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       1                 :            : /* Get previous frame state for an existing frame state.
       2                 :            :    Copyright (C) 2013 Red Hat, Inc.
       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                 :            : #include <stdlib.h>
      34                 :            : #include <assert.h>
      35                 :            : 
      36                 :            : #define BACKEND s390_
      37                 :            : #include "libebl_CPU.h"
      38                 :            : 
      39                 :            : /* s390/s390x do not annotate signal handler frame by CFI.  It would be also
      40                 :            :    difficult as PC points into a stub built on stack.  Function below is called
      41                 :            :    only if unwinder could not find CFI.  Function then verifies the register
      42                 :            :    state for this frame really belongs to a signal frame.  In such case it
      43                 :            :    fetches original registers saved by the signal frame.  */
      44                 :            : 
      45                 :            : bool
      46                 :         16 : s390_unwind (Ebl *ebl, Dwarf_Addr pc, ebl_tid_registers_t *setfunc,
      47                 :            :              ebl_tid_registers_get_t *getfunc, ebl_pid_memory_read_t *readfunc,
      48                 :            :              void *arg, bool *signal_framep)
      49                 :            : {
      50                 :            :   /* Caller already assumed caller adjustment but S390 instructions are 4 bytes
      51                 :            :      long.  Undo it.  */
      52         [ +  + ]:         16 :   if ((pc & 0x3) != 0x3)
      53                 :            :     return false;
      54                 :         12 :   pc++;
      55                 :            :   /* We can assume big-endian read here.  */
      56                 :         12 :   Dwarf_Word instr;
      57         [ -  + ]:         12 :   if (! readfunc (pc, &instr, arg))
      58                 :            :     return false;
      59                 :            :   /* Fetch only the very first two bytes.  */
      60         [ +  + ]:         12 :   instr = (instr >> (ebl->class == ELFCLASS64 ? 48 : 16)) & 0xffff;
      61                 :            :   /* See GDB s390_sigtramp_frame_sniffer.  */
      62                 :            :   /* Check for 'svc' as the first instruction.  */
      63         [ +  - ]:         12 :   if (((instr >> 8) & 0xff) != 0x0a)
      64                 :            :     return false;
      65                 :            :   /* Check for 'sigreturn' or 'rt_sigreturn' as the second instruction.  */
      66         [ #  # ]:          0 :   if ((instr & 0xff) != 119 && (instr & 0xff) != 173)
      67                 :            :     return false;
      68                 :            :   /* See GDB s390_sigtramp_frame_unwind_cache.  */
      69                 :          0 :   Dwarf_Word this_sp;
      70         [ #  # ]:          0 :   if (! getfunc (0 + 15, 1, &this_sp, arg))
      71                 :            :     return false;
      72         [ #  # ]:          0 :   unsigned word_size = ebl->class == ELFCLASS64 ? 8 : 4;
      73                 :          0 :   Dwarf_Addr next_cfa = this_sp + 16 * word_size + 32;
      74                 :            :   /* "New-style RT frame" is not supported,
      75                 :            :      assuming "Old-style RT frame and all non-RT frames".
      76                 :            :      Pointer to the array of saved registers is at NEXT_CFA + 8.  */
      77                 :          0 :   Dwarf_Word sigreg_ptr;
      78         [ #  # ]:          0 :   if (! readfunc (next_cfa + 8, &sigreg_ptr, arg))
      79                 :            :     return false;
      80                 :            :   /* Skip PSW mask.  */
      81                 :          0 :   sigreg_ptr += word_size;
      82                 :            :   /* Read PSW address.  */
      83                 :          0 :   Dwarf_Word val;
      84         [ #  # ]:          0 :   if (! readfunc (sigreg_ptr, &val, arg))
      85                 :            :     return false;
      86         [ #  # ]:          0 :   if (! setfunc (-1, 1, &val, arg))
      87                 :            :     return false;
      88                 :          0 :   sigreg_ptr += word_size;
      89                 :            :   /* Then the GPRs.  */
      90                 :          0 :   Dwarf_Word gprs[16];
      91         [ #  # ]:          0 :   for (int i = 0; i < 16; i++)
      92                 :            :     {
      93         [ #  # ]:          0 :       if (! readfunc (sigreg_ptr, &gprs[i], arg))
      94                 :            :         return false;
      95                 :          0 :       sigreg_ptr += word_size;
      96                 :            :     }
      97                 :            :   /* Then the ACRs.  Skip them, they are not used in CFI.  */
      98         [ #  # ]:          0 :   for (int i = 0; i < 16; i++)
      99                 :          0 :     sigreg_ptr += 4;
     100                 :            :   /* The floating-point control word.  */
     101                 :          0 :   sigreg_ptr += 8;
     102                 :            :   /* And finally the FPRs.  */
     103                 :          0 :   Dwarf_Word fprs[16];
     104         [ #  # ]:          0 :   for (int i = 0; i < 16; i++)
     105                 :            :     {
     106         [ #  # ]:          0 :       if (! readfunc (sigreg_ptr, &val, arg))
     107                 :            :         return false;
     108         [ #  # ]:          0 :       if (ebl->class == ELFCLASS32)
     109                 :            :         {
     110                 :          0 :           Dwarf_Addr val_low;
     111         [ #  # ]:          0 :           if (! readfunc (sigreg_ptr + 4, &val_low, arg))
     112                 :          0 :             return false;
     113                 :          0 :           val = (val << 32) | val_low;
     114                 :            :         }
     115                 :          0 :       fprs[i] = val;
     116                 :          0 :       sigreg_ptr += 8;
     117                 :            :     }
     118                 :            :   /* If we have them, the GPR upper halves are appended at the end.  */
     119         [ #  # ]:          0 :   if (ebl->class == ELFCLASS32)
     120                 :            :     {
     121                 :            :       /* Skip signal number.  */
     122                 :          0 :       sigreg_ptr += 4;
     123         [ #  # ]:          0 :       for (int i = 0; i < 16; i++)
     124                 :            :         {
     125         [ #  # ]:          0 :           if (! readfunc (sigreg_ptr, &val, arg))
     126                 :            :             return false;
     127                 :          0 :           Dwarf_Word val_low = gprs[i];
     128                 :          0 :           val = (val << 32) | val_low;
     129                 :          0 :           gprs[i] = val;
     130                 :          0 :           sigreg_ptr += 4;
     131                 :            :         }
     132                 :            :     }
     133         [ #  # ]:          0 :   if (! setfunc (0, 16, gprs, arg))
     134                 :            :     return false;
     135         [ #  # ]:          0 :   if (! setfunc (16, 16, fprs, arg))
     136                 :            :     return false;
     137                 :          0 :   *signal_framep = true;
     138                 :          0 :   return true;
     139                 :            : }