src/ppc32/Gstep.c - platform/external/libunwind - Git at Google

 /* libunwind - a platform-independent unwind library
    Copyright (C) 2006-2007 IBM
    Contributed by
      Corey Ashford <cjashfor@us.ibm.com>
      Jose Flavio Aguilar Paulino <jflavio@br.ibm.com> <joseflavio@gmail.com>

 This file is part of libunwind.

 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
 without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
 permit persons to whom the Software is furnished to do so, subject to
 the following conditions:

 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */

 #include "unwind_i.h"
 #include "ucontext_i.h"
 #include <signal.h>

 /* This definition originates in /usr/include/asm-ppc64/ptrace.h, but is
    defined there only when __KERNEL__ is defined.  We reproduce it here for
    our use at the user level in order to locate the ucontext record, which
    appears to be at this offset relative to the stack pointer when in the
    context of the signal handler return trampoline code -
    __kernel_sigtramp_rt64.  */
 #define __SIGNAL_FRAMESIZE 128

 /* This definition comes from the document "64-bit PowerPC ELF Application
    Binary Interface Supplement 1.9", section 3.2.2.
    http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK */

 typedef struct
 {
   long unsigned back_chain;
   long unsigned lr_save;
   /* many more fields here, but they are unused by this code */
 } stack_frame_t;


 PROTECTED int
 unw_step (unw_cursor_t * cursor)
 {
   struct cursor *c = (struct cursor *) cursor;
   stack_frame_t dummy;
   unw_word_t back_chain_offset, lr_save_offset;
   struct dwarf_loc back_chain_loc, lr_save_loc, sp_loc, ip_loc;
   int ret;

   Debug (1, "(cursor=%p, ip=0x%016lx)\n", c, (unsigned long) c->dwarf.ip);

   if (c->dwarf.ip == 0)
     {
       /* Unless the cursor or stack is corrupt or uninitialized,
          we've most likely hit the top of the stack */
       return 0;
     }

   /* Try DWARF-based unwinding... */

   ret = dwarf_step (&c->dwarf);

   if (ret < 0 && ret != -UNW_ENOINFO)
     {
       Debug (2, "returning %d\n", ret);
       return ret;
     }

   if (unlikely (ret < 0))
     {
       if (likely (!unw_is_signal_frame (cursor)))
 	{
 	  /* DWARF unwinding failed.  As of 09/26/2006, gcc in 64-bit mode
 	     produces the mandatory level of traceback record in the code, but
 	     I get the impression that this is transitory, that eventually gcc
 	     will not produce any traceback records at all.  So, for now, we
 	     won't bother to try to find and use these records.

 	     We can, however, attempt to unwind the frame by using the callback
 	     chain.  This is very crude, however, and won't be able to unwind
 	     any registers besides the IP, SP, and LR . */

 	  back_chain_offset = ((void *) &dummy.back_chain - (void *) &dummy);
 	  lr_save_offset = ((void *) &dummy.lr_save - (void *) &dummy);

 	  back_chain_loc = DWARF_LOC (c->dwarf.cfa + back_chain_offset, 0);

 	  if ((ret =
 	       dwarf_get (&c->dwarf, back_chain_loc, &c->dwarf.cfa)) < 0)
 	    {
 	      Debug (2,
 		 "Unable to retrieve CFA from back chain in stack frame - %d\n",
 		 ret);
 	      return ret;
 	    }
 	  if (c->dwarf.cfa == 0)
 	    /* Unless the cursor or stack is corrupt or uninitialized we've most
 	       likely hit the top of the stack */
 	    return 0;

 	  lr_save_loc = DWARF_LOC (c->dwarf.cfa + lr_save_offset, 0);

 	  if ((ret = dwarf_get (&c->dwarf, lr_save_loc, &c->dwarf.ip)) < 0)
 	    {
 	      Debug (2,
 		 "Unable to retrieve IP from lr save in stack frame - %d\n",
 		 ret);
 	      return ret;
 	    }
 	  ret = 1;
 	}
       else
 	{
           /* Find the sigcontext record by taking the CFA and adjusting by
              the dummy signal frame size.

              Note that there isn't any way to determined if SA_SIGINFO was
              set in the sa_flags parameter to sigaction when the signal
              handler was established.  If it was not set, the ucontext
              record is not required to be on the stack, in which case the
              following code will likely cause a seg fault or other crash
              condition.  */

 	  unw_word_t ucontext = c->dwarf.cfa + __SIGNAL_FRAMESIZE;

 	  Debug (1, "signal frame, skip over trampoline\n");

 	  c->sigcontext_format = PPC_SCF_LINUX_RT_SIGFRAME;
 	  c->sigcontext_addr = ucontext;

 	  sp_loc = DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R1, 0);
 	  ip_loc = DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_LINK, 0);

 	  ret = dwarf_get (&c->dwarf, sp_loc, &c->dwarf.cfa);
 	  if (ret < 0)
 	    {
 	      Debug (2, "returning %d\n", ret);
 	      return ret;
 	    }
 	  ret = dwarf_get (&c->dwarf, ip_loc, &c->dwarf.ip);
 	  if (ret < 0)
 	    {
 	      Debug (2, "returning %d\n", ret);
 	      return ret;
 	    }

 	  /* Instead of just restoring the non-volatile registers, do all
 	     of the registers for now.  This will incur a performance hit,
 	     but it's rare enough not to cause too much of a problem, and
 	     might be useful in some cases.  */
 	  c->dwarf.loc[UNW_PPC32_R0] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R0, 0);
 	  c->dwarf.loc[UNW_PPC32_R1] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R1, 0);
 	  c->dwarf.loc[UNW_PPC32_R2] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R2, 0);
 	  c->dwarf.loc[UNW_PPC32_R3] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R3, 0);
 	  c->dwarf.loc[UNW_PPC32_R4] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R4, 0);
 	  c->dwarf.loc[UNW_PPC32_R5] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R5, 0);
 	  c->dwarf.loc[UNW_PPC32_R6] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R6, 0);
 	  c->dwarf.loc[UNW_PPC32_R7] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R7, 0);
 	  c->dwarf.loc[UNW_PPC32_R8] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R8, 0);
 	  c->dwarf.loc[UNW_PPC32_R9] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R9, 0);
 	  c->dwarf.loc[UNW_PPC32_R10] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R10, 0);
 	  c->dwarf.loc[UNW_PPC32_R11] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R11, 0);
 	  c->dwarf.loc[UNW_PPC32_R12] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R12, 0);
 	  c->dwarf.loc[UNW_PPC32_R13] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R13, 0);
 	  c->dwarf.loc[UNW_PPC32_R14] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R14, 0);
 	  c->dwarf.loc[UNW_PPC32_R15] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R15, 0);
 	  c->dwarf.loc[UNW_PPC32_R16] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R16, 0);
 	  c->dwarf.loc[UNW_PPC32_R17] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R17, 0);
 	  c->dwarf.loc[UNW_PPC32_R18] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R18, 0);
 	  c->dwarf.loc[UNW_PPC32_R19] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R19, 0);
 	  c->dwarf.loc[UNW_PPC32_R20] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R20, 0);
 	  c->dwarf.loc[UNW_PPC32_R21] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R21, 0);
 	  c->dwarf.loc[UNW_PPC32_R22] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R22, 0);
 	  c->dwarf.loc[UNW_PPC32_R23] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R23, 0);
 	  c->dwarf.loc[UNW_PPC32_R24] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R24, 0);
 	  c->dwarf.loc[UNW_PPC32_R25] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R25, 0);
 	  c->dwarf.loc[UNW_PPC32_R26] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R26, 0);
 	  c->dwarf.loc[UNW_PPC32_R27] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R27, 0);
 	  c->dwarf.loc[UNW_PPC32_R28] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R28, 0);
 	  c->dwarf.loc[UNW_PPC32_R29] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R29, 0);
 	  c->dwarf.loc[UNW_PPC32_R30] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R30, 0);
 	  c->dwarf.loc[UNW_PPC32_R31] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R31, 0);

 	  c->dwarf.loc[UNW_PPC32_LR] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_LINK, 0);
 	  c->dwarf.loc[UNW_PPC32_CTR] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_CTR, 0);

 	  /* This CR0 assignment is probably wrong.  There are 8 dwarf columns
 	     assigned to the CR registers, but only one CR register in the
 	     mcontext structure */
 	  c->dwarf.loc[UNW_PPC32_CCR] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_CCR, 0);
 	  c->dwarf.loc[UNW_PPC32_XER] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_XER, 0);

 	  c->dwarf.loc[UNW_PPC32_F0] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R0, 0);
 	  c->dwarf.loc[UNW_PPC32_F1] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R1, 0);
 	  c->dwarf.loc[UNW_PPC32_F2] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R2, 0);
 	  c->dwarf.loc[UNW_PPC32_F3] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R3, 0);
 	  c->dwarf.loc[UNW_PPC32_F4] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R4, 0);
 	  c->dwarf.loc[UNW_PPC32_F5] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R5, 0);
 	  c->dwarf.loc[UNW_PPC32_F6] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R6, 0);
 	  c->dwarf.loc[UNW_PPC32_F7] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R7, 0);
 	  c->dwarf.loc[UNW_PPC32_F8] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R8, 0);
 	  c->dwarf.loc[UNW_PPC32_F9] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R9, 0);
 	  c->dwarf.loc[UNW_PPC32_F10] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R10, 0);
 	  c->dwarf.loc[UNW_PPC32_F11] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R11, 0);
 	  c->dwarf.loc[UNW_PPC32_F12] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R12, 0);
 	  c->dwarf.loc[UNW_PPC32_F13] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R13, 0);
 	  c->dwarf.loc[UNW_PPC32_F14] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R14, 0);
 	  c->dwarf.loc[UNW_PPC32_F15] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R15, 0);
 	  c->dwarf.loc[UNW_PPC32_F16] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R16, 0);
 	  c->dwarf.loc[UNW_PPC32_F17] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R17, 0);
 	  c->dwarf.loc[UNW_PPC32_F18] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R18, 0);
 	  c->dwarf.loc[UNW_PPC32_F19] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R19, 0);
 	  c->dwarf.loc[UNW_PPC32_F20] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R20, 0);
 	  c->dwarf.loc[UNW_PPC32_F21] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R21, 0);
 	  c->dwarf.loc[UNW_PPC32_F22] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R22, 0);
 	  c->dwarf.loc[UNW_PPC32_F23] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R23, 0);
 	  c->dwarf.loc[UNW_PPC32_F24] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R24, 0);
 	  c->dwarf.loc[UNW_PPC32_F25] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R25, 0);
 	  c->dwarf.loc[UNW_PPC32_F26] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R26, 0);
 	  c->dwarf.loc[UNW_PPC32_F27] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R27, 0);
 	  c->dwarf.loc[UNW_PPC32_F28] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R28, 0);
 	  c->dwarf.loc[UNW_PPC32_F29] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R29, 0);
 	  c->dwarf.loc[UNW_PPC32_F30] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R30, 0);
 	  c->dwarf.loc[UNW_PPC32_F31] =
 	    DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R31, 0);

 	  ret = 1;
 	}
     }
   return ret;
 }
	/* libunwind - a platform-independent unwind library
	Copyright (C) 2006-2007 IBM
	Contributed by
	Corey Ashford <cjashfor@us.ibm.com>
	Jose Flavio Aguilar Paulino <jflavio@br.ibm.com> <joseflavio@gmail.com>

	This file is part of libunwind.

	Permission is hereby granted, free of charge, to any person obtaining
	a copy of this software and associated documentation files (the
	"Software"), to deal in the Software without restriction, including
	without limitation the rights to use, copy, modify, merge, publish,
	distribute, sublicense, and/or sell copies of the Software, and to
	permit persons to whom the Software is furnished to do so, subject to
	the following conditions:

	The above copyright notice and this permission notice shall be
	included in all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */

	#include "unwind_i.h"
	#include "ucontext_i.h"
	#include <signal.h>

	/* This definition originates in /usr/include/asm-ppc64/ptrace.h, but is
	defined there only when __KERNEL__ is defined. We reproduce it here for
	our use at the user level in order to locate the ucontext record, which
	appears to be at this offset relative to the stack pointer when in the
	context of the signal handler return trampoline code -
	__kernel_sigtramp_rt64. */
	#define __SIGNAL_FRAMESIZE 128

	/* This definition comes from the document "64-bit PowerPC ELF Application
	Binary Interface Supplement 1.9", section 3.2.2.
	http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK */

	typedef struct
	{
	long unsigned back_chain;
	long unsigned lr_save;
	/* many more fields here, but they are unused by this code */
	} stack_frame_t;


	PROTECTED int
	unw_step (unw_cursor_t * cursor)
	{
	struct cursor c = (struct cursor ) cursor;
	stack_frame_t dummy;
	unw_word_t back_chain_offset, lr_save_offset;
	struct dwarf_loc back_chain_loc, lr_save_loc, sp_loc, ip_loc;
	int ret;

	Debug (1, "(cursor=%p, ip=0x%016lx)\n", c, (unsigned long) c->dwarf.ip);

	if (c->dwarf.ip == 0)
	{
	/* Unless the cursor or stack is corrupt or uninitialized,
	we've most likely hit the top of the stack */
	return 0;
	}

	/* Try DWARF-based unwinding... */

	ret = dwarf_step (&c->dwarf);

	if (ret < 0 && ret != -UNW_ENOINFO)
	{
	Debug (2, "returning %d\n", ret);
	return ret;
	}

	if (unlikely (ret < 0))
	{
	if (likely (!unw_is_signal_frame (cursor)))
	{
	/* DWARF unwinding failed. As of 09/26/2006, gcc in 64-bit mode
	produces the mandatory level of traceback record in the code, but
	I get the impression that this is transitory, that eventually gcc
	will not produce any traceback records at all. So, for now, we
	won't bother to try to find and use these records.

	We can, however, attempt to unwind the frame by using the callback
	chain. This is very crude, however, and won't be able to unwind
	any registers besides the IP, SP, and LR . */

	back_chain_offset = ((void ) &dummy.back_chain - (void ) &dummy);
	lr_save_offset = ((void ) &dummy.lr_save - (void ) &dummy);

	back_chain_loc = DWARF_LOC (c->dwarf.cfa + back_chain_offset, 0);

	if ((ret =
	dwarf_get (&c->dwarf, back_chain_loc, &c->dwarf.cfa)) < 0)
	{
	Debug (2,
	"Unable to retrieve CFA from back chain in stack frame - %d\n",
	ret);
	return ret;
	}
	if (c->dwarf.cfa == 0)
	/* Unless the cursor or stack is corrupt or uninitialized we've most
	likely hit the top of the stack */
	return 0;

	lr_save_loc = DWARF_LOC (c->dwarf.cfa + lr_save_offset, 0);

	if ((ret = dwarf_get (&c->dwarf, lr_save_loc, &c->dwarf.ip)) < 0)
	{
	Debug (2,
	"Unable to retrieve IP from lr save in stack frame - %d\n",
	ret);
	return ret;
	}
	ret = 1;
	}
	else
	{
	/* Find the sigcontext record by taking the CFA and adjusting by
	the dummy signal frame size.

	Note that there isn't any way to determined if SA_SIGINFO was
	set in the sa_flags parameter to sigaction when the signal
	handler was established. If it was not set, the ucontext
	record is not required to be on the stack, in which case the
	following code will likely cause a seg fault or other crash
	condition. */

	unw_word_t ucontext = c->dwarf.cfa + __SIGNAL_FRAMESIZE;

	Debug (1, "signal frame, skip over trampoline\n");

	c->sigcontext_format = PPC_SCF_LINUX_RT_SIGFRAME;
	c->sigcontext_addr = ucontext;

	sp_loc = DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R1, 0);
	ip_loc = DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_LINK, 0);

	ret = dwarf_get (&c->dwarf, sp_loc, &c->dwarf.cfa);
	if (ret < 0)
	{
	Debug (2, "returning %d\n", ret);
	return ret;
	}
	ret = dwarf_get (&c->dwarf, ip_loc, &c->dwarf.ip);
	if (ret < 0)
	{
	Debug (2, "returning %d\n", ret);
	return ret;
	}

	/* Instead of just restoring the non-volatile registers, do all
	of the registers for now. This will incur a performance hit,
	but it's rare enough not to cause too much of a problem, and
	might be useful in some cases. */
	c->dwarf.loc[UNW_PPC32_R0] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R0, 0);
	c->dwarf.loc[UNW_PPC32_R1] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R1, 0);
	c->dwarf.loc[UNW_PPC32_R2] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R2, 0);
	c->dwarf.loc[UNW_PPC32_R3] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R3, 0);
	c->dwarf.loc[UNW_PPC32_R4] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R4, 0);
	c->dwarf.loc[UNW_PPC32_R5] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R5, 0);
	c->dwarf.loc[UNW_PPC32_R6] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R6, 0);
	c->dwarf.loc[UNW_PPC32_R7] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R7, 0);
	c->dwarf.loc[UNW_PPC32_R8] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R8, 0);
	c->dwarf.loc[UNW_PPC32_R9] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R9, 0);
	c->dwarf.loc[UNW_PPC32_R10] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R10, 0);
	c->dwarf.loc[UNW_PPC32_R11] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R11, 0);
	c->dwarf.loc[UNW_PPC32_R12] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R12, 0);
	c->dwarf.loc[UNW_PPC32_R13] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R13, 0);
	c->dwarf.loc[UNW_PPC32_R14] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R14, 0);
	c->dwarf.loc[UNW_PPC32_R15] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R15, 0);
	c->dwarf.loc[UNW_PPC32_R16] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R16, 0);
	c->dwarf.loc[UNW_PPC32_R17] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R17, 0);
	c->dwarf.loc[UNW_PPC32_R18] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R18, 0);
	c->dwarf.loc[UNW_PPC32_R19] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R19, 0);
	c->dwarf.loc[UNW_PPC32_R20] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R20, 0);
	c->dwarf.loc[UNW_PPC32_R21] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R21, 0);
	c->dwarf.loc[UNW_PPC32_R22] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R22, 0);
	c->dwarf.loc[UNW_PPC32_R23] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R23, 0);
	c->dwarf.loc[UNW_PPC32_R24] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R24, 0);
	c->dwarf.loc[UNW_PPC32_R25] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R25, 0);
	c->dwarf.loc[UNW_PPC32_R26] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R26, 0);
	c->dwarf.loc[UNW_PPC32_R27] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R27, 0);
	c->dwarf.loc[UNW_PPC32_R28] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R28, 0);
	c->dwarf.loc[UNW_PPC32_R29] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R29, 0);
	c->dwarf.loc[UNW_PPC32_R30] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R30, 0);
	c->dwarf.loc[UNW_PPC32_R31] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_R31, 0);

	c->dwarf.loc[UNW_PPC32_LR] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_LINK, 0);
	c->dwarf.loc[UNW_PPC32_CTR] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_CTR, 0);

	/* This CR0 assignment is probably wrong. There are 8 dwarf columns
	assigned to the CR registers, but only one CR register in the
	mcontext structure */
	c->dwarf.loc[UNW_PPC32_CCR] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_CCR, 0);
	c->dwarf.loc[UNW_PPC32_XER] =
	DWARF_LOC (ucontext + UC_MCONTEXT_GREGS_XER, 0);

	c->dwarf.loc[UNW_PPC32_F0] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R0, 0);
	c->dwarf.loc[UNW_PPC32_F1] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R1, 0);
	c->dwarf.loc[UNW_PPC32_F2] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R2, 0);
	c->dwarf.loc[UNW_PPC32_F3] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R3, 0);
	c->dwarf.loc[UNW_PPC32_F4] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R4, 0);
	c->dwarf.loc[UNW_PPC32_F5] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R5, 0);
	c->dwarf.loc[UNW_PPC32_F6] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R6, 0);
	c->dwarf.loc[UNW_PPC32_F7] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R7, 0);
	c->dwarf.loc[UNW_PPC32_F8] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R8, 0);
	c->dwarf.loc[UNW_PPC32_F9] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R9, 0);
	c->dwarf.loc[UNW_PPC32_F10] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R10, 0);
	c->dwarf.loc[UNW_PPC32_F11] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R11, 0);
	c->dwarf.loc[UNW_PPC32_F12] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R12, 0);
	c->dwarf.loc[UNW_PPC32_F13] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R13, 0);
	c->dwarf.loc[UNW_PPC32_F14] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R14, 0);
	c->dwarf.loc[UNW_PPC32_F15] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R15, 0);
	c->dwarf.loc[UNW_PPC32_F16] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R16, 0);
	c->dwarf.loc[UNW_PPC32_F17] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R17, 0);
	c->dwarf.loc[UNW_PPC32_F18] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R18, 0);
	c->dwarf.loc[UNW_PPC32_F19] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R19, 0);
	c->dwarf.loc[UNW_PPC32_F20] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R20, 0);
	c->dwarf.loc[UNW_PPC32_F21] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R21, 0);
	c->dwarf.loc[UNW_PPC32_F22] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R22, 0);
	c->dwarf.loc[UNW_PPC32_F23] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R23, 0);
	c->dwarf.loc[UNW_PPC32_F24] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R24, 0);
	c->dwarf.loc[UNW_PPC32_F25] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R25, 0);
	c->dwarf.loc[UNW_PPC32_F26] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R26, 0);
	c->dwarf.loc[UNW_PPC32_F27] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R27, 0);
	c->dwarf.loc[UNW_PPC32_F28] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R28, 0);
	c->dwarf.loc[UNW_PPC32_F29] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R29, 0);
	c->dwarf.loc[UNW_PPC32_F30] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R30, 0);
	c->dwarf.loc[UNW_PPC32_F31] =
	DWARF_LOC (ucontext + UC_MCONTEXT_FREGS_R31, 0);

	ret = 1;
	}
	}
	return ret;
	}