--- ./gdb/rs6000-tdep.h_orig	2017-01-21 07:46:47 -0600
+++ ./gdb/rs6000-tdep.h	2017-05-22 06:56:37 -0500
@@ -18,3 +18,21 @@
 /* Minimum possible text address in AIX.  */
 #define AIX_TEXT_SEGMENT_BASE 0x10000000
 
+/* For sighandler */
+
+/* STKMIN(minimum stack size) is 56 for 32-bit process
+   and iar offset under sc_jmpbuf.jmp_context is 40 under the sigconext structure.
+   ie offsetof(struct sigcontext, sc_jmpbuf.jmp_context.iar).
+   so PC offset in this case is STKIM+iar offset, which is 96 */
+#define SIG_FRAME_PC_OFFSET 96
+#define SIG_FRAME_LR_OFFSET 108
+/* STKMIN+grp1 offset, which is 56+228=284 */
+#define SIG_FRAME_FP_OFFSET 284
+
+/* 64 bit process */
+/* STKMIN64  is 112 and iar offset is 312. So 112+312=424 */
+#define SIG_FRAME_PC_OFFSET64 424
+/* STKMIN64+grp1 offset. 112+56=168 */
+#define SIG_FRAME_FP_OFFSET64 168 
+
+#define EXT_CONTEXT64 452
--- ./gdb/frame.c_orig	2017-01-21 07:48:42 -0600
+++ ./gdb/frame.c	2017-05-22 06:56:57 -0500
@@ -42,6 +42,10 @@
 #include "tracepoint.h"
 #include "hashtab.h"
 #include "valprint.h"
+#include "rs6000-tdep.h"
+#include "xcoffread.h"
+
+CORE_ADDR aix_sig_millicode;
 
 static struct frame_info *get_prev_frame_raw (struct frame_info *this_frame);
 static const char *frame_stop_reason_symbol_string (enum unwind_stop_reason reason);
@@ -756,7 +760,16 @@
        comment in "frame.h", there is some fuzz here.  Frameless
        functions are not strictly inner than (same .stack but
        different .code and/or .special address).  */
-    inner = gdbarch_inner_than (gdbarch, l.stack_addr, r.stack_addr);
+
+     /* For xlc generated address and signal handler case, their can be cases where
+        stack address of l frame is less than r frame. 
+        We may need to skip those cases for checking inner than. */ 
+       if (aix_sig_millicode && (aix_sig_millicode < AIX_TEXT_SEGMENT_BASE)) {
+           inner = 0;
+           aix_sig_millicode = 0;
+       }
+       else
+           inner = gdbarch_inner_than (gdbarch, l.stack_addr, r.stack_addr);
   if (frame_debug)
     {
       fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
@@ -1233,10 +1246,44 @@
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   int size = register_size (gdbarch, regnum);
   gdb_byte buf[MAX_REGISTER_SIZE];
+  CORE_ADDR pc, base_addr;
 
   frame_unwind_register (frame, regnum, buf);
-  return extract_unsigned_integer (buf, size, byte_order);
-}
+  pc = extract_unsigned_integer (buf, size, byte_order);
+  /* Like to save the orignal pc value when handler is being called in AIX
+     When signal handler is being called pc value is actually the millicode address. */
+  /* if pc is something like 0x46dc, 0x4a5c etc..
+  Then it is most likekly the aix signal handler frame.
+  Read the pc from the signal handler frame at an offset 96+lr_offset. */
+  if (pc && (pc < AIX_TEXT_SEGMENT_BASE)) {
+      aix_sig_millicode = pc;
+      if (is64)  {
+	  if (frame_id_p(get_frame_id (frame)) == 0) {
+              base_addr =  get_frame_register_unsigned (frame, gdbarch_sp_regnum (gdbarch)); 
+              pc = read_memory_unsigned_integer
+                 (base_addr + SIG_FRAME_PC_OFFSET64,
+                 size, byte_order);
+          } else {
+		pc = read_memory_unsigned_integer
+                     (get_frame_base (frame) + SIG_FRAME_PC_OFFSET64,
+                     size, byte_order);
+          }
+      }
+      else {
+         if (frame_id_p(get_frame_id (frame)) == 0) {
+             base_addr =  get_frame_register_unsigned (frame, gdbarch_sp_regnum (gdbarch)); 
+             pc = read_memory_unsigned_integer
+                (base_addr + SIG_FRAME_PC_OFFSET+8,
+                size, byte_order);
+        } else {
+            pc = read_memory_unsigned_integer
+                 (get_frame_base (frame) + SIG_FRAME_PC_OFFSET+8,
+                size, byte_order);
+        }
+      }
+  }
+  return pc;
+  }
 
 ULONGEST
 get_frame_register_unsigned (struct frame_info *frame, int regnum)
--- ./gdb/xcoffread.h_orig	2017-01-21 07:46:47 -0600
+++ ./gdb/xcoffread.h	2017-05-22 06:57:13 -0500
@@ -23,4 +23,6 @@
 
 extern int xcoff_get_n_import_files (bfd *abfd);
 
+extern int is64;
+
 #endif /* xcoffread.h */
--- ./gdb/xcoffread.c_orig	2017-05-22 06:27:30 -0500
+++ ./gdb/xcoffread.c	2017-05-22 06:57:11 -0500
@@ -49,6 +49,8 @@
 
 #include "gdb-stabs.h"
 
+int is64;
+
 /* For interface with stabsread.c.  */
 #include "aout/stab_gnu.h"
 
@@ -1747,6 +1749,7 @@
 {
   struct objfile *objfile = this_symtab_objfile;
   int xcoff64 = bfd_xcoff_is_xcoff64 (objfile->obfd);
+  is64 = xcoff64;
 
   struct coff_symfile_info *info = XCOFF_DATA (objfile);
   int nsyms = info->symtbl_num_syms;