src/x86_64/Gstep.c - platform/external/libunwind - Git at Google

 /* libunwind - a platform-independent unwind library
    Copyright (C) 2002-2004 Hewlett-Packard Co
 	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>

    Modified for x86_64 by Max Asbock <masbock@us.ibm.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 <signal.h>

 /* Recognise PLT entries such as:
      3bdf0: ff 25 e2 49 13 00 jmpq   *0x1349e2(%rip)
      3bdf6: 68 ae 03 00 00    pushq  $0x3ae
      3bdfb: e9 00 c5 ff ff    jmpq   38300 <_init+0x18> */
 static int
 is_plt_entry (struct dwarf_cursor *c)
 {
   unw_word_t w0, w1;
   unw_accessors_t *a;
   int ret;

   a = unw_get_accessors (c->as);
   if ((ret = (*a->access_mem) (c->as, c->ip, &w0, 0, c->as_arg)) < 0
       || (ret = (*a->access_mem) (c->as, c->ip + 8, &w1, 0, c->as_arg)) < 0)
     return 0;

   ret = (((w0 & 0xffff) == 0x25ff)
 	 && (((w0 >> 48) & 0xff) == 0x68)
 	 && (((w1 >> 24) & 0xff) == 0xe9));

   Debug (14, "ip=0x%lx => 0x%016lx 0x%016lx, ret = %d\n", c->ip, w0, w1, ret);
   return ret;
 }

 PROTECTED int
 unw_step (unw_cursor_t *cursor)
 {
   struct cursor *c = (struct cursor *) cursor;
   int ret, i;

 #if CONSERVATIVE_CHECKS
   int val = c->validate;
   c->validate = 1;
 #endif

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

   unw_word_t old_ip = c->dwarf.ip;
   unw_word_t old_cfa = c->dwarf.cfa;

   /* Try DWARF-based unwinding... */
   c->sigcontext_format = X86_64_SCF_NONE;
   ret = dwarf_step (&c->dwarf);

 #if CONSERVATIVE_CHECKS
   c->validate = val;
 #endif

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

   if (likely (ret >= 0))
     {
       /* x86_64 ABI specifies that end of call-chain is marked with a
 	 NULL RBP.  */
       if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
 	{
 	  c->dwarf.ip = 0;
 	  ret = 0;
 	}
     }
   else
     {
       /* DWARF failed.  There isn't much of a usable frame-chain on x86-64,
 	 but we do need to handle two special-cases:

 	  (i) signal trampoline: Old kernels and older libcs don't
 	      export the vDSO needed to get proper unwind info for the
 	      trampoline.  Recognize that case by looking at the code
 	      and filling in things by hand.

 	  (ii) PLT (shared-library) call-stubs: PLT stubs are invoked
 	      via CALLQ.  Try this for all non-signal trampoline
 	      code.  */

       unw_word_t prev_ip = c->dwarf.ip, prev_cfa = c->dwarf.cfa;
       struct dwarf_loc rbp_loc, rsp_loc, rip_loc;

       /* We could get here because of missing/bad unwind information.
          Validate all addresses before dereferencing. */
       c->validate = 1;

       Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);

       if (unw_is_signal_frame (cursor))
 	{
           ret = unw_handle_signal_frame(cursor);
 	  if (ret < 0)
 	    {
 	      Debug (2, "returning 0\n");
 	      return 0;
 	    }
 	}
       else if (is_plt_entry (&c->dwarf))
 	{
           /* Like regular frame, CFA = RSP+8, RA = [CFA-8], no regs saved. */
 	  Debug (2, "found plt entry\n");
           c->frame_info.cfa_reg_offset = 8;
           c->frame_info.cfa_reg_rsp = -1;
           c->frame_info.frame_type = UNW_X86_64_FRAME_STANDARD;
           c->dwarf.loc[RIP] = DWARF_LOC (c->dwarf.cfa, 0);
           c->dwarf.cfa += 8;
 	}
       else if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
         {
 	  for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
 	    c->dwarf.loc[i] = DWARF_NULL_LOC;
 	}
       else
 	{
 	  unw_word_t rbp;

 	  ret = dwarf_get (&c->dwarf, c->dwarf.loc[RBP], &rbp);
 	  if (ret < 0)
 	    {
 	      Debug (2, "returning %d [RBP=0x%lx]\n", ret,
 		     DWARF_GET_LOC (c->dwarf.loc[RBP]));
 	      return ret;
 	    }

 	  if (!rbp)
 	    {
 	      /* Looks like we may have reached the end of the call-chain.  */
 	      rbp_loc = DWARF_NULL_LOC;
 	      rsp_loc = DWARF_NULL_LOC;
 	      rip_loc = DWARF_NULL_LOC;
 	    }
 	  else
 	    {
 	      unw_word_t rbp1 = 0;
 	      rbp_loc = DWARF_LOC(rbp, 0);
 	      rsp_loc = DWARF_NULL_LOC;
 	      rip_loc = DWARF_LOC (rbp + 8, 0);
 	      ret = dwarf_get (&c->dwarf, rbp_loc, &rbp1);
 	      Debug (1, "[RBP=0x%lx] = 0x%lx (cfa = 0x%lx) -> 0x%lx\n",
 		     (unsigned long) DWARF_GET_LOC (c->dwarf.loc[RBP]),
 		     rbp, c->dwarf.cfa, rbp1);

 	      /* Heuristic to determine incorrect guess.  For RBP to be a
 	         valid frame it needs to be above current CFA, but don't
 		 let it go more than a little.  Note that we can't deduce
 		 anything about new RBP (rbp1) since it may not be a frame
 		 pointer in the frame above.  Just check we get the value. */
               if (ret < 0
 		  || rbp <= c->dwarf.cfa
 		  || (rbp - c->dwarf.cfa) > 0x4000)
 	        {
                   rip_loc = DWARF_NULL_LOC;
                   rbp_loc = DWARF_NULL_LOC;
 		}

               c->frame_info.frame_type = UNW_X86_64_FRAME_GUESSED;
               c->frame_info.cfa_reg_rsp = 0;
               c->frame_info.cfa_reg_offset = 16;
               c->frame_info.rbp_cfa_offset = -16;
 	      c->dwarf.cfa += 16;
 	    }

 	  /* Mark all registers unsaved */
 	  for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
 	    c->dwarf.loc[i] = DWARF_NULL_LOC;

           c->dwarf.loc[RBP] = rbp_loc;
           c->dwarf.loc[RSP] = rsp_loc;
           c->dwarf.loc[RIP] = rip_loc;
 	}

       c->dwarf.ret_addr_column = RIP;

       if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
         {
 	  ret = 0;
 	  Debug (2, "NULL %%rbp loc, returning %d\n", ret);
 	  return ret;
         }
       if (!DWARF_IS_NULL_LOC (c->dwarf.loc[RIP]))
 	{
 	  ret = dwarf_get (&c->dwarf, c->dwarf.loc[RIP], &c->dwarf.ip);
 	  Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n",
 		     (unsigned long long) DWARF_GET_LOC (c->dwarf.loc[RIP]),
 		     (unsigned long long) c->dwarf.ip);
 	  if (ret < 0)
 	    {
 	      Debug (2, "returning %d\n", ret);
 	      return ret;
 	    }
 	  ret = 1;
 	}
       else
 	c->dwarf.ip = 0;

       if (c->dwarf.ip == prev_ip && c->dwarf.cfa == prev_cfa)
 	return -UNW_EBADFRAME;
     }
   /* ANDROID support update. */
   /* Adjust the pc to the instruction before. */
   if (c->dwarf.ip)
     c->dwarf.ip--;
   /* If the decode yields the exact same ip/cfa as before, then indicate
      the unwind is complete. */
   if (c->dwarf.ip == old_ip && c->dwarf.cfa == old_cfa)
     {
       Dprintf ("%s: ip and cfa unchanged; stopping here (ip=0x%lx)\n",
                __FUNCTION__, (long) c->dwarf.ip);
       return -UNW_EBADFRAME;
     }
   /* End of ANDROID update. */
   Debug (2, "returning %d\n", ret);
   return ret;
 }
	/* libunwind - a platform-independent unwind library
	Copyright (C) 2002-2004 Hewlett-Packard Co
	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>

	Modified for x86_64 by Max Asbock <masbock@us.ibm.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 <signal.h>

	/* Recognise PLT entries such as:
	3bdf0: ff 25 e2 49 13 00 jmpq *0x1349e2(%rip)
	3bdf6: 68 ae 03 00 00 pushq $0x3ae
	3bdfb: e9 00 c5 ff ff jmpq 38300 <_init+0x18> */
	static int
	is_plt_entry (struct dwarf_cursor *c)
	{
	unw_word_t w0, w1;
	unw_accessors_t *a;
	int ret;

	a = unw_get_accessors (c->as);
	if ((ret = (*a->access_mem) (c->as, c->ip, &w0, 0, c->as_arg)) < 0
	\|\| (ret = (*a->access_mem) (c->as, c->ip + 8, &w1, 0, c->as_arg)) < 0)
	return 0;

	ret = (((w0 & 0xffff) == 0x25ff)
	&& (((w0 >> 48) & 0xff) == 0x68)
	&& (((w1 >> 24) & 0xff) == 0xe9));

	Debug (14, "ip=0x%lx => 0x%016lx 0x%016lx, ret = %d\n", c->ip, w0, w1, ret);
	return ret;
	}

	PROTECTED int
	unw_step (unw_cursor_t *cursor)
	{
	struct cursor c = (struct cursor ) cursor;
	int ret, i;

	#if CONSERVATIVE_CHECKS
	int val = c->validate;
	c->validate = 1;
	#endif

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

	unw_word_t old_ip = c->dwarf.ip;
	unw_word_t old_cfa = c->dwarf.cfa;

	/* Try DWARF-based unwinding... */
	c->sigcontext_format = X86_64_SCF_NONE;
	ret = dwarf_step (&c->dwarf);

	#if CONSERVATIVE_CHECKS
	c->validate = val;
	#endif

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

	if (likely (ret >= 0))
	{
	/* x86_64 ABI specifies that end of call-chain is marked with a
	NULL RBP. */
	if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
	{
	c->dwarf.ip = 0;
	ret = 0;
	}
	}
	else
	{
	/* DWARF failed. There isn't much of a usable frame-chain on x86-64,
	but we do need to handle two special-cases:

	(i) signal trampoline: Old kernels and older libcs don't
	export the vDSO needed to get proper unwind info for the
	trampoline. Recognize that case by looking at the code
	and filling in things by hand.

	(ii) PLT (shared-library) call-stubs: PLT stubs are invoked
	via CALLQ. Try this for all non-signal trampoline
	code. */

	unw_word_t prev_ip = c->dwarf.ip, prev_cfa = c->dwarf.cfa;
	struct dwarf_loc rbp_loc, rsp_loc, rip_loc;

	/* We could get here because of missing/bad unwind information.
	Validate all addresses before dereferencing. */
	c->validate = 1;

	Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);

	if (unw_is_signal_frame (cursor))
	{
	ret = unw_handle_signal_frame(cursor);
	if (ret < 0)
	{
	Debug (2, "returning 0\n");
	return 0;
	}
	}
	else if (is_plt_entry (&c->dwarf))
	{
	/* Like regular frame, CFA = RSP+8, RA = [CFA-8], no regs saved. */
	Debug (2, "found plt entry\n");
	c->frame_info.cfa_reg_offset = 8;
	c->frame_info.cfa_reg_rsp = -1;
	c->frame_info.frame_type = UNW_X86_64_FRAME_STANDARD;
	c->dwarf.loc[RIP] = DWARF_LOC (c->dwarf.cfa, 0);
	c->dwarf.cfa += 8;
	}
	else if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
	{
	for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
	c->dwarf.loc[i] = DWARF_NULL_LOC;
	}
	else
	{
	unw_word_t rbp;

	ret = dwarf_get (&c->dwarf, c->dwarf.loc[RBP], &rbp);
	if (ret < 0)
	{
	Debug (2, "returning %d [RBP=0x%lx]\n", ret,
	DWARF_GET_LOC (c->dwarf.loc[RBP]));
	return ret;
	}

	if (!rbp)
	{
	/* Looks like we may have reached the end of the call-chain. */
	rbp_loc = DWARF_NULL_LOC;
	rsp_loc = DWARF_NULL_LOC;
	rip_loc = DWARF_NULL_LOC;
	}
	else
	{
	unw_word_t rbp1 = 0;
	rbp_loc = DWARF_LOC(rbp, 0);
	rsp_loc = DWARF_NULL_LOC;
	rip_loc = DWARF_LOC (rbp + 8, 0);
	ret = dwarf_get (&c->dwarf, rbp_loc, &rbp1);
	Debug (1, "[RBP=0x%lx] = 0x%lx (cfa = 0x%lx) -> 0x%lx\n",
	(unsigned long) DWARF_GET_LOC (c->dwarf.loc[RBP]),
	rbp, c->dwarf.cfa, rbp1);

	/* Heuristic to determine incorrect guess. For RBP to be a
	valid frame it needs to be above current CFA, but don't
	let it go more than a little. Note that we can't deduce
	anything about new RBP (rbp1) since it may not be a frame
	pointer in the frame above. Just check we get the value. */
	if (ret < 0
	\|\| rbp <= c->dwarf.cfa
	\|\| (rbp - c->dwarf.cfa) > 0x4000)
	{
	rip_loc = DWARF_NULL_LOC;
	rbp_loc = DWARF_NULL_LOC;
	}

	c->frame_info.frame_type = UNW_X86_64_FRAME_GUESSED;
	c->frame_info.cfa_reg_rsp = 0;
	c->frame_info.cfa_reg_offset = 16;
	c->frame_info.rbp_cfa_offset = -16;
	c->dwarf.cfa += 16;
	}

	/* Mark all registers unsaved */
	for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
	c->dwarf.loc[i] = DWARF_NULL_LOC;

	c->dwarf.loc[RBP] = rbp_loc;
	c->dwarf.loc[RSP] = rsp_loc;
	c->dwarf.loc[RIP] = rip_loc;
	}

	c->dwarf.ret_addr_column = RIP;

	if (DWARF_IS_NULL_LOC (c->dwarf.loc[RBP]))
	{
	ret = 0;
	Debug (2, "NULL %%rbp loc, returning %d\n", ret);
	return ret;
	}
	if (!DWARF_IS_NULL_LOC (c->dwarf.loc[RIP]))
	{
	ret = dwarf_get (&c->dwarf, c->dwarf.loc[RIP], &c->dwarf.ip);
	Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n",
	(unsigned long long) DWARF_GET_LOC (c->dwarf.loc[RIP]),
	(unsigned long long) c->dwarf.ip);
	if (ret < 0)
	{
	Debug (2, "returning %d\n", ret);
	return ret;
	}
	ret = 1;
	}
	else
	c->dwarf.ip = 0;

	if (c->dwarf.ip == prev_ip && c->dwarf.cfa == prev_cfa)
	return -UNW_EBADFRAME;
	}
	/* ANDROID support update. */
	/* Adjust the pc to the instruction before. */
	if (c->dwarf.ip)
	c->dwarf.ip--;
	/* If the decode yields the exact same ip/cfa as before, then indicate
	the unwind is complete. */
	if (c->dwarf.ip == old_ip && c->dwarf.cfa == old_cfa)
	{
	Dprintf ("%s: ip and cfa unchanged; stopping here (ip=0x%lx)\n",
	__FUNCTION__, (long) c->dwarf.ip);
	return -UNW_EBADFRAME;
	}
	/* End of ANDROID update. */
	Debug (2, "returning %d\n", ret);
	return ret;
	}