gdb/

* frame.c (get_prev_frame_1) <UNWIND_INNER_ID>: New variables
	this_pc_in_block, morestack_msym and morestack_name.  Check for
	"__morestack" minimal symbol there.

gdb/testsuite/
	* gdb.base/morestack.exp: New file.
	* gdb.base/morestack.c: New file.

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2011-01-03  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* frame.c (get_prev_frame_1) <UNWIND_INNER_ID>: New variables
+	this_pc_in_block, morestack_msym and morestack_name.  Check for
+	"__morestack" minimal symbol there.
+
 2011-01-03  Joel Brobecker  <brobecker@adacore.com>
 
 	* symfile.c (find_sym_fns): Add call to dont_repeat.

gdb/frame.c

@@ -1502,14 +1502,26 @@ get_prev_frame_1 (struct frame_info *this_frame)
       && frame_id_inner (get_frame_arch (this_frame->next), this_id,
 			 get_frame_id (this_frame->next)))
     {
-      if (frame_debug)
+      CORE_ADDR this_pc_in_block;
+      struct minimal_symbol *morestack_msym;
+      const char *morestack_name = NULL;
+      
+      /* gcc -fsplit-stack __morestack can continue the stack anywhere.  */
+      this_pc_in_block = get_frame_address_in_block (this_frame);
+      morestack_msym = lookup_minimal_symbol_by_pc (this_pc_in_block);
+      if (morestack_msym)
+	morestack_name = SYMBOL_LINKAGE_NAME (morestack_msym);
+      if (!morestack_name || strcmp (morestack_name, "__morestack") != 0)
 	{
-	  fprintf_unfiltered (gdb_stdlog, "-> ");
-	  fprint_frame (gdb_stdlog, NULL);
-	  fprintf_unfiltered (gdb_stdlog, " // this frame ID is inner }\n");
+	  if (frame_debug)
+	    {
+	      fprintf_unfiltered (gdb_stdlog, "-> ");
+	      fprint_frame (gdb_stdlog, NULL);
+	      fprintf_unfiltered (gdb_stdlog, " // this frame ID is inner }\n");
+	    }
+	  this_frame->stop_reason = UNWIND_INNER_ID;
+	  return NULL;
 	}
-      this_frame->stop_reason = UNWIND_INNER_ID;
-      return NULL;
     }
 
   /* Check that this and the next frame are not identical.  If they

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2011-01-03  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.base/morestack.exp: New file.
+	* gdb.base/morestack.c: New file.
+
 2011-01-02  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* gdb.ada/gnat_ada.gpr: Fix copyright comment line regression by 2011.

gdb/testsuite/gdb.base/morestack.c

@@ -0,0 +1,105 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011 Free Software Foundation, Inc.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Based on the gcc testcase `gcc/testsuite/gcc.dg/split-1.c'.  This test
+   needs to use setrlimit to set the stack size, so it can only run on Unix.
+   */
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/resource.h>
+#include <stdio.h>
+#include <sys/mman.h>
+
+/* Use a noinline function to ensure that the buffer is not removed
+   from the stack.  */
+static void use_buffer (char *buf) __attribute__ ((noinline));
+static void
+use_buffer (char *buf)
+{
+  buf[0] = '\0';
+}
+
+static volatile int marker_var;
+
+static void
+marker_miss (void)
+{
+  marker_var = 0;
+}
+
+static void
+marker_hit (void)
+{
+  marker_var = 0;
+}
+
+void *reserved;
+#define RESERVED_SIZE 0x1000000
+
+/* Each recursive call uses 10,000 bytes.  We call it 1000 times,
+   using a total of 10,000,000 bytes.  If -fsplit-stack is not
+   working, that will overflow our stack limit.  */
+
+static void
+down (int i)
+{
+  char buf[10000];
+  static void *last;
+
+  if (last && last < (void *) buf)
+    {
+      printf ("%d: %p < %p\n", i, last, buf);
+      marker_hit ();
+    }
+  last = buf;
+
+  if (i == 500)
+    {
+      if (munmap (reserved, RESERVED_SIZE) != 0)
+        abort ();
+      reserved = NULL;
+    }
+
+  if (i > 0)
+    {
+      use_buffer (buf);
+      down (i - 1);
+    }
+  else
+    marker_miss ();
+}
+
+int
+main (void)
+{
+  struct rlimit r;
+
+  reserved = mmap (NULL, RESERVED_SIZE, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  if (reserved == MAP_FAILED)
+    abort ();
+
+  /* We set a stack limit because we are usually invoked via make, and
+     make sets the stack limit to be as large as possible.  */
+  r.rlim_cur = 8192 * 1024;
+  r.rlim_max = 8192 * 1024;
+  if (setrlimit (RLIMIT_STACK, &r) != 0)
+    abort ();
+  down (1000);
+  return 0;
+}

gdb/testsuite/gdb.base/morestack.exp

@@ -0,0 +1,52 @@
+# Copyright (C) 2011 Free Software Foundation, Inc.
+
+# This program 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 of the License, or
+# (at your option) any later version.
+#
+# This program 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.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if [get_compiler_info "ignored"] {
+    return -1
+}
+
+if {$gcc_compiled == 0} {
+    return -1
+}
+
+set testfile morestack
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${testfile}.c {additional_flags=-fsplit-stack}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint "marker_hit"
+gdb_breakpoint "marker_miss"
+
+set test "continue"
+gdb_test_multiple $test $test {
+    -re "marker_hit.*$gdb_prompt $" {
+	pass $test
+    }
+    -re "marker_miss.*$gdb_prompt $" {
+	# The testcase failed to violated the frame_id_inner condition by
+	# handing inner frame with higher (on the stack-grows-down arches)
+	# $sp address than the outer frame.
+	xfail $test
+	return 0
+    }
+}
+
+# FAIL was on `bt' producing:
+# Backtrace stopped: previous frame inner to this frame (corrupt stack?)
+gdb_test "up 3000" " in main .*"