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Linux/arch/powerpc/boot/simple_alloc.c

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  1 /*
  2  * Implement primitive realloc(3) functionality.
  3  *
  4  * Author: Mark A. Greer <mgreer@mvista.com>
  5  *
  6  * 2006 (c) MontaVista, Software, Inc.  This file is licensed under
  7  * the terms of the GNU General Public License version 2.  This program
  8  * is licensed "as is" without any warranty of any kind, whether express
  9  * or implied.
 10  */
 11 
 12 #include <stddef.h>
 13 #include "types.h"
 14 #include "page.h"
 15 #include "string.h"
 16 #include "ops.h"
 17 
 18 #define ENTRY_BEEN_USED 0x01
 19 #define ENTRY_IN_USE    0x02
 20 
 21 static struct alloc_info {
 22         unsigned long   flags;
 23         unsigned long   base;
 24         unsigned long   size;
 25 } *alloc_tbl;
 26 
 27 static unsigned long tbl_entries;
 28 static unsigned long alloc_min;
 29 static unsigned long next_base;
 30 static unsigned long space_left;
 31 
 32 /*
 33  * First time an entry is used, its base and size are set.
 34  * An entry can be freed and re-malloc'd but its base & size don't change.
 35  * Should be smart enough for needs of bootwrapper.
 36  */
 37 static void *simple_malloc(unsigned long size)
 38 {
 39         unsigned long i;
 40         struct alloc_info *p = alloc_tbl;
 41 
 42         if (size == 0)
 43                 goto err_out;
 44 
 45         size = _ALIGN_UP(size, alloc_min);
 46 
 47         for (i=0; i<tbl_entries; i++, p++)
 48                 if (!(p->flags & ENTRY_BEEN_USED)) { /* never been used */
 49                         if (size <= space_left) {
 50                                 p->base = next_base;
 51                                 p->size = size;
 52                                 p->flags = ENTRY_BEEN_USED | ENTRY_IN_USE;
 53                                 next_base += size;
 54                                 space_left -= size;
 55                                 return (void *)p->base;
 56                         }
 57                         goto err_out; /* not enough space left */
 58                 }
 59                 /* reuse an entry keeping same base & size */
 60                 else if (!(p->flags & ENTRY_IN_USE) && (size <= p->size)) {
 61                         p->flags |= ENTRY_IN_USE;
 62                         return (void *)p->base;
 63                 }
 64 err_out:
 65         return NULL;
 66 }
 67 
 68 static struct alloc_info *simple_find_entry(void *ptr)
 69 {
 70         unsigned long i;
 71         struct alloc_info *p = alloc_tbl;
 72 
 73         for (i=0; i<tbl_entries; i++,p++) {
 74                 if (!(p->flags & ENTRY_BEEN_USED))
 75                         break;
 76                 if ((p->flags & ENTRY_IN_USE) &&
 77                     (p->base == (unsigned long)ptr))
 78                         return p;
 79         }
 80         return NULL;
 81 }
 82 
 83 static void simple_free(void *ptr)
 84 {
 85         struct alloc_info *p = simple_find_entry(ptr);
 86 
 87         if (p != NULL)
 88                 p->flags &= ~ENTRY_IN_USE;
 89 }
 90 
 91 /*
 92  * Change size of area pointed to by 'ptr' to 'size'.
 93  * If 'ptr' is NULL, then its a malloc().  If 'size' is 0, then its a free().
 94  * 'ptr' must be NULL or a pointer to a non-freed area previously returned by
 95  * simple_realloc() or simple_malloc().
 96  */
 97 static void *simple_realloc(void *ptr, unsigned long size)
 98 {
 99         struct alloc_info *p;
100         void *new;
101 
102         if (size == 0) {
103                 simple_free(ptr);
104                 return NULL;
105         }
106 
107         if (ptr == NULL)
108                 return simple_malloc(size);
109 
110         p = simple_find_entry(ptr);
111         if (p == NULL) /* ptr not from simple_malloc/simple_realloc */
112                 return NULL;
113         if (size <= p->size) /* fits in current block */
114                 return ptr;
115 
116         new = simple_malloc(size);
117         memcpy(new, ptr, p->size);
118         simple_free(ptr);
119         return new;
120 }
121 
122 /*
123  * Returns addr of first byte after heap so caller can see if it took
124  * too much space.  If so, change args & try again.
125  */
126 void *simple_alloc_init(char *base, unsigned long heap_size,
127                         unsigned long granularity, unsigned long max_allocs)
128 {
129         unsigned long heap_base, tbl_size;
130 
131         heap_size = _ALIGN_UP(heap_size, granularity);
132         alloc_min = granularity;
133         tbl_entries = max_allocs;
134 
135         tbl_size = tbl_entries * sizeof(struct alloc_info);
136 
137         alloc_tbl = (struct alloc_info *)_ALIGN_UP((unsigned long)base, 8);
138         memset(alloc_tbl, 0, tbl_size);
139 
140         heap_base = _ALIGN_UP((unsigned long)alloc_tbl + tbl_size, alloc_min);
141 
142         next_base = heap_base;
143         space_left = heap_size;
144 
145         platform_ops.malloc = simple_malloc;
146         platform_ops.free = simple_free;
147         platform_ops.realloc = simple_realloc;
148 
149         return (void *)(heap_base + heap_size);
150 }
151 

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