[00/63] Fix CONFIG_DRM_USE_DYNAMIC_DEBUG=y

Message

Jim Cromie Jan. 25, 2025, 6:45 a.m. UTC

This series fixes dynamic-debug's support for DRM debug-categories.
Classmaps-v1 evaded full review, and got committed in 2 chunks:

  b7b4eebdba7b..6ea3bf466ac6	# core dyndbg changes
  0406faf25fb1..ee7d633f2dfb	# drm adoption

DRM-CI found a regression during init with drm.debug=<initval>; the
static-keys under the drm-dbgs in drm.ko got enabled, but those in
drivers & helpers did not.

Root Problem:

DECLARE_DYNDBG_CLASSMAP violated a K&R rule "define once, refer
afterwards".  Replace it with DYNDBG_CLASSMAP_DEFINE (invoked once in
drm-core) and DYNDBG_CLASSMAP_USE (invoked repeatedly, in drivers &
helpers).

_DEFINE exports the classmap it creates (in drm.ko), other modules
_USE the classmap.  The _USE adds a record ref'g the _DEFINEd (&
exported) classmap, in a 2nd __dyndbg_class_users section.

So now at modprobe, dyndbg scans the new section after the 1st
__dyndbg_class_maps section, follows the linkage to the _DEFINEr
module, finds the (optional) kernel-param controlling the classmap,
examines its drm.debug=<initval>, and applies it to the module being
initialized.

To recapitulate the multi-module problem wo DRM involvement, Add:

A. tools/testing/selftests/dynamic_debug/*

This alters pr_debugs in the test-modules, counts the results and
checks them against expectations.  It uses this formula to test most
of the control grammar, including the new class keyword.

B. test_dynamic_debug_submod.ko

This alters the test-module to build both parent & _submod ko's, with
_DEFINE and _USE inside #if/#else blocks.  This recap's DRM's 2 module
failure scenario, allowing A to exersize several cases.

The #if/#else puts the 2 macro uses together for clarity, and gives
the 2 modules identical sets of debugs.

Recent DRM-CI tests are here:
  https://patchwork.freedesktop.org/series/139147/

Previous rev:
  https://lore.kernel.org/lkml/[e-mail]/

Noteworthy Additions:

1- drop class "protection" special case, per JBaron's preference.
   only current use is marked BROKEN so nobody to affect.
   now framed as policy-choice:
   #define ddebug_client_module_protects_classes() false
   subsystems wanting protection can change this.

2- compile-time arg-tests in DYNDBG_CLASSMAP_DEFINE
   implement several required constraints, and fail obviously.

3- modprobe time check of conflicting class-id reservations
   only affects 2+classmaps users.
   compile-time solution not apparent.

4- dyndbg can now cause modprobe to fail.
   needed to catch 3.
   maybe some loose ends here on failure.

5- refactor & rename ddebug_attach_*module_classes
   reduce repetetive boilerplate on 2 types: maps, users.
   rework mostly brought forward in patchset to reduce churn
   TBD: maybe squash more.

Several recent trybot submissions (against drm-tip) have been passing
CI.BAT, and failing one or few CI.IGT tests randomly; re-tests do not
reliably repeat the failures.

its also at github.com:jimc/linux.git
  dd-fix-9[st]-ontip  &  dd-fix-9-13

Ive been running it on my desktop w/o issues.

The drivers/gpu/drm patches are RFC, I think there might be a single
place to call DRM_CLASSMAP_USE(drm_dedbug_classes) to replace the
sprinkling of _USEs in drivers and helpers.  IIRC, I tried adding a
_DEFINE into drm_drv.c, that didn't do it, so I punted for now.

I think the dyndbg core additions are ready for review and merging
into a (next-next) test/integration tree.

Jim Cromie (63):
  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
  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
  dyndbg-API: remove DD_CLASS_TYPE_(DISJOINT|LEVEL)_NAMES and code
  checkpatch: add an exception to the do-while wrapper advice
  dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP
  dyndbg: check DYNDBG_CLASSMAP_DEFINE args at compile-time
  dyndbg: add/use for_subvec() to reduce boilerplate
  dyndbg: make proper substructs in _ddebug_info
  dyndbg: drop premature optimization in ddebug_add_module
  dyndbg: allow ddebug_add_module to fail
  dyndbg: rework ddebug_attach_*module_classes()
  dyndbg: fail modprobe on ddebug_class_range_overlap()
  dyndbg: hoist the range-overlap checks
  ddebug: cleanup-range-overlap fails
  dyndbg-test: change do_prints testpoint to accept a loopct
  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
  docs/dyndbg: explain flags parse 1st
  dyndbg: change __dynamic_func_call_cls* macros into expressions
  dyndbg: drop "protection" of class'd pr_debugs from legacy queries
  drm: use correct ccflags-y spelling
  checkpatch: dont warn about unused macro arg on empty body
  drm-dyndbg: adapt drm core to use dyndbg classmaps-v2
  drm-dyndbg: adapt DRM to invoke DYNDBG_CLASSMAP_PARAM
  drm-print: fix config-dependent unused variable
  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-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       | 116 +++-
 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        |   1 +
 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                       |  12 +
 include/linux/dynamic_debug.h                 | 193 ++++--
 kernel/module/main.c                          |  15 +-
 lib/Kconfig.debug                             |  24 +-
 lib/Makefile                                  |   3 +
 lib/dynamic_debug.c                           | 555 +++++++++++-------
 lib/test_dynamic_debug.c                      | 181 +++---
 lib/test_dynamic_debug_submod.c               |  17 +
 scripts/checkpatch.pl                         |   3 +-
 tools/testing/selftests/Makefile              |   1 +
 .../testing/selftests/dynamic_debug/Makefile  |   9 +
 tools/testing/selftests/dynamic_debug/config  |   2 +
 .../dynamic_debug/dyndbg_selftest.sh          | 364 ++++++++++++
 38 files changed, 1205 insertions(+), 425 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