libgcc/config/s390/linux-unwind.h

   1 /* DWARF2 EH unwinding support for S/390 Linux.
   2    Copyright (C) 2004-2013 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 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 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
  28 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
  29
  30 static _Unwind_Reason_Code
  31 s390_fallback_frame_state (struct _Unwind_Context *context,
  32                            _Unwind_FrameState *fs)
  33 {
  34   unsigned char *pc = context->ra;
  35   long new_cfa;
  36   int i;
  37
  38   typedef struct
  39   {
  40     unsigned long psw_mask;
  41     unsigned long psw_addr;
  42     unsigned long gprs[16];
  43     unsigned int  acrs[16];
  44     unsigned int  fpc;
  45     unsigned int  __pad;
  46     double        fprs[16];
  47   } __attribute__ ((__aligned__ (8))) sigregs_;
  48
  49   sigregs_ *regs;
  50   int *signo;
  51
  52   /* svc $__NR_sigreturn or svc $__NR_rt_sigreturn  */
  53   if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
  54     return _URC_END_OF_STACK;
  55
  56   /* Legacy frames:
  57        old signal mask (8 bytes)
  58        pointer to sigregs (8 bytes) - points always to next location
  59        sigregs
  60        retcode
  61      This frame layout was used on kernels < 2.6.9 for non-RT frames,
  62      and on kernels < 2.4.13 for RT frames as well.  Note that we need
  63      to look at RA to detect this layout -- this means that if you use
  64      sa_restorer to install a different signal restorer on a legacy
  65      kernel, unwinding from signal frames will not work.  */
  66   if (context->ra == context->cfa + 16 + sizeof (sigregs_))
  67     {
  68       regs = (sigregs_ *)(context->cfa + 16);
  69       signo = NULL;
  70     }
  71
  72   /* New-style RT frame:
  73      retcode + alignment (8 bytes)
  74      siginfo (128 bytes)
  75      ucontext (contains sigregs)  */
  76   else if (pc[1] == 173 /* __NR_rt_sigreturn */)
  77     {
  78       struct ucontext_
  79       {
  80         unsigned long     uc_flags;
  81         struct ucontext_ *uc_link;
  82         unsigned long     uc_stack[3];
  83         sigregs_          uc_mcontext;
  84       } *uc = context->cfa + 8 + 128;
  85
  86       regs = &uc->uc_mcontext;
  87       signo = context->cfa + sizeof(long);
  88     }
  89
  90   /* New-style non-RT frame:
  91      old signal mask (8 bytes)
  92      pointer to sigregs (followed by signal number)  */
  93   else
  94     {
  95       regs = *(sigregs_ **)(context->cfa + 8);
  96       signo = (int *)(regs + 1);
  97     }
  98
  99   new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;
 100   fs->regs.cfa_how = CFA_REG_OFFSET;
 101   fs->regs.cfa_reg = 15;
 102   fs->regs.cfa_offset =
 103     new_cfa - (long) context->cfa + 16*sizeof(long) + 32;
 104
 105   for (i = 0; i < 16; i++)
 106     {
 107       fs->regs.reg[i].how = REG_SAVED_OFFSET;
 108       fs->regs.reg[i].loc.offset =
 109         (long)&regs->gprs[i] - new_cfa;
 110     }
 111   for (i = 0; i < 16; i++)
 112     {
 113       fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
 114       fs->regs.reg[16+i].loc.offset =
 115         (long)&regs->fprs[i] - new_cfa;
 116     }
 117
 118   /* Load return addr from PSW into dummy register 32.  */
 119
 120   fs->regs.reg[32].how = REG_SAVED_OFFSET;
 121   fs->regs.reg[32].loc.offset = (long)&regs->psw_addr - new_cfa;
 122   fs->retaddr_column = 32;
 123   /* SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
 124      after the faulting instruction rather than before it.
 125      Don't set FS->signal_frame in that case.  */
 126   if (!signo || (*signo != 4 && *signo != 5 && *signo != 8))
 127     fs->signal_frame = 1;
 128
 129   return _URC_NO_REASON;
 130 }