1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Implement primitive realloc(3) functionality.
4  *
5  * Author: Mark A. Greer <mgreer@mvista.com>
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 
19 static struct alloc_info {
20 	unsigned long	flags;
21 	unsigned long	base;
22 	unsigned long	size;
23 } *alloc_tbl;
24 
25 static unsigned long tbl_entries;
26 static unsigned long alloc_min;
27 static unsigned long next_base;
28 static 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  */
simple_malloc(unsigned long size)35 static 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 		}
62 err_out:
63 	return NULL;
64 }
65 
simple_find_entry(void * ptr)66 static 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 
simple_free(void * ptr)81 static 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  */
simple_realloc(void * ptr,unsigned long size)95 static 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 	memcpy(new, ptr, p->size);
116 	simple_free(ptr);
117 	return new;
118 }
119 
120 /*
121  * Returns addr of first byte after heap so caller can see if it took
122  * too much space.  If so, change args & try again.
123  */
simple_alloc_init(char * base,unsigned long heap_size,unsigned long granularity,unsigned long max_allocs)124 void *simple_alloc_init(char *base, unsigned long heap_size,
125 			unsigned long granularity, unsigned long max_allocs)
126 {
127 	unsigned long heap_base, tbl_size;
128 
129 	heap_size = _ALIGN_UP(heap_size, granularity);
130 	alloc_min = granularity;
131 	tbl_entries = max_allocs;
132 
133 	tbl_size = tbl_entries * sizeof(struct alloc_info);
134 
135 	alloc_tbl = (struct alloc_info *)_ALIGN_UP((unsigned long)base, 8);
136 	memset(alloc_tbl, 0, tbl_size);
137 
138 	heap_base = _ALIGN_UP((unsigned long)alloc_tbl + tbl_size, alloc_min);
139 
140 	next_base = heap_base;
141 	space_left = heap_size;
142 
143 	platform_ops.malloc = simple_malloc;
144 	platform_ops.free = simple_free;
145 	platform_ops.realloc = simple_realloc;
146 
147 	return (void *)(heap_base + heap_size);
148 }
149