objtool: Add --hacks=skylake

Make the call/func sections selectable via the --hacks option.

Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

scripts/Makefile.lib

···
 
 objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK)		+= --hacks=jump_label
 objtool-args-$(CONFIG_HAVE_NOINSTR_HACK)		+= --hacks=noinstr
+objtool-args-$(CONFIG_CALL_DEPTH_TRACKING)		+= --hacks=skylake
 objtool-args-$(CONFIG_X86_KERNEL_IBT)			+= --ibt
 objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL)	+= --mcount
 objtool-args-$(CONFIG_UNWINDER_ORC)			+= --orc

tools/objtool/builtin-check.c

···
 		found = true;
 	}
 
+	if (!str || strstr(str, "skylake")) {
+		opts.hack_skylake = true;
+		found = true;
+	}
+
 	return found ? 0 : -1;
 }
 
 const struct option check_options[] = {
 	OPT_GROUP("Actions:"),
-	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr", "patch toolchain bugs/limitations", parse_hacks),
+	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
 	OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
 	OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
 	OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),

tools/objtool/check.c

···
 			goto out;
 		warnings += ret;
 
-		ret = create_direct_call_sections(file);
-		if (ret < 0)
-			goto out;
-		warnings += ret;
+		if (opts.hack_skylake) {
+			ret = create_direct_call_sections(file);
+			if (ret < 0)
+				goto out;
+			warnings += ret;
+		}
 	}
 
 	if (opts.mcount) {

tools/objtool/include/objtool/builtin.h

···
 	bool dump_orc;
 	bool hack_jump_label;
 	bool hack_noinstr;
+	bool hack_skylake;
 	bool ibt;
 	bool mcount;
 	bool noinstr;