perf probe: Fix to die_entrypc() returns error correctly

Fix die_entrypc() to return error correctly if the DIE has no
DW_AT_ranges attribute. Since dwarf_ranges() will treat the case as an
empty ranges and return 0, we have to check it by ourselves.

Fixes: 91e2f53 ("perf probe: Fix to show function entry line as probe-able")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: http://lore.kernel.org/lkml/160645612634.2824037.5284932731175079426.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: mhiramat

tools/perf/util/dwarf-aux.c

@@ -373,13 +373,21 @@ bool die_is_func_def(Dwarf_Die *dw_die)
 int die_entrypc(Dwarf_Die *dw_die, Dwarf_Addr *addr)
 {
 	Dwarf_Addr base, end;
+	Dwarf_Attribute attr;
 
 	if (!addr)
 		return -EINVAL;
 
 	if (dwarf_entrypc(dw_die, addr) == 0)
 		return 0;
 
+	/*
+	 *  Since the dwarf_ranges() will return 0 if there is no
+	 * DW_AT_ranges attribute, we should check it first.
+	 */
+	if (!dwarf_attr(dw_die, DW_AT_ranges, &attr))
+		return -ENOENT;
+
 	return dwarf_ranges(dw_die, 0, &base, addr, &end) < 0 ? -ENOENT : 0;
 }