lwn.git/Documentation/trace, branch master

Merge tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-16T00:15:18+00:00

Pull runtime verification updates from Steven Rostedt: - Refactor da_monitor header to share handlers across monitor types No functional changes, only less code duplication. - Add Hybrid Automata model class Add a new model class that extends deterministic automata by adding constraints on transitions and states. Those constraints can take into account wall-clock time and as such allow RV monitor to make assertions on real time. Add documentation and code generation scripts. - Add stall monitor as hybrid automaton example Add a monitor that triggers a violation when a task is stalling as an example of automaton working with real time variables. - Convert the opid monitor to a hybrid automaton The opid monitor can be heavily simplified if written as a hybrid automaton: instead of tracking preempt and interrupt enable/disable events, it can just run constraints on the preemption/interrupt states when events like wakeup and need_resched verify. - Add support for per-object monitors in DA/HA Allow writing deterministic and hybrid automata monitors for generic objects (e.g. any struct), by exploiting a hash table where objects are saved. This allows to track more than just tasks in RV. For instance it will be used to track deadline entities in deadline monitors. - Add deadline tracepoints and move some deadline utilities Prepare the ground for deadline monitors by defining events and exporting helpers. - Add nomiss deadline monitor Add first example of deadline monitor asserting all entities complete before their deadline. - Improve rvgen error handling Introduce AutomataError exception class and better handle expected exceptions while showing a backtrace for unexpected ones. - Improve python code quality in rvgen Refactor the rvgen generation scripts to align with python best practices: use f-strings instead of %, use len() instead of __len__(), remove semicolons, use context managers for file operations, fix whitespace violations, extract magic strings into constants, remove unused imports and methods. - Fix small bugs in rvgen The generator scripts presented some corner case bugs: logical error in validating what a correct dot file looks like, fix an isinstance() check, enforce a dot file has an initial state, fix type annotations and typos in comments. - rvgen refactoring Refactor automata.py to use iterator-based parsing and handle required arguments directly in argparse. - Allow epoll in rtapp-sleep monitor The epoll_wait call is now rt-friendly so it should be allowed in the sleep monitor as a valid sleep method. * tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (32 commits) rv: Allow epoll in rtapp-sleep monitor rv/rvgen: fix _fill_states() return type annotation rv/rvgen: fix unbound loop variable warning rv/rvgen: enforce presence of initial state rv/rvgen: extract node marker string to class constant rv/rvgen: fix isinstance check in Variable.expand() rv/rvgen: make monitor arguments required in rvgen rv/rvgen: remove unused __get_main_name method rv/rvgen: remove unused sys import from dot2c rv/rvgen: refactor automata.py to use iterator-based parsing rv/rvgen: use class constant for init marker rv/rvgen: fix DOT file validation logic error rv/rvgen: fix PEP 8 whitespace violations rv/rvgen: fix typos in automata and generator docstring and comments rv/rvgen: use context managers for file operations rv/rvgen: remove unnecessary semicolons rv/rvgen: replace __len__() calls with len() rv/rvgen: replace % string formatting with f-strings rv/rvgen: remove bare except clauses in generator rv/rvgen: introduce AutomataError exception class ...

Merge tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-15T22:59:46+00:00

Pull ring-buffer updates from Steven Rostedt: - Add remote buffers for pKVM pKVM has a hypervisor component that is used to protect the guest from the host kernel. This hypervisor is a black box to the kernel as the kernel is to user space. The remote buffers are used to have a memory mapping between the hypervisor and the kernel where kernel may send commands to enable tracing within the hypervisor. Then the kernel will read this memory mapping just like user space can read the memory mapped ring buffer of the kernel tracing system. Since the hypervisor only has a single context, it doesn't need to worry about races between normal context, interrupt context and NMIs like the kernel does. The ring buffer it uses doesn't need to be as complex. The remote buffers are a simple version of the ring buffer that works in a single context. They are still per-CPU and use sub buffers. The data layout is the same as the kernel's ring buffer to share the same parsing. Currently, only ARM64 implements pKVM, but there's work to implement it also in x86. The remote buffer code is separated out from the ARM implementation so that it can be used in the future by x86. The ARM64 updates for pKVM is in the ARM/KVM tree and it merged in the remote buffers of this tree. - Make the backup instance non reusable The backup instance is a copy of the persistent ring buffer so that the persistent ring buffer could start recording again without using the data from the previous boot. The backup isn't for normal tracing. It is made read-only, and after it is consumed, it is automatically removed. - Have backup copy persistent instance before it starts recording To allow the persistent ring buffer to start recording from the kernel command line commands, move the copy of the backup instance to before the the command line options start recording. - Report header_page overwrite field as "char" and not "int' The rust parser of the header_page file was triggering a warning when it defined the overwrite variable as "int" but it was only a single byte in size. - Fix memory barriers for the trace_buffer CPU mask When a CPU comes online, the bit is set to allow readers to know that the CPU buffer is allocated. The bit is set after the allocation is done, and a smp_wmb() is performed after the allocation and before the setting of the bit. But instead of adding a smp_rmb() to all readers, since once a buffer is created for a CPU it is not deleted if that CPU goes offline, so this allocation is almost always done at boot up before any readers exist. If for the unlikely case where a CPU comes online for the first time after the system boot has finished, send an IPI to all CPUs to force the smp_rmb() for each CPU. - Show clock function being used in debugging ring buffer data When the ring buffer checks are enabled and the ring buffer detects an inconsistency in the times of the invents, print out the clock being used when the error occurred. There was a very hard to hit bug that would happen every so often and it ended up being only triggered when the jiffies clock was being used. If the bug showed the clock being used, it would have been much easier to find the problem (which was an internal function was being traced which caused the clock accounting to go off). * tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits) ring-buffer: Prevent off-by-one array access in ring_buffer_desc_page() ring-buffer: Report header_page overwrite as char tracing: Allow backup to save persistent ring buffer before it starts tracing/Documentation: Add a section about backup instance tracing: Remove the backup instance automatically after read tracing: Make the backup instance non-reusable ring-buffer: Enforce read ordering of trace_buffer cpumask and buffers ring-buffer: Show what clock function is used on timestamp errors tracing: Check for undefined symbols in simple_ring_buffer tracing: load/unload page callbacks for simple_ring_buffer Documentation: tracing: Add tracing remotes tracing: selftests: Add trace remote tests tracing: Add a trace remote module for testing tracing: Introduce simple_ring_buffer ring-buffer: Export buffer_data_page and macros tracing: Add helpers to create trace remote events tracing: Add events/ root files to trace remotes tracing: Add events to trace remotes tracing: Add init callback to trace remotes tracing: Add non-consuming read to trace remotes ...

Merge tag 'pci-v7.1-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci

2026-04-15T21:41:21+00:00

Pull pci updates from Bjorn Helgaas: "Enumeration: - Allow TLP Processing Hints to be enabled for RCiEPs (George Abraham P) - Enable AtomicOps only if we know the Root Port supports them (Gerd Bayer) - Don't enable AtomicOps for RCiEPs since none of them need Atomic Ops and we can't tell whether the Root Complex would support them (Gerd Bayer) - Leave Precision Time Measurement disabled until a driver enables it to avoid PCIe errors (Mika Westerberg) - Make pci_set_vga_state() fail if bridge doesn't support VGA routing, i.e., PCI_BRIDGE_CTL_VGA is not writable, and return errors to vga_get() callers including userspace via /dev/vga_arbiter (Simon Richter) - Validate max-link-speed from DT in j721e, brcmstb, mediatek-gen3, rzg3s drivers (where the actual controller constraints are known), and remove validation from the generic OF DT accessor (Hans Zhang) - Remove pc110pad driver (no longer useful after 486 CPU support removed) and no_pci_devices() (pc110pad was the last user) (Dmitry Torokhov, Heiner Kallweit) Resource management: - Prevent assigning space to unimplemented bridge windows; previously we mistakenly assumed prefetchable window existed and assigned space and put a BAR there (Ahmed Naseef) - Avoid shrinking bridge windows to fit in the initial Root Port window; fixes one problem with devices with large BARs connected via switches, e.g., Thunderbolt (Ilpo Järvinen) - Pass full extent of empty space, not just the aligned space, to resource_alignf callback so free space before the requested alignment can be used (Ilpo Järvinen) - Place small resources before larger ones for better utilization of address space (Ilpo Järvinen) - Fix alignment calculation for resource size larger than align, e.g., bridge windows larger than the 1MB required alignment (Ilpo Järvinen) Reset: - Update slot handling so all ARI functions are treated as being in the same slot. They're all reset by Secondary Bus Reset, but previously drivers of ARI functions that appeared to be on a non-zero device weren't notified and fatal hardware errors could result (Keith Busch) - Make sysfs reset_subordinate hotplug safe to avoid spurious hotplug events (Keith Busch) - Hide Secondary Bus Reset ('bus') from sysfs reset_methods if masked by CXL because it has no effect (Vidya Sagar) - Avoid FLR for AMD NPU device, where it causes the device to hang (Lizhi Hou) Error handling: - Clear only error bits in PCIe Device Status to avoid accidentally clearing Emergency Power Reduction Detected (Shuai Xue) - Check for AER errors even in devices without drivers (Lukas Wunner) - Initialize ratelimit info so DPC and EDR paths log AER error information (Kuppuswamy Sathyanarayanan) Power control: - Add UPD720201/UPD720202 USB 3.0 xHCI Host Controller .compatible so generic pwrctrl driver can control it (Neil Armstrong) Hotplug: - Set LED_HW_PLUGGABLE for NPEM hotplug-capable ports so LED core doesn't complain when setting brightness fails because the endpoint is gone (Richard Cheng) Peer-to-peer DMA: - Allow wildcards in list of host bridges that support peer-to-peer DMA between hierarchy domains and add all Google SoCs (Jacob Moroni) Endpoint framework: - Advertise dynamic inbound mapping support in pci-epf-test and update host pci_endpoint_test to skip doorbell testing if not advertised by endpoint (Koichiro Den) - Return 0, not remaining timeout, when MHI eDMA ops complete so mhi_ep_ring_add_element() doesn't interpret non-zero as failure (Daniel Hodges) - Remove vntb and ntb duplicate resource teardown that leads to oops when .allow_link() fails or .drop_link() is called (Koichiro Den) - Disable vntb delayed work before clearing BAR mappings and doorbells to avoid oops caused by doing the work after resources have been torn down (Koichiro Den) - Add a way to describe reserved subregions within BARs, e.g., platform-owned fixed register windows, and use it for the RK3588 BAR4 DMA ctrl window (Koichiro Den) - Add BAR_DISABLED for BARs that will never be available to an EPF driver, and change some BAR_RESERVED annotations to BAR_DISABLED (Niklas Cassel) - Add NTB .get_dma_dev() callback for cases where DMA API requires a different device, e.g., vNTB devices (Koichiro Den) - Add reserved region types for MSI-X Table and PBA so Endpoint controllers can them as describe hardware-owned regions in a BAR_RESERVED BAR (Manikanta Maddireddy) - Make Tegra194/234 BAR0 programmable and remove 1MB size limit (Manikanta Maddireddy) - Expose Tegra BAR2 (MSI-X) and BAR4 (DMA) as 64-bit BAR_RESERVED (Manikanta Maddireddy) - Add Tegra194 and Tegra234 device table entries to pci_endpoint_test (Manikanta Maddireddy) - Skip the BAR subrange selftest if there are not enough inbound window resources to run the test (Christian Bruel) New native PCIe controller drivers: - Add DT binding and driver for Andes QiLai SoC PCIe host controller (Randolph Lin) - Add DT binding and driver for ESWIN PCIe Root Complex (Senchuan Zhang) Baikal T-1 PCIe controller driver: - Remove driver since it never quite became usable (Andy Shevchenko) Cadence PCIe controller driver: - Implement byte/word config reads with dword (32-bit) reads because some Cadence controllers don't support sub-dword accesses (Aksh Garg) CIX Sky1 PCIe controller driver: - Add 'power-domains' to DT binding for SCMI power domain (Gary Yang) Freescale i.MX6 PCIe controller driver: - Add i.MX94 and i.MX943 to fsl,imx6q-pcie-ep DT binding (Richard Zhu) - Delay instead of polling for L2/L3 Ready after PME_Turn_off when suspending i.MX6SX because LTSSM registers are inaccessible (Richard Zhu) - Separate PERST# assertion (for resetting endpoints) from core reset (for resetting the RC itself) to prepare for new DTs with PERST# GPIO in per-Root Port nodes (Sherry Sun) - Retain Root Port MSI capability on i.MX7D, i.MX8MM, and i.MX8MQ so MSI from downstream devices will work (Richard Zhu) - Fix i.MX95 reference clock source selection when internal refclk is used (Franz Schnyder) Freescale Layerscape PCIe controller driver: - Allow building as a removable module (Sascha Hauer) MediaTek PCIe Gen3 controller driver: - Use dev_err_probe() to simplify error paths and make deferred probe messages visible in /sys/kernel/debug/devices_deferred (Chen-Yu Tsai) - Power off device if setup fails (Chen-Yu Tsai) - Integrate new pwrctrl API to enable power control for WiFi/BT adapters on mainboard or in PCIe or M.2 slots (Chen-Yu Tsai) NVIDIA Tegra194 PCIe controller driver: - Poll less aggressively and non-atomically for PME_TO_Ack during transition to L2 (Vidya Sagar) - Disable LTSSM after transition to Detect on surprise link down to stop toggling between Polling and Detect (Manikanta Maddireddy) - Don't force the device into the D0 state before L2 when suspending or shutting down the controller (Vidya Sagar) - Disable PERST# IRQ only in Endpoint mode because it's not registered in Root Port mode (Manikanta Maddireddy) - Handle 'nvidia,refclk-select' as optional (Vidya Sagar) - Disable direct speed change in Endpoint mode so link speed change is controlled by the host (Vidya Sagar) - Set LTR values before link up to avoid bogus LTR messages with 0 latency (Vidya Sagar) - Allow system suspend when the Endpoint link is down (Vidya Sagar) - Use DWC IP core version, not Tegra custom values, to avoid DWC core version check warnings (Manikanta Maddireddy) - Apply ECRC workaround to devices based on DesignWare 5.00a as well as 4.90a (Manikanta Maddireddy) - Disable PM Substate L1.2 in Endpoint mode to work around Tegra234 erratum (Vidya Sagar) - Delay post-PERST# cleanup until core is powered on to avoid CBB timeout (Manikanta Maddireddy) - Assert CLKREQ# so switches that forward it to their downstream side can bring up those links successfully (Vidya Sagar) - Calibrate pipe to UPHY for Endpoint mode to reset stale PLL state from any previous bad link state (Vidya Sagar) - Remove IRQF_ONESHOT flag from Endpoint interrupt registration so DMA driver and Endpoint controller driver can share the interrupt line (Vidya Sagar) - Enable DMA interrupt to support DMA in both Root Port and Endpoint modes (Vidya Sagar) - Enable hardware link retraining after link goes down in Endpoint mode (Vidya Sagar) - Add DT binding and driver support for core clock monitoring (Vidya Sagar) Qualcomm PCIe controller driver: - Advertise 'Hot-Plug Capable' and set 'No Command Completed Support' since Qcom Root Ports support hotplug events like DL_Up/Down and can accept writes to Slot Control without delays between writes (Krishna Chaitanya Chundru) Renesas R-Car PCIe controller driver: - Mark Endpoint BAR0 and BAR2 as Resizable (Koichiro Den) - Reduce EPC BAR alignment requirement to 4K (Koichiro Den) Renesas RZ/G3S PCIe controller driver: - Add RZ/G3E to DT binding and to driver (John Madieu) - Assert (not deassert) resets in probe error path (John Madieu) - Assert resets in suspend path in reverse order they were deasserted during probe (John Madieu) - Rework inbound window algorithm to prevent mapping more than intended region and enforce alignment on size, to prepare for RZ/G3E support (John Madieu) Rockchip DesignWare PCIe controller driver: - Add tracepoints for PCIe controller LTSSM transitions and link rate changes (Shawn Lin) - Trace LTSSM events collected by the dw-rockchip debug FIFO (Shawn Lin) SOPHGO PCIe controller driver: - Disable ASPM L0s and L1 on Sophgo 2042 PCIe Root Ports that advertise support for them (Yao Zi) Synopsys DesignWare PCIe controller driver: - Continue with system suspend even if an Endpoint doesn't respond with PME_TO_Ack message (Manivannan Sadhasivam) - Set Endpoint MSI-X Table Size in the correct function of a multi-function device when configuring MSI-X, not in Function 0 (Aksh Garg) - Set Max Link Width and Max Link Speed for all functions of a multi-function device, not just Function 0 (Aksh Garg) - Expose PCIe event counters in groups 5-7 in debugfs (Hans Zhang) Miscellaneous: - Warn only once about invalid ACS kernel parameter format (Richard Cheng) - Suppress FW_BUG warning when writing sysfs 'numa_node' with the current value (Li RongQing) - Drop redundant 'depends on PCI' from Kconfig (Julian Braha)" * tag 'pci-v7.1-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci: (165 commits) PCI/P2PDMA: Add Google SoCs to the P2P DMA host bridge list PCI/P2PDMA: Allow wildcard Device IDs in host bridge list PCI: sg2042: Avoid L0s and L1 on Sophgo 2042 PCIe Root Ports PCI: cadence: Add flags for disabling ASPM capability for broken Root Ports PCI: tegra194: Add core monitor clock support dt-bindings: PCI: tegra194: Add monitor clock support PCI: tegra194: Enable hardware hot reset mode in Endpoint mode PCI: tegra194: Enable DMA interrupt PCI: tegra194: Remove IRQF_ONESHOT flag during Endpoint interrupt registration PCI: tegra194: Calibrate pipe to UPHY for Endpoint mode PCI: tegra194: Assert CLKREQ# explicitly by default PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on PCI: tegra194: Disable L1.2 capability of Tegra234 EP PCI: dwc: Apply ECRC workaround to DesignWare 5.00a as well PCI: tegra194: Use DWC IP core version PCI: tegra194: Free up Endpoint resources during remove() PCI: tegra194: Allow system suspend when the Endpoint link is not up PCI: tegra194: Set LTR message request before PCIe link up in Endpoint mode PCI: tegra194: Disable direct speed change for Endpoint mode PCI: tegra194: Use devm_gpiod_get_optional() to parse "nvidia,refclk-select" ...

tracing: Documentation: Update histogram-design.rst for fn() handling

2026-04-09T14:46:39+00:00

The histogram documentation describes the old method of the histogram triggers using the fn() field of the histogram field structure to process the field. But due to Spectre mitigation, the function pointer to handle the fields at runtime caused a noticeable overhead. It was converted over to a fn_num and hist_fn_call() is now used to call the specific functions for the fields via a switch statement based on the field's fn_num value. Update the documentation to reflect this change. Signed-off-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20260126181742.03e8f0d5@gandalf.local.home>

Documentation: tracing: Add PCI controller event documentation

2026-04-07T14:43:12+00:00

The PCI controller tracepoint, pcie_ltssm_state_transition, monitors the LTSSM state transition and data rate changes for debugging purposes. Add documentation for it. Signed-off-by: Shawn Lin [mani: added MAINTAINERS entry] Signed-off-by: Manivannan Sadhasivam Reviewed-by: Steven Rostedt (Google) Link: https://patch.msgid.link/1774403912-210670-3-git-send-email-shawn.lin@rock-chips.com

tracing/Documentation: Add a section about backup instance

2026-04-02T17:27:21+00:00

Add a section about backup instance to the debugging.rst. Cc: Mathieu Desnoyers Link: https://patch.msgid.link/177502548479.1311542.7062269603547001007.stgit@mhiramat.tok.corp.google.com Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

rv: Add nomiss deadline monitor

2026-03-31T14:47:18+00:00

Add the deadline monitors collection to validate the deadline scheduler, both for deadline tasks and servers. The currently implemented monitors are: * nomiss: validate dl entities run to completion before their deadiline Reviewed-by: Nam Cao Reviewed-by: Juri Lelli Link: https://lore.kernel.org/r/20260330111010.153663-13-gmonaco@redhat.com Signed-off-by: Gabriele Monaco

rv: Convert the opid monitor to a hybrid automaton

2026-03-31T14:47:17+00:00

The opid monitor validates that wakeup and need_resched events only occur with interrupts and preemption disabled by following the preemptirq tracepoints. As reported in [1], those tracepoints might be inaccurate in some situations (e.g. NMIs). Since the monitor doesn't validate other ordering properties, remove the dependency on preemptirq tracepoints and convert the monitor to a hybrid automaton to validate the constraint during event handling. This makes the monitor more robust by also removing the workaround for interrupts missing the preemption tracepoints, which was working on PREEMPT_RT only and allows the monitor to be built on kernels without the preemptirqs tracepoints. [1] - https://lore.kernel.org/lkml/20250625120823.60600-1-gmonaco@redhat.com Reviewed-by: Nam Cao Link: https://lore.kernel.org/r/20260330111010.153663-8-gmonaco@redhat.com Signed-off-by: Gabriele Monaco

rv: Add sample hybrid monitor stall

2026-03-31T14:47:17+00:00

Add a sample monitor to showcase hybrid/timed automata. The stall monitor identifies tasks stalled for longer than a threshold and reacts when that happens. Reviewed-by: Nam Cao Link: https://lore.kernel.org/r/20260330111010.153663-7-gmonaco@redhat.com Signed-off-by: Gabriele Monaco

Documentation/rv: Add documentation about hybrid automata

2026-03-31T14:47:17+00:00

Describe theory and implementation of hybrid automata in the dedicated page hybrid_automata.rst Include a section on how to integrate a hybrid automaton in monitor_synthesis.rst Also remove a hanging $ in deterministic_automata.rst Reviewed-by: Nam Cao Reviewed-by: Juri Lelli Link: https://lore.kernel.org/r/20260330111010.153663-6-gmonaco@redhat.com Signed-off-by: Gabriele Monaco