This fixes dynamic-debug support for DRM.debug, added via classmaps. commit bb2ff6c27bc9 (drm: Disable dynamic debug as broken) CONFIG_DRM_USE_DYNAMIC_DEBUG=y was marked broken because drm.debug=val was applied when drm.ko was modprobed; too early for the yet-to-load drivers, which thus missed the enablement. My testing with /etc/modprobe.d/ entries and modprobes with dyndbg=$querycmd options obscured this omission. The fix is to replace invocations of DECLARE_DYNDBG_CLASSMAP with DYNDBG_CLASSMAP_DEFINE for core, and DYNDBG_CLASSMAP_USE for drivers. The distinction allows dyndbg to also handle the users properly. DRM is the only current classmaps user, and is not really using it, so if you think DRM could benefit from zero-off-cost debugs based on static-keys, please test. HISTORY 9/4/22 - ee879be38bc8..ace7c4bbb240 commited - classmaps-v1 dyndbg parts 9/11/22 - 0406faf25fb1..16deeb8e18ca commited - classmaps-v1 drm parts https://lore.kernel.org/lkml/Y3XUrOGAV4I7bB3M@xxxxxxxxx/ greg k-h says: This should go through the drm tree now. The rest probably should also go that way and not through my tree as well. https://lore.kernel.org/lkml/20221206003424.592078-1-jim.cromie@xxxxxxxxx/ v1- RFC. adds DYNDBG_CLASSMAP_DEFINE + test-submod to recap DRM failure https://lore.kernel.org/lkml/20230113193016.749791-1-jim.cromie@xxxxxxxxx/ v2- w RFC on "tolerate toggled state" https://lore.kernel.org/lkml/Y8aNMxHpvZ8qecSc@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ - PeterZ - nacks tolerance of insane/uninit static-key state https://lore.kernel.org/lkml/8ca08fba-1120-ca86-6129-0b33afb4a1da@xxxxxxxxxx/ - JasonB diagnoses prob - set jump-label b4 init 7deabd674988 dyndbg: use the module notifier callbacks - JasonB lands fix for my problem he moves dyndbg to use notifiers to do init, like & after jump-labels https://lore.kernel.org/lkml/20230125203743.564009-20-jim.cromie@xxxxxxxxx/ v3- probing, workaround-ish https://lore.kernel.org/lkml/20230713163626.31338-1-jim.cromie@xxxxxxxxx/ v4 - 7/13/23 - had extra/unused __UNIQUE_ID warnings/errs on lkp-tested arches due to unmatched __used marks - RandyD doc fixes, thx. https://lore.kernel.org/lkml/20230801170255.163237-1-jim.cromie@xxxxxxxxx/ v5 - 8/1/23 - lkp-test reported panics-on-boot https://lore.kernel.org/lkml/202308031432.fcb4197-oliver.sang@xxxxxxxxx/ - DRM=y in apply-params - missing align(8) in init-macro, failed only for builtin modules https://lore.kernel.org/lkml/20230911230838.14461-1-jim.cromie@xxxxxxxxx/ v6 - 9/11/23 - no feedback v7[a-d] - attempts to get into/thru DRM patchwork CI.. - "jenius" struck, I preserved DECLARE_DYNDBG_CLASSMAP til later v8[a-i] - added tools/testing/selftests/dynamic_debug/* - now turnkey testable without DRM CLASSMAPS FROM THE TOP dynamic-debug classmap's primary goal was to bring zero-off-cost debugs, via static-keys, to DRM. drm.debug: is ~5000 debugs across core, drivers, helpers; each in 1 of 10 exclusive categories, all controlled by bits in a sysfs knob. drm.debug=0x1ff # bootarg echo 0x4 > /sys/module/drm/parameters/debug # run-time setting Below the sysfs interface, classmaps are exposed in the >control grammar with a new "class" keyword. This is mostly like the other keywords, differing by: a- classnames are client/subsystem/domain defined, not code-name-structural. the classnames are global, across system IOW: "class DRM_UT_CORE" selects on any module which knows the class b- classes are protected from unqualified modification. # cannot disable any DRM (or other) classes echo -p > /proc/dynamic_debug/control c- classes don't have wildcards - add if needed. DRM uses "${SUBSYS}_${CATNAME}" probably more useful with "${TOP}_${MID}_${LOW}" classnames API in use: DRM defines its categories with an enum-type, the obvious thing to do was to copy/emulate that for classmaps; this also preserves the __pr_dbg_class(DRM_UT_CORE, "core stuff") style already used in drm's ~5000 drm_dbg_* macro calls. DYNDBG_CLASSMAP_DEFINE(drm_debug_classes, ...); DYNDBG_CLASSMAP_USE(drm_debug_classes); Classmaps get DEFINEd once (in drm.ko for core) and USEd (in drivers and helpers), these 2 declarations respectively define and export a classmap (in core), and refer to the exported class-struct from the modules. They both tell dynamic-debug that the module has some of these class'd pr_debugs, so dyndbg uses the classmap's names to validate >control inputs. The distinction allows USErs to act differently than the DEFINEr; they have to follow the ref back to the DEFINEing module, find the kparam connected to the classmap, and lookup and apply its modprobed value. (this is the bug-fix). Dyndbg uses the classnames to validate "class FOO" >control inputs, and apply the changes to each module that has DEFINEd or USEd the classmap. This makes classmaps opt-in: modules must _DEFINE or _USE a classmap for their class'd pr_debug()s to be >control'd. NOTE: __pr_dbg_class(1, "const-int unreachable class 1"); is legal, but not controllable unless the const 1 has been mapped to a _DEFINE'd classname. NB: and __pr_dbg_class(i++, "undeclared class") is illegal. In drm_print.c we have: /* classnames must match value-symbols of enum drm_debug_category */ DRM_CLASSMAP_DEFINE(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, DRM_UT_CORE, "DRM_UT_CORE", "DRM_UT_DRIVER", "DRM_UT_KMS", "DRM_UT_PRIME", "DRM_UT_ATOMIC", "DRM_UT_VBL", "DRM_UT_STATE", "DRM_UT_LEASE", "DRM_UT_DP", "DRM_UT_DRMRES"); This maps the sequence of "classnames" to ints starting with DRM_UT_CORE. other offsets allow sharing the per-module 0..63 class-id space Only complete, linear maps are recommended. An APPLY_FN(__stringify, __VA_ARGS__) would fix the "string-indirection" I have one written, but didnt want to overload this submission. DYNDBG_CLASSMAP_PARAM_REF() creates the sysfs-kparam classbits knob, binding the extern'd long-int/bitvec to the classmap. DRM's categories are independent of each other. The other possible classmap-type/behavior is "related", ie somehow "ordered": V3>V2. The relatedness of classes in a classmap is enforced at the kparam, where they are all set together, not at the >control interface. THE PATCHSET has 2 halves: 1- dynamic-debug fix - API change The root cause was DECLARE_DYNDBG_CLASSMAP tried to do too much, and its use in both core and drivers, helpers couldnt sort the difference. The fix is to replace it with DYNDBG_CLASSMAP_DEFINE in core, and DYNDBG_CLASSMAP_USE in drivers,helpers. The 1st differs from -v1 by exporting the classmap, allowing 2nd to ref it. They respectively add records to 2 ELF sections in the module. Now, dyndbg's on-modprobe handler follows the _USE/refs to the owning module, finds the controlling kparam: drm.debug, and applies its value thru the classmap, to the module's pr_debugs. Recent revs of this patchset added a selftest for dyndbg, which recapitulates the DRM regression scenario using the 2 test modules. The test verifies that the dependent module is initialized properly from the parent's classmap kparam. So it gives a basic turnkey selftest: [root@v6 b0-dd-drm]# V=0 ../../tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh # consulting KCONFIG_CONFIG: .config # BASIC_TESTS : 0 matches on =p : 14 matches on =p : 0 matches on =p : 21 matches on =mf : 0 matches on =ml : 6 matches on =mfl ... # Done on: Sun Jun 30 10:34:24 PM MDT 2024 This latest rev fixes the test for the various CONFIG_DYNAMIC_DEBUG* build combos, by skipping some subtests where the expected counts are wrong. Lukasz Bartosik caught this - thanks. CC: ukaszb@xxxxxxxxxxxx 2- DRM fixes - use new api. These are largely unchanged since -v1 above: a. update core to invoke DRM_CLASSMAP_DEFINE b. wrap DYNDBG_CLASSMAP_* with DRM_CLASSMAP_* - hide ifdef c. now with separate +DRM_CLASSMAP_USE patches for each driver/helper: d. and defer dropping DECLARE_DYNDBG_CLASSMAP til later Maybe theres a single place to invoke DRM_CLASSMAP_USE just once, perhaps from a client library c-file. I poked a little, didn't find it. Patches are against v6.9 theyre also at: tree/branch: https://github.com/jimc/linux.git dd-classmap-fix-8i branch HEAD: dd31011435409a5bd70cc92bfd846407f6f1a2d8 drm: restore CONFIG_DRM_USE_DYNAMIC_DEBUG un-BROKEN Finally, classmaps are in a meta-stable state right now; some governor might walk it over to the gravel pit out back. Tested-bys would help greatly, get it off the fence it straddles. Please specify method: selftest or drm.debug=0x1ff boot. Also entertaining Reviewed-bys :-} Jim Cromie (52): DYNAMIC-DEBUG parts: cleanup: docs/dyndbg: update examples \012 to \n test-dyndbg: fixup CLASSMAP usage error dyndbg: reword "class unknown," to "class:_UNKNOWN_" dyndbg: make ddebug_class_param union members same size dyndbg: replace classmap list with a vector prep: dyndbg: ddebug_apply_class_bitmap - add module arg, select on it dyndbg: split param_set_dyndbg_classes to _module & wrapper fns dyndbg: drop NUM_TYPE_ARRAY dyndbg: reduce verbose/debug clutter dyndbg: silence debugs with no-change updates dyndbg: tighten ddebug_class_name() 1st arg type dyndbg: tighten fn-sig of ddebug_apply_class_bitmap dyndbg: reduce verbose=3 messages in ddebug_add_module API changes & selftest: dyndbg-API: remove DD_CLASS_TYPE_(DISJOINT|LEVEL)_NAMES and code dyndbg-API: fix DECLARE_DYNDBG_CLASSMAP selftests-dyndbg: add tools/testing/selftests/dynamic_debug/* dyndbg-API: promote DYNDBG_CLASSMAP_PARAM to API dyndbg-doc: add classmap info to howto dyndbg: treat comma as a token separator selftests-dyndbg: add comma_terminator_tests dyndbg: split multi-query strings with % selftests-dyndbg: test_percent_splitting docs/dyndbg: explain new delimiters: comma, percent selftests-dyndbg: add test_mod_submod dyndbg-doc: explain flags parse 1st dyndbg: change __dynamic_func_call_cls* macros into expressions selftests-dyndbg: check KCONFIG_CONFIG to avoid silly fails dyndbg-selftest: reduce default verbosity DRM-parts: drm: use correct ccflags-y spelling drm-dyndbg: adapt drm core to use dyndbg classmaps-v2 drm-dyndbg: adapt DRM to invoke DYNDBG_CLASSMAP_PARAM drm-dyndbg: DRM_CLASSMAP_USE in amdgpu driver drm-dyndbg: DRM_CLASSMAP_USE in i915 driver drm-dyndbg: DRM_CLASSMAP_USE in drm_crtc_helper drm-dyndbg: DRM_CLASSMAP_USE in drm_dp_helper drm-dyndbg: DRM_CLASSMAP_USE in nouveau drm-print: workaround unused variable compiler meh drm-dyndbg: add DRM_CLASSMAP_USE to Xe driver drm-dyndbg: add DRM_CLASSMAP_USE to virtio_gpu drm-dyndbg: add DRM_CLASSMAP_USE to simpledrm drm-dyndbg: add DRM_CLASSMAP_USE to bochs drm-dyndbg: add DRM_CLASSMAP_USE to etnaviv drm-dyndbg: add DRM_CLASSMAP_USE to gma500 driver drm-dyndbg: add DRM_CLASSMAP_USE to radeon drm-dyndbg: add DRM_CLASSMAP_USE to vmwgfx driver drm-dyndbg: add DRM_CLASSMAP_USE to vkms driver drm-dyndbg: add DRM_CLASSMAP_USE to udl driver drm-dyndbg: add DRM_CLASSMAP_USE to mgag200 driver drm-dyndbg: add DRM_CLASSMAP_USE to the gud driver drm-dyndbg: add DRM_CLASSMAP_USE to the qxl driver drm-dyndbg: add DRM_CLASSMAP_USE to the drm_gem_shmem_helper driver drm: restore CONFIG_DRM_USE_DYNAMIC_DEBUG un-BROKEN .../admin-guide/dynamic-debug-howto.rst | 99 ++- MAINTAINERS | 3 +- drivers/gpu/drm/Kconfig | 3 +- drivers/gpu/drm/Makefile | 3 +- drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 12 +- drivers/gpu/drm/display/drm_dp_helper.c | 12 +- drivers/gpu/drm/drm_crtc_helper.c | 12 +- drivers/gpu/drm/drm_gem_shmem_helper.c | 2 + drivers/gpu/drm/drm_print.c | 38 +- drivers/gpu/drm/etnaviv/etnaviv_drv.c | 2 + drivers/gpu/drm/gma500/psb_drv.c | 2 + drivers/gpu/drm/gud/gud_drv.c | 2 + drivers/gpu/drm/i915/i915_params.c | 12 +- drivers/gpu/drm/mgag200/mgag200_drv.c | 2 + drivers/gpu/drm/nouveau/nouveau_drm.c | 12 +- drivers/gpu/drm/qxl/qxl_drv.c | 2 + drivers/gpu/drm/radeon/radeon_drv.c | 2 + drivers/gpu/drm/tiny/bochs.c | 2 + drivers/gpu/drm/tiny/simpledrm.c | 2 + drivers/gpu/drm/udl/udl_main.c | 2 + drivers/gpu/drm/virtio/virtgpu_drv.c | 2 + drivers/gpu/drm/vkms/vkms_drv.c | 2 + drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 2 + drivers/gpu/drm/xe/xe_drm_client.c | 2 + include/asm-generic/vmlinux.lds.h | 1 + include/drm/drm_print.h | 10 + include/linux/dynamic_debug.h | 135 ++- kernel/module/main.c | 3 + lib/Kconfig.debug | 24 +- lib/Makefile | 3 + lib/dynamic_debug.c | 436 ++++++---- lib/test_dynamic_debug.c | 131 +-- lib/test_dynamic_debug_submod.c | 17 + tools/testing/selftests/Makefile | 1 + .../testing/selftests/dynamic_debug/Makefile | 9 + tools/testing/selftests/dynamic_debug/config | 2 + .../dynamic_debug/dyndbg_selftest.sh | 810 ++++++++++++++++++ 37 files changed, 1453 insertions(+), 363 deletions(-) create mode 100644 lib/test_dynamic_debug_submod.c create mode 100644 tools/testing/selftests/dynamic_debug/Makefile create mode 100644 tools/testing/selftests/dynamic_debug/config create mode 100755 tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh -- 2.45.2
