Subversion Repositories openrisc

/* DWARF2 EH unwinding support for PA Linux.

   Copyright (C) 2004, 2005, 2009 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

GCC is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

Under Section 7 of GPL version 3, you are granted additional

permissions described in the GCC Runtime Library Exception, version

3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and

a copy of the GCC Runtime Library Exception along with this program;

see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

<http://www.gnu.org/licenses/>.  */

/* Do code reading to identify a signal frame, and set the frame

   state data appropriately.  See unwind-dw2.c for the structs.  */

/* Don't use this if inhibit_libc is set.

   The build for this target will fail trying to include missing headers. */

#ifndef inhibit_libc

#include <signal.h>

#include <sys/ucontext.h>

/* Unfortunately, because of various bugs and changes to the kernel,

   we have several cases to deal with.

   In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should

   point directly at the beginning of the trampoline and struct rt_sigframe.

   In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and

   (CONTEXT)->ra points at the 4th word in the trampoline structure.  This

   is wrong, it should point at the 5th word.  This is fixed in 2.6.5-rc2-pa4.

   To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes

   to get the beginning of the signal frame, and then check offsets 0, 4

   and 5 to see if we found the beginning of the trampoline.  This will

   tell us how to locate the sigcontext structure.

   Note that with a 2.4 64-bit kernel, the signal context is not properly

   passed back to userspace so the unwind will not work correctly.  */

#define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state

static _Unwind_Reason_Code

pa32_fallback_frame_state (struct _Unwind_Context *context,

                           _Unwind_FrameState *fs)

{

  unsigned long sp = (unsigned long)context->ra & ~63;

  unsigned int *pc = (unsigned int *)sp;

  unsigned long off;

  _Unwind_Ptr new_cfa;

  int i;

  struct sigcontext *sc;

  struct rt_sigframe {

    struct siginfo info;

    struct ucontext uc;

  } *frame;

  /* rt_sigreturn trampoline:

     3419000x ldi 0, %r25 or ldi 1, %r25   (x = 0 or 2)

     3414015a ldi __NR_rt_sigreturn, %r20

     e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31

     08000240 nop  */

  if (pc[0] == 0x34190000 || pc[0] == 0x34190002)

    off = 4*4;

  else if (pc[4] == 0x34190000 || pc[4] == 0x34190002)

    {

      pc += 4;

      off = 10 * 4;

    }

  else if (pc[5] == 0x34190000 || pc[5] == 0x34190002)

    {

      pc += 5;

      off = 10 * 4;

    }

  else

    {

      /* We may have to unwind through an alternate signal stack.

         We assume that the alignment of the alternate signal stack

         is BIGGEST_ALIGNMENT (i.e., that it has been allocated using

         malloc).  As a result, we can't distinguish trampolines

         used prior to 2.6.5-rc2-pa4.  However after 2.6.5-rc2-pa4,

         the return address of a signal trampoline will be on an odd

         word boundary and we can then determine the frame offset.  */

      sp = (unsigned long)context->ra;

      pc = (unsigned int *)sp;

      if ((pc[0] == 0x34190000 || pc[0] == 0x34190002) && (sp & 4))

        off = 5 * 4;

      else

        return _URC_END_OF_STACK;

    }

  if (pc[1] != 0x3414015a

      || pc[2] != 0xe4008200

      || pc[3] != 0x08000240)

    return _URC_END_OF_STACK;

  frame = (struct rt_sigframe *)(sp + off);

  sc = &frame->uc.uc_mcontext;

  new_cfa = sc->sc_gr[30];

  fs->regs.cfa_how = CFA_REG_OFFSET;

  fs->regs.cfa_reg = 30;

  fs->regs.cfa_offset = new_cfa - (long) context->cfa;

  for (i = 1; i <= 31; i++)

    {

      fs->regs.reg[i].how = REG_SAVED_OFFSET;

      fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;

    }

  for (i = 4; i <= 31; i++)

    {

      /* FP regs have left and right halves */

      fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;

      fs->regs.reg[2*i+24].loc.offset

        = (long)&sc->sc_fr[i] - new_cfa;

      fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;

      fs->regs.reg[2*i+24+1].loc.offset

        = (long)&sc->sc_fr[i] + 4 - new_cfa;

    }

  fs->regs.reg[88].how = REG_SAVED_OFFSET;

  fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;

  fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].how = REG_SAVED_OFFSET;

  fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].loc.offset

    = (long) &sc->sc_iaoq[0] - new_cfa;

  fs->retaddr_column = DWARF_ALT_FRAME_RETURN_COLUMN;

  fs->signal_frame = 1;

  return _URC_NO_REASON;

}

#endif /* inhibit_libc */