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/* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.

   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011

   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/>.  */

#define R_LR            65

#define R_CR2           70

#define R_VR0           77

#define R_VRSAVE        109

#define R_VSCR          110

struct gcc_vregs

{

  __attribute__ ((vector_size (16))) int vr[32];

#ifdef __powerpc64__

  unsigned int pad1[3];

  unsigned int vscr;

  unsigned int vsave;

  unsigned int pad2[3];

#else

  unsigned int vsave;

  unsigned int pad[2];

  unsigned int vscr;

#endif

};

struct gcc_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;

  unsigned long softe;

  unsigned long trap;

  unsigned long dar;

  unsigned long dsisr;

  unsigned long result;

  unsigned long pad1[4];

  double fpr[32];

  unsigned int pad2;

  unsigned int fpscr;

#ifdef __powerpc64__

  struct gcc_vregs *vp;

#else

  unsigned int pad3[2];

#endif

  struct gcc_vregs vregs;

};

struct gcc_ucontext

{

#ifdef __powerpc64__

  unsigned long pad[28];

#else

  unsigned long pad[12];

#endif

  struct gcc_regs *regs;

  struct gcc_regs rsave;

};

#ifdef __powerpc64__

enum { SIGNAL_FRAMESIZE = 128 };

/* If PC is at a sigreturn trampoline, return a pointer to the

   regs.  Otherwise return NULL.  */

static struct gcc_regs *

get_regs (struct _Unwind_Context *context)

{

  const unsigned int *pc = context->ra;

  /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */

  /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */

  if (pc[0] != 0x38210000 + SIGNAL_FRAMESIZE || pc[2] != 0x44000002)

    return NULL;

  if (pc[1] == 0x38000077)

    {

      struct sigframe {

        char gap[SIGNAL_FRAMESIZE];

        unsigned long pad[7];

        struct gcc_regs *regs;

      } *frame = (struct sigframe *) context->cfa;

      return frame->regs;

    }

  else if (pc[1] == 0x380000AC)

    {

      /* This works for 2.4 kernels, but not for 2.6 kernels with vdso

         because pc isn't pointing into the stack.  Can be removed when

         no one is running 2.4.19 or 2.4.20, the first two ppc64

         kernels released.  */

      const struct rt_sigframe_24 {

        int tramp[6];

        void *pinfo;

        struct gcc_ucontext *puc;

      } *frame24 = (const struct rt_sigframe_24 *) context->ra;

      /* Test for magic value in *puc of vdso.  */

      if ((long) frame24->puc != -21 * 8)

        return frame24->puc->regs;

      else

        {

          /* This works for 2.4.21 and later kernels.  */

          struct rt_sigframe {

            char gap[SIGNAL_FRAMESIZE];

            struct gcc_ucontext uc;

            unsigned long pad[2];

            int tramp[6];

            void *pinfo;

            struct gcc_ucontext *puc;

          } *frame = (struct rt_sigframe *) context->cfa;

          return frame->uc.regs;

        }

    }

  return NULL;

}

#else  /* !__powerpc64__ */

enum { SIGNAL_FRAMESIZE = 64 };

static struct gcc_regs *

get_regs (struct _Unwind_Context *context)

{

  const unsigned int *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 (pc[1] != 0x44000002)

    return NULL;

  if (pc[0] == 0x38007777 || pc[0] == 0x38000077)

    {

      struct sigframe {

        char gap[SIGNAL_FRAMESIZE];

        unsigned long pad[7];

        struct gcc_regs *regs;

      } *frame = (struct sigframe *) context->cfa;

      return frame->regs;

    }

  else if (pc[0] == 0x38006666 || pc[0] == 0x380000AC)

    {

      struct rt_sigframe {

        char gap[SIGNAL_FRAMESIZE + 16];

        char siginfo[128];

        struct gcc_ucontext uc;

      } *frame = (struct rt_sigframe *) context->cfa;

      return frame->uc.regs;

    }

  return NULL;

}

#endif

/* Find an entry in the process auxiliary vector.  The canonical way to

   test for VMX is to look at AT_HWCAP.  */

static long

ppc_linux_aux_vector (long which)

{

  /* __libc_stack_end holds the original stack passed to a process.  */

  extern long *__libc_stack_end;

  long argc;

  char **argv;

  char **envp;

  struct auxv

  {

    long a_type;

    long a_val;

  } *auxp;

  /* The Linux kernel puts argc first on the stack.  */

  argc = __libc_stack_end[0];

  /* Followed by argv, NULL terminated.  */

  argv = (char **) __libc_stack_end + 1;

  /* Followed by environment string pointers, NULL terminated. */

  envp = argv + argc + 1;

  while (*envp++)

    continue;

  /* Followed by the aux vector, zero terminated.  */

  for (auxp = (struct auxv *) envp; auxp->a_type != 0; ++auxp)

    if (auxp->a_type == which)

      return auxp->a_val;

  return 0;

}

/* 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)

{

  static long hwcap = 0;

  struct gcc_regs *regs = get_regs (context);

  long new_cfa;

  int i;

  if (regs == NULL)

    return _URC_END_OF_STACK;

  new_cfa = regs->gpr[STACK_POINTER_REGNUM];

  fs->regs.cfa_how = CFA_REG_OFFSET;

  fs->regs.cfa_reg = STACK_POINTER_REGNUM;

  fs->regs.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) &regs->gpr[i] - new_cfa;

      }

  fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;

  /* CR? regs are always 32-bit and PPC is big-endian, so in 64-bit

     libgcc loc.offset needs to point to the low 32 bits of regs->ccr.  */

  fs->regs.reg[R_CR2].loc.offset = (long) &regs->ccr - new_cfa

                                   + sizeof (long) - 4;

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

  fs->regs.reg[R_LR].loc.offset = (long) &regs->link - new_cfa;

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

  fs->regs.reg[ARG_POINTER_REGNUM].loc.offset = (long) &regs->nip - new_cfa;

  fs->retaddr_column = ARG_POINTER_REGNUM;

  fs->signal_frame = 1;

  if (hwcap == 0)

    {

      hwcap = ppc_linux_aux_vector (16);

      /* These will already be set if we found AT_HWCAP.  A nonzero

         value stops us looking again if for some reason we couldn't

         find AT_HWCAP.  */

#ifdef __powerpc64__

      hwcap |= 0xc0000000;

#else

      hwcap |= 0x80000000;

#endif

    }

  /* If we have a FPU...  */

  if (hwcap & 0x08000000)

    for (i = 0; i < 32; i++)

      {

        fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;

        fs->regs.reg[i + 32].loc.offset = (long) &regs->fpr[i] - new_cfa;

      }

  /* If we have a VMX unit...  */

  if (hwcap & 0x10000000)

    {

      struct gcc_vregs *vregs;

#ifdef __powerpc64__

      vregs = regs->vp;

#else

      vregs = &regs->vregs;

#endif

      if (regs->msr & (1 << 25))

        {

          for (i = 0; i < 32; i++)

            {

              fs->regs.reg[i + R_VR0].how = REG_SAVED_OFFSET;

              fs->regs.reg[i + R_VR0].loc.offset

                = (long) &vregs->vr[i] - new_cfa;

            }

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

          fs->regs.reg[R_VSCR].loc.offset = (long) &vregs->vscr - new_cfa;

        }

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

      fs->regs.reg[R_VRSAVE].loc.offset = (long) &vregs->vsave - new_cfa;

    }

  /* If we have SPE register high-parts... we check at compile-time to

     avoid expanding the code for all other PowerPC.  */

#ifdef __SPE__

  for (i = 0; i < 32; i++)

    {

      fs->regs.reg[i + FIRST_PSEUDO_REGISTER - 1].how = REG_SAVED_OFFSET;

      fs->regs.reg[i + FIRST_PSEUDO_REGISTER - 1].loc.offset

        = (long) &regs->vregs - new_cfa + 4 * i;

    }

#endif

  return _URC_NO_REASON;

}

#define MD_FROB_UPDATE_CONTEXT frob_update_context

static void

frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATTRIBUTE_UNUSED)

{

  const unsigned int *pc = (const unsigned int *) context->ra;

  /* Fix up for 2.6.12 - 2.6.16 Linux kernels that have vDSO, but don't

     have S flag in it.  */

#ifdef __powerpc64__

  /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */

  /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */

  if (pc[0] == 0x38210000 + SIGNAL_FRAMESIZE

      && (pc[1] == 0x38000077 || pc[1] == 0x380000AC)

      && pc[2] == 0x44000002)

    _Unwind_SetSignalFrame (context, 1);

#else

  /* 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 ((pc[0] == 0x38007777 || pc[0] == 0x38000077

       || pc[0] == 0x38006666 || pc[0] == 0x380000AC)

      && pc[1] == 0x44000002)

    _Unwind_SetSignalFrame (context, 1);

#endif

#ifdef __powerpc64__

  if (fs->regs.reg[2].how == REG_UNSAVED)

    {

      /* 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.  */

      if (pc[0] == 0xF8410028

          || ((pc[0] & 0xFFFF0000) == 0x3D820000

              && pc[1] == 0xF8410028))

        {

          /* We are in a plt call stub or r2 adjusting long branch stub,

             before r2 has been saved.  Keep REG_UNSAVED.  */

        }

      else

        {

          unsigned int *insn

            = (unsigned int *) _Unwind_GetGR (context, R_LR);

          if (insn && *insn == 0xE8410028)

            _Unwind_SetGRPtr (context, 2, context->cfa + 40);

          else if (pc[0] == 0x4E800421

                   && pc[1] == 0xE8410028)

            {

              /* We are at the bctrl instruction in a call via function

                 pointer.  gcc always emits the load of the new R2 just

                 before the bctrl so this is the first and only place

                 we need to use the stored R2.  */

              _Unwind_Word sp = _Unwind_GetGR (context, 1);

              _Unwind_SetGRPtr (context, 2, (void *)(sp + 40));

            }

        }

    }

#endif

}