Add dynamic_debug_register_classes() to API, allowing user modules (builtin and loadable) to register class_names for the .class_id's they are using. Knowing classes is 1st step to validating with them. Add dynamic_debug_unregister_classes() also.
Add struct ddebug_known_classes_map: maps known class_name strings to .class_id[0..N], where N<31. .base allows sharing of that range.
A wrapper macro: DYNAMIC_DEBUG_CLASSES(_var, _modmatch, _base, classes) defines and initializes that struct var, _maybe_unused is added so the decl doesn't draw warnings when dyndbg is not enabled; a small list of classnames is tolerable wasted space.
_var: user passes this into dynamic_debug_register_classes(var).
_base: usually 0, it allows splitting 31 classes into subranges, so that multiple sysfs-nodes can share the module's class-id space.
classes: list of strings with classnames, mapped to class-id=idx(+_base)
mod_name: KBUILD_MODNAME, available for builtins, loadables mod: ref to loadable module. allows ==, distinguishing loadables.
When modules register known classnames, they opt-in to permit dyndbg to allow "class <name>" queries to manipulate their class'd pr_debugs (if any), default class_id pr_debugs are still controllable as before.
dynamic_debug_register_classes(&map) finds the module's ddebug_table record, and attaches the map to it. This makes it available to ddebug_change(), which will use it to validate class'd commands.
Sharing class-names across multiple modules is how those modules coordinate; all drm* and drivers would respond to:
#> echo class DRM_UT_CORE +p > /proc/dynamic_debug/control
Therefore no class-name uniqueness check is useful.
TODO: Eventually we need a list of registered classes, not just the zero-or-one implemented here. This will support multiple sysfs-nodes, one each for print-to-syslog, print-to-tracefs, or subranges using _base.
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- . fix register_classes() for !CONFIG_MODULES . add maybe-unused to var decl in DYNAMIC_DEBUG_CLASSES . kdoc for DYNAMIC_DEBUG_CLASSES . add dynamic_debug_unregister_classes --- include/linux/dynamic_debug.h | 36 ++++++++++++++++++++++++ lib/dynamic_debug.c | 53 +++++++++++++++++++++++++++++++++++ 2 files changed, 89 insertions(+)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index 39550fefcf0f..328722ba2d8e 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -56,6 +56,34 @@ struct _ddebug { #endif } __attribute__((aligned(8)));
+struct ddebug_known_classes_map { + struct list_head link; + struct module *mod; + const char *mod_name; /* needed for builtins */ + const int base; /* index of 1st .class_id, allows split/shared space */ + const int length; + const char *classes[]; /* index maps .class_id */ +}; + +#define NUM_TYPE_ARGS(eltype, ...) \ + (sizeof((eltype[]) {__VA_ARGS__}) / sizeof(eltype)) +/** + * DYNAMIC_DEBUG_CLASSES - declare classnames known by a module + * @_var: passed to dynamic_debug_register_classes(_var) + * @_base: offset of 1st class-name. splits .class_id space + * @classes: class-names known/used by of .class_ids[_base.._base+length] + * + * @classes specifies names for the classids used by a module; dyndbg + * accepts "class <name>" commands if <name> is known and registered. + */ +#define DYNAMIC_DEBUG_CLASSES(_var, _base, ...) \ + static __maybe_unused struct ddebug_known_classes_map _var = { \ + .mod = THIS_MODULE, \ + .mod_name = KBUILD_MODNAME, \ + .base = _base, \ + .length = NUM_TYPE_ARGS(char*, __VA_ARGS__), \ + .classes = { __VA_ARGS__ } \ + }
#if defined(CONFIG_DYNAMIC_DEBUG_CORE) @@ -206,6 +234,9 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, KERN_DEBUG, prefix_str, prefix_type, \ rowsize, groupsize, buf, len, ascii)
+int dynamic_debug_register_classes(struct ddebug_known_classes_map *map); +void dynamic_debug_unregister_classes(struct ddebug_known_classes_map *map); + #else /* !CONFIG_DYNAMIC_DEBUG_CORE */
#include <linux/string.h> @@ -247,6 +278,11 @@ static inline int ddebug_dyndbg_module_param_cb(char *param, char *val, } while (0)
+static inline int dynamic_debug_register_classes(const struct ddebug_known_classes_map *map) +{ return 0; } +static inline void dynamic_debug_unregister_classes(struct ddebug_known_classes_map *map) +{} + #endif /* !CONFIG_DYNAMIC_DEBUG_CORE */
#endif diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index cdc0b03b1148..8f600c13048a 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -45,6 +45,8 @@ extern struct _ddebug __stop___dyndbg[]; struct ddebug_table { struct list_head link; const char *mod_name; + /* a module can have multiple class-sets eventually, but not yet */ + struct ddebug_known_classes_map const *map; unsigned int num_ddebugs; struct _ddebug *ddebugs; }; @@ -916,6 +918,57 @@ static const struct proc_ops proc_fops = { .proc_write = ddebug_proc_write };
+/** + * dynamic_debug_register_classes - register a module's known classes + * @map: &struct ddebug_known_classes_map + * + * modules using non-default pr_debug.class_id's should call this to + * inform dyndbg which classes they use (0..N), and what their + * classnames are. They are then usable in ```echo $cmd >control``` + */ +int dynamic_debug_register_classes(struct ddebug_known_classes_map *map) +{ + struct ddebug_table *dt; + int rc = -ENOENT; + + mutex_lock(&ddebug_lock); +#ifdef CONFIG_MODULES + if (map->mod) { + /* loadable module */ + list_for_each_entry(dt, &ddebug_tables, link) { + if (dt->mod_name == map->mod->name) { + rc = 0; + dt->map = map; + break; + } + } + } +#endif + if (!map->mod) { + /* builtin module */ + list_for_each_entry(dt, &ddebug_tables, link) { + if (!strcmp(dt->mod_name, map->mod_name)) { + rc = 0; + dt->map = map; + break; + } + } + } + mutex_unlock(&ddebug_lock); + if (rc) + pr_warn("register_classes: module %s not found\n", map->mod_name); + else + vpr_info("register_classes: %s\n", map->mod_name); + + return rc; +} +EXPORT_SYMBOL(dynamic_debug_register_classes); + +void dynamic_debug_unregister_classes(struct ddebug_known_classes_map *map) +{ + vpr_info("unregister_classes: %s\n", map->mod_name); +} + /* * Allocate a new ddebug_table for the given module * and add it to the global list.