gcc/config/pa/linux-unwind.h

   1 /* DWARF2 EH unwinding support for PA Linux.
   2    Copyright (C) 2004 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 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 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 /* Do code reading to identify a signal frame, and set the frame
  22    state data appropriately.  See unwind-dw2.c for the structs.  */
  23
  24 #include <signal.h>
  25 #include <sys/ucontext.h>
  26
  27 /* Unfortunately, because of various bugs and changes to the kernel,
  28    we have several cases to deal with.
  29
  30    In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should
  31    point directly at the beginning of the trampoline and struct rt_sigframe.
  32
  33    In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and
  34    (CONTEXT)->ra points at the 4th word in the trampoline structure.  This
  35    is wrong, it should point at the 5th word.  This is fixed in 2.6.5-rc2-pa4.
  36
  37    To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes
  38    to get the beginning of the signal frame, and then check offsets 0, 4
  39    and 5 to see if we found the beginning of the trampoline.  This will
  40    tell us how to locate the sigcontext structure.
  41
  42    Note that with a 2.4 64-bit kernel, the signal context is not properly
  43    passed back to userspace so the unwind will not work correctly.  */
  44
  45 #define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state
  46
  47 static _Unwind_Reason_Code
  48 pa32_fallback_frame_state (struct _Unwind_Context *context,
  49                            _Unwind_FrameState *fs)
  50 {
  51   unsigned long sp = (unsigned long)context->ra & ~63;
  52   unsigned int *pc = (unsigned int *)sp;
  53   unsigned long off;
  54   _Unwind_Ptr new_cfa;
  55   int i;
  56   struct sigcontext *sc;
  57   struct rt_sigframe {
  58     struct siginfo info;
  59     struct ucontext uc;
  60   } *frame;
  61
  62   /* rt_sigreturn trampoline:
  63      3419000x ldi 0, %r25 or ldi 1, %r25   (x = 0 or 2)
  64      3414015a ldi __NR_rt_sigreturn, %r20
  65      e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31
  66      08000240 nop  */
  67
  68   if (pc[0] == 0x34190000 || pc[0] == 0x34190002)
  69     off = 4*4;
  70   else if (pc[4] == 0x34190000 || pc[4] == 0x34190002)
  71     {
  72       pc += 4;
  73       off = 10 * 4;
  74     }
  75   else if (pc[5] == 0x34190000 || pc[5] == 0x34190002)
  76     {
  77       pc += 5;
  78       off = 10 * 4;
  79     }
  80   else
  81     return _URC_END_OF_STACK;
  82   if (pc[1] != 0x3414015a
  83       || pc[2] != 0xe4008200
  84       || pc[3] != 0x08000240)
  85     return _URC_END_OF_STACK;
  86
  87   frame = (struct rt_sigframe *)(sp + off);
  88   sc = &frame->uc.uc_mcontext;
  89
  90   new_cfa = sc->sc_gr[30];
  91   fs->cfa_how = CFA_REG_OFFSET;
  92   fs->cfa_reg = 30;
  93   fs->cfa_offset = new_cfa - (long) context->cfa;
  94   for (i = 1; i <= 31; i++)
  95     {
  96       fs->regs.reg[i].how = REG_SAVED_OFFSET;
  97       fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
  98     }
  99   for (i = 4; i <= 31; i++)
 100     {
 101       /* FP regs have left and right halves */
 102       fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
 103       fs->regs.reg[2*i+24].loc.offset
 104         = (long)&sc->sc_fr[i] - new_cfa;
 105       fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
 106       fs->regs.reg[2*i+24+1].loc.offset
 107         = (long)&sc->sc_fr[i] + 4 - new_cfa;
 108     }
 109   fs->regs.reg[88].how = REG_SAVED_OFFSET;
 110   fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
 111   fs->regs.reg[2].how = REG_SAVED_OFFSET;
 112   fs->regs.reg[2].loc.offset = (long) &sc->sc_iaoq[0] - new_cfa;
 113   fs->retaddr_column = 2;
 114   return _URC_NO_REASON;
 115 }