/* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.
   Copyright (C) 2004 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 2, 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.

   You should have received a copy of the GNU General Public License
   along with GCC; see the file COPYING.  If not, write to the
   Free Software Foundation, 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA.  */

/* This file defines our own versions of various kernel and user
   structs, so that system headers are not needed, which otherwise
   can make bootstrapping a new toolchain difficult.  Do not use
   these structs elsewhere;  Many fields are missing, particularly
   from the end of the structures.  */

struct gcc_pt_regs
{
  unsigned long gpr[32];
  unsigned long nip;
  unsigned long msr;
  unsigned long orig_gpr3;
  unsigned long ctr;
  unsigned long link;
  unsigned long xer;
  unsigned long ccr;
};

struct gcc_sigcontext
{
  unsigned long	pad[7];
  struct gcc_pt_regs *regs;
};

struct gcc_ucontext
{
#ifdef __powerpc64__
  unsigned long pad[21];
#else
  unsigned long pad[5];
#endif
  struct gcc_sigcontext uc_mcontext;
};

#ifdef __powerpc64__

enum { SIGNAL_FRAMESIZE = 128 };

/* If the current unwind info (FS) does not contain explicit info
   saving R2, then we have to do a minor amount of code reading to
   figure out if it was saved.  The big problem here is that the
   code that does the save/restore is generated by the linker, so
   we have no good way to determine at compile time what to do.  */

#define MD_FROB_UPDATE_CONTEXT frob_update_context

static void
frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
{
  if (fs->regs.reg[2].how == REG_UNSAVED)
    {
      unsigned int *insn
	= (unsigned int *) _Unwind_GetGR (context, LINK_REGISTER_REGNUM);
      if (*insn == 0xE8410028)
	_Unwind_SetGRPtr (context, 2, context->cfa + 40);
    }
}

/* If PC is at a sigreturn trampoline, return a pointer to the
   sigcontext.  Otherwise return NULL.  */

static struct gcc_sigcontext *
get_sigcontext (struct _Unwind_Context *context)
{
  const unsigned char *pc = context->ra;

  /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */
  /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */
  if (*(unsigned int *) (pc+0) != 0x38210000 + SIGNAL_FRAMESIZE
      || *(unsigned int *) (pc+8) != 0x44000002)
    return NULL;
  if (*(unsigned int *) (pc+4) == 0x38000077)
    {
      struct sigframe {
	char gap[SIGNAL_FRAMESIZE];
	struct gcc_sigcontext sigctx;
      } *rt_ = context->cfa;
      return &rt_->sigctx;
    }
  else if (*(unsigned int *) (pc+4) == 0x380000AC)
    {
      struct rt_sigframe {
	int tramp[6];
	void *pinfo;
	struct gcc_ucontext *puc;
      } *rt_ = (struct rt_sigframe *) pc;
      return &rt_->puc->uc_mcontext;
    }
  return NULL;
}

#else  /* !__powerpc64__ */

enum { SIGNAL_FRAMESIZE = 64 };

static struct gcc_sigcontext *
get_sigcontext (struct _Unwind_Context *context)
{
  const unsigned char *pc = context->ra;

  /* li r0, 0x7777; sc  (sigreturn old)  */
  /* li r0, 0x0077; sc  (sigreturn new)  */
  /* li r0, 0x6666; sc  (rt_sigreturn old)  */
  /* li r0, 0x00AC; sc  (rt_sigreturn new)  */
  if (*(unsigned int *) (pc+4) != 0x44000002)
    return NULL;
  if (*(unsigned int *) (pc+0) == 0x38007777
      || *(unsigned int *) (pc+0) == 0x38000077)
    {
      struct sigframe {
	char gap[SIGNAL_FRAMESIZE];
	struct gcc_sigcontext sigctx;
      } *rt_ = context->cfa;
      return &rt_->sigctx;
    }
  else if (*(unsigned int *) (pc+0) == 0x38006666
	   || *(unsigned int *) (pc+0) == 0x380000AC)
    {
      struct rt_sigframe {
	char gap[SIGNAL_FRAMESIZE + 16];
	char siginfo[128];
	struct gcc_ucontext uc;
      } *rt_ = context->cfa;
      return &rt_->uc.uc_mcontext;
    }
  return NULL;
}
#endif

/* Do code reading to identify a signal frame, and set the frame
   state data appropriately.  See unwind-dw2.c for the structs.  */

#define MD_FALLBACK_FRAME_STATE_FOR ppc_fallback_frame_state

static _Unwind_Reason_Code
ppc_fallback_frame_state (struct _Unwind_Context *context,
			  _Unwind_FrameState *fs)
{
  struct gcc_sigcontext *sc = get_sigcontext (context);
  long new_cfa;
  int i;

  if (sc == NULL)
    return _URC_END_OF_STACK;

  new_cfa = sc->regs->gpr[STACK_POINTER_REGNUM];
  fs->cfa_how = CFA_REG_OFFSET;
  fs->cfa_reg = STACK_POINTER_REGNUM;
  fs->cfa_offset = new_cfa - (long) context->cfa;

  for (i = 0; i < 32; i++)
    if (i != STACK_POINTER_REGNUM)
      {
	fs->regs.reg[i].how = REG_SAVED_OFFSET;
	fs->regs.reg[i].loc.offset
	  = (long)&(sc->regs->gpr[i]) - new_cfa;
      }

  fs->regs.reg[CR2_REGNO].how = REG_SAVED_OFFSET;
  fs->regs.reg[CR2_REGNO].loc.offset
    = (long)&(sc->regs->ccr) - new_cfa;

  fs->regs.reg[LINK_REGISTER_REGNUM].how = REG_SAVED_OFFSET;
  fs->regs.reg[LINK_REGISTER_REGNUM].loc.offset
    = (long)&(sc->regs->link) - new_cfa;

  fs->regs.reg[ARG_POINTER_REGNUM].how = REG_SAVED_OFFSET;
  fs->regs.reg[ARG_POINTER_REGNUM].loc.offset
    = (long)&(sc->regs->nip) - new_cfa;
  fs->retaddr_column = ARG_POINTER_REGNUM;
  return _URC_NO_REASON;
}