forked from Archive/PX4-Autopilot
175 lines
6.7 KiB
C
175 lines
6.7 KiB
C
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/****************************************************************************
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* fs/mmap/fs_mmap.c
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*
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* Copyright (C) 2008-2009, 2011 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <sys/types.h>
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#include <sys/mman.h>
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#include <sys/ioctl.h>
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#include <stdint.h>
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#include <errno.h>
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#include <debug.h>
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#include "fs_internal.h"
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#include "fs_rammap.h"
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/****************************************************************************
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* Global Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mmap
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*
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* Description:
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* NuttX operates in a flat open address space. Therefore, it generally
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* does not require mmap() functionality. There are two exceptions:
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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 supports the FIOC_MMAP ioctl command. 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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* 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.
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*
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* Parameters:
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* start A hint at where to map the memory -- ignored. The address
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* of the underlying media is fixed and cannot be re-mapped without
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* MMU support.
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* length The length of the mapping. For exception #1 above, this length
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* ignored: The entire underlying media is always accessible.
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* prot See the PROT_* definitions in sys/mman.h.
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* PROT_NONE - Will cause an error
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* PROT_READ - PROT_WRITE and PROT_EXEC also assumed
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* PROT_WRITE - PROT_READ and PROT_EXEC also assumed
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* PROT_EXEC - PROT_READ and PROT_WRITE also assumed
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* flags See the MAP_* definitions in sys/mman.h.
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* MAP_SHARED - Required
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* MAP_PRIVATE - Will cause an error
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* MAP_FIXED - Will cause an error
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* MAP_FILE - Ignored
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* MAP_ANONYMOUS - Will cause an error
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* MAP_ANON - Will cause an error
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* MAP_GROWSDOWN - Ignored
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* MAP_DENYWRITE - Will cause an error
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* MAP_EXECUTABLE - Ignored
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* MAP_LOCKED - Ignored
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* MAP_NORESERVE - Ignored
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* MAP_POPULATE - Ignored
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* MAP_NONBLOCK - Ignored
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* fd file descriptor of the backing file -- required.
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* offset The offset into the file to map
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*
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* Returned Value:
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* On success, mmap() returns a pointer to the mapped area. On error, the
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* value MAP_FAILED is returned, and errno is set appropriately.
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*
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* ENOSYS
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* Returned if any of the unsupported mmap() features are attempted
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* EBADF
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* 'fd' is not a valid file descriptor.
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* EINVAL
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* Length is 0. flags contained neither MAP_PRIVATE or MAP_SHARED, or
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* contained both of these values.
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* ENODEV
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* The underlying filesystem of the specified file does not support
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* memory mapping.
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*
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****************************************************************************/
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FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
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int fd, off_t offset)
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{
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FAR void *addr;
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int ret;
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/* Since only a tiny subset of mmap() functionality, we have to verify many
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* things.
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*/
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#ifdef CONFIG_DEBUG
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if (prot == PROT_NONE ||
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(flags & (MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_DENYWRITE)) != 0)
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{
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fdbg("Unsupported options, prot=%x flags=%04x\n", prot, flags);
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errno = ENOSYS;
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return MAP_FAILED;
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}
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if (length == 0 || (flags & MAP_SHARED) == 0)
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{
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fdbg("Invalid options, lengt=%d flags=%04x\n", length, flags);
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errno = EINVAL;
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return MAP_FAILED;
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}
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#endif
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/* Okay now we can assume a shared mapping from a file. This is the
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* only option supported
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*
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* Perform the ioctl to get the base address of the file in 'mapped'
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* in memory. (casting to uintptr_t first eliminates complaints on some
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* architectures where the sizeof long is different from the size of
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* a pointer).
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*/
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ret = ioctl(fd, FIOC_MMAP, (unsigned long)((uintptr_t)&addr));
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if (ret < 0)
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{
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#ifdef CONFIG_FS_RAMMAP
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return rammap(fd, length, offset);
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#else
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fdbg("ioctl(FIOC_MMAP) failed: %d\n", errno);
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return MAP_FAILED;
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#endif
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}
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/* Return the offset address */
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return (void*)(((uint8_t*)addr) + offset);
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}
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