217 lines
7.0 KiB
C
217 lines
7.0 KiB
C
/****************************************************************************
|
|
* fs/mmap/fs_munmap.c
|
|
*
|
|
* Copyright (C) 2011, 2017 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 "inode/inode.h"
|
|
#include "fs_rammap.h"
|
|
|
|
#ifdef CONFIG_FS_RAMMAP
|
|
|
|
/****************************************************************************
|
|
* Public 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.
|
|
*
|
|
* Input 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 errcode;
|
|
|
|
/* Find a region containing this start and length in the list of regions */
|
|
|
|
rammap_initialize();
|
|
ret = nxsem_wait(&g_rammaps.exclsem);
|
|
if (ret < 0)
|
|
{
|
|
errcode = ret;
|
|
goto errout;
|
|
}
|
|
|
|
/* 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)
|
|
{
|
|
ferr("ERROR: Region not found\n");
|
|
errcode = 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 kumm_realloc() to
|
|
* simulate the unmapping.
|
|
*/
|
|
|
|
offset = start - curr->addr;
|
|
if (offset + length < curr->length)
|
|
{
|
|
ferr("ERROR: Cannot umap without unmapping to the end\n");
|
|
errcode = 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 */
|
|
|
|
kumm_free(curr);
|
|
}
|
|
|
|
/* No.. We have been asked to "unmap' only a portion of the memory
|
|
* (offset > 0).
|
|
*/
|
|
|
|
else
|
|
{
|
|
newaddr = kumm_realloc(curr->addr, sizeof(struct fs_rammap_s) + length);
|
|
DEBUGASSERT(newaddr == (FAR void *)(curr->addr));
|
|
UNUSED(newaddr); /* May not be used */
|
|
curr->length = length;
|
|
}
|
|
|
|
nxsem_post(&g_rammaps.exclsem);
|
|
return OK;
|
|
|
|
errout_with_semaphore:
|
|
nxsem_post(&g_rammaps.exclsem);
|
|
|
|
errout:
|
|
set_errno(errcode);
|
|
return ERROR;
|
|
}
|
|
|
|
#endif /* CONFIG_FS_RAMMAP */
|