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       1                 :             : /* Get previous frame state for an existing frame state.
       2                 :             :    Copyright (C) 2016 The Qt Company Ltd.
       3                 :             :    This file is part of elfutils.
       4                 :             : 
       5                 :             :    This file is free software; you can redistribute it and/or modify
       6                 :             :    it under the terms of either
       7                 :             : 
       8                 :             :      * the GNU Lesser General Public License as published by the Free
       9                 :             :        Software Foundation; either version 3 of the License, or (at
      10                 :             :        your option) any later version
      11                 :             : 
      12                 :             :    or
      13                 :             : 
      14                 :             :      * the GNU General Public License as published by the Free
      15                 :             :        Software Foundation; either version 2 of the License, or (at
      16                 :             :        your option) any later version
      17                 :             : 
      18                 :             :    or both in parallel, as here.
      19                 :             : 
      20                 :             :    elfutils is distributed in the hope that it will be useful, but
      21                 :             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22                 :             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23                 :             :    General Public License for more details.
      24                 :             : 
      25                 :             :    You should have received copies of the GNU General Public License and
      26                 :             :    the GNU Lesser General Public License along with this program.  If
      27                 :             :    not, see <http://www.gnu.org/licenses/>.  */
      28                 :             : 
      29                 :             : #ifdef HAVE_CONFIG_H
      30                 :             : # include <config.h>
      31                 :             : #endif
      32                 :             : 
      33                 :             : #define BACKEND aarch64_
      34                 :             : #define FP_REG 29
      35                 :             : #define LR_REG 30
      36                 :             : #define SP_REG 31
      37                 :             : #define FP_OFFSET 0
      38                 :             : #define LR_OFFSET 8
      39                 :             : #define SP_OFFSET 16
      40                 :             : 
      41                 :             : #include "libebl_CPU.h"
      42                 :             : 
      43                 :             : /* There was no CFI. Maybe we happen to have a frame pointer and can unwind from that?  */
      44                 :             : 
      45                 :             : bool
      46                 :          26 : EBLHOOK(unwind) (Ebl *ebl __attribute__ ((unused)), Dwarf_Addr pc __attribute__ ((unused)),
      47                 :             :                  ebl_tid_registers_t *setfunc, ebl_tid_registers_get_t *getfunc,
      48                 :             :                  ebl_pid_memory_read_t *readfunc, void *arg,
      49                 :             :                  bool *signal_framep __attribute__ ((unused)))
      50                 :             : {
      51                 :          26 :   Dwarf_Word fp, lr, sp;
      52                 :             : 
      53         [ +  - ]:          26 :   if (!getfunc(LR_REG, 1, &lr, arg))
      54                 :             :     return false;
      55                 :             : 
      56   [ +  +  -  + ]:          26 :   if (lr == 0 || !setfunc(-1, 1, &lr, arg))
      57                 :           4 :     return false;
      58                 :             : 
      59         [ -  + ]:          22 :   if (!getfunc(FP_REG, 1, &fp, arg))
      60                 :           0 :     fp = 0;
      61                 :             : 
      62         [ -  + ]:          22 :   if (!getfunc(SP_REG, 1, &sp, arg))
      63                 :           0 :     sp = 0;
      64                 :             : 
      65                 :          22 :   Dwarf_Word newLr, newFp, newSp;
      66                 :             : 
      67         [ +  + ]:          22 :   if (!readfunc(fp + LR_OFFSET, &newLr, arg))
      68                 :           6 :     newLr = 0;
      69                 :             : 
      70         [ +  + ]:          22 :   if (!readfunc(fp + FP_OFFSET, &newFp, arg))
      71                 :           6 :     newFp = 0;
      72                 :             : 
      73                 :          22 :   newSp = fp + SP_OFFSET;
      74                 :             : 
      75                 :             :   // These are not fatal if they don't work. They will just prevent unwinding at the next frame.
      76                 :          22 :   setfunc(LR_REG, 1, &newLr, arg);
      77                 :          22 :   setfunc(FP_REG, 1, &newFp, arg);
      78                 :          22 :   setfunc(SP_REG, 1, &newSp, arg);
      79                 :             : 
      80                 :             :   // If the fp is invalid, we might still have a valid lr.
      81                 :             :   // But if the fp is valid, then the stack should be moving in the right direction.
      82   [ +  +  +  + ]:          26 :   return fp == 0 || newSp > sp;
      83                 :             : }