UBUNTU: SAUCE: objtool: Make objtool check actually fatal upon fatal errors

BugLink: https://bugs.launchpad.net/bugs/2046440

Currently function calls within check() are sensitive to fatal errors
(negative return codes) and abort execution prematurely. However, in
all such cases the check() function still returns 0, and thus
resulting in a successful kernel build.

The only correct code paths were the ones that escpae the control flow
with `return ret`.

Make the check() function return `ret` status code, and make all
negative return codes goto that instruction. This makes fatal errors
(not warnings) from various function calls actually fail the
build. E.g. if create_retpoline_sites_sections() fails to create elf
section pair retpoline_sites the tool now exits with an error code.

Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Link: https://lore.kernel.org/all/20231213134303.2302285-2-dimitri.ledkov@canonical.com/
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

tools/objtool/check.c

@@ -4677,8 +4677,10 @@ int check(struct objtool_file *file)
 	init_cfi_state(&force_undefined_cfi);
 	force_undefined_cfi.force_undefined = true;
 
-	if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
+	if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) {
+		ret = -1;
 		goto out;
+	}
 
 	cfi_hash_add(&init_cfi);
 	cfi_hash_add(&func_cfi);
@@ -4695,7 +4697,7 @@ int check(struct objtool_file *file)
 	if (opts.retpoline) {
 		ret = validate_retpoline(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}
 
@@ -4731,7 +4733,7 @@ int check(struct objtool_file *file)
 		 */
 		ret = validate_unrets(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}
 
@@ -4794,7 +4796,7 @@ int check(struct objtool_file *file)
 	if (opts.prefix) {
 		ret = add_prefix_symbols(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}
 
@@ -4825,10 +4827,5 @@ int check(struct objtool_file *file)
 	}
 
 out:
-	/*
-	 *  For now, don't fail the kernel build on fatal warnings.  These
-	 *  errors are still fairly common due to the growing matrix of
-	 *  supported toolchains and their recent pace of change.
-	 */
-	return 0;
+	return ret < 0 ? ret : 0;
 }