perf: net_dropmonitor: Fix symbol-relative addresses

The comparison between traced and symbol addresses is backwards: if
the traced address doesn't exactly match a symbol (which we don't
expect it to), we'll show the next symbol and the offset to it,
whereas we should show the previous symbol and the offset from it.

Cc: stable@vger.kernel.org
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/perf/scripts/python/net_dropmonitor.py

@@ -40,9 +40,9 @@ def get_kallsyms_table():
 
 def get_sym(sloc):
 	loc = int(sloc)
-	for i in kallsyms:
-		if (i['loc'] >= loc):
-			return (i['name'], i['loc']-loc)
+	for i in kallsyms[::-1]:
+		if loc >= i['loc']:
+			return (i['name'], loc - i['loc'])
 	return (None, 0)
 
 def print_drop_table():