From: Jim Cromie <[email protected]> classmap-v1 code protected class'd pr_debugs from unintended changes by unclassed/_DFLT queries:
# - to declutter examples: alias ddcmd='echo $* > /proc/dynamic_debug/control' # IOW, this should NOT alter drm.debug settings ddcmd -p # Instead, you must name the class to change it. # Protective but tedious ddcmd class DRM_UT_CORE +p # Or do it the (old school) subsystem way # This is ABI !! echo 1 > /sys/module/drm/parameters/debug Since the debug sysfs-node is ABI, if dyndbg is going to implement it, it must also honor its settings; it must at least protect against accidental changes to its classes from legacy queries. The protection allows all previously conceived queries to work the way they always have; ie select the same set of pr_debugs, despite the inclusion of whole new classes of pr_debugs. But that choice has 2 downsides: 1. "name the class to change it" makes a tedious long-winded interface, needing many commands to set DRM_UT_* one at a time. 2. It makes the class keyword special in some sense; the other keywords skip only on query mismatch, otherwise the code falls thru to adjust the pr-debug site. Jason Baron didn't like v1 on point 2. Louis Chauvet didn't like recent rev on point 1 tedium. But that said: /sys/ is ABI, so this must be reliable: #> echo 0x1f > /sys/module/drm/parameters/debug It 'just works' without dyndbg underneath; we must deliver that same stability. Convenience is secondary. The new resolution: If ABI is the blocking issue, then no ABI means no blocking issue. IOW, if the classmap has no presence under /sys/*, ie no PARAM, there is no ABI to guard, and no reason to enforce a tedious interface. In the future, if DRM wants to alter this protection, that is practical, but I think default-on is the correct mode. So atm classes without a PARAM are unprotected at >control, allowing admins their shortcuts. I think this could satisfy all viewpoints. That said, theres also a possibility of wildcard classes: #> ddcmd class '*' +p Currently, the query-class is exact-matched against each module's classmaps.names. This gives precise behavior, a good basis. But class wildcards are possible, they just did'nt appear useful for DRM, whose classmap names are a flat DRM_UT_* namespace. IOW, theres no useful selectivity there: #> ddcmd class "DRM_*" +p # these enable every DRM_* class #> ddcmd class "DRM_UT_*" +p #> ddcmd class "DRM_UT_V*" +p # finally select just 1: DRM_UT_VBL #> ddcmd class "DRM_UT_D*" +p # but this gets 3 #> ddcmd class "D*V*" +p # here be dragons But there is debatable utility in the feature. #> ddcmd class __DEFAULT__ -p # what about this ? #> ddcmd -p # thats what this does. automatically Anyway, this patch does: 1. adds link field from _ddebug_class_map to the .controlling_param 2. sets it in ddebug_match_apply_kparam(), during modprobe/init, when options like drm.debug=VAL are handled. 3. ddebug_class_has_param() now checks .controlling_param 4. ddebug_class_wants_protection() macro renames 3. this frames it as a separable policy decision 5. ddebug_match_desc() gets the most attention: a. move classmap consideration to the bottom this insures all other constraints act 1st. allows simpler 'final' decisions. b. split class choices cleanly on query: class FOO vs none, and class'd vs _DPRINTK_CLASS_DFLT site. c. calls 4 when applying a class-less query to a class'd pr_debug here we need a new fn to find the classmap with this .class_id d. calls new ddebug_find_classmap_by_class_id(). when class-less query looks at a class'd pr_debug. finds classmap, which can then decide, currently by PARAM existence. NOTES: protection is only against class-less queries, explicit "class FOO" adjustments are allowed (that is the mechanism). The drm.debug sysfs-node heavily under-specifies the class'd pr_debugs it controls; none of the +mfls prefixing flags have any effect, and each callsite remains individually controllable. drm.debug just toggles the +p flag for all the modules' class'd pr_debugs. Signed-off-by: Jim Cromie <[email protected]> Reviewed-by: Louis Chauvet <[email protected]> --- v2: RvB after SoB old-v12 minor fixup after squashing subsequent commits to previous ones --- include/linux/dynamic_debug.h | 14 ++- lib/dynamic_debug.c | 130 +++++++++++++++++---- .../selftests/dynamic_debug/dyndbg_selftest.sh | 4 +- 3 files changed, 121 insertions(+), 27 deletions(-) diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index a740b3fabc09..d00605ef651e 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -92,6 +92,7 @@ enum ddebug_class_map_type { * map @class_names 0..N to consecutive constants starting at @base. */ struct ddebug_class_map { + struct ddebug_class_param *controlling_param; const struct module *mod; /* NULL for builtins */ const char *mod_name; /* needed for builtins */ const char **class_names; @@ -299,7 +300,12 @@ struct ddebug_class_param { * * Creates a sysfs-param to control the classes defined by the * exported classmap, with bits 0..N-1 mapped to the classes named. - * This version keeps class-state in a private long int. + * + * Since sysfs-params are ABI, this also protects the classmap'd + * pr_debugs from un-class'd `echo -p > /proc/dynamic_debug/control` + * changes. + * + * This keeps class-state in a private long int. */ #define DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _var, _flags) \ static u32 _name##_bvec; \ @@ -312,10 +318,8 @@ struct ddebug_class_param { * @_var: name of the (exported) classmap var defining the classes/bits * @_flags: flags to be toggled, typically just 'p' * - * Creates a sysfs-param to control the classes defined by the - * exported clasmap, with bits 0..N-1 mapped to the classes named. - * This version keeps class-state in user @_bits. This lets drm check - * __drm_debug elsewhere too. + * Like DYNAMIC_DEBUG_CLASSMAP_PARAM, but maintains param-state in + * extern @_bits. This lets DRM check __drm_debug elsewhere too. */ #define DYNAMIC_DEBUG_CLASSMAP_PARAM_REF(_name, _bits, _var, _flags) \ __DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _bits, _var, _flags) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 93a5a481c8b8..a5d813ad323a 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -71,6 +71,10 @@ struct flag_settings { unsigned int mask; }; +static bool ddebug_class_map_in_range(const int class_id, + const struct ddebug_class_map *map); +static bool ddebug_class_user_in_range(const int class_id, + const struct ddebug_class_user *user); static DEFINE_MUTEX(ddebug_lock); static LIST_HEAD(ddebug_tables); static int verbose; @@ -200,6 +204,46 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct _ddebug_info cons return NULL; } + + +static struct ddebug_class_map * +ddebug_find_map_by_class_id(struct _ddebug_info *di, int class_id) +{ + struct ddebug_class_map *map; + struct ddebug_class_user *cli; + int i; + + for_subvec(i, map, di, maps) + if (ddebug_class_map_in_range(class_id, map)) + return map; + + for_subvec(i, cli, di, users) + if (ddebug_class_user_in_range(class_id, cli)) + return cli->map; + + return NULL; +} + +/* + * classmaps-V1 protected classes from changes by legacy commands + * (those selecting _DPRINTK_CLASS_DFLT by omission). This had the + * downside that saying "class FOO" for every change can get tedious. + * + * V2 is smarter, it protects class-maps if the defining module also + * calls DYNAMIC_DEBUG_CLASSMAP_PARAM to create a sysfs parameter. + * Since the author wants the knob, we should assume they intend to + * use it (in preference to "class FOO +p" >control), and want to + * trust its settings. This gives protection when its useful, and not + * when its just tedious. + */ +static inline bool ddebug_class_has_param(const struct ddebug_class_map *map) +{ + return !!(map->controlling_param); +} + +/* re-framed as a policy choice */ +#define ddebug_class_wants_protection(map) (ddebug_class_has_param(map)) + /* * Search the tables for _ddebug's which match the given `query' and * apply the `flags' and `mask' to them. Returns number of matching @@ -208,11 +252,10 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct _ddebug_info cons */ static bool ddebug_match_desc(const struct ddebug_query *query, struct _ddebug *dp, - int valid_class) + struct _ddebug_info *di, + int selected_class) { - /* match site against query-class */ - if (dp->class_id != valid_class) - return false; + struct ddebug_class_map *site_map; /* match against the source filename */ if (query->filename && @@ -256,7 +299,28 @@ static bool ddebug_match_desc(const struct ddebug_query *query, dp->lineno > query->last_lineno) return false; - return true; + /* + * above are all satisfied, so we can make final decisions: + * 1- class FOO or implied class __DEFAULT__ + * 2- site.is_classed or not + */ + if (query->class_string) { + /* class FOO given, exact match required */ + return (dp->class_id == selected_class); + } + /* query class __DEFAULT__ by omission. */ + if (dp->class_id == _DPRINTK_CLASS_DFLT) { + /* un-classed site */ + return true; + } + /* site is class'd */ + site_map = ddebug_find_map_by_class_id(di, dp->class_id); + if (!site_map) { + WARN_ONCE(1, "unknown class_id %d, check %s's CLASSMAP definitions", dp->class_id, di->mod_name); + return false; + } + /* module(-param) decides protection */ + return !ddebug_class_wants_protection(site_map); } static int ddebug_change(const struct ddebug_query *query, struct flag_settings *modifiers) @@ -266,13 +330,13 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings unsigned int newflags; unsigned int nfound = 0; struct flagsbuf fbuf, nbuf; - struct ddebug_class_map *map = NULL; - int valid_class; + int selected_class; /* search for matching ddebugs */ mutex_lock(&ddebug_lock); list_for_each_entry(dt, &ddebug_tables, link) { struct _ddebug_info *di = &dt->info; + struct ddebug_class_map *mods_map; /* match against the module name */ if (query->module && @@ -280,20 +344,18 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings !match_wildcard_hyphen(query->module, kbasename(di->mod_name))) continue; + selected_class = _DPRINTK_CLASS_DFLT; if (query->class_string) { - map = ddebug_find_valid_class(&dt->info, query->class_string, - &valid_class); - if (!map) + mods_map = ddebug_find_valid_class(di, query->class_string, + &selected_class); + if (!mods_map) continue; - } else { - /* constrain query, do not touch class'd callsites */ - valid_class = _DPRINTK_CLASS_DFLT; } for (i = 0; i < di->descs.len; i++) { struct _ddebug *dp = &di->descs.start[i]; - if (!ddebug_match_desc(query, dp, valid_class)) + if (!ddebug_match_desc(query, dp, di, selected_class)) continue; nfound++; @@ -1147,7 +1209,6 @@ static bool ddebug_class_user_in_range(const int class_id, const struct ddebug_c return false; return ddebug_class_map_in_range(class_id - user->offset, user->map); } - static const char *ddebug_class_name(struct _ddebug_info *di, struct _ddebug *dp) { struct ddebug_class_map *map; @@ -1298,16 +1359,25 @@ static void ddebug_sync_classbits(const struct kernel_param *kp, const char *mod } } -static void ddebug_match_apply_kparam(const struct kernel_param *kp, - const struct ddebug_class_map *map, - const char *mod_name) +static struct ddebug_class_param * +ddebug_get_classmap_kparam(const struct kernel_param *kp, + const struct ddebug_class_map *map) { struct ddebug_class_param *dcp; if (kp->ops != ¶m_ops_dyndbg_classes) - return; + return NULL; dcp = (struct ddebug_class_param *)kp->arg; + return (map == dcp->map) + ? dcp : (struct ddebug_class_param *)NULL; +} + +static void ddebug_match_apply_kparam(const struct kernel_param *kp, + struct ddebug_class_map *map, + const char *mod_name) +{ + struct ddebug_class_param *dcp = ddebug_get_classmap_kparam(kp, map); if (dcp && dcp->map == map) { v2pr_info(" kp:%s.%s =0x%x", mod_name, kp->name, *dcp->bits); @@ -1316,7 +1386,7 @@ static void ddebug_match_apply_kparam(const struct kernel_param *kp, } } -static void ddebug_apply_params(const struct ddebug_class_map *cm, const char *mod_name) +static void ddebug_apply_params(struct ddebug_class_map *cm, const char *mod_name) { const struct kernel_param *kp; @@ -1339,6 +1409,26 @@ static void ddebug_apply_params(const struct ddebug_class_map *cm, const char *m } } +#if 0 +/* + * called from add_module, ie early. it can find controlling kparams, + * which can/does? enable protection of this classmap from class-less + * queries, on the grounds that the user created the kparam, means to + * use it, and expects it to reflect reality. We should oblige him, + * and protect those classmaps from classless "-p" changes. + */ +static void ddebug_apply_class_maps(const struct _ddebug_info *di) +{ + struct ddebug_class_map *cm; + int i; + + for_subvec(i, cm, di, maps) + ddebug_apply_params(cm, cm->mod_name); + + v2pr_di_info(di, "attached %d class-maps to ", i); +} +#endif + static void ddebug_apply_class_users(const struct _ddebug_info *di) { struct ddebug_class_user *cli; diff --git a/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh b/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh index 0bb3c3e11df7..194e9c9d4544 100755 --- a/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh +++ b/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh @@ -686,8 +686,8 @@ function GOLDEN_RECORDS { #K= d4923595eea382923aee64aed15c7c35 FT_test_classes.1 #K= a15ec4843acd721fbdfddc0b512c8032 FT_test_classes.2 #K= 40a294034c886787960f4c751b196da9 FT_test_classes.3 -#K= 38e813e9025107ac3e24226b8d487a92 FT_classmap_inheritance.1 -#K= 9b82b12a35ad98ef26183db15071f70e FT_classmap_inheritance.2 +#K= 3af642df3771be04ab4428ce7f6d53a2 FT_classmap_inheritance.1 +#K= d6135911e9cff22d701ad0c3fdbb1c35 FT_classmap_inheritance.2 #K= d4937472530af6fdcb0a2440d4a366ea FT_classmap_inheritance.3 #K= fea6f925b829f75a5b2d4e837738fa12 FT_classmap_inheritance.4 #K= 7e92245008439ee79fe2460aeaa16a9b FT_classmap_inheritance.5 -- 2.55.0
