objtool: Fix 32-bit build

Fix the objtool build when cross-compiling a 64-bit kernel on a 32-bit
host.  This also simplifies read_retpoline_hints() a bit and makes its
implementation similar to most of the other annotation reading
functions.
Reported-by: Sven Joachim <svenjoac@gmx.de>
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>
Fixes: b5bc2231 ("objtool: Add retpoline validation")
Link: http://lkml.kernel.org/r/2ca46c636c23aa9c9d57d53c75de4ee3ddf7a7df.1520380691.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/objtool/check.c

@@ -1116,42 +1116,29 @@ static int read_unwind_hints(struct objtool_file *file)
 
 static int read_retpoline_hints(struct objtool_file *file)
 {
-	struct section *sec, *relasec;
+	struct section *sec;
 	struct instruction *insn;
 	struct rela *rela;
-	int i;
 
-	sec = find_section_by_name(file->elf, ".discard.retpoline_safe");
+	sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
 	if (!sec)
 		return 0;
 
-	relasec = sec->rela;
-	if (!relasec) {
-		WARN("missing .rela.discard.retpoline_safe section");
-		return -1;
-	}
-
-	if (sec->len % sizeof(unsigned long)) {
-		WARN("retpoline_safe size mismatch: %d %ld", sec->len, sizeof(unsigned long));
-		return -1;
-	}
-
-	for (i = 0; i < sec->len / sizeof(unsigned long); i++) {
-		rela = find_rela_by_dest(sec, i * sizeof(unsigned long));
-		if (!rela) {
-			WARN("can't find rela for retpoline_safe[%d]", i);
+	list_for_each_entry(rela, &sec->rela_list, list) {
+		if (rela->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
 			return -1;
 		}
 
 		insn = find_insn(file, rela->sym->sec, rela->addend);
 		if (!insn) {
-			WARN("can't find insn for retpoline_safe[%d]", i);
+			WARN("bad .discard.retpoline_safe entry");
 			return -1;
 		}
 
 		if (insn->type != INSN_JUMP_DYNAMIC &&
 		    insn->type != INSN_CALL_DYNAMIC) {
-			WARN_FUNC("retpoline_safe hint not a indirect jump/call",
+			WARN_FUNC("retpoline_safe hint not an indirect jump/call",
 				  insn->sec, insn->offset);
 			return -1;
 		}