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      1 /* DWARF2 EH unwinding support for Linux/m68k.
      2    Copyright (C) 2006-2024 Free Software Foundation, Inc.
      3 
      4 This file is part of GCC.
      5 
      6 GCC is free software; you can redistribute it and/or modify
      7 it under the terms of the GNU General Public License as published by
      8 the Free Software Foundation; either version 3, or (at your option)
      9 any later version.
     10 
     11 GCC is distributed in the hope that it will be useful,
     12 but WITHOUT ANY WARRANTY; without even the implied warranty of
     13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     14 GNU General Public License for more details.
     15 
     16 Under Section 7 of GPL version 3, you are granted additional
     17 permissions described in the GCC Runtime Library Exception, version
     18 3.1, as published by the Free Software Foundation.
     19 
     20 You should have received a copy of the GNU General Public License and
     21 a copy of the GCC Runtime Library Exception along with this program;
     22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     23 <http://www.gnu.org/licenses/>.  */
     24 
     25 /* Do code reading to identify a signal frame, and set the frame
     26    state data appropriately.  See unwind-dw2.c for the structs.
     27    Don't use this at all if inhibit_libc is used.  */
     28 
     29 #ifndef inhibit_libc
     30 
     31 #include <signal.h>
     32 
     33 /* <sys/ucontext.h> is unfortunately broken right now.  */
     34 struct uw_ucontext {
     35 	unsigned long	  uc_flags;
     36 	ucontext_t	 *uc_link;
     37 	stack_t		  uc_stack;
     38 	mcontext_t	  uc_mcontext;
     39 	unsigned long	  uc_filler[80];
     40 	sigset_t	  uc_sigmask;
     41 };
     42 
     43 #define MD_FALLBACK_FRAME_STATE_FOR m68k_fallback_frame_state
     44 
     45 #ifdef __mcoldfire__
     46 #define M68K_FP_SIZE  8
     47 #else
     48 #define M68K_FP_SIZE  12
     49 #endif
     50 
     51 static _Unwind_Reason_Code
     52 m68k_fallback_frame_state (struct _Unwind_Context *context,
     53 			   _Unwind_FrameState *fs)
     54 {
     55   unsigned short *pc = context->ra;
     56   long cfa;
     57 
     58   /* moveq #__NR_sigreturn,%d0; trap #0  */
     59   if (pc[0] == 0x7077 && pc[1] == 0x4e40)
     60     {
     61       struct sigcontext *sc;
     62 
     63       /* Context is passed as the 3rd argument.  */
     64       sc = *(struct sigcontext **) (context->cfa + 8);
     65 
     66       cfa = sc->sc_usp;
     67       fs->regs.cfa_how = CFA_REG_OFFSET;
     68       fs->regs.cfa_reg = 15;
     69       fs->regs.cfa_offset = cfa - (long) context->cfa;
     70 
     71       fs->regs.how[0] = REG_SAVED_OFFSET;
     72       fs->regs.reg[0].loc.offset = (long) &sc->sc_d0 - cfa;
     73       fs->regs.how[1] = REG_SAVED_OFFSET;
     74       fs->regs.reg[1].loc.offset = (long) &sc->sc_d1 - cfa;
     75       fs->regs.how[8] = REG_SAVED_OFFSET;
     76       fs->regs.reg[8].loc.offset = (long) &sc->sc_a0 - cfa;
     77       fs->regs.how[9] = REG_SAVED_OFFSET;
     78       fs->regs.reg[9].loc.offset = (long) &sc->sc_a1 - cfa;
     79 
     80 #ifdef __uClinux__
     81       fs->regs.how[13] = REG_SAVED_OFFSET;
     82       fs->regs.reg[13].loc.offset = (long) &sc->sc_a5 - cfa;
     83 #endif
     84 
     85       fs->regs.how[24] = REG_SAVED_OFFSET;
     86       fs->regs.reg[24].loc.offset = (long) &sc->sc_pc - cfa;
     87 
     88 #ifndef __uClinux__
     89       if (*(int *) sc->sc_fpstate)
     90 	{
     91 	  int *fpregs = (int *) sc->sc_fpregs;
     92 
     93 	  fs->regs.how[16] = REG_SAVED_OFFSET;
     94 	  fs->regs.reg[16].loc.offset = (long) &fpregs[0] - cfa;
     95 	  fs->regs.how[17] = REG_SAVED_OFFSET;
     96 	  fs->regs.reg[17].loc.offset = (long) &fpregs[M68K_FP_SIZE/4] - cfa;
     97 	}
     98 #elif defined __mcffpu__
     99 # error Implement this when uClinux kernel is ported to an FPU architecture
    100 #endif
    101     }
    102 #ifdef __mcoldfire__
    103   /* move.l #__NR_rt_sigreturn,%d0; trap #0 */
    104   else if (pc[0] == 0x203c && pc[1] == 0x0000 &&
    105 	   pc[2] == 0x00ad && pc[3] == 0x4e40)
    106 #else
    107   /* moveq #~__NR_rt_sigreturn,%d0; not.b %d0; trap #0 */
    108   else if (pc[0] == 0x7052 && pc[1] == 0x4600 && pc[2] == 0x4e40)
    109 #endif
    110     {
    111       struct uw_ucontext *uc;
    112       greg_t *gregs;
    113       int i;
    114 
    115       /* Context is passed as the 3rd argument.  */
    116       uc = *(struct uw_ucontext **) (context->cfa + 8);
    117 
    118       gregs = uc->uc_mcontext.gregs;
    119       cfa = gregs[15];
    120       fs->regs.cfa_how = CFA_REG_OFFSET;
    121       fs->regs.cfa_reg = 15;
    122       fs->regs.cfa_offset = cfa - (long) context->cfa;
    123 
    124       /* register %d0-%d7/%a0-%a6  */
    125       for (i = 0; i <= 14; i++)
    126 	{
    127 	  fs->regs.how[i] = REG_SAVED_OFFSET;
    128 	  fs->regs.reg[i].loc.offset = (long) &gregs[i] - cfa;
    129 	}
    130 
    131       /* return address  */
    132       fs->regs.how[24] = REG_SAVED_OFFSET;
    133       fs->regs.reg[24].loc.offset = (long) &gregs[16] - cfa;
    134 
    135 #define uc_fpstate      uc_filler[0]
    136 
    137       if (uc->uc_fpstate)
    138 	{
    139 	  long fpregs = (long) uc->uc_mcontext.fpregs.f_fpregs;
    140 
    141 	  /* register %fp0-%fp7  */
    142 	  for (i = 16; i <= 23; i++)
    143 	    {
    144 	      fs->regs.how[i] = REG_SAVED_OFFSET;
    145 	      fs->regs.reg[i].loc.offset = fpregs - cfa;
    146 	      fpregs += M68K_FP_SIZE;
    147 	    }
    148 	}
    149     }
    150   else
    151     return _URC_END_OF_STACK;
    152 
    153   fs->retaddr_column = 24;
    154   fs->signal_frame = 1;
    155 
    156   return _URC_NO_REASON;
    157 }
    158 #endif /* ifdef inhibit_libc  */
    159