kbuild: filter away debug symbols from kernel symbols

Andi Kleen <andi@firstfloor.org>
reported that he saw a lot of symbols like this:

0000000000000b24 N DW.aio.h.903a6d92.2
0000000000000bce N DW.task_io_accounting.h.8d8de327.0
0000000000000bec N DW.hrtimer.h.c23659c6.0

in his System.map / kallsyms output.

Simple solution is to skip all debugging
symbols (they are marked 'N').
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Paulo Marques <pmarques@grupopie.com>

scripts/kallsyms.c

@@ -108,6 +108,9 @@ static int read_symbol(FILE *in, struct sym_entry *s)
 	/* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
 	else if (str[0] == '$')
 		return -1;
+	/* exclude debugging symbols */
+	else if (stype == 'N')
+		return -1;
 
 	/* include the type field in the symbol name, so that it gets
 	 * compressed together */

scripts/mksysmap

@@ -32,6 +32,7 @@
 # For System.map filter away:
 #   a - local absolute symbols
 #   U - undefined global symbols
+#   N - debugging symbols
 #   w - local weak symbols
 
 # readprofile starts reading symbols when _stext is found, and
@@ -40,5 +41,5 @@
 # so we just ignore them to let readprofile continue to work.
 # (At least sparc64 has __crc_ in the middle).
 
-$NM -n $1 | grep -v '\( [aUw] \)\|\(__crc_\)\|\( \$[adt]\)' > $2
+$NM -n $1 | grep -v '\( [aNUw] \)\|\(__crc_\)\|\( \$[adt]\)' > $2