2005-09-27  Jeff Johnston  <jjohnstn@redhat.com>

	* libunwind-frame.c (libunwind_frame_cache): Save the current

	stack pointer in the cache.

	(libunwind_sigtramp_frame_this_id): New function.

	(libunwind_sigtramp_frame_unwind): New unwinder.

	(libunwind_sigtramp_frame_sniffer): Return 

	libunwind_sigtramp_frame_unwind address.

	* libunwind-frame.h (libunwind_sigtramp_frame_this_id): New

	prototype.

	* ia64-tdep.c (ia64_libunwind_sigtramp_frame_this_id): Calculate

	the base address using the current stack pointer plus a fixed

	offset.

Index: gdb-6.5/gdb/libunwind-frame.c

===================================================================

--- gdb-6.5.orig/gdb/libunwind-frame.c	2006-07-07 03:04:32.000000000 -0300

+++ gdb-6.5/gdb/libunwind-frame.c	2006-07-07 03:07:33.000000000 -0300

@@ -62,6 +62,7 @@ static unw_word_t (*unw_find_dyn_list_p)

 struct libunwind_frame_cache

 {

   CORE_ADDR base;

+  CORE_ADDR sp;

   CORE_ADDR func_addr;

   unw_cursor_t cursor;

 };

@@ -131,7 +132,7 @@ libunwind_frame_cache (struct frame_info

   unw_accessors_t *acc;

   unw_addr_space_t as;

   unw_cursor_t *cursor_addr;

-  unw_word_t fp;

+  unw_word_t fp, sp;

   unw_regnum_t uw_sp_regnum;

   struct libunwind_frame_cache *cache;

   struct libunwind_descr *descr;

@@ -176,15 +177,28 @@ libunwind_frame_cache (struct frame_info

   else /* make copy */

     cache->cursor = *cursor_addr;

+  /* For the base address, we have a small problem.  The majority

+     of the time, we can get the stack pointer of the previous

+     frame to use as a frame pointer.  In the case where we have

+     a signal trampoline, the stack may change due to a sigaltstack

+     being set up.  In that case, the normal mechanism will give us

+     an address in the regular stack which is not at the end of the

+     sigaltstack as we want.  To handle this, we record the stack

+     address so the caller may calculate a more correct base address

+     to use.  */

+  uw_sp_regnum = descr->gdb2uw (SP_REGNUM);

+  ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &sp);

+  if (ret < 0)

+    error ("Can't get libunwind sp register.");

+

   if (unw_step_p (&cache->cursor) < 0)

     return NULL;

-  /* To get base address, get sp from previous frame.  */

-  uw_sp_regnum = descr->gdb2uw (SP_REGNUM);

   ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &fp);

   if (ret < 0)

     error (_("Can't get libunwind sp register."));

+  cache->sp = (CORE_ADDR)sp;

   cache->base = (CORE_ADDR)fp;

   *this_cache = cache;

@@ -371,6 +385,31 @@ libunwind_search_unwind_table (void *as,

 				    di, pi, need_unwind_info, args);

 }

+void

+libunwind_sigtramp_frame_this_id (struct frame_info *next_frame, 

+				  void **this_cache,

+		      		  struct frame_id *this_id)

+{

+  struct libunwind_frame_cache *cache =

+    libunwind_frame_cache (next_frame, this_cache);

+

+  /* Unlike a regular frame, we can't use the normal frame pointer

+     mechanism because a sigaltstack may have been used.  Instead,

+     we return the current stack pointer for the caller to use

+     to calculate the base address.  */

+  if (cache != NULL)

+    (*this_id) = frame_id_build (cache->sp, cache->func_addr);

+  else

+    (*this_id) = null_frame_id;

+}

+

+static const struct frame_unwind libunwind_sigtramp_frame_unwind =

+{

+  SIGTRAMP_FRAME,

+  libunwind_sigtramp_frame_this_id,

+  libunwind_frame_prev_register

+};

+

 /* Verify if we are in a sigtramp frame and we can use libunwind to unwind.  */

 const struct frame_unwind *

 libunwind_sigtramp_frame_sniffer (struct frame_info *next_frame)

@@ -403,7 +442,7 @@ libunwind_sigtramp_frame_sniffer (struct

   /* Check to see if we are in a signal frame.  */

   ret = unw_is_signal_frame_p (&cursor);

   if (ret > 0)

-    return &libunwind_frame_unwind;

+    return &libunwind_sigtramp_frame_unwind;

   return NULL;

 }

Index: gdb-6.5/gdb/libunwind-frame.h

===================================================================

--- gdb-6.5.orig/gdb/libunwind-frame.h	2006-07-07 02:51:32.000000000 -0300

+++ gdb-6.5/gdb/libunwind-frame.h	2006-07-07 03:05:49.000000000 -0300

@@ -49,6 +49,9 @@ void libunwind_frame_set_descr (struct g

 void libunwind_frame_this_id (struct frame_info *next_frame, void **this_cache,

 			      struct frame_id *this_id);

+void libunwind_sigtramp_frame_this_id (struct frame_info *next_frame, 

+				       void **this_cache,

+			      	       struct frame_id *this_id);

 void libunwind_frame_prev_register (struct frame_info *next_frame, void **this_cache,

 				    int regnum, int *optimizedp,

 				    enum lval_type *lvalp, CORE_ADDR *addrp,

Index: gdb-6.5/gdb/ia64-tdep.c

===================================================================

--- gdb-6.5.orig/gdb/ia64-tdep.c	2006-07-07 02:51:32.000000000 -0300

+++ gdb-6.5/gdb/ia64-tdep.c	2006-07-07 03:05:49.000000000 -0300

@@ -3031,7 +3031,7 @@ ia64_libunwind_sigtramp_frame_this_id (s

   struct frame_id id;

   CORE_ADDR prev_ip;

-  libunwind_frame_this_id (next_frame, this_cache, &id;;

+  libunwind_sigtramp_frame_this_id (next_frame, this_cache, &id;;

   if (frame_id_eq (id, null_frame_id))

     {

       (*this_id) = null_frame_id;

@@ -3043,8 +3043,14 @@ ia64_libunwind_sigtramp_frame_this_id (s

   frame_unwind_register (next_frame, IA64_BSP_REGNUM, buf);

   bsp = extract_unsigned_integer (buf, 8);

-  /* For a sigtramp frame, we don't make the check for previous ip being 0.  */

-  (*this_id) = frame_id_build_special (id.stack_addr, id.code_addr, bsp);

+  /* For a sigtramp frame, we don't make the check for previous ip being 0.  

+     We also must calculate the frame pointer because libunwind will give

+     us back the current stack pointer instead of the frame pointer since

+     it cannot figure this out when in a sigaltstack.  We make a basic

+     assumption of 16 (default size) + 8 bytes for sigcontext address.

+     FIXME: if libunwind were to export the frame pointer address, we

+            could eliminate the assumption and get the actual value.  */

+  (*this_id) = frame_id_build_special (id.stack_addr + 24, id.code_addr, bsp);

   if (gdbarch_debug >= 1)

     fprintf_unfiltered (gdb_stdlog,