linux/Documentation/trace, branch v6.12

tracing/Documentation: Start a document on how to debug with tracing

2024-08-26T17:54:08Z

Add a new document Documentation/trace/debugging.rst that will hold various ways to debug tracing. This initial version mentions trace_printk and how to create persistent buffers that can last across bootups. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Vincent Donnefort Cc: Joel Fernandes Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vineeth Pillai Cc: Beau Belgrave Cc: Alexander Graf Cc: Baoquan He Cc: Borislav Petkov Cc: "Paul E. McKenney" Cc: David Howells Cc: Mike Rapoport Cc: Dave Hansen Cc: Tony Luck Cc: Guenter Roeck Cc: Ross Zwisler Cc: Kees Cook Cc: Alexander Aring Cc: "Luis Claudio R. Goncalves" Cc: Tomas Glozar Cc: John Kacur Cc: Clark Williams Cc: Linus Torvalds Cc: "Jonathan Corbet" Link: https://lore.kernel.org/20240823014019.702433486@goodmis.org Signed-off-by: Steven Rostedt (Google)

tracing: Add option to set an instance to be the trace_printk destination

2024-08-26T17:54:08Z

Add a option "trace_printk_dest" that will make the tracing instance the location that trace_printk() will go to. This is useful if the trace_printk or one of the top level tracers is too noisy and there's a need to separate the two. Then an instance can be created, the trace_printk can be set to go there instead, where it will not be lost in the noise of the top level tracer. Note, only one instance can be the destination of trace_printk at a time. If an instance sets this flag, the instance that had it set will have it cleared. There is always one instance that has this set. By default, that is the top instance. This flag cannot be cleared from the top instance. Doing so will result in an -EINVAL. The only way this flag can be cleared from the top instance is by another instance setting it. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Vincent Donnefort Cc: Joel Fernandes Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vineeth Pillai Cc: Beau Belgrave Cc: Alexander Graf Cc: Baoquan He Cc: Borislav Petkov Cc: "Paul E. McKenney" Cc: David Howells Cc: Mike Rapoport Cc: Dave Hansen Cc: Tony Luck Cc: Guenter Roeck Cc: Ross Zwisler Cc: Kees Cook Cc: Alexander Aring Cc: "Luis Claudio R. Goncalves" Cc: Tomas Glozar Cc: John Kacur Cc: Clark Williams Cc: Linus Torvalds Cc: "Jonathan Corbet" Link: https://lore.kernel.org/20240823014019.545459018@goodmis.org Signed-off-by: Steven Rostedt (Google)

Merge tag 'ftrace-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2024-07-18T20:36:33Z

Pull ftrace updates from Steven Rostedt: "Rewrite of function graph tracer to allow multiple users Up until now, the function graph tracer could only have a single user attached to it. If another user tried to attach to the function graph tracer while one was already attached, it would fail. Allowing function graph tracer to have more than one user has been asked for since 2009, but it required a rewrite to the logic to pull it off so it never happened. Until now! There's three systems that trace the return of a function. That is kretprobes, function graph tracer, and BPF. kretprobes and function graph tracing both do it similarly. The difference is that kretprobes uses a shadow stack per callback and function graph tracer creates a shadow stack for all tasks. The function graph tracer method makes it possible to trace the return of all functions. As kretprobes now needs that feature too, allowing it to use function graph tracer was needed. BPF also wants to trace the return of many probes and its method doesn't scale either. Having it use function graph tracer would improve that. By allowing function graph tracer to have multiple users allows both kretprobes and BPF to use function graph tracer in these cases. This will allow kretprobes code to be removed in the future as it's version will no longer be needed. Note, function graph tracer is only limited to 16 simultaneous users, due to shadow stack size and allocated slots" * tag 'ftrace-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (49 commits) fgraph: Use str_plural() in test_graph_storage_single() function_graph: Add READ_ONCE() when accessing fgraph_array[] ftrace: Add missing kerneldoc parameters to unregister_ftrace_direct() function_graph: Everyone uses HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, remove it function_graph: Fix up ftrace_graph_ret_addr() function_graph: Make fgraph_update_pid_func() a stub for !DYNAMIC_FTRACE function_graph: Rename BYTE_NUMBER to CHAR_NUMBER in selftests fgraph: Remove some unused functions ftrace: Hide one more entry in stack trace when ftrace_pid is enabled function_graph: Do not update pid func if CONFIG_DYNAMIC_FTRACE not enabled function_graph: Make fgraph_do_direct static key static ftrace: Fix prototypes for ftrace_startup/shutdown_subops() ftrace: Assign RCU list variable with rcu_assign_ptr() ftrace: Assign ftrace_list_end to ftrace_ops_list type cast to RCU ftrace: Declare function_trace_op in header to quiet sparse warning ftrace: Add comments to ftrace_hash_move() and friends ftrace: Convert "inc" parameter to bool in ftrace_hash_rec_update_modify() ftrace: Add comments to ftrace_hash_rec_disable/enable() ftrace: Remove "filter_hash" parameter from __ftrace_hash_rec_update() ftrace: Rename dup_hash() and comment it ...

rtla/osnoise: set the default threshold to 1us

2024-07-01T22:54:31Z

Change the default threshold for osnoise to 1us, so that any noise equal or above this value is recorded. Let the user set a higher threshold if necessary. Link: https://lore.kernel.org/linux-trace-kernel/Zmb-QhiiiI6jM9To@uudg.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Jonathan Corbet Suggested-by: Daniel Bristot de Oliveira Reviewed-by: Clark Williams Signed-off-by: Luis Claudio R. Goncalves Acked-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

function_graph: Everyone uses HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, remove it

2024-06-11T15:18:24Z

All architectures that implement function graph also implements HAVE_FUNCTION_GRAPH_RET_ADDR_PTR. Remove it, as it is no longer a differentiator. Link: https://lore.kernel.org/linux-trace-kernel/20240611031737.982047614@goodmis.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Jonathan Corbet Cc: Catalin Marinas Cc: Will Deacon Cc: Guo Ren Cc: Huacai Chen Cc: WANG Xuerui Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: "Naveen N. Rao" Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Signed-off-by: Steven Rostedt (Google)

Merge tag 'char-misc-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2024-05-22T19:26:46Z

Pull char/misc and other driver subsystem updates from Greg KH: "Here is the big set of char/misc and other driver subsystem updates for 6.10-rc1. Nothing major here, just lots of new drivers and updates for apis and new hardware types. Included in here are: - big IIO driver updates with more devices and drivers added - fpga driver updates - hyper-v driver updates - uio_pruss driver removal, no one uses it, other drivers control the same hardware now - binder minor updates - mhi driver updates - excon driver updates - counter driver updates - accessability driver updates - coresight driver updates - other hwtracing driver updates - nvmem driver updates - slimbus driver updates - spmi driver updates - other smaller misc and char driver updates All of these have been in linux-next for a while with no reported issues" * tag 'char-misc-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (319 commits) misc: ntsync: mark driver as "broken" to prevent from building spmi: pmic-arb: Add multi bus support spmi: pmic-arb: Register controller for bus instead of arbiter spmi: pmic-arb: Make core resources acquiring a version operation spmi: pmic-arb: Make the APID init a version operation spmi: pmic-arb: Fix some compile warnings about members not being described dt-bindings: spmi: Deprecate qcom,bus-id dt-bindings: spmi: Add X1E80100 SPMI PMIC ARB schema spmi: pmic-arb: Replace three IS_ERR() calls by null pointer checks in spmi_pmic_arb_probe() spmi: hisi-spmi-controller: Do not override device identifier dt-bindings: spmi: hisilicon,hisi-spmi-controller: clean up example dt-bindings: spmi: hisilicon,hisi-spmi-controller: fix binding references spmi: make spmi_bus_type const extcon: adc-jack: Document missing struct members extcon: realtek: Remove unused of_gpio.h extcon: usbc-cros-ec: Convert to platform remove callback returning void extcon: usb-gpio: Convert to platform remove callback returning void extcon: max77843: Convert to platform remove callback returning void extcon: max3355: Convert to platform remove callback returning void extcon: intel-mrfld: Convert to platform remove callback returning void ...

Merge tag 'trace-ringbuffer-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2024-05-18T01:40:37Z

Pull tracing ring buffer updates from Steven Rostedt: "Add ring_buffer memory mappings. The tracing ring buffer was created based on being mostly used with the splice system call. It is broken up into page ordered sub-buffers and the reader swaps a new sub-buffer with an existing sub-buffer that's part of the write buffer. It then has total access to the swapped out sub-buffer and can do copyless movements of the memory into other mediums (file system, network, etc). The buffer is great for passing around the ring buffer contents in the kernel, but is not so good for when the consumer is the user space task itself. A new interface is added that allows user space to memory map the ring buffer. It will get all the write sub-buffers as well as reader sub-buffer (that is not written to). It can send an ioctl to change which sub-buffer is the new reader sub-buffer. The ring buffer is read only to user space. It only needs to call the ioctl when it is finished with a sub-buffer and needs a new sub-buffer that the writer will not write over. A self test program was also created for testing and can be used as an example for the interface to user space. The libtracefs (external to the kernel) also has code that interacts with this, although it is disabled until the interface is in a official release. It can be enabled by compiling the library with a special flag. This was used for testing applications that perform better with the buffer being mapped. Memory mapped buffers have limitations. The main one is that it can not be used with the snapshot logic. If the buffer is mapped, snapshots will be disabled. If any logic is set to trigger snapshots on a buffer, that buffer will not be allowed to be mapped" * tag 'trace-ringbuffer-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Add cast to unsigned long addr passed to virt_to_page() ring-buffer: Have mmapped ring buffer keep track of missed events ring-buffer/selftest: Add ring-buffer mapping test Documentation: tracing: Add ring-buffer mapping tracing: Allow user-space mapping of the ring-buffer ring-buffer: Introducing ring-buffer mapping functions ring-buffer: Allocate sub-buffers with __GFP_COMP

Merge tag 'probes-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2024-05-18T01:29:30Z

Pull probes updates from Masami Hiramatsu: - tracing/probes: Add new pseudo-types %pd and %pD support for dumping dentry name from 'struct dentry *' and file name from 'struct file *' - uprobes performance optimizations: - Speed up the BPF uprobe event by delaying the fetching of the uprobe event arguments that are not used in BPF - Avoid locking by speculatively checking whether uprobe event is valid - Reduce lock contention by using read/write_lock instead of spinlock for uprobe list operation. This improved BPF uprobe benchmark result 43% on average - rethook: Remove non-fatal warning messages when tracing stack from BPF and skip rcu_is_watching() validation in rethook if possible - objpool: Optimize objpool (which is used by kretprobes and fprobe as rethook backend storage) by inlining functions and avoid caching nr_cpu_ids because it is a const value - fprobe: Add entry/exit callbacks types (code cleanup) - kprobes: Check ftrace was killed in kprobes if it uses ftrace * tag 'probes-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: kprobe/ftrace: bail out if ftrace was killed selftests/ftrace: Fix required features for VFS type test case objpool: cache nr_possible_cpus() and avoid caching nr_cpu_ids objpool: enable inlining objpool_push() and objpool_pop() operations rethook: honor CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING in rethook_try_get() ftrace: make extra rcu_is_watching() validation check optional uprobes: reduce contention on uprobes_tree access rethook: Remove warning messages printed for finding return address of a frame. fprobe: Add entry/exit callbacks types selftests/ftrace: add fprobe test cases for VFS type "%pd" and "%pD" selftests/ftrace: add kprobe test cases for VFS type "%pd" and "%pD" Documentation: tracing: add new type '%pd' and '%pD' for kprobe tracing/probes: support '%pD' type for print struct file's name tracing/probes: support '%pd' type for print struct dentry's name uprobes: add speculative lockless system-wide uprobe filter check uprobes: prepare uprobe args buffer lazily uprobes: encapsulate preparation of uprobe args buffer

Documentation: tracing: Add ring-buffer mapping

2024-05-13T22:09:56Z

It is now possible to mmap() a ring-buffer to stream its content. Add some documentation and a code example. Link: https://lore.kernel.org/linux-trace-kernel/20240510140435.3550353-5-vdonnefort@google.com Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

Documentation: tracing: Fix spelling mistakes

2024-05-07T14:00:25Z

Fix spelling mistakes in the documentation. Signed-off-by: Saurav Shah Link: https://lore.kernel.org/r/20240501233659.25441-1-sauravshah.31@gmail.com Signed-off-by: Jonathan Corbet