From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/gpu/drm/Kconfig.debug | 115 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 drivers/gpu/drm/Kconfig.debug (limited to 'drivers/gpu/drm/Kconfig.debug') diff --git a/drivers/gpu/drm/Kconfig.debug b/drivers/gpu/drm/Kconfig.debug new file mode 100644 index 000000000..1f4c98cbf --- /dev/null +++ b/drivers/gpu/drm/Kconfig.debug @@ -0,0 +1,115 @@ +config DRM_USE_DYNAMIC_DEBUG + bool "use dynamic debug to implement drm.debug" + default n + depends on BROKEN + depends on DRM + depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE + depends on JUMP_LABEL + help + Use dynamic-debug to avoid drm_debug_enabled() runtime overheads. + Due to callsite counts in DRM drivers (~4k in amdgpu) and 56 + bytes per callsite, the .data costs can be substantial, and + are therefore configurable. + +config DRM_WERROR + bool "Compile the drm subsystem with warnings as errors" + depends on DRM && EXPERT + depends on !WERROR + default n + help + A kernel build should not cause any compiler warnings, and this + enables the '-Werror' flag to enforce that rule in the drm subsystem. + + The drm subsystem enables more warnings than the kernel default, so + this config option is disabled by default. + + If in doubt, say N. + +config DRM_HEADER_TEST + bool "Ensure DRM headers are self-contained and pass kernel-doc" + depends on DRM && EXPERT && BROKEN + default n + help + Ensure the DRM subsystem headers both under drivers/gpu/drm and + include/drm compile, are self-contained, have header guards, and have + no kernel-doc warnings. + + If in doubt, say N. + +config DRM_DEBUG_MM + bool "Insert extra checks and debug info into the DRM range managers" + default n + depends on DRM + depends on STACKTRACE_SUPPORT + select STACKDEPOT + help + Enable allocation tracking of memory manager and leak detection on + shutdown. + + Recommended for driver developers only. + + If in doubt, say "N". + +config DRM_KUNIT_TEST_HELPERS + tristate + depends on DRM && KUNIT + select DRM_KMS_HELPER + help + KUnit Helpers for KMS drivers. + +config DRM_KUNIT_TEST + tristate "KUnit tests for DRM" if !KUNIT_ALL_TESTS + depends on DRM && KUNIT && MMU + select DRM_BRIDGE_CONNECTOR + select DRM_BUDDY + select DRM_DISPLAY_DP_HELPER + select DRM_DISPLAY_HDMI_STATE_HELPER + select DRM_DISPLAY_HELPER + select DRM_EXEC + select DRM_EXPORT_FOR_TESTS if m + select DRM_GEM_SHMEM_HELPER + select DRM_KUNIT_TEST_HELPERS + select DRM_SYSFB_HELPER + select PRIME_NUMBERS + default KUNIT_ALL_TESTS + help + This builds unit tests for DRM. This option is not useful for + distributions or general kernels, but only for kernel + developers working on DRM and associated drivers. + + For more information on KUnit and unit tests in general, + please refer to the KUnit documentation in + Documentation/dev-tools/kunit/. + + If in doubt, say "N". + +config DRM_TTM_KUNIT_TEST + tristate "KUnit tests for TTM" if !KUNIT_ALL_TESTS + depends on DRM && KUNIT && MMU && (UML || COMPILE_TEST) + select DRM_TTM + select DRM_BUDDY + select DRM_EXPORT_FOR_TESTS if m + select DRM_KUNIT_TEST_HELPERS + default KUNIT_ALL_TESTS + help + Enables unit tests for TTM, a GPU memory manager subsystem used + to manage memory buffers. This option is mostly useful for kernel + developers. It depends on (UML || COMPILE_TEST) since no other driver + which uses TTM can be loaded while running the tests. + + If in doubt, say "N". + +config DRM_SCHED_KUNIT_TEST + tristate "KUnit tests for the DRM scheduler" if !KUNIT_ALL_TESTS + select DRM_SCHED + depends on DRM && KUNIT + default KUNIT_ALL_TESTS + help + Choose this option to build unit tests for the DRM scheduler. + + Recommended for driver developers only. + + If in doubt, say "N". + +config DRM_EXPORT_FOR_TESTS + bool -- cgit v1.3.1