1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
|
/*
* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/**
* @file
*
* External memory allocation
*
*/
#include <gpxe/uaccess.h>
#include <gpxe/hidemem.h>
#include <gpxe/emalloc.h>
/** Alignment of external allocated memory */
#define EM_ALIGN ( 4 * 1024 )
/** Equivalent of NOWHERE for user pointers */
#define UNOWHERE ( ~UNULL )
/** Top of allocatable memory */
#define TOP ( virt_to_user ( NULL ) )
/** An external memory block */
struct external_memory {
/** Size of this memory block (excluding this header) */
size_t size;
/** Block is currently in use */
int used;
};
/** Current lowest allocated block
*
* A value of UNULL indicates that no blocks are currently allocated.
*/
userptr_t bottom = UNULL;
/**
* Collect free blocks
*
*/
static void ecollect_free ( void ) {
struct external_memory extmem;
/* Walk the free list and collect empty blocks */
while ( bottom != TOP ) {
copy_from_user ( &extmem, bottom, -sizeof ( extmem ),
sizeof ( extmem ) );
if ( extmem.used )
break;
DBG ( "EXTMEM freeing [%lx,%lx)\n", user_to_phys ( bottom, 0 ),
user_to_phys ( bottom, extmem.size ) );
bottom = userptr_add ( bottom,
( extmem.size + sizeof ( extmem ) ) );
}
}
/**
* Reallocate external memory
*
* @v old_ptr Memory previously allocated by emalloc(), or UNULL
* @v new_size Requested size
* @ret new_ptr Allocated memory, or UNULL
*
* Calling realloc() with a new size of zero is a valid way to free a
* memory block.
*/
userptr_t erealloc ( userptr_t ptr, size_t new_size ) {
struct external_memory extmem;
userptr_t new = ptr;
size_t align;
/* Initialise external memory allocator if necessary */
if ( ! bottom )
bottom = TOP;
/* Get block properties into extmem */
if ( ptr && ( ptr != UNOWHERE ) ) {
/* Determine old size */
copy_from_user ( &extmem, ptr, -sizeof ( extmem ),
sizeof ( extmem ) );
} else {
/* Create a zero-length block */
ptr = bottom = userptr_add ( bottom, -sizeof ( extmem ) );
DBG ( "EXTMEM allocating [%lx,%lx)\n",
user_to_phys ( ptr, 0 ), user_to_phys ( ptr, 0 ) );
extmem.size = 0;
}
extmem.used = ( new_size > 0 );
/* Expand/shrink block if possible */
if ( ptr == bottom ) {
/* Update block */
new = userptr_add ( ptr, - ( new_size - extmem.size ) );
align = ( user_to_phys ( new, 0 ) & ( EM_ALIGN - 1 ) );
new_size += align;
new = userptr_add ( new, -align );
DBG ( "EXTMEM expanding [%lx,%lx) to [%lx,%lx)\n",
user_to_phys ( ptr, 0 ),
user_to_phys ( ptr, extmem.size ),
user_to_phys ( new, 0 ),
user_to_phys ( new, new_size ));
memmove_user ( new, 0, ptr, 0, ( ( extmem.size < new_size ) ?
extmem.size : new_size ) );
extmem.size = new_size;
bottom = new;
} else {
/* Cannot expand; can only pretend to shrink */
if ( new_size > extmem.size ) {
/* Refuse to expand */
DBG ( "EXTMEM cannot expand [%lx,%lx)\n",
user_to_phys ( ptr, 0 ),
user_to_phys ( ptr, extmem.size ) );
return UNULL;
}
}
/* Write back block properties */
copy_to_user ( new, -sizeof ( extmem ), &extmem,
sizeof ( extmem ) );
/* Collect any free blocks and update hidden memory region */
ecollect_free();
hide_region ( EXTMEM, user_to_phys ( bottom, -sizeof ( extmem ) ),
user_to_phys ( TOP, 0 ) );
return ( new_size ? new : UNOWHERE );
}
/**
* Allocate external memory
*
* @v size Requested size
* @ret ptr Memory, or UNULL
*
* Memory is guaranteed to be aligned to a page boundary.
*/
userptr_t emalloc ( size_t size ) {
return erealloc ( UNULL, size );
}
/**
* Free external memory
*
* @v ptr Memory allocated by emalloc(), or UNULL
*
* If @c ptr is UNULL, no action is taken.
*/
void efree ( userptr_t ptr ) {
erealloc ( ptr, 0 );
}
|
