b8f23fc3f7
Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>
155 lines
5.2 KiB
C
155 lines
5.2 KiB
C
/****************************************************************************
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* fs/mmap/fs_munmap.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/mm/map.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <stdint.h>
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#include <errno.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include "inode/inode.h"
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#include "fs_rammap.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static int file_munmap_(FAR void *start, size_t length, bool kernel)
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{
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FAR struct tcb_s *tcb = nxsched_self();
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FAR struct task_group_s *group = tcb->group;
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FAR struct mm_map_entry_s *entry = NULL;
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int ret = OK;
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/* Iterate through all the mappings and call the underlying
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* unmap for every mapping where "start" lies
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* break loop on any errors.
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*
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* Get exclusive access to mm_map for this
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*/
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ret = mm_map_lock();
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if (ret == OK)
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{
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while (ret == OK && (entry = mm_map_find(start, length)))
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{
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DEBUGASSERT(entry->munmap);
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ret = entry->munmap(group, entry, start, length);
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}
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mm_map_unlock();
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}
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return ret;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: file_mummap
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*
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* Description:
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* Equivalent to the standard file_mummap() function except it does not set
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* the errno variable.
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*
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****************************************************************************/
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int file_munmap(FAR void *start, size_t length)
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{
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return file_munmap_(start, length, true);
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}
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/****************************************************************************
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* Name: munmap
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*
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* Description:
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*
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* munmap() system call deletes mappings for the specified address range.
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* All memory starting with 'start' and continuing for a length of 'length'
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* bytes are removed.
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*
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* NuttX operates in a flat open address space. Therefore, it generally
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* does not require mmap() and, hence, munmap functionality. There are
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* two exceptions where mmap() is available:
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*
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* 1. mmap() is the API that is used to support direct access to random
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* access media under the following very restrictive conditions:
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*
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* a. The filesystem impelements the mmap file operation. Any file
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* system that maps files contiguously on the media should support
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* this ioctl. (vs. file system that scatter files over the media
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* in non-contiguous sectors). As of this writing, ROMFS is the
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* only file system that meets this requirement.
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* b. The underlying block driver supports the BIOC_XIPBASE ioctl
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* command that maps the underlying media to a randomly accessible
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* address. At present, only the RAM/ROM disk driver does this.
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*
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* munmap() is still not required in this first case. In this first
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* The mapped address is a static address in the MCUs address space
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* does not need to be munmapped. Support for munmap() in this case
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* provided by the simple definition in sys/mman.h:
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*
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* #define munmap(start, length)
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*
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* 2. If CONFIG_FS_RAMMAP is defined in the configuration, then mmap() will
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* support simulation of memory mapped files by copying files whole
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* into RAM. munmap() is required in this case to free the allocated
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* memory holding the shared copy of the file.
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*
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* Input Parameters:
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* start The start address of the mapping to delete. For this
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* simplified munmap() implementation, the *must* be the start
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* address of the memory region (the same address returned by
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* mmap()).
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* length The length region to be umapped.
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*
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* Returned Value:
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* On success, munmap() returns 0, on failure -1, and errno is set
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* (probably to EINVAL).
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*
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****************************************************************************/
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int munmap(FAR void *start, size_t length)
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{
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int ret;
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ret = file_munmap_(start, length, false);
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if (ret < 0)
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{
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set_errno(-ret);
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ret = ERROR;
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}
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return ret;
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}
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