kernel/linux.git/lib/dynamic_debug.c, branch v6.6.132

dyndbg: fix old BUG_ON in >control parser

2024-05-17T10:02:33+00:00

commit 00e7d3bea2ce7dac7bee1cf501fb071fd0ea8f6c upstream. Fix a BUG_ON from 2009. Even if it looks "unreachable" (I didn't really look), lets make sure by removing it, doing pr_err and return -EINVAL instead. Cc: stable Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20240429193145.66543-2-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

dyndbg: add source filename to prefix

2023-08-04T13:28:41+00:00

Printing the line number without the file is of limited usefulness. Knowing the filename also makes it also easier to relate the logged information to the controlfile. Example: # modprobe test_dynamic_debug # echo 'file test_dynamic_debug.c =pfsl' > /proc/dynamic_debug/control # echo 1 > /sys/module/test_dynamic_debug/parameters/do_prints # dmesg | tail -2 [ 71.802212] do_cats:lib/test_dynamic_debug.c:103: test_dd: doing categories [ 71.802227] do_levels:lib/test_dynamic_debug.c:123: test_dd: doing levels Signed-off-by: Thomas Weißschuh Acked-by: Jim Cromie Acked-by: Jason Baron Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-3-fd83beef0925@weissschuh.net Signed-off-by: Greg Kroah-Hartman

dyndbg: increase PREFIX_SIZE to 128

2023-08-04T13:28:41+00:00

A follow-up patch will add the possibility to print the filename as part of the prefix. Increase the maximum prefix size to accommodate this. Signed-off-by: Thomas Weißschuh Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-2-fd83beef0925@weissschuh.net Signed-off-by: Greg Kroah-Hartman

dyndbg: constify opt_array

2023-08-04T13:28:40+00:00

It is never modified, so mark it const. Signed-off-by: Thomas Weißschuh Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-1-fd83beef0925@weissschuh.net Signed-off-by: Greg Kroah-Hartman

dyndbg: use the module notifier callbacks

2023-03-09T20:58:36+00:00

Bring dynamic debug in line with other subsystems by using the module notifier callbacks. This results in a net decrease in core module code. Additionally, Jim Cromie has a new dynamic debug classmap feature, which requires that jump labels be initialized prior to dynamic debug. Specifically, the new feature toggles a jump label from the existing dynamic_debug_setup() function. However, this does not currently work properly, because jump labels are initialized via the 'module_notify_list' notifier chain, which is invoked after the current call to dynamic_debug_setup(). Thus, this patch ensures that jump labels are initialized prior to dynamic debug by setting the dynamic debug notifier priority to 0, while jump labels have the higher priority of 1. Tested by Jim using his new test case, and I've verfied the correct printing via: # modprobe test_dynamic_debug dyndbg. Link: https://lore.kernel.org/lkml/20230113193016.749791-21-jim.cromie@gmail.com/ Reported-by: kernel test robot Link: https://lore.kernel.org/oe-kbuild-all/202302190427.9iIK2NfJ-lkp@intel.com/ Tested-by: Jim Cromie Reviewed-by: Vincenzo Palazzo Cc: Peter Zijlstra CC: Jim Cromie Cc: Luis Chamberlain Cc: Greg Kroah-Hartman Signed-off-by: Jason Baron Signed-off-by: Luis Chamberlain

dyndbg: remove unused 'base' arg from __ddebug_add_module()

2023-03-09T20:57:24+00:00

The 'base' parameter to __ddebug_add_module() is no longer in use after: Commit b7b4eebdba7b ("dyndbg: gather __dyndbg[] state into struct _ddebug_info"). Cc: Jim Cromie Cc: Greg Kroah-Hartman Tested-by: Jim Cromie Reviewed-by: Vincenzo Palazzo Signed-off-by: Jason Baron Signed-off-by: Luis Chamberlain

dyndbg: add drm.debug style (drm/parameters/debug) bitmap support

2022-09-07T15:04:49+00:00

Add kernel_param_ops and callbacks to use a class-map to validate and apply input to a sysfs-node, which allows users to control classes defined in that class-map. This supports uses like: echo 0x3 > /sys/module/drm/parameters/debug IE add these: - int param_set_dyndbg_classes() - int param_get_dyndbg_classes() - struct kernel_param_ops param_ops_dyndbg_classes Following the model of kernel/params.c STANDARD_PARAM_DEFS, these are non-static and exported. This might be unnecessary here. get/set use an augmented kernel_param; the arg refs a new struct ddebug_class_param, which contains: - A ptr to user's state-store; a union of &ulong for drm.debug, &int for nouveau level debug. By ref'g the client's bit-state _var, code coordinates with existing code (like drm_debug_enabled) which uses it, so existing/remaining calls can work unchanged. Changing drm.debug to a ulong allows use of BIT() etc. - FLAGS: dyndbg.flags toggled by changes to bitmap. Usually just "p". - MAP: a pointer to struct ddebug_classes_map, which maps those class-names to .class_ids 0..N that the module is using. This class-map is declared & initialized by DECLARE_DYNDBG_CLASSMAP. - map-type: 4 enums DD_CLASS_TYPE_* select 2 input forms and 2 meanings. numeric input: DD_CLASS_TYPE_DISJOINT_BITS integer input, independent bits. ie: drm.debug DD_CLASS_TYPE_LEVEL_NUM integer input, 0..N levels classnames-list (comma separated) input: DD_CLASS_TYPE_DISJOINT_NAMES each name affects a bit, others preserved DD_CLASS_TYPE_LEVEL_NAMES names have level meanings, like kern_levels.h _NAMES - comma-separated classnames (with optional +-) _NUM - numeric input, 0-N expected _BITS - numeric input, 0x1F bitmap form expected _DISJOINT - bits are independent _LEVEL - (x /sys/module/drm/parameters/debug_catnames A naive _LEVEL_NAMES use, with one class, that sets all in the class-map according to (x /sys/module/test_dynamic_debug/parameters/p_level_names : problem solved echo -L1 > /sys/module/test_dynamic_debug/parameters/p_level_names Note this artifact: : this is same as prev cmd (due to +/-) echo L0 > /sys/module/test_dynamic_debug/parameters/p_level_names : this is "even-more" off, but same wo __pr_debug_class(L0, ".."). echo -L0 > /sys/module/test_dynamic_debug/parameters/p_level_names A stress-test/make-work usage (kid toggling a light switch): echo +L7,L0,L7,L0,L7,L0,L7,L0,L7,L0,L7,L0,L7 \ > /sys/module/test_dynamic_debug/parameters/p_level_names ddebug_apply_class_bitmap(): inside-fn, works on bitmaps, receives new-bits, finds diffs vs client-bitvector holding "current" state, and issues exec_query to commit the adjustment. param_set_dyndbg_classes(): interface fn, sends _NAMES to param_set_dyndbg_classnames() and returns, falls thru to handle _BITS, _NUM internally, and calls ddebug_apply_class_bitmap(). Finishes by updating state. param_set_dyndbg_classnames(): handles classnames-list in loop, calls ddebug_apply_class_bitmap for each, then updates state. NOTES: _LEVEL_ is overlay on _DISJOINT_; inputs are converted to a bitmask, by the callbacks. IOW this is possible, and possibly confusing: echo class V3 +p > control echo class V1 -p > control IMO thats ok, relative verbosity is an interface property. _LEVEL_NUM maps still need class-names, even though the names are not usable at the sysfs interface (unlike with _NAMES style). The names are the only way to >control the classes. - It must have a "V0" name, something below "V1" to turn "V1" off. __pr_debug_cls(V0,..) is printk, don't do that. - "class names" is required at the >control interface. - relative levels are not enforced at >control _LEVEL_NAMES bear +/- signs, which alters the on-bit-pos by 1. IOW, +L2 means L0,L1,L2, and -L2 means just L0,L1. This kinda spoils the readback fidelity, since the L0 bit gets turned on by any use of any L*, except "-L0". All the interface uncertainty here pertains to the _NAMES features. Nobody has actually asked for this, so its practical (if a little tedious) to split it out. Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-21-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

dyndbg: validate class FOO by checking with module

2022-09-07T15:04:49+00:00

Add module-to-class validation: #> echo class DRM_UT_KMS +p > /proc/dynamic_debug/control If a query has "class FOO", then ddebug_find_valid_class(), called from ddebug_change(), requires that FOO is known to module X, otherwize the query is skipped entirely for X. This protects each module's class-space, other than the default:31. The authors' choice of FOO is highly selective, giving isolation and/or coordinated sharing of FOOs. For example, only DRM modules should know and respond to DRM_UT_KMS. So this, combined with module's opt-in declaration of known classes, effectively privatizes the .class_id space for each module (or coordinated set of modules). Notes: For all "class FOO" queries, ddebug_find_valid_class() is called, it returns the map matching the query, and sets valid_class via an *outvar). If no "class FOO" is supplied, valid_class = _CLASS_DFLT. This insures that legacy queries do not trample on new class'd callsites, as they get added. Also add a new column to control-file output, displaying non-default class-name (when found) or the "unknown _id:", if it has not been (correctly) declared with one of the declarator macros. Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-18-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

dyndbg: add ddebug_attach_module_classes

2022-09-07T15:04:49+00:00

Add ddebug_attach_module_classes(), call it from ddebug_add_module(). It scans the classes/section its given, finds records where the module-name matches the module being added, and adds them to the module's maps list. No locking here, since the record isn't yet linked into the ddebug_tables list. It is called indirectly from 2 sources: - from load_module(), where it scans the module's __dyndbg_classes section, which contains DYNAMIC_DEBUG_CLASSES definitions from just the module. - from dynamic_debug_init(), where all DYNAMIC_DEBUG_CLASSES definitions of each builtin module have been packed together. This is why ddebug_attach_module_classes() checks module-name. NOTES Its (highly) likely that builtin classes will be ordered by module name (just like prdbg descriptors are in the __dyndbg section). So the list can be replaced by a vector (ptr + length), which will work for loaded modules too. This would imitate whats currently done for the _ddebug descriptors. That said, converting to vector,len is close to pointless; a small minority of modules will ever define a class-map, and almost all of them will have only 1 or 2 class-maps, so theres only a couple dozen pointers to save. TODO: re-evaluate for lines removable. Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-17-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

kernel/module: add __dyndbg_classes section

2022-09-07T15:04:49+00:00

Add __dyndbg_classes section, using __dyndbg as a model. Use it: vmlinux.lds.h: KEEP the new section, which also silences orphan section warning on loadable modules. Add (__start_/__stop_)__dyndbg_classes linker symbols for the c externs (below). kernel/module/main.c: - fill new fields in find_module_sections(), using section_objs() - extend callchain prototypes to pass classes, length load_module(): pass new info to dynamic_debug_setup() dynamic_debug_setup(): new params, pass through to ddebug_add_module() dynamic_debug.c: - add externs to the linker symbols. ddebug_add_module(): - It currently builds a debug_table, and *will* find and attach classes. dynamic_debug_init(): - add class fields to the _ddebug_info cursor var: di. Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-16-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman