linux/Documentation/trace, branch v6.14

Merge tag 'trace-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-01-24T01:51:16Z

Pull tracing updates from Steven Rostedt: - Cleanup with guard() and free() helpers There were several places in the code that had a lot of "goto out" in the error paths to either unlock a lock or free some memory that was allocated. But this is error prone. Convert the code over to use the guard() and free() helpers that let the compiler unlock locks or free memory when the function exits. - Update the Rust tracepoint code to use the C code too There was some duplication of the tracepoint code for Rust that did the same logic as the C code. Add a helper that makes it possible for both algorithms to use the same logic in one place. - Add poll to trace event hist files It is useful to know when an event is triggered, or even with some filtering. Since hist files of events get updated when active and the event is triggered, allow applications to poll the hist file and wake up when an event is triggered. This will let the application know that the event it is waiting for happened. - Add :mod: command to enable events for current or future modules The function tracer already has a way to enable functions to be traced in modules by writing ":mod:" into set_ftrace_filter. That will enable either all the functions for the module if it is loaded, or if it is not, it will cache that command, and when the module is loaded that matches , its functions will be enabled. This also allows init functions to be traced. But currently events do not have that feature. Add the command where if ':mod:' is written into set_event, then either all the modules events are enabled if it is loaded, or cache it so that the module's events are enabled when it is loaded. This also works from the kernel command line, where "trace_event=:mod:", when the module is loaded at boot up, its events will be enabled then. * tag 'trace-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits) tracing: Fix output of set_event for some cached module events tracing: Fix allocation of printing set_event file content tracing: Rename update_cache() to update_mod_cache() tracing: Fix #if CONFIG_MODULES to #ifdef CONFIG_MODULES selftests/ftrace: Add test that tests event :mod: commands tracing: Cache ":mod:" events for modules not loaded yet tracing: Add :mod: command to enabled module events selftests/tracing: Add hist poll() support test tracing/hist: Support POLLPRI event for poll on histogram tracing/hist: Add poll(POLLIN) support on hist file tracing: Fix using ret variable in tracing_set_tracer() tracepoint: Reduce duplication of __DO_TRACE_CALL tracing/string: Create and use __free(argv_free) in trace_dynevent.c tracing: Switch trace_stat.c code over to use guard() tracing: Switch trace_stack.c code over to use guard() tracing: Switch trace_osnoise.c code over to use guard() and __free() tracing: Switch trace_events_synth.c code over to use guard() tracing: Switch trace_events_filter.c code over to use guard() tracing: Switch trace_events_trigger.c code over to use guard() tracing: Switch trace_events_hist.c code over to use guard() ...

Merge tag 'docs-6.14' of git://git.lwn.net/linux

2025-01-22T02:00:00Z

Pull Documentation updates from Jonathan Corbet: - Quite a bit of Chinese and Spanish translation work - Clarifying that Git commit IDs >12chars are OK - A new nvme-multipath document - A reorganization of the admin-guide top-level page to make it readable - Clarification of the role of Acked-by and maintainer discretion on their acceptance - Some reorganization of debugging-oriented docs ... and typo fixes, documentation updates, etc as usual * tag 'docs-6.14' of git://git.lwn.net/linux: (50 commits) Documentation: Fix x86_64 UEFI outdated references to elilo Documentation/sysctl: Add timer_migration to kernel.rst docs/mm: Physical memory: Remove zone_t docs: submitting-patches: clarify that signers may use their discretion on tags docs: submitting-patches: clarify difference between Acked-by and Reviewed-by docs: submitting-patches: clarify Acked-by and introduce "# Suffix" Documentation: bug-hunting.rst: remove odd contact information docs/zh_CN: Add sak index Chinese translation doc: module: DEFAULT_SYMBOL_NAMESPACE must be defined before #includes doc: module: Fix documented type of namespace Documentation/kernel-parameters: Fix a reference to vga-softcursor.rst docs/zh_CN: Add landlock index Chinese translation Documentation: Fix typo localmodonfig -> localmodconfig overlayfs.rst: Fix and improve grammar docs/zh_CN: Add siphash index Chinese translation docs/zh_CN: Add security IMA-templates Chinese translation docs/zh_CN: Add security digsig Chinese translation Align git commit ID abbreviation guidelines and checks docs: process: submitting-patches: split canonical patch format section docs/zh_CN: Add security lsm Chinese translation ...

Merge tag 'ftrace-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-01-21T23:15:28Z

Pull ftrace updates from Steven Rostedt: - Have fprobes built on top of function graph infrastructure The fprobe logic is an optimized kprobe that uses ftrace to attach to functions when a probe is needed at the start or end of the function. The fprobe and kretprobe logic implements a similar method as the function graph tracer to trace the end of the function. That is to hijack the return address and jump to a trampoline to do the trace when the function exits. To do this, a shadow stack needs to be created to store the original return address. Fprobes and function graph do this slightly differently. Fprobes (and kretprobes) has slots per callsite that are reserved to save the return address. This is fine when just a few points are traced. But users of fprobes, such as BPF programs, are starting to add many more locations, and this method does not scale. The function graph tracer was created to trace all functions in the kernel. In order to do this, when function graph tracing is started, every task gets its own shadow stack to hold the return address that is going to be traced. The function graph tracer has been updated to allow multiple users to use its infrastructure. Now have fprobes be one of those users. This will also allow for the fprobe and kretprobe methods to trace the return address to become obsolete. With new technologies like CFI that need to know about these methods of hijacking the return address, going toward a solution that has only one method of doing this will make the kernel less complex. - Cleanup with guard() and free() helpers There were several places in the code that had a lot of "goto out" in the error paths to either unlock a lock or free some memory that was allocated. But this is error prone. Convert the code over to use the guard() and free() helpers that let the compiler unlock locks or free memory when the function exits. - Remove disabling of interrupts in the function graph tracer When function graph tracer was first introduced, it could race with interrupts and NMIs. To prevent that race, it would disable interrupts and not trace NMIs. But the code has changed to allow NMIs and also interrupts. This change was done a long time ago, but the disabling of interrupts was never removed. Remove the disabling of interrupts in the function graph tracer is it is not needed. This greatly improves its performance. - Allow the :mod: command to enable tracing module functions on the kernel command line. The function tracer already has a way to enable functions to be traced in modules by writing ":mod:" into set_ftrace_filter. That will enable either all the functions for the module if it is loaded, or if it is not, it will cache that command, and when the module is loaded that matches , its functions will be enabled. This also allows init functions to be traced. But currently events do not have that feature. Because enabling function tracing can be done very early at boot up (before scheduling is enabled), the commands that can be done when function tracing is started is limited. Having the ":mod:" command to trace module functions as they are loaded is very useful. Update the kernel command line function filtering to allow it. * tag 'ftrace-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits) ftrace: Implement :mod: cache filtering on kernel command line tracing: Adopt __free() and guard() for trace_fprobe.c bpf: Use ftrace_get_symaddr() for kprobe_multi probes ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr Documentation: probes: Update fprobe on function-graph tracer selftests/ftrace: Add a test case for repeating register/unregister fprobe selftests: ftrace: Remove obsolate maxactive syntax check tracing/fprobe: Remove nr_maxactive from fprobe fprobe: Add fprobe_header encoding feature fprobe: Rewrite fprobe on function-graph tracer s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS tracing: Add ftrace_fill_perf_regs() for perf event tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs fprobe: Use ftrace_regs in fprobe exit handler fprobe: Use ftrace_regs in fprobe entry handler fgraph: Pass ftrace_regs to retfunc fgraph: Replace fgraph_ret_regs with ftrace_regs ...

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

2025-01-16T14:41:08Z

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

2025-01-16T14:41:07Z

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)

ftrace: Document that multiple function_graph tracing may have different times

2025-01-14T15:45:24Z

The function graph tracer now calculates the calltime internally and for each instance. If there are two instances that are running function graph tracer and are tracing the same functions, the timings of the length of those functions may be slightly different: # trace-cmd record -B foo -p function_graph -B bar -p function_graph sleep 5 # trace-cmd report [..] bar: sleep-981 [000] ...1. 1101.109027: funcgraph_entry: 0.764 us | mutex_unlock(); (ret=0xffff8abcc256c300) foo: sleep-981 [000] ...1. 1101.109028: funcgraph_entry: 0.748 us | mutex_unlock(); (ret=0xffff8abcc256c300) bar: sleep-981 [000] ..... 1101.109029: funcgraph_exit: 2.456 us | } (ret=0xffff8abcc256c300) foo: sleep-981 [000] ..... 1101.109029: funcgraph_exit: 2.403 us | } (ret=0xffff8abcc256c300) bar: sleep-981 [000] d..1. 1101.109031: funcgraph_entry: 0.844 us | fpregs_assert_state_consistent(); (ret=0x0) foo: sleep-981 [000] d..1. 1101.109032: funcgraph_entry: 0.803 us | fpregs_assert_state_consistent(); (ret=0x0) Link: https://lore.kernel.org/all/20250114101806.b2778cb01f34f5be9d23ad98@kernel.org/ Cc: Mark Rutland Cc: Mathieu Desnoyers Suggested-by: Masami Hiramatsu Link: https://lore.kernel.org/20250114101202.02e7bc68@gandalf.local.home Signed-off-by: Steven Rostedt (Google)

Documentation: probes: Update fprobe on function-graph tracer

2024-12-26T15:50:06Z

Update fprobe documentation for the new fprobe on function-graph tracer. This includes some bahvior changes and pt_regs to ftrace_regs interface change. Cc: Alexei Starovoitov Cc: Florent Revest Cc: Martin KaFai Lau Cc: bpf Cc: Alexei Starovoitov Cc: Jiri Olsa Cc: Alan Maguire Cc: Mark Rutland Link: https://lore.kernel.org/173519010442.391279.10732749889346824783.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

Documentation/rv: Fix typos

2024-12-13T15:42:23Z

There are some typos in the documentation: 'a' -> 'at', missing 'to'. Fix them. Signed-off-by: Andrew Kreimer Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20241209130640.10954-1-algonell@gmail.com

tracing: Record task flag NEED_RESCHED_LAZY.

2024-11-22T22:49:39Z

The scheduler added NEED_RESCHED_LAZY scheduling. Record this state as part of trace flags and expose it in the need_resched field. Record and expose NEED_RESCHED_LAZY. [bigeasy: Commit description, documentation bits.] Cc: Peter Zijlstra Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20241122202849.7DfYpJR0@linutronix.de Reviewed-by: Ankur Arora Reviewed-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (Google)

Merge tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2024-11-22T21:27:01Z

Pull tracing updates from Steven Rostedt: - Addition of faultable tracepoints There's a tracepoint attached to both a system call entry and exit. This location is known to allow page faults. The tracepoints are called under an rcu_read_lock() which does not allow faults that can sleep. This limits the ability of tracepoint handlers to page fault in user space system call parameters. Now these tracepoints have been made "faultable", allowing the callbacks to fault in user space parameters and record them. Note, only the infrastructure has been implemented. The consumers (perf, ftrace, BPF) now need to have their code modified to allow faults. - Fix up of BPF code for the tracepoint faultable logic - Update tracepoints to use the new static branch API - Remove trace_*_rcuidle() variants and the SRCU protection they used - Remove unused TRACE_EVENT_FL_FILTERED logic - Replace strncpy() with strscpy() and memcpy() - Use replace per_cpu_ptr(smp_processor_id()) with this_cpu_ptr() - Fix perf events to not duplicate samples when tracing is enabled - Replace atomic64_add_return(1, counter) with atomic64_inc_return(counter) - Make stack trace buffer 4K instead of PAGE_SIZE - Remove TRACE_FLAG_IRQS_NOSUPPORT flag as it was never used - Get the true return address for function tracer when function graph tracer is also running. When function_graph trace is running along with function tracer, the parent function of the function tracer sometimes is "return_to_handler", which is the function graph trampoline to record the exit of the function. Use existing logic that calls into the fgraph infrastructure to find the real return address. - Remove (un)regfunc pointers out of tracepoint structure - Added last minute bug fix for setting pending modules in stack function filter. echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter Would cause a kernel NULL dereference. - Minor clean ups * tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits) ftrace: Fix regression with module command in stack_trace_filter tracing: Fix function name for trampoline ftrace: Get the true parent ip for function tracer tracing: Remove redundant check on field->field in histograms bpf: ensure RCU Tasks Trace GP for sleepable raw tracepoint BPF links bpf: decouple BPF link/attach hook and BPF program sleepable semantics bpf: put bpf_link's program when link is safe to be deallocated tracing: Replace strncpy() with strscpy() when copying comm tracing: Add might_fault() check in __DECLARE_TRACE_SYSCALL tracing: Fix syscall tracepoint use-after-free tracing: Introduce tracepoint_is_faultable() tracing: Introduce tracepoint extended structure tracing: Remove TRACE_FLAG_IRQS_NOSUPPORT tracing: Replace multiple deprecated strncpy with memcpy tracing: Make percpu stack trace buffer invariant to PAGE_SIZE tracing: Use atomic64_inc_return() in trace_clock_counter() trace/trace_event_perf: remove duplicate samples on the first tracepoint event tracing/bpf: Add might_fault check to syscall probes tracing/perf: Add might_fault check to syscall probes tracing/ftrace: Add might_fault check to syscall probes ...