projects/linux·blob master · refs

151 lines · 3.4 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implement primitive realloc(3) functionality.
4 *
5 * Author: Mark A. Greer <[email protected]>
6 *
7 * 2006 (c) MontaVista, Software, Inc.
8 */
9
10#include <stddef.h>
11#include "types.h"
12#include "page.h"
13#include "string.h"
14#include "ops.h"
15
16#define ENTRY_BEEN_USED 0x01
17#define ENTRY_IN_USE 0x02
18
19static struct alloc_info {
20 unsigned long flags;
21 unsigned long base;
22 unsigned long size;
23} *alloc_tbl;
24
25static unsigned long tbl_entries;
26static unsigned long alloc_min;
27static unsigned long next_base;
28static unsigned long space_left;
29
30/*
31 * First time an entry is used, its base and size are set.
32 * An entry can be freed and re-malloc'd but its base & size don't change.
33 * Should be smart enough for needs of bootwrapper.
34 */
35static void *simple_malloc(unsigned long size)
36{
37 unsigned long i;
38 struct alloc_info *p = alloc_tbl;
39
40 if (size == 0)
41 goto err_out;
42
43 size = _ALIGN_UP(size, alloc_min);
44
45 for (i=0; i<tbl_entries; i++, p++)
46 if (!(p->flags & ENTRY_BEEN_USED)) { /* never been used */
47 if (size <= space_left) {
48 p->base = next_base;
49 p->size = size;
50 p->flags = ENTRY_BEEN_USED | ENTRY_IN_USE;
51 next_base += size;
52 space_left -= size;
53 return (void *)p->base;
54 }
55 goto err_out; /* not enough space left */
56 }
57 /* reuse an entry keeping same base & size */
58 else if (!(p->flags & ENTRY_IN_USE) && (size <= p->size)) {
59 p->flags |= ENTRY_IN_USE;
60 return (void *)p->base;
61 }
62err_out:
63 return NULL;
64}
65
66static struct alloc_info *simple_find_entry(void *ptr)
67{
68 unsigned long i;
69 struct alloc_info *p = alloc_tbl;
70
71 for (i=0; i<tbl_entries; i++,p++) {
72 if (!(p->flags & ENTRY_BEEN_USED))
73 break;
74 if ((p->flags & ENTRY_IN_USE) &&
75 (p->base == (unsigned long)ptr))
76 return p;
77 }
78 return NULL;
79}
80
81static void simple_free(void *ptr)
82{
83 struct alloc_info *p = simple_find_entry(ptr);
84
85 if (p != NULL)
86 p->flags &= ~ENTRY_IN_USE;
87}
88
89/*
90 * Change size of area pointed to by 'ptr' to 'size'.
91 * If 'ptr' is NULL, then its a malloc(). If 'size' is 0, then its a free().
92 * 'ptr' must be NULL or a pointer to a non-freed area previously returned by
93 * simple_realloc() or simple_malloc().
94 */
95static void *simple_realloc(void *ptr, unsigned long size)
96{
97 struct alloc_info *p;
98 void *new;
99
100 if (size == 0) {
101 simple_free(ptr);
102 return NULL;
103 }
104
105 if (ptr == NULL)
106 return simple_malloc(size);
107
108 p = simple_find_entry(ptr);
109 if (p == NULL) /* ptr not from simple_malloc/simple_realloc */
110 return NULL;
111 if (size <= p->size) /* fits in current block */
112 return ptr;
113
114 new = simple_malloc(size);
115 if (new) {
116 memcpy(new, ptr, p->size);
117 simple_free(ptr);
118 }
119
120 return new;
121}
122
123/*
124 * Returns addr of first byte after heap so caller can see if it took
125 * too much space. If so, change args & try again.
126 */
127void *simple_alloc_init(char *base, unsigned long heap_size,
128 unsigned long granularity, unsigned long max_allocs)
129{
130 unsigned long heap_base, tbl_size;
131
132 heap_size = _ALIGN_UP(heap_size, granularity);
133 alloc_min = granularity;
134 tbl_entries = max_allocs;
135
136 tbl_size = tbl_entries * sizeof(struct alloc_info);
137
138 alloc_tbl = (struct alloc_info *)_ALIGN_UP((unsigned long)base, 8);
139 memset(alloc_tbl, 0, tbl_size);
140
141 heap_base = _ALIGN_UP((unsigned long)alloc_tbl + tbl_size, alloc_min);
142
143 next_base = heap_base;
144 space_left = heap_size;
145
146 platform_ops.malloc = simple_malloc;
147 platform_ops.free = simple_free;
148 platform_ops.realloc = simple_realloc;
149
150 return (void *)(heap_base + heap_size);
151}