[PATCH 4.14 002/159] objtool: Dont report end of section error after an empty unwind hint

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

commit 00d96180dc38ef872ac471c2d3e14b067cbd895d upstream.

If asm code specifies an UNWIND_HINT_EMPTY hint, don't warn if the
section ends unexpectedly.  This can happen with the xen-head.S code
because the hypercall_page is "text" but it's all zeros.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/ddafe199dd8797e40e3c2777373347eba1d65572.1505764066.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 tools/objtool/check.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1757,11 +1757,14 @@ static int validate_branch(struct objtoo
 		if (insn->dead_end)
 			return 0;
 
-		insn = next_insn;
-		if (!insn) {
+		if (!next_insn) {
+			if (state.cfa.base == CFI_UNDEFINED)
+				return 0;
 			WARN("%s: unexpected end of section", sec->name);
 			return 1;
 		}
+
+		insn = next_insn;
 	}
 
 	return 0;