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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.2.2/] [gcc/] [config/] [pa/] [linux-unwind.h] - Blame information for rev 154

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1 38 julius
/* DWARF2 EH unwinding support for PA Linux.
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   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file with other programs, and to distribute
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those programs without any restriction coming from the use of this
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file.  (The General Public License restrictions do apply in other
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respects; for example, they cover modification of the file, and
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distribution when not linked into another program.)
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING.  If not, write to
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the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.  */
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/* Do code reading to identify a signal frame, and set the frame
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   state data appropriately.  See unwind-dw2.c for the structs.  */
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#include <signal.h>
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#include <sys/ucontext.h>
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/* Unfortunately, because of various bugs and changes to the kernel,
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   we have several cases to deal with.
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   In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should
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   point directly at the beginning of the trampoline and struct rt_sigframe.
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   In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and
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   (CONTEXT)->ra points at the 4th word in the trampoline structure.  This
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   is wrong, it should point at the 5th word.  This is fixed in 2.6.5-rc2-pa4.
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   To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes
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   to get the beginning of the signal frame, and then check offsets 0, 4
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   and 5 to see if we found the beginning of the trampoline.  This will
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   tell us how to locate the sigcontext structure.
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   Note that with a 2.4 64-bit kernel, the signal context is not properly
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   passed back to userspace so the unwind will not work correctly.  */
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#define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state
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static _Unwind_Reason_Code
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pa32_fallback_frame_state (struct _Unwind_Context *context,
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                           _Unwind_FrameState *fs)
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{
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  unsigned long sp = (unsigned long)context->ra & ~63;
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  unsigned int *pc = (unsigned int *)sp;
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  unsigned long off;
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  _Unwind_Ptr new_cfa;
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  int i;
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  struct sigcontext *sc;
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  struct rt_sigframe {
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    struct siginfo info;
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    struct ucontext uc;
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  } *frame;
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  /* rt_sigreturn trampoline:
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     3419000x ldi 0, %r25 or ldi 1, %r25   (x = 0 or 2)
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     3414015a ldi __NR_rt_sigreturn, %r20
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     e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31
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     08000240 nop  */
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  if (pc[0] == 0x34190000 || pc[0] == 0x34190002)
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    off = 4*4;
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  else if (pc[4] == 0x34190000 || pc[4] == 0x34190002)
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    {
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      pc += 4;
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      off = 10 * 4;
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    }
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  else if (pc[5] == 0x34190000 || pc[5] == 0x34190002)
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    {
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      pc += 5;
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      off = 10 * 4;
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    }
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  else
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    {
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      /* We may have to unwind through an alternate signal stack.
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         We assume that the alignment of the alternate signal stack
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         is BIGGEST_ALIGNMENT (i.e., that it has been allocated using
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         malloc).  As a result, we can't distinguish trampolines
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         used prior to 2.6.5-rc2-pa4.  However after 2.6.5-rc2-pa4,
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         the return address of a signal trampoline will be on an odd
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         word boundary and we can then determine the frame offset.  */
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      sp = (unsigned long)context->ra;
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      pc = (unsigned int *)sp;
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      if ((pc[0] == 0x34190000 || pc[0] == 0x34190002) && (sp & 4))
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        off = 5 * 4;
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      else
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        return _URC_END_OF_STACK;
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    }
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  if (pc[1] != 0x3414015a
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      || pc[2] != 0xe4008200
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      || pc[3] != 0x08000240)
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    return _URC_END_OF_STACK;
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  frame = (struct rt_sigframe *)(sp + off);
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  sc = &frame->uc.uc_mcontext;
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  new_cfa = sc->sc_gr[30];
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  fs->cfa_how = CFA_REG_OFFSET;
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  fs->cfa_reg = 30;
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  fs->cfa_offset = new_cfa - (long) context->cfa;
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  for (i = 1; i <= 31; i++)
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    {
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      fs->regs.reg[i].how = REG_SAVED_OFFSET;
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      fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
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    }
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  for (i = 4; i <= 31; i++)
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    {
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      /* FP regs have left and right halves */
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      fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
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      fs->regs.reg[2*i+24].loc.offset
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        = (long)&sc->sc_fr[i] - new_cfa;
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      fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
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      fs->regs.reg[2*i+24+1].loc.offset
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        = (long)&sc->sc_fr[i] + 4 - new_cfa;
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    }
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  fs->regs.reg[88].how = REG_SAVED_OFFSET;
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  fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
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  fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].how = REG_SAVED_OFFSET;
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  fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].loc.offset
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    = (long) &sc->sc_iaoq[0] - new_cfa;
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  fs->retaddr_column = DWARF_ALT_FRAME_RETURN_COLUMN;
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  return _URC_NO_REASON;
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}

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