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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/****************************************************************************
* fs/mmap/fs_munmap.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <stdint.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include "fs_internal.h"
#include "fs_rammap.h"
#ifdef CONFIG_FS_RAMMAP
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: munmap
*
* Description:
*
* munmap() system call deletes mappings for the specified address range.
* All memory starting with 'start' and continuing for a length of 'length'
* bytes are removed.
*
* NuttX operates in a flat open address space. Therefore, it generally
* does not require mmap() and, hence, munmap functionality. There are
* two exceptions where mmap() is available:
*
* 1. mmap() is the API that is used to support direct access to random
* access media under the following very restrictive conditions:
*
* a. The filesystem supports the FIOC_MMAP ioctl command. Any file
* system that maps files contiguously on the media should support
* this ioctl. (vs. file system that scatter files over the media
* in non-contiguous sectors). As of this writing, ROMFS is the
* only file system that meets this requirement.
* b. The underlying block driver supports the BIOC_XIPBASE ioctl
* command that maps the underlying media to a randomly accessible
* address. At present, only the RAM/ROM disk driver does this.
*
* munmap() is still not required in this first case. In this first
* The mapped address is a static address in the MCUs address space
* does not need to be munmapped. Support for munmap() in this case
* provided by the simple definition in sys/mman.h:
*
* #define munmap(start, length)
*
* 2. If CONFIG_FS_RAMMAP is defined in the configuration, then mmap() will
* support simulation of memory mapped files by copying files whole
* into RAM. munmap() is required in this case to free the allocated
* memory holding the shared copy of the file.
*
* Parameters:
* start The start address of the mapping to delete. For this
* simplified munmap() implementation, the *must* be the start
* address of the memory region (the same address returned by
* mmap()).
* length The length region to be umapped.
*
* Returned Value:
* On success, munmap() returns 0, on failure -1, and errno is set
* (probably to EINVAL).
*
****************************************************************************/
int munmap(FAR void *start, size_t length)
{
FAR struct fs_rammap_s *prev;
FAR struct fs_rammap_s *curr;
FAR void *newaddr;
unsigned int offset;
int ret;
int err;
/* Find a region containing this start and length in the list of regions */
rammap_initialize();
ret = sem_wait(&g_rammaps.exclsem);
if (ret < 0)
{
return ERROR;
}
/* Seach the list of regions */
for (prev = NULL, curr = g_rammaps.head; curr; prev = curr, curr = curr->flink)
{
/* Does this region include any part of the specified range? */
if ((uintptr_t)start < (uintptr_t)curr->addr + curr->length &&
(uintptr_t)start + length >= (uintptr_t)curr->addr)
{
break;
}
}
/* Did we find the region */
if (!curr)
{
fdbg("Region not found\n");
err = EINVAL;
goto errout_with_semaphore;
}
/* Get the offset from the beginning of the region and the actual number
* of bytes to "unmap". All mappings must extend to the end of the region.
* There is no support for free a block of memory but leaving a block of
* memory at the end. This is a consequence of using realloc() to
* simulate the unmapping.
*/
offset = start - curr->addr;
if (offset + length < curr->length)
{
fdbg("Cannot umap without unmapping to the end\n");
err = ENOSYS;
goto errout_with_semaphore;
}
/* Okay.. the region is beging umapped to the end. Make sure the length
* indicates that.
*/
length = curr->length - offset;
/* Are we unmapping the entire region (offset == 0)? */
if (length >= curr->length)
{
/* Yes.. remove the mapping from the list */
if (prev)
{
prev->flink = curr->flink;
}
else
{
g_rammaps.head = curr->flink;
}
/* Then free the region */
kfree(curr);
}
/* No.. We have been asked to "unmap' only a portion of the memory
* (offset > 0).
*/
else
{
newaddr = krealloc(curr->addr, sizeof(struct fs_rammap_s) + length);
DEBUGASSERT(newaddr == (FAR void*)(curr->addr));
curr->length = length;
}
sem_post(&g_rammaps.exclsem);
return OK;
errout_with_semaphore:
sem_post(&g_rammaps.exclsem);
errno = err;
return ERROR;
}
#endif /* CONFIG_FS_RAMMAP */
|
