;
  121.  
  122.     if (!ptr)
  123.         panic("free on NULL");
  124.  
  125.  
  126.     y = (chunk_t *) (((__u8 *) ptr) - sizeof(chunk_t));
  127.     if (y->used != 1)
  128.         panic("freeing unused/damaged chunk");
  129.  
  130.     ipl = interrupts_disable();
  131.     spinlock_lock(&heaplock);
  132.     x = y->prev;
  133.     z = y->next;
  134.     /* merge x and y */
  135.     if (x && !x->used) {
  136.         x->size += y->size + sizeof(chunk_t);
  137.         x->next = z;
  138.         if (z)
  139.             z->prev = x;
  140.         y = x;
  141.     }
  142.     /* merge y and z or merge (x merged with y) and z */
  143.     if (z && !z->used) {
  144.         y->size += z->size + sizeof(chunk_t);
  145.         y->next = z->next;
  146.         if (z->next)  {
  147.             /* y is either y or x */
  148.             z->next->prev = y;
  149.         }
  150.     }
  151.     y->used = 0;
  152.     spinlock_unlock(&heaplock);
  153.     interrupts_restore(ipl);
  154. }
  155.