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 --- Documentation/trace/events-pci-controller.rst | 42 +++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 Documentation/trace/events-pci-controller.rst (limited to 'Documentation/trace/events-pci-controller.rst') diff --git a/Documentation/trace/events-pci-controller.rst b/Documentation/trace/events-pci-controller.rst new file mode 100644 index 000000000..cb9f71592 --- /dev/null +++ b/Documentation/trace/events-pci-controller.rst @@ -0,0 +1,42 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================== +Subsystem Trace Points: PCI Controller +====================================== + +Overview +======== +The PCI controller tracing system provides tracepoints to monitor controller +level information for debugging purpose. The events normally show up here: + + /sys/kernel/tracing/events/pci_controller + +Cf. include/trace/events/pci_controller.h for the events definitions. + +Available Tracepoints +===================== + +pcie_ltssm_state_transition +--------------------------- + +Monitors PCIe LTSSM state transition including state and rate information +:: + + pcie_ltssm_state_transition "dev: %s state: %s rate: %s\n" + +**Parameters**: + +* ``dev`` - PCIe controller instance +* ``state`` - PCIe LTSSM state +* ``rate`` - PCIe date rate + +**Example Usage**: + +.. code-block:: shell + + # Enable the tracepoint + echo 1 > /sys/kernel/debug/tracing/events/pci_controller/pcie_ltssm_state_transition/enable + + # Monitor events (the following output is generated when a device is linking) + cat /sys/kernel/debug/tracing/trace_pipe + kworker/0:0-9 [000] ..... 5.600221: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ2 rate: 8.0 GT/s -- cgit v1.3.1