get back PT_IA_64_UNWIND program header

["David Mosberger-Tang" <dmosberger@gmail.com>]

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I noticed that Ski was unable to do a stacktrace on the kernel.  Turns
out that's because the PT_IA_64_UNWIND program-header is missing.
Perhaps this is due to a change in binutils, but in any case, it seems
like we should be explicit about the unwind header, so this patch is
probably a good idea no matter what.  Note that the patch assumes that
the earlier patch to add a PT_NOTE header has been applied already.

Regards,

  --david
-- 
Mosberger Consulting LLC, http://www.mosberger-consulting.com/

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[IA64] Explicitly put the unwind section into its own program-header.  This
       used to be unnecessary (probably because binutils did it for us), but
       with current binutils (e.g., v2.17.50.20070804) we won't get
       the PT_IA_64_UNWIND header without this patch which will break
       unwinding in a debugger and simulators such as Ski.

Signed-off-by: David Mosberger-Tang <dmosberger@gmail.com>

--- arch/ia64/kernel/vmlinux.lds.S~	2007-08-09 11:38:28.000000000 -0600
+++ arch/ia64/kernel/vmlinux.lds.S	2007-08-09 19:40:08.000000000 -0600
@@ -21,6 +21,7 @@
   percpu PT_LOAD;
   data   PT_LOAD;
   note   PT_NOTE;
+  unwind 0x70000001; /* PT_IA_64_UNWIND, but ld doesn't match the name */
 }
 SECTIONS
 {
@@ -103,7 +104,8 @@
 	  __start_unwind = .;
 	  *(.IA_64.unwind*)
 	  __end_unwind = .;
-	}
+	} :code :unwind
+  code_continues2 : {} : code
 
   RODATA