nuttx/libs/libc/machine/arm/gnu_unwind_find_exidx.c

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/****************************************************************************
* libs/libc/machine/arm/gnu_unwind_find_exidx.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/elf.h>
#include <unwind.h>
/****************************************************************************
* Private Types
****************************************************************************/
typedef struct __EIT_entry
{
_uw fnoffset;
_uw content;
} __EIT_entry;
/****************************************************************************
* Private Data
****************************************************************************/
static __EIT_entry *__exidx_start_elf;
static __EIT_entry *__exidx_end_elf;
/****************************************************************************
* Public Data
****************************************************************************/
extern __EIT_entry __exidx_start;
extern __EIT_entry __exidx_end;
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: __gnu_Unwind_Find_exidx
*
* Description:
* This function is called (if exists) by the gcc generated unwind
* run-time in order to retrieve an alternative .ARM.exidx Exception
* index section.
* This is the case for an ELF module loaded by the elf binary loader.
* It is needed to support exception handling for loadable ELF modules.
*
* NOTES:
*
* 1. The section to be searched is chosen by the address of the calling
* site: if we are in a runtime loaded ELF, the code will be executed
* in ram ( > 0x20000000 ) otherwise we will be executing code from
* flash (0x08000000) (running nuttx from ram will break this logic)
*
* 2. __exidx_start and __exidx_end refers to main nuttx elf image and
* are defined in its linker script.
*
* 2. __exidx_start_elf and __exidx_end_elf refers to the elf module
* loaded by the elf binary loader, and are initialized at run-time.
*
* 3. TODO: if nuttx itself is running from ram, this logic will not work
*
* 4. TODO: in order to support multiple elf modules running at the same
* time, this error logic needs to be extended to store multiple
* start/end ranges that refers to the loaded binaries.
*
****************************************************************************/
int up_init_exidx(Elf_Addr start, Elf_Word size)
{
__exidx_start_elf = (__EIT_entry *)start;
__exidx_end_elf = (__EIT_entry *)(start + size);
return 0;
}
_Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr return_address, int *nrecp)
{
if (return_address < 0x20000000)
{
*nrecp = &__exidx_end - &__exidx_start;
return (_Unwind_Ptr)&__exidx_start;
}
else
{
*nrecp = __exidx_end_elf - __exidx_start_elf;
return (_Unwind_Ptr)__exidx_start_elf;
}
}