9af8b740e6
When the .elf file is loaded from disk, the kernel must be given write access to the allocated .text section in the task's address environment. The access is removed after the elf is loaded and relocations are done. NOTE: The reason this works for the ARM implementation, is that the ARM MMU can be configured to give write access for the privileged mode, but revoke write access for the user mode. Regardless, it would be smart to revoke write access even for the kernel, when the kernel does not need it. This framework allows doing that, if someone wishes to take up the task.
289 lines
8.4 KiB
C
289 lines
8.4 KiB
C
/****************************************************************************
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* binfmt/libelf/libelf_addrenv.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 <errno.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include <nuttx/kmalloc.h>
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#include "libelf.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Constant Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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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: elf_addrenv_alloc
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*
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* Description:
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* Allocate memory for the ELF image (textalloc and dataalloc). If
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* CONFIG_ARCH_ADDRENV=n, textalloc will be allocated using kmm_zalloc()
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* and dataalloc will be a offset from textalloc. If
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* CONFIG_ARCH_ADDRENV=y, then textalloc and dataalloc will be allocated
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* using up_addrenv_create(). In either case, there will be a unique
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* instance of textalloc and dataalloc (and stack) for each instance of a
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* process.
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*
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* Input Parameters:
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* loadinfo - Load state information
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* textsize - The size (in bytes) of the .text address environment needed
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* for the ELF image (read/execute).
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* datasize - The size (in bytes) of the .bss/.data address environment
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* needed for the ELF image (read/write).
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* heapsize - The initial size (in bytes) of the heap address environment
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* needed by the task. This region may be read/write only.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int elf_addrenv_alloc(FAR struct elf_loadinfo_s *loadinfo, size_t textsize,
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size_t datasize, size_t heapsize)
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{
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#ifdef CONFIG_ARCH_ADDRENV
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FAR void *vtext;
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FAR void *vdata;
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int ret;
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/* Create an address environment for the new ELF task */
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ret = up_addrenv_create(textsize, datasize, heapsize, &loadinfo->addrenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_create failed: %d\n", ret);
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return ret;
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}
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/* Get the virtual address associated with the start of the address
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* environment. This is the base address that we will need to use to
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* access the ELF image (but only if the address environment has been
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* selected.
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*/
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ret = up_addrenv_vtext(&loadinfo->addrenv, &vtext);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_vtext failed: %d\n", ret);
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return ret;
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}
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ret = up_addrenv_vdata(&loadinfo->addrenv, textsize, &vdata);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_vdata failed: %d\n", ret);
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return ret;
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}
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loadinfo->textalloc = (uintptr_t)vtext;
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loadinfo->dataalloc = (uintptr_t)vdata;
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return OK;
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#else
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/* Allocate memory to hold the ELF image */
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#if defined(CONFIG_ARCH_USE_TEXT_HEAP)
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loadinfo->textalloc = (uintptr_t)
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up_textheap_memalign(loadinfo->textalign,
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textsize);
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#else
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loadinfo->textalloc = (uintptr_t)kumm_memalign(loadinfo->textalign,
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textsize);
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#endif
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if (!loadinfo->textalloc)
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{
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return -ENOMEM;
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}
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if (loadinfo->datasize > 0)
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{
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loadinfo->dataalloc = (uintptr_t)kumm_memalign(loadinfo->dataalign,
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datasize);
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if (!loadinfo->dataalloc)
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{
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return -ENOMEM;
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}
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}
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return OK;
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#endif
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}
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/****************************************************************************
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* Name: elf_addrenv_restore
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*
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* Description:
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* Restore the address environment before elf_addrenv_select() was called..
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*
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* Input Parameters:
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* loadinfo - Load state information
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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#ifdef CONFIG_ARCH_ADDRENV
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int elf_addrenv_select(FAR struct elf_loadinfo_s *loadinfo)
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{
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int ret;
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/* Instantiate the new address environment */
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ret = up_addrenv_select(&loadinfo->addrenv, &loadinfo->oldenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_select failed: %d\n", ret);
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return ret;
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}
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/* Allow write access to .text */
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ret = up_addrenv_text_enable_write(&loadinfo->addrenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_text_enable_write failed: %d\n", ret);
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return ret;
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Name: elf_addrenv_free
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*
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* Description:
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* Release the address environment previously created by
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* elf_addrenv_alloc(). This function is called only under certain error
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* conditions after the module has been loaded but not yet started.
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* After the module has been started, the address environment will
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* automatically be freed when the module exits.
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*
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* Input Parameters:
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* loadinfo - Load state information
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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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#ifdef CONFIG_ARCH_ADDRENV
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int elf_addrenv_restore(FAR struct elf_loadinfo_s *loadinfo)
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{
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int ret;
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/* Remove write access to .text */
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ret = up_addrenv_text_disable_write(&loadinfo->addrenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_text_disable_write failed: %d\n", ret);
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return ret;
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}
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/* Restore the old address environment */
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ret = up_addrenv_restore(&loadinfo->oldenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_restore failed: %d\n", ret);
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return ret;
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Name: elf_addrenv_free
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*
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* Description:
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* Release the address environment previously created by
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* elf_addrenv_alloc(). This function is called only under certain error
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* conditions after the module has been loaded but not yet started.
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* After the module has been started, the address environment will
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* automatically be freed when the module exits.
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*
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* Input Parameters:
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* loadinfo - Load state information
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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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void elf_addrenv_free(FAR struct elf_loadinfo_s *loadinfo)
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{
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#ifdef CONFIG_ARCH_ADDRENV
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int ret;
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/* Free the address environment */
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ret = up_addrenv_destroy(&loadinfo->addrenv);
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if (ret < 0)
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{
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berr("ERROR: up_addrenv_destroy failed: %d\n", ret);
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}
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#else
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if (loadinfo->textalloc != 0)
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{
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#if defined(CONFIG_ARCH_USE_TEXT_HEAP)
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up_textheap_free((FAR void *)loadinfo->textalloc);
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#else
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kumm_free((FAR void *)loadinfo->textalloc);
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#endif
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}
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if (loadinfo->dataalloc != 0)
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{
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kumm_free((FAR void *)loadinfo->dataalloc);
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}
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#endif
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/* Clear out all indications of the allocated address environment */
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loadinfo->textalloc = 0;
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loadinfo->dataalloc = 0;
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loadinfo->textsize = 0;
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loadinfo->datasize = 0;
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}
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