gcc/config/mips/linux-unwind.h

   1 /* DWARF2 EH unwinding support for MIPS Linux.
   2    Copyright (C) 2004, 2005, 2006, 2007 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 2, or (at your option)
   9 any later 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,
  20 but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 GNU General Public License 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
  26 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  27 Boston, MA 02110-1301, USA.  */
  28
  29 #ifndef inhibit_libc
  30 /* Do code reading to identify a signal frame, and set the frame
  31    state data appropriately.  See unwind-dw2.c for the structs.  */
  32
  33 #include <signal.h>
  34 #include <asm/unistd.h>
  35
  36 /* The third parameter to the signal handler points to something with
  37  * this structure defined in asm/ucontext.h, but the name clashes with
  38  * struct ucontext from sys/ucontext.h so this private copy is used.  */
  39 typedef struct _sig_ucontext {
  40     unsigned long         uc_flags;
  41     struct _sig_ucontext  *uc_link;
  42     stack_t               uc_stack;
  43     struct sigcontext uc_mcontext;
  44     sigset_t      uc_sigmask;
  45 } _sig_ucontext_t;
  46
  47 #define MD_FALLBACK_FRAME_STATE_FOR mips_fallback_frame_state
  48
  49 static _Unwind_Reason_Code
  50 mips_fallback_frame_state (struct _Unwind_Context *context,
  51                            _Unwind_FrameState *fs)
  52 {
  53   u_int32_t *pc = (u_int32_t *) context->ra;
  54   struct sigcontext *sc;
  55   _Unwind_Ptr new_cfa;
  56   int i;
  57
  58   /* 24021061 li v0, 0x1061 (rt_sigreturn)*/
  59   /* 0000000c syscall    */
  60   /*    or */
  61   /* 24021017 li v0, 0x1017 (sigreturn) */
  62   /* 0000000c syscall  */
  63   if (pc[1] != 0x0000000c)
  64     return _URC_END_OF_STACK;
  65 #if _MIPS_SIM == _ABIO32
  66   if (pc[0] == (0x24020000 | __NR_sigreturn))
  67     {
  68       struct sigframe {
  69         u_int32_t trampoline[2];
  70         struct sigcontext sigctx;
  71       } *rt_ = context->ra;
  72       sc = &rt_->sigctx;
  73     }
  74   else
  75 #endif
  76   if (pc[0] == (0x24020000 | __NR_rt_sigreturn))
  77     {
  78       struct rt_sigframe {
  79         u_int32_t trampoline[2];
  80         struct siginfo info;
  81         _sig_ucontext_t uc;
  82       } *rt_ = context->ra;
  83       sc = &rt_->uc.uc_mcontext;
  84     }
  85   else
  86     return _URC_END_OF_STACK;
  87
  88   new_cfa = (_Unwind_Ptr)sc;
  89   fs->regs.cfa_how = CFA_REG_OFFSET;
  90   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
  91   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
  92
  93 #if _MIPS_SIM == _ABIO32 && defined __MIPSEB__
  94   /* On o32 Linux, the register save slots in the sigcontext are
  95      eight bytes.  We need the lower half of each register slot,
  96      so slide our view of the structure back four bytes.  */
  97   new_cfa -= 4;
  98 #endif
  99
 100   for (i = 0; i < 32; i++) {
 101     fs->regs.reg[i].how = REG_SAVED_OFFSET;
 102     fs->regs.reg[i].loc.offset
 103       = (_Unwind_Ptr)&(sc->sc_regs[i]) - new_cfa;
 104   }
 105   /* The PC points to the faulting instruction, but the unwind tables
 106      expect it point to the following instruction.  We compensate by
 107      reporting a return address at the next instruction. */
 108   fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].how = REG_SAVED_VAL_OFFSET;
 109   fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].loc.offset
 110     = (_Unwind_Ptr)(sc->sc_pc) + 4 - new_cfa;
 111   fs->retaddr_column = DWARF_ALT_FRAME_RETURN_COLUMN;
 112
 113   return _URC_NO_REASON;
 114 }
 115 #endif