objtool: Fix STACK_FRAME_NON_STANDARD macro checking for function symbols

Mathieu Desnoyers reported that the STACK_FRAME_NON_STANDARD macro
wasn't working with the lttng_filter_interpret_bytecode() function in
the lttng-modules code.

Usually the relocation created by STACK_FRAME_NON_STANDARD creates a
reference to a section symbol like this:

  Offset              Type            Value               Addend Name
  000000000000000000  X86_64_64       000000000000000000   +3136 .text

But in this case it created a reference to a function symbol:

  Offset              Type            Value               Addend Name
  000000000000000000  X86_64_64       0x00000000000003a0      +0 lttng_filter_interpret_bytecode

To be honest I have no idea what causes gcc to decide to do one over the
other.  But both are valid ELF, so add support for the function symbol.
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lttng-dev@lists.lttng.org
Link: http://lkml.kernel.org/r/9cee42843bc6d94e990a152e4e0319cfdf6756ef.1466023450.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/objtool/builtin-check.c

@@ -122,10 +122,14 @@ static bool ignore_func(struct objtool_file *file, struct symbol *func)
 
 	/* check for STACK_FRAME_NON_STANDARD */
 	if (file->whitelist && file->whitelist->rela)
-		list_for_each_entry(rela, &file->whitelist->rela->rela_list, list)
-			if (rela->sym->sec == func->sec &&
+		list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
+			if (rela->sym->type == STT_SECTION &&
+			    rela->sym->sec == func->sec &&
 			    rela->addend == func->offset)
 				return true;
+			if (rela->sym->type == STT_FUNC && rela->sym == func)
+				return true;
+		}
 
 	/* check if it has a context switching instruction */
 	func_for_each_insn(file, func, insn)