[PATCH v5 29/30] dyndbg: add DYNAMIC_DEBUG_CLASSMAP_USE_(clname, _base)

[Jim Cromie <jim.cromie@gmail.com>]

The @_base parameter in @DYNAMIC_DEBUG_CLASSMAP_DEFINE exists to
de-conflict a second classmap definition from a first, by setting
different .class_id constants for all of the second map's pr_debug
callsites.

This gives the same _base param, and thus more flexible usage via
@DYNAMIC_DEBUG_CLASSMAP_USE_(clname,_base).  So now 2nd classmap used
can be deconflicted from the 1st used or defined.

1st the range-checking logic is refined into two distinct macros,
@ddebug_class_map_in_range() and @ddebug_class_user_in_range(), which
are then applied to the lookup functions: @ddebug_find_valid_class(),
@ddebug_find_map_by_class_id(), and @ddebug_class_name().

@DYNAMIC_DEBUG_CLASSMAP_USE* macro API kdoc is adjusted accordingly.

TODO: This is just an api placeholder, it anticipates a possible need
that may never arise.  The normal way to add a new classmap to a drm
driver would be to define the enum to avoid DRM_UT_CORE..RES vals.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 include/linux/dynamic_debug.h | 28 ++++++++++++++++++++++------
 lib/dynamic_debug.c           | 21 +++++++++++++--------
 2 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 588e03e8d157..d1e38158c485 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -87,7 +87,7 @@ struct _ddebug_class_map {
 struct _ddebug_class_user {
 	char *mod_name;
 	struct _ddebug_class_map *map;
-	const int base;		/* user offset to re-number the used map */
+	const int base;		/* offset .class_id range to share space */
 };
 
 /*
@@ -235,15 +235,31 @@ struct _ddebug_class_param {
 /**
  * DYNAMIC_DEBUG_CLASSMAP_USE - refer to a classmap, DEFINEd elsewhere.
  * @_var: name of the exported classmap var
- * @_not_yet: _base-like, but applies only to this USEr. (if needed)
  *
  * This tells dyndbg that the module has prdbgs with classids defined
  * in the named classmap.  This qualifies "class NAME" >controls on
- * the user module, and ignores unknown names.
+ * the user module, and ignores unknown names. This is a wrapper for
+ * DYNAMIC_DEBUG_CLASSMAP_USE_() with a base offset of 0.
  */
-#define DYNAMIC_DEBUG_CLASSMAP_USE(_var)				\
-	DYNAMIC_DEBUG_CLASSMAP_USE_(_var, 0, __UNIQUE_ID(_ddebug_class_user))
-#define DYNAMIC_DEBUG_CLASSMAP_USE_(_var, _base, _uname)		\
+#define DYNAMIC_DEBUG_CLASSMAP_USE(_var) \
+	DYNAMIC_DEBUG_CLASSMAP_USE_(_var, 0)
+
+/**
+ * DYNAMIC_DEBUG_CLASSMAP_USE_ - refer to a classmap with a manual offset.
+ * @_var:   name of the exported classmap var to use.
+ * @_base:  an integer offset to add to the class IDs of the used map.
+ *
+ * This is an extended version of DYNAMIC_DEBUG_CLASSMAP_USE(). It should
+ * be used to resolve class ID conflicts when a module uses multiple
+ * classmaps that have overlapping ID ranges.
+ *
+ * The final class IDs for the used map will be calculated as:
+ * original_map_base + class_index + @_base.
+ */
+#define DYNAMIC_DEBUG_CLASSMAP_USE_(_var, _base)			\
+	__DYNAMIC_DEBUG_CLASSMAP_USE(_var, _base, __UNIQUE_ID(_ddebug_class_user))
+
+#define __DYNAMIC_DEBUG_CLASSMAP_USE(_var, _base, _uname)		\
 	extern struct _ddebug_class_map _var;				\
 	static struct _ddebug_class_user __aligned(8) __used		\
 	__section("__dyndbg_class_users") _uname = {			\
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 6e0c978bc7c4..68bd2dbdacfb 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -169,6 +169,12 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 		  _di->users.len);					\
 	})
 
+#define ddebug_class_map_in_range(id, map) \
+	((id) >= (map)->base && (id) < (map)->base + (map)->length)
+#define ddebug_class_user_in_range(id, user) \
+	((id) >= ((user)->map->base + (user)->base) && \
+	 (id) < ((user)->map->base + (user)->base + (user)->map->length))
+
 static struct _ddebug_class_map *
 ddebug_find_valid_class(struct _ddebug_info const *di, const char *query_class, int *class_id)
 {
@@ -189,7 +195,7 @@ ddebug_find_valid_class(struct _ddebug_info const *di, const char *query_class,
 		if (idx >= 0) {
 			vpr_di_info(di, "class-ref: %s -> %s.%s ",
 				    cli->mod_name, cli->map->mod_name, query_class);
-			*class_id = idx + cli->map->base;
+			*class_id = idx + cli->map->base + cli->base;
 			return cli->map;
 		}
 	}
@@ -197,8 +203,7 @@ ddebug_find_valid_class(struct _ddebug_info const *di, const char *query_class,
 	return NULL;
 }
 
-#define class_in_range(class_id, map)					\
-	(class_id >= map->base && class_id < map->base + map->length)
+
 
 static struct _ddebug_class_map *
 ddebug_find_map_by_class_id(struct _ddebug_info *di, int class_id)
@@ -208,11 +213,11 @@ ddebug_find_map_by_class_id(struct _ddebug_info *di, int class_id)
 	int i;
 
 	for_subvec(i, map, di, maps)
-		if (class_in_range(class_id, map))
+		if (ddebug_class_map_in_range(class_id, map))
 			return map;
 
 	for_subvec(i, cli, di, users)
-		if (class_in_range(class_id, cli->map))
+		if (ddebug_class_user_in_range(class_id, cli))
 			return cli->map;
 
 	return NULL;
@@ -1146,12 +1151,12 @@ static const char *ddebug_class_name(struct _ddebug_info *di, struct _ddebug *dp
 	int i;
 
 	for_subvec(i, map, di, maps)
-		if (class_in_range(dp->class_id, map))
+		if (ddebug_class_map_in_range(dp->class_id, map))
 			return map->class_names[dp->class_id - map->base];
 
 	for_subvec(i, cli, di, users)
-		if (class_in_range(dp->class_id, cli->map))
-			return cli->map->class_names[dp->class_id - cli->map->base];
+		if (ddebug_class_user_in_range(dp->class_id, cli))
+			return cli->map->class_names[dp->class_id - cli->map->base - cli->base];
 
 	return NULL;
 }
-- 
2.51.0