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Diffstat (limited to 'nuttx/fs/mmap/fs_munmap.c')
| -rw-r--r-- | nuttx/fs/mmap/fs_munmap.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/nuttx/fs/mmap/fs_munmap.c b/nuttx/fs/mmap/fs_munmap.c new file mode 100644 index 000000000..a4b9dc609 --- /dev/null +++ b/nuttx/fs/mmap/fs_munmap.c @@ -0,0 +1,212 @@ +/**************************************************************************** + * fs/mmap/fs_munmap.c + * + * Copyright (C) 2011 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * 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 */ |