kernel/linux.git/Documentation/trace/events.rst, branch linux-7.1.y

docs: Corrected typo in trace/events

2025-08-21T17:59:11+00:00

-Changed 'Dyamically' to 'Dynamically' in trace/events.rst under sections 7.1 and 7.3 Signed-off-by: Mehdi Ben Hadj Khelifa Reviewed-by: Randy Dunlap Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250819085040.974388-1-mehdi.benhadjkhelifa@gmail.com

tracing: Cache ":mod:" events for modules not loaded yet

2025-01-16T14:41:08+00:00

When the :mod: command is written into /sys/kernel/tracing/set_event (or that file within an instance), if the module specified after the ":mod:" is not yet loaded, it will store that string internally. When the module is loaded, it will enable the events as if the module was loaded when the string was written into the set_event file. This can also be useful to enable events that are in the init section of the module, as the events are enabled before the init section is executed. This also works on the kernel command line: trace_event=:mod: Will enable the events for when it is loaded. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250116143533.514730995@goodmis.org Signed-off-by: Steven Rostedt (Google)

tracing: Add :mod: command to enabled module events

2025-01-16T14:41:07+00:00

Add a :mod: command to enable only events from a given module from the set_events file. echo '*:mod:' > set_events Or echo ':mod:' > set_events Will enable all events for that module. Specific events can also be enabled via: echo ':mod:' > set_events Or echo '::mod:' > set_events Or echo '*::mod:' > set_events The ":mod:" keyword is consistent with the function tracing filter to enable functions from a given module. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250116143533.214496360@goodmis.org Signed-off-by: Steven Rostedt (Google)

Merge tag 'trace-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-09-01T23:34:25+00:00

Pull tracing updates from Steven Rostedt: "User visible changes: - Added a way to easier filter with cpumasks: # echo 'cpumask & CPUS{17-42}' > /sys/kernel/tracing/events/ipi_send_cpumask/filter - Show actual size of ring buffer after modifying the ring buffer size via buffer_size_kb. Currently it just returns what was written, but the actual size rounds up to the sub buffer size. Show that real size instead. Major changes: - Added "eventfs". This is the code that handles the inodes and dentries of tracefs/events directory. As there are thousands of events, and each event has several inodes and dentries that currently exist even when tracing is never used, they take up precious memory. Instead, eventfs will allocate the inodes and dentries in a JIT way (similar to what procfs does). There is now metadata that handles the events and subdirectories, and will create the inodes and dentries when they are used. Note, I also have patches that remove the subdirectory meta data, but will wait till the next merge window before applying them. It's a little more complex, and I want to make sure the dynamic code works properly before adding more complexity, making it easier to revert if need be. Minor changes: - Optimization to user event list traversal - Remove intermediate permission of tracefs files (note the intermediate permission removes all access to the files so it is not a security concern, but just a clean up) - Add the complex fix to FORTIFY_SOURCE to the kernel stack event logic - Other minor cleanups" * tag 'trace-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (29 commits) tracefs: Remove kerneldoc from struct eventfs_file tracefs: Avoid changing i_mode to a temp value tracing/user_events: Optimize safe list traversals ftrace: Remove empty declaration ftrace_enable_daemon() and ftrace_disable_daemon() tracing: Remove unused function declarations tracing/filters: Document cpumask filtering tracing/filters: Further optimise scalar vs cpumask comparison tracing/filters: Optimise CPU vs cpumask filtering when the user mask is a single CPU tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU tracing/filters: Optimise cpumask vs cpumask filtering when user mask is a single CPU tracing/filters: Enable filtering the CPU common field by a cpumask tracing/filters: Enable filtering a scalar field by a cpumask tracing/filters: Enable filtering a cpumask field by another cpumask tracing/filters: Dynamically allocate filter_pred.regex test: ftrace: Fix kprobe test for eventfs eventfs: Move tracing/events to eventfs eventfs: Implement removal of meta data from eventfs eventfs: Implement functions to create files and dirs when accessed eventfs: Implement eventfs lookup, read, open functions eventfs: Implement eventfs file add functions ...

tracing/filters: Document cpumask filtering

2023-08-22T09:13:29+00:00

Cpumask, scalar and CPU fields can now be filtered by a user-provided cpumask, document the syntax. Link: https://lkml.kernel.org/r/20230707172155.70873-10-vschneid@redhat.com Cc: Masami Hiramatsu Cc: Jonathan Corbet Cc: Juri Lelli Cc: Daniel Bristot de Oliveira Cc: Marcelo Tosatti Cc: Leonardo Bras Cc: Frederic Weisbecker Signed-off-by: Valentin Schneider Signed-off-by: Steven Rostedt (Google)

Documentation: Fix typos

2023-08-18T17:29:03+00:00

Fix typos in Documentation. Signed-off-by: Bjorn Helgaas Link: https://lore.kernel.org/r/20230814212822.193684-4-helgaas@kernel.org Signed-off-by: Jonathan Corbet

Merge tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-02-23T18:20:49+00:00

Pull tracing updates from Steven Rostedt: - Add function names as a way to filter function addresses - Add sample module to test ftrace ops and dynamic trampolines - Allow stack traces to be passed from beginning event to end event for synthetic events. This will allow seeing the stack trace of when a task is scheduled out and recorded when it gets scheduled back in. - Add trace event helper __get_buf() to use as a temporary buffer when printing out trace event output. - Add kernel command line to create trace instances on boot up. - Add enabling of events to instances created at boot up. - Add trace_array_puts() to write into instances. - Allow boot instances to take a snapshot at the end of boot up. - Allow live patch modules to include trace events - Minor fixes and clean ups * tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits) tracing: Remove unnecessary NULL assignment tracepoint: Allow livepatch module add trace event tracing: Always use canonical ftrace path tracing/histogram: Fix stacktrace histogram Documententation tracing/histogram: Fix stacktrace key tracing/histogram: Fix a few problems with stacktrace variable printing tracing: Add BUILD_BUG() to make sure stacktrace fits in strings tracing/histogram: Don't use strlen to find length of stacktrace variables tracing: Allow boot instances to have snapshot buffers tracing: Add trace_array_puts() to write into instance tracing: Add enabling of events to boot instances tracing: Add creation of instances at boot command line tracing: Fix trace_event_raw_event_synth() if else statement samples: ftrace: Make some global variables static ftrace: sample: avoid open-coded 64-bit division samples: ftrace: Include the nospec-branch.h only for x86 tracing: Acquire buffer from temparary trace sequence tracing/histogram: Wrap remaining shell snippets in code blocks tracing/osnoise: No need for schedule_hrtimeout range bpf/tracing: Use stage6 of tracing to not duplicate macros ...

docs: ftrace: always use canonical ftrace path

2023-01-31T21:02:30+00:00

The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing Many parts of Documentation still reference this older debugfs path, so let's update them to avoid confusion. Signed-off-by: Ross Zwisler Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20230125213251.2013791-1-zwisler@google.com Signed-off-by: Jonathan Corbet

tracing: Add a way to filter function addresses to function names

2023-01-25T15:31:11+00:00

There's been several times where an event records a function address in its field and I needed to filter on that address for a specific function name. It required looking up the function in kallsyms, finding its size, and doing a compare of "field >= function_start && field < function_end". But this would change from boot to boot and is unreliable in scripts. Also, it is useful to have this at boot up, where the addresses will not be known. For example, on the boot command line: trace_trigger="initcall_finish.traceoff if func.function == acpi_init" To implement this, add a ".function" prefix, that will check that the field is of size long, and the only operations allowed (so far) are "==" and "!=". Link: https://lkml.kernel.org/r/20221219183213.916833763@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Tom Zanussi Cc: Zheng Yejian Reviewed-by: Ross Zwisler Signed-off-by: Steven Rostedt (Google)

docs: ftrace: fix a issue with duplicated subtitle number

2023-01-02T23:29:48+00:00

The subtitle "5.3 Clearing filters" and "5.3 Subsystem filters" has the same index number, let's fix it. Fixes: 95b696088c1c ("tracing/filters: add filter Documentation") Signed-off-by: Donglin Peng Acked-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20221209025119.1371570-1-dolinux.peng@gmail.com Signed-off-by: Jonathan Corbet