dyndbg: add class_id to pr_debug callsites

DRM issues ~10 exclusive categories of debug messages; to represent
this directly in dyndbg, add a new 6-bit field: struct _ddebug.class_id.
This gives us 64 classes, which should be more than enough.

  #> echo 0x012345678 > /sys/module/drm/parameters/debug

All existing callsites are initialized with _DPRINTK_CLASS_DFLT, which
is 2^6-1.  This reserves 0-62 for use in new categorized/class'd
pr_debugs, which fits perfectly with natural enums (ints: 0..N).

Thats done by extending the init macro: DEFINE_DYNAMIC_DEBUG_METADATA()
with _CLS(cls, ...) suffix, and redefing old name using extended name.

Then extend the factory macro callchain with _cls() versions to provide
the callsite.class_id, with old-names passing _DPRINTK_CLASS_DFLT.

This sets us up to create class'd prdebug callsites (class'd callsites
are those with .class_id != _DPRINTK_CLASS_DFLT).

No behavior change.

cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-13-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/dynamic_debug.h

@@ -6,6 +6,8 @@
 #include <linux/jump_label.h>
 #endif
 
+#include <linux/build_bug.h>
+
 /*
  * An instance of this structure is created in a special
  * ELF section at every dynamic debug callsite.  At runtime,
@@ -21,6 +23,9 @@ struct _ddebug {
 	const char *filename;
 	const char *format;
 	unsigned int lineno:18;
+#define CLS_BITS 6
+	unsigned int class_id:CLS_BITS;
+#define _DPRINTK_CLASS_DFLT		((1 << CLS_BITS) - 1)
 	/*
 	 * The flags field controls the behaviour at the callsite.
 	 * The bits here are changed dynamically when the user
@@ -88,7 +93,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 			 const struct ib_device *ibdev,
 			 const char *fmt, ...);
 
-#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
+#define DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, cls, fmt)	\
 	static struct _ddebug  __aligned(8)			\
 	__section("__dyndbg") name = {				\
 		.modname = KBUILD_MODNAME,			\
@@ -97,8 +102,14 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 		.format = (fmt),				\
 		.lineno = __LINE__,				\
 		.flags = _DPRINTK_FLAGS_DEFAULT,		\
+		.class_id = cls,				\
 		_DPRINTK_KEY_INIT				\
-	}
+	};							\
+	BUILD_BUG_ON_MSG(cls > _DPRINTK_CLASS_DFLT,		\
+			 "classid value overflow")
+
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, _DPRINTK_CLASS_DFLT, fmt)
 
 #ifdef CONFIG_JUMP_LABEL
 
@@ -129,17 +140,34 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 
 #endif /* CONFIG_JUMP_LABEL */
 
-#define __dynamic_func_call(id, fmt, func, ...) do {	\
-	DEFINE_DYNAMIC_DEBUG_METADATA(id, fmt);		\
+/*
+ * Factory macros: ($prefix)dynamic_func_call($suffix)
+ *
+ * Lower layer (with __ prefix) gets the callsite metadata, and wraps
+ * the func inside a debug-branch/static-key construct.  Upper layer
+ * (with _ prefix) does the UNIQUE_ID once, so that lower can ref the
+ * name/label multiple times, and tie the elements together.
+ * Multiple flavors:
+ * (|_cls):	adds in _DPRINT_CLASS_DFLT as needed
+ * (|_no_desc):	former gets callsite descriptor as 1st arg (for prdbgs)
+ */
+#define __dynamic_func_call_cls(id, cls, fmt, func, ...) do {	\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);	\
 	if (DYNAMIC_DEBUG_BRANCH(id))				\
 		func(&id, ##__VA_ARGS__);			\
 } while (0)
+#define __dynamic_func_call(id, fmt, func, ...)				\
+	__dynamic_func_call_cls(id, _DPRINTK_CLASS_DFLT, fmt,		\
+				func, ##__VA_ARGS__)
 
-#define __dynamic_func_call_no_desc(id, fmt, func, ...) do {	\
-	DEFINE_DYNAMIC_DEBUG_METADATA(id, fmt);			\
+#define __dynamic_func_call_cls_no_desc(id, cls, fmt, func, ...) do {	\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);		\
 	if (DYNAMIC_DEBUG_BRANCH(id))					\
 		func(__VA_ARGS__);					\
 } while (0)
+#define __dynamic_func_call_no_desc(id, fmt, func, ...)			\
+	__dynamic_func_call_cls_no_desc(id, _DPRINTK_CLASS_DFLT,	\
+					fmt, func, ##__VA_ARGS__)
 
 /*
  * "Factory macro" for generating a call to func, guarded by a
@@ -149,22 +177,33 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
  * the varargs. Note that fmt is repeated in invocations of this
  * macro.
  */
+#define _dynamic_func_call_cls(cls, fmt, func, ...)			\
+	__dynamic_func_call_cls(__UNIQUE_ID(ddebug), cls, fmt, func, ##__VA_ARGS__)
 #define _dynamic_func_call(fmt, func, ...)				\
-	__dynamic_func_call(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
+	_dynamic_func_call_cls(_DPRINTK_CLASS_DFLT, fmt, func, ##__VA_ARGS__)
+
 /*
  * A variant that does the same, except that the descriptor is not
  * passed as the first argument to the function; it is only called
  * with precisely the macro's varargs.
  */
+#define _dynamic_func_call_cls_no_desc(cls, fmt, func, ...)		\
+	__dynamic_func_call_cls_no_desc(__UNIQUE_ID(ddebug), cls, fmt,	\
+					func, ##__VA_ARGS__)
 #define _dynamic_func_call_no_desc(fmt, func, ...)			\
-	__dynamic_func_call_no_desc(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
+	_dynamic_func_call_cls_no_desc(_DPRINTK_CLASS_DFLT, fmt,	\
+				       func, ##__VA_ARGS__)
+
+#define dynamic_pr_debug_cls(cls, fmt, ...)				\
+	_dynamic_func_call_cls(cls, fmt, __dynamic_pr_debug,		\
+			   pr_fmt(fmt), ##__VA_ARGS__)
 
 #define dynamic_pr_debug(fmt, ...)				\
 	_dynamic_func_call(fmt, __dynamic_pr_debug,		\
 			   pr_fmt(fmt), ##__VA_ARGS__)
 
 #define dynamic_dev_dbg(dev, fmt, ...)				\
-	_dynamic_func_call(fmt,__dynamic_dev_dbg, 		\
+	_dynamic_func_call(fmt, __dynamic_dev_dbg, 		\
 			   dev, fmt, ##__VA_ARGS__)
 
 #define dynamic_netdev_dbg(dev, fmt, ...)			\