libgcc/config/rs6000/linux-unwind.h - gcc - Git at Google

 /* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.
    Copyright (C) 2004-2021 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_CR3		71
 #define R_CR4		72
 #define R_VR0		77
 #define R_VRSAVE	109

 #ifdef __powerpc64__
 #if _CALL_ELF == 2
 #define TOC_SAVE_SLOT	24
 #else
 #define TOC_SAVE_SLOT	40
 #endif
 #endif

 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)
     {
 #if _CALL_ELF != 2
       /* These old kernel versions never supported ELFv2.  */
       /* 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
 #endif
 	{
 	  /* 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

 /* 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_regs *regs = get_regs (context);
   struct gcc_vregs *vregs;
   long cr_offset;
   long new_cfa;
   int i;

   if (regs == NULL)
     return _URC_END_OF_STACK;

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

 #ifdef __powerpc64__
   fs->regs.reg[2].how = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long) &regs->gpr[2] - new_cfa;
 #endif
   for (i = 14; i < 32; i++)
     {
       fs->regs.reg[i].how = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
     }

   /* The CR is saved in the low 32 bits of regs->ccr.  */
   cr_offset = (long) &regs->ccr - new_cfa;
 #ifndef __LITTLE_ENDIAN__
   cr_offset += sizeof (long) - 4;
 #endif
   /* In the ELFv1 ABI, CR2 stands in for the whole CR.  */
   fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR2].loc.offset = cr_offset;
 #if _CALL_ELF == 2
   /* In the ELFv2 ABI, every CR field has a separate CFI entry.  */
   fs->regs.reg[R_CR3].how = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR3].loc.offset = cr_offset;
   fs->regs.reg[R_CR4].how = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR4].loc.offset = cr_offset;
 #endif

   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 we have a FPU...  */
   for (i = 14; 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...  */
 #ifdef __powerpc64__
   vregs = regs->vp;
 #else
   vregs = &regs->vregs;
 #endif
   if (regs->msr & (1 << 25))
     {
       for (i = 20; 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_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 = 14; i < 32; i++)
     {
       fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].how = REG_SAVED_OFFSET;
       fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].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] == 0xF8410000 + TOC_SAVE_SLOT
 #if _CALL_ELF != 2
 	  /* The ELFv2 linker never generates the old PLT stub form.  */
 	  || ((pc[0] & 0xFFFF0000) == 0x3D820000
 	      && pc[1] == 0xF8410000 + TOC_SAVE_SLOT)
 #endif
 	  )
 	{
 	  /* 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 == 0xE8410000 + TOC_SAVE_SLOT)
 	    _Unwind_SetGRPtr (context, 2, context->cfa + TOC_SAVE_SLOT);
 #if _CALL_ELF != 2
 	  /* ELFv2 does not use this function pointer call sequence.  */
 	  else if (pc[0] == 0x4E800421
 		   && pc[1] == 0xE8410000 + TOC_SAVE_SLOT)
 	    {
 	      /* 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 + TOC_SAVE_SLOT));
 	    }
 #endif
 	}
     }
 #endif
 }
	/* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.
	Copyright (C) 2004-2021 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_CR3 71
	#define R_CR4 72
	#define R_VR0 77
	#define R_VRSAVE 109

	#ifdef __powerpc64__
	#if _CALL_ELF == 2
	#define TOC_SAVE_SLOT 24
	#else
	#define TOC_SAVE_SLOT 40
	#endif
	#endif

	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)
	{
	#if _CALL_ELF != 2
	/* These old kernel versions never supported ELFv2. */
	/* 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
	#endif
	{
	/* 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

	/* 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_regs *regs = get_regs (context);
	struct gcc_vregs *vregs;
	long cr_offset;
	long new_cfa;
	int i;

	if (regs == NULL)
	return _URC_END_OF_STACK;

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

	#ifdef __powerpc64__
	fs->regs.reg[2].how = REG_SAVED_OFFSET;
	fs->regs.reg[2].loc.offset = (long) &regs->gpr[2] - new_cfa;
	#endif
	for (i = 14; i < 32; i++)
	{
	fs->regs.reg[i].how = REG_SAVED_OFFSET;
	fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
	}

	/* The CR is saved in the low 32 bits of regs->ccr. */
	cr_offset = (long) &regs->ccr - new_cfa;
	#ifndef __LITTLE_ENDIAN__
	cr_offset += sizeof (long) - 4;
	#endif
	/* In the ELFv1 ABI, CR2 stands in for the whole CR. */
	fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
	fs->regs.reg[R_CR2].loc.offset = cr_offset;
	#if _CALL_ELF == 2
	/* In the ELFv2 ABI, every CR field has a separate CFI entry. */
	fs->regs.reg[R_CR3].how = REG_SAVED_OFFSET;
	fs->regs.reg[R_CR3].loc.offset = cr_offset;
	fs->regs.reg[R_CR4].how = REG_SAVED_OFFSET;
	fs->regs.reg[R_CR4].loc.offset = cr_offset;
	#endif

	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 we have a FPU... */
	for (i = 14; 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... */
	#ifdef __powerpc64__
	vregs = regs->vp;
	#else
	vregs = &regs->vregs;
	#endif
	if (regs->msr & (1 << 25))
	{
	for (i = 20; 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_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 = 14; i < 32; i++)
	{
	fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].how = REG_SAVED_OFFSET;
	fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].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] == 0xF8410000 + TOC_SAVE_SLOT
	#if _CALL_ELF != 2
	/* The ELFv2 linker never generates the old PLT stub form. */
	\|\| ((pc[0] & 0xFFFF0000) == 0x3D820000
	&& pc[1] == 0xF8410000 + TOC_SAVE_SLOT)
	#endif
	)
	{
	/* 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 == 0xE8410000 + TOC_SAVE_SLOT)
	_Unwind_SetGRPtr (context, 2, context->cfa + TOC_SAVE_SLOT);
	#if _CALL_ELF != 2
	/* ELFv2 does not use this function pointer call sequence. */
	else if (pc[0] == 0x4E800421
	&& pc[1] == 0xE8410000 + TOC_SAVE_SLOT)
	{
	/* 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 + TOC_SAVE_SLOT));
	}
	#endif
	}
	}
	#endif
	}