gcc/config/s390/linux-unwind.h

   1 /* DWARF2 EH unwinding support for S/390 Linux.
   2    Copyright (C) 2004, 2005, 2006 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 it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 In addition to the permissions in the GNU General Public License, the
  12 Free Software Foundation gives you unlimited permission to link the
  13 compiled version of this file with other programs, and to distribute
  14 those programs without any restriction coming from the use of this
  15 file.  (The General Public License restrictions do apply in other
  16 respects; for example, they cover modification of the file, and
  17 distribution when not linked into another program.)
  18
  19 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  20 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  21 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  22 for more details.
  23
  24 You should have received a copy of the GNU General Public License
  25 along with GCC; see the file COPYING.  If not, write to the Free
  26 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  27 02110-1301, USA.  */
  28
  29 /* Do code reading to identify a signal frame, and set the frame
  30    state data appropriately.  See unwind-dw2.c for the structs.  */
  31
  32 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
  33
  34 static _Unwind_Reason_Code
  35 s390_fallback_frame_state (struct _Unwind_Context *context,
  36                            _Unwind_FrameState *fs)
  37 {
  38   unsigned char *pc = context->ra;
  39   long new_cfa;
  40   int i;
  41
  42   typedef struct
  43   {
  44     unsigned long psw_mask;
  45     unsigned long psw_addr;
  46     unsigned long gprs[16];
  47     unsigned int  acrs[16];
  48     unsigned int  fpc;
  49     unsigned int  __pad;
  50     double        fprs[16];
  51   } __attribute__ ((__aligned__ (8))) sigregs_;
  52
  53   sigregs_ *regs;
  54   int *signo;
  55
  56   /* svc $__NR_sigreturn or svc $__NR_rt_sigreturn  */
  57   if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
  58     return _URC_END_OF_STACK;
  59
  60   /* Legacy frames:
  61        old signal mask (8 bytes)
  62        pointer to sigregs (8 bytes) - points always to next location
  63        sigregs
  64        retcode
  65      This frame layout was used on kernels < 2.6.9 for non-RT frames,
  66      and on kernels < 2.4.13 for RT frames as well.  Note that we need
  67      to look at RA to detect this layout -- this means that if you use
  68      sa_restorer to install a different signal restorer on a legacy
  69      kernel, unwinding from signal frames will not work.  */
  70   if (context->ra == context->cfa + 16 + sizeof (sigregs_))
  71     {
  72       regs = (sigregs_ *)(context->cfa + 16);
  73       signo = NULL;
  74     }
  75
  76   /* New-style RT frame:
  77      retcode + alignment (8 bytes)
  78      siginfo (128 bytes)
  79      ucontext (contains sigregs)  */
  80   else if (pc[1] == 173 /* __NR_rt_sigreturn */)
  81     {
  82       struct ucontext_
  83       {
  84         unsigned long     uc_flags;
  85         struct ucontext_ *uc_link;
  86         unsigned long     uc_stack[3];
  87         sigregs_          uc_mcontext;
  88       } *uc = context->cfa + 8 + 128;
  89
  90       regs = &uc->uc_mcontext;
  91       signo = context->cfa + sizeof(long);
  92     }
  93
  94   /* New-style non-RT frame:
  95      old signal mask (8 bytes)
  96      pointer to sigregs (followed by signal number)  */
  97   else
  98     {
  99       regs = *(sigregs_ **)(context->cfa + 8);
 100       signo = (int *)(regs + 1);
 101     }
 102
 103   new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;
 104   fs->regs.cfa_how = CFA_REG_OFFSET;
 105   fs->regs.cfa_reg = 15;
 106   fs->regs.cfa_offset =
 107     new_cfa - (long) context->cfa + 16*sizeof(long) + 32;
 108
 109   for (i = 0; i < 16; i++)
 110     {
 111       fs->regs.reg[i].how = REG_SAVED_OFFSET;
 112       fs->regs.reg[i].loc.offset =
 113         (long)&regs->gprs[i] - new_cfa;
 114     }
 115   for (i = 0; i < 16; i++)
 116     {
 117       fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
 118       fs->regs.reg[16+i].loc.offset =
 119         (long)&regs->fprs[i] - new_cfa;
 120     }
 121
 122   /* Load return addr from PSW into dummy register 32.  */
 123
 124   fs->regs.reg[32].how = REG_SAVED_OFFSET;
 125   fs->regs.reg[32].loc.offset = (long)&regs->psw_addr - new_cfa;
 126   fs->retaddr_column = 32;
 127   /* SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
 128      after the faulting instruction rather than before it.
 129      Don't set FS->signal_frame in that case.  */
 130   if (!signo || (*signo != 4 && *signo != 5 && *signo != 8))
 131     fs->signal_frame = 1;
 132
 133   return _URC_NO_REASON;
 134 }