Dynamic debug classmaps allow modules to _DEFINE or _USE classmaps, which map classnames to a range of class-IDs (0..62) that they are using. This names => IDs mapping allows many modules to use 0..N independently, and even allows (carefully) shared classnames.
Previously, class validation only caught some violations in _DEFINEd classmaps; 0..62 range checks, overlaps among _DEFINEd classmaps, but left blind spots in _USEs, for out of bounds manual offsets, overlapping _USEd classmaps, unknown map types, and orphaned callsite IDs. These oversights could lead to ambiguous routing or spammy warnings during control query execution. This commit hardens classmap and descriptor validation: - Mirror the compile-time limits of _DEFINE by adding a static_assert to validate the _offset value passed to DYNAMIC_DEBUG_CLASSMAP_USE_. - Add run-time overlap checks for _USEd classmaps in ddebug_add_module() to prevent collisions between private maps and imported APIs. - Validate that module classmaps use known enum map types. - Scan module descriptors at load time to print a single warning per missing class_id, rather than waiting for a user query to trip over it. - Downgrade the global WARN_ONCE in ddebug_match_desc() to a pr_warn_ratelimited, since orphaned class IDs are now tracked and warned about early at module load. Signed-off-by: Jim Cromie <[email protected]> --- include/linux/dynamic_debug.h | 2 ++ lib/dynamic_debug.c | 52 +++++++++++++++++++++++++++++++---- 2 files changed, 48 insertions(+), 6 deletions(-) diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index 0d1245aefc69..28684cfc0937 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -262,6 +262,8 @@ struct _ddebug_class_param { #define __DYNAMIC_DEBUG_CLASSMAP_USE(_var, _offset, _uname) \ extern struct _ddebug_class_map _var; \ + static_assert((_offset) >= 0 && (_offset) < _DPRINTK_CLASS_DFLT, \ + "classmap use offset must be in 0..62"); \ static struct _ddebug_class_user __aligned(8) __used \ __section("__dyndbg_class_users") _uname = { \ .mod_name = KBUILD_MODNAME, \ diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 2083a8546460..635df6edb4cf 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -320,7 +320,7 @@ static bool ddebug_match_desc(const struct ddebug_query *query, /* 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", + pr_warn_ratelimited("unknown class_id %d, check %s's CLASSMAP definitions\n", dp->class_id, di->mod_name); return false; } @@ -1404,9 +1404,8 @@ static void ddebug_apply_class_users(const struct _ddebug_info *di) (__dst)->info._vec.len = __nc; \ }) -static int __maybe_unused -ddebug_class_range_overlap(struct _ddebug_class_map *cm, - u64 *reserved_ids) +static int ddebug_class_range_overlap(struct _ddebug_class_map *cm, + u64 *reserved_ids) { u64 range = (((1ULL << cm->length) - 1) << cm->base); @@ -1420,6 +1419,23 @@ ddebug_class_range_overlap(struct _ddebug_class_map *cm, return 0; } +static int ddebug_class_user_overlap(struct _ddebug_class_user *cli, + u64 *reserved_ids) +{ + struct _ddebug_class_map *cm = cli->map; + int base = cm->base + cli->offset; + u64 range = (((1ULL << cm->length) - 1) << base); + + if (range & *reserved_ids) { + pr_err("[%d..%d] (from %s) conflicts with %llx\n", base, + base + cm->length - 1, cm->class_names[0], + *reserved_ids); + return -EINVAL; + } + *reserved_ids |= range; + return 0; +} + /* * Allocate a new ddebug_table for the given module * and add it to the global list. @@ -1430,6 +1446,7 @@ static int ddebug_add_module(struct _ddebug_info *di) struct _ddebug_class_map *cm; struct _ddebug_class_user *cli; u64 reserved_ids = 0; + u64 bad_ids = 0; int i; if (!di->descs.len) @@ -1454,10 +1471,33 @@ static int ddebug_add_module(struct _ddebug_info *di) dd_mark_vector_subrange(i, cli, &dt->info, users, dt); /* now di is stale */ - /* insure 2+ classmaps share the per-module 0..62 class_id space */ - for_subvec(i, cm, &dt->info, maps) + /* validate class map types and the per-module 0..62 class_id space */ + for_subvec(i, cm, &dt->info, maps) { + if (cm->map_type > DD_CLASS_TYPE_LEVEL_NUM) { + pr_err("module %s has unknown classmap type %d\n", dt->info.mod_name, cm->map_type); + goto cleanup; + } if (ddebug_class_range_overlap(cm, &reserved_ids)) goto cleanup; + } + + for_subvec(i, cli, &dt->info, users) + if (ddebug_class_user_overlap(cli, &reserved_ids)) + goto cleanup; + + /* validate all class_ids against module's classmaps/users */ + for (i = 0; i < dt->info.descs.len; i++) { + struct _ddebug *dp = &dt->info.descs.start[i]; + + if (dp->class_id == _DPRINTK_CLASS_DFLT) + continue; + if (bad_ids & (1ULL << dp->class_id)) + continue; + if (!ddebug_find_map_by_class_id(&dt->info, dp->class_id)) { + pr_warn("module %s uses unknown class_id %d\n", dt->info.mod_name, dp->class_id); + bad_ids |= (1ULL << dp->class_id); + } + } mutex_lock(&ddebug_lock); list_add_tail(&dt->link, &ddebug_tables); -- 2.53.0
