lib/test_map_h: add new module to test map.h macros

Build test_map_h.ko to validate MAP & MAP_LIST

To test include/linux/map.h, this adds lib/test_map_h.c and config
TEST_MAP_H to build test_map_h.ko.  It uses BUILD_BUG_DEBUG, so that
failures of the macro just break the build.

So this adds config TEST_MAP_H stanza into:
menu "Compile-time checks and compiler options",
and fixes endmenu comment to match.

avoid __i386__, __builtin_memcmp ??

do runtime tests at modprobe, including a purposeful failure and warn.

default m, to maximize robot coverage. builtin doesn't add anything more.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>

lib/Kconfig.debug

@@ -576,7 +576,20 @@ config DEBUG_FORCE_WEAK_PER_CPU
 	  To ensure that generic code follows the above rules, this
 	  option forces all percpu variables to be defined as weak.
 
-endmenu # "Compiler options"
+config TEST_MAP_H
+	tristate "module to test include/linux/map.h"
+	depends on DYNAMIC_DEBUG_CORE
+	default m
+	help
+	  Adding include/linux/map.h requires proof that it works.
+
+	  This adds test_map_h.ko, with BUILD_BUG_ON/compile-time
+	  tests for MAP_LIST(__stringify, ...).  Other macro_fn()s
+	  are deemed equivalent.
+
+	  Default m to see more compilers/cpps via @robots
+
+endmenu # "Compile-time checks and compiler options"
 
 menu "Generic Kernel Debugging Instruments"
 

lib/Makefile

@@ -100,6 +100,7 @@ obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
 obj-$(CONFIG_TEST_REF_TRACKER) += test_ref_tracker.o
 CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
 obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
+obj-$(CONFIG_TEST_MAP_H) += test_map_h.o
 #
 # CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns
 # off the generation of FPU/SSE* instructions for kernel proper but FPU_FLAGS

lib/test_map_h.c

@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * test include/linux/map.h macros: MAP_LIST & MAP
+ *
+ * Authors:
+ *      Jim Cromie	<jim.cromie@gmail.com>
+ */
+
+#include <linux/map.h>
+#include <linux/module.h>
+
+/* compile-time test MAP */
+static int sum = MAP( +, 1, 2, 3);
+static char* caten = MAP(__stringify, YES, NO, MAYBE);
+
+/* client/user defines enum NAMES as source of truth */
+enum client_categories { DRMx_CORE, DRMx_DRIVER, DRMx_KMS };
+
+/* test MAP_LIST(__stringify, ...). others deemed equivalent */
+#define DEFINE_SLIST_FROM_ENUM_VALS_(_vec_, ...)			\
+	const char *_vec_##_names[] = {					\
+		MAP_LIST(__stringify, ##__VA_ARGS__) }
+
+static DEFINE_SLIST_FROM_ENUM_VALS_(debug_cats, DRMx_CORE, DRMx_DRIVER, DRMx_KMS);
+
+#if defined(__i386__)
+/* avoid a "__compiletime_assert_" error */
+#define BUILD_BUG_STREQ(_var, ref)	 BUILD_BUG_ON(0)
+#else
+/* test w 2 exprs, for now */
+#define BUILD_BUG_STREQ(_var, ref) do {					\
+	BUILD_BUG_ON(__builtin_memcmp(_var, ref, sizeof(ref)));		\
+	BUILD_BUG_ON(__builtin_memcmp(_var, ref, __builtin_strlen(ref))); \
+} while (0)
+#endif
+#define BUILD_BUG_STREQ_VI(_vec_, idx, ref) \
+	BUILD_BUG_STREQ(_vec_##_names[idx], ref)
+
+/* force compile, even if its not called */
+static void __used MAPH_BUILD_BUG(void)
+{
+	BUILD_BUG_ON(sum != 6);
+	BUILD_BUG_STREQ(caten, "YESNOMAYBE");
+
+	BUILD_BUG_STREQ_VI(debug_cats, 0, "DRMx_CORE");
+	BUILD_BUG_STREQ_VI(debug_cats, 1, "DRMx_DRIVER");
+	BUILD_BUG_STREQ_VI(debug_cats, 2, "DRMx_KMS");
+
+#ifdef MAPH_FORCE_FAIL
+	/* either breaks compile */
+	BUILD_BUG_ON(sum != 8);
+	BUILD_BUG_STREQ(debug_cats, 1, "'not-in-map'");
+#endif
+}
+
+#define rTEST_eq(_v_, _ref)						\
+	({								\
+		if (strcmp(_v_, _ref)) {				\
+			pr_warn("failed: %s eq %s\n", _v_, _ref);	\
+		} else {						\
+			pr_debug("ok: %s eq %s\n", _v_, _ref);		\
+		}							\
+	})
+#define rTEST_eq_VI(_v_, _i, _ref)	rTEST_eq(_v_##_names[_i], _ref)
+
+static int __init test_maph_init(void)
+{
+	pr_debug("init start\n");
+
+	MAPH_BUILD_BUG();
+
+	rTEST_eq(caten, "YESNOMAYBE");
+	rTEST_eq_VI(debug_cats, 0, "DRMx_CORE");
+	rTEST_eq_VI(debug_cats, 1, "DRMx_DRIVER");
+	rTEST_eq_VI(debug_cats, 2, "DRMx_KMS");
+
+	/* force fail and ignore */
+	rTEST_eq_VI(debug_cats, 1, "'not-in-map'");
+	return 0;
+}
+
+static void __exit test_maph_exit(void)
+{
+	pr_debug("exited\n");
+}
+
+module_init(test_maph_init);
+module_exit(test_maph_exit);
+
+MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
+MODULE_LICENSE("GPL");