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2022-04-26tracing: Have existing event_command.parse() implementations use helpersTom Zanussi1-1/+2
Simplify the existing event_command.parse() implementations by having them make use of the helper functions previously introduced. Link: https://lkml.kernel.org/r/b353e3427a81f9d3adafd98fd7d73e78a8209f43.1644010576.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-04-26tracing: Remove redundant trigger_ops paramsTom Zanussi1-10/+4
Since event_trigger_data contains the .ops trigger_ops field, there's no reason to pass the trigger_ops separately. Remove it as a param from functions whenever event_trigger_data is passed. Link: https://lkml.kernel.org/r/9856c9bc81bde57077f5b8d6f8faa47156c6354a.1644010575.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-04-26tracing: Remove logic for registering multiple event triggers at a timeTom Zanussi1-4/+5
Code for registering triggers assumes it's possible to register more than one trigger at a time. In fact, it's unimplemented and there doesn't seem to be a reason to do that. Remove the n_registered param from event_trigger_register() and fix up callers. Doing so simplifies the logic in event_trigger_register to the point that it just becomes a wrapper calling event_command.reg(). It also removes the problematic call to event_command.unreg() in case of failure. A new function, event_trigger_unregister() is also added for callers to call themselves. The changes to trace_events_hist.c simply allow compilation; a separate patch follows which updates the hist triggers to work correctly with the new changes. Link: https://lkml.kernel.org/r/6149fec7a139d93e84fa4535672fb5bef88006b0.1644010575.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-03-23Merge tag 'trace-v5.18' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - New user_events interface. User space can register an event with the kernel describing the format of the event. Then it will receive a byte in a page mapping that it can check against. A privileged task can then enable that event like any other event, which will change the mapped byte to true, telling the user space application to start writing the event to the tracing buffer. - Add new "ftrace_boot_snapshot" kernel command line parameter. When set, the tracing buffer will be saved in the snapshot buffer at boot up when the kernel hands things over to user space. This will keep the traces that happened at boot up available even if user space boot up has tracing as well. - Have TRACE_EVENT_ENUM() also update trace event field type descriptions. Thus if a static array defines its size with an enum, the user space trace event parsers can still know how to parse that array. - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the TRACE_EVENT() macro, but will attach to an existing tracepoint. This will make one tracepoint be able to trace different content and not be stuck at only what the original TRACE_EVENT() macro exports. - Fixes to tracing error logging. - Better saving of cmdlines to PIDs when tracing (use the wakeup events for mapping). * tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits) tracing: Have type enum modifications copy the strings user_events: Add trace event call as root for low permission cases tracing/user_events: Use alloc_pages instead of kzalloc() for register pages tracing: Add snapshot at end of kernel boot up tracing: Have TRACE_DEFINE_ENUM affect trace event types as well tracing: Fix strncpy warning in trace_events_synth.c user_events: Prevent dyn_event delete racing with ioctl add/delete tracing: Add TRACE_CUSTOM_EVENT() macro tracing: Move the defines to create TRACE_EVENTS into their own files tracing: Add sample code for custom trace events tracing: Allow custom events to be added to the tracefs directory tracing: Fix last_cmd_set() string management in histogram code user_events: Fix potential uninitialized pointer while parsing field tracing: Fix allocation of last_cmd in last_cmd_set() user_events: Add documentation file user_events: Add sample code for typical usage user_events: Add self-test for validator boundaries user_events: Add self-test for perf_event integration user_events: Add self-test for dynamic_events integration user_events: Add self-test for ftrace integration ...
2022-02-25eprobes: Remove redundant event type informationSteven Rostedt (Google)1-1/+0
Currently, the event probes save the type of the event they are attached to when recording the event. For example: # echo 'e:switch sched/sched_switch prev_state=$prev_state prev_prio=$prev_prio next_pid=$next_pid next_prio=$next_prio' > dynamic_events # cat events/eprobes/switch/format name: switch ID: 1717 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned int __probe_type; offset:8; size:4; signed:0; field:u64 prev_state; offset:12; size:8; signed:0; field:u64 prev_prio; offset:20; size:8; signed:0; field:u64 next_pid; offset:28; size:8; signed:0; field:u64 next_prio; offset:36; size:8; signed:0; print fmt: "(%u) prev_state=0x%Lx prev_prio=0x%Lx next_pid=0x%Lx next_prio=0x%Lx", REC->__probe_type, REC->prev_state, REC->prev_prio, REC->next_pid, REC->next_prio The __probe_type adds 4 bytes to every event. One of the reasons for creating eprobes is to limit what is traced in an event to be able to limit what is written into the ring buffer. Having this redundant 4 bytes to every event takes away from this. The event that is recorded can be retrieved from the event probe itself, that is available when the trace is happening. For user space tools, it could simply read the dynamic_event file to find the event they are for. So there is really no reason to write this information into the ring buffer for every event. Link: https://lkml.kernel.org/r/20220218190057.2f5a19a8@gandalf.local.home Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Joel Fernandes <joel@joelfernandes.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-02-10tracing: Remove size restriction on tracing_log_err cmd stringsTom Zanussi1-1/+1
Currently, tracing_log_err.cmd strings are restricted to a length of MAX_FILTER_STR_VAL (256), which is too short for some commands already seen in the wild (with cmd strings longer than that showing up truncated). Remove the restriction so that no command string is ever truncated. Link: https://lkml.kernel.org/r/ca965f23256b350ebd94b3dc1a319f28e8267f5f.1643319703.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-01-10tracing: Add helper functions to simplify event_command.parse() callback ↵Tom Zanussi1-0/+24
handling The event_command.parse() callback is responsible for parsing and registering triggers. The existing command implementions for this callback duplicate a lot of the same code, so to clean up and consolidate those implementations, introduce a handful of helper functions for implementors to use. This also makes it easier for new commands to be implemented and allows them to focus more on the customizations they provide rather than obscuring and complicating it with boilerplate code. Link: https://lkml.kernel.org/r/c1ff71f594d45177706571132bd3119491097221.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2022-01-10tracing: Remove ops param from event_command reg()/unreg() callbacksTom Zanussi1-4/+0
The event_trigger_ops for an event_command are already accessible via event_trigger_data.ops so remove the redundant ops from the callback. Link: https://lkml.kernel.org/r/4c6f2a41820452f9cacddc7634ad442928aa2aa6.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2022-01-10tracing: Change event_trigger_ops func() to trigger()Tom Zanussi1-4/+15
The name of the func() callback on event_trigger_ops is too generic and is easily confused with other callbacks with that name, so change it to something that reflects its actual purpose. In this case, the main purpose of the callback is to implement an event trigger, so call it trigger() instead. Also add some more documentation to event_trigger_ops describing the callbacks a bit better. Link: https://lkml.kernel.org/r/36ab812e3ee74ee03ae0043fda41a858ee728c00.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2022-01-10tracing: Change event_command func() to parse()Tom Zanussi1-7/+12
The name of the func() callback on event_command is too generic and is easily confused with other callbacks with that name, so change it to something that reflects its actual purpose. In this case, the main purpose of the callback is to parse an event command, so call it parse() instead. Link: https://lkml.kernel.org/r/7784e321840752ed88aac0b349c0c685fc9247b1.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2021-12-11tracing: Use memset_startat helper in trace_iterator_reset()Xiu Jianfeng1-8/+1
Make use of memset_startat helper to simplify the code, there should be no functional change as a result of this patch. Link: https://lkml.kernel.org/r/20211210012245.207489-1-xiujianfeng@huawei.com Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-12-06tracing: Disable preemption when using the filter bufferSteven Rostedt (VMware)1-1/+3
In case trace_event_buffer_lock_reserve() is called with preemption enabled, the algorithm that defines the usage of the per cpu filter buffer may fail if the task schedules to another CPU after determining which buffer it will use. Disable preemption when using the filter buffer. And because that same buffer must be used throughout the call, keep preemption disabled until the filter buffer is released. This will also keep the semantics between the use case of when the filter buffer is used, and when the ring buffer itself is used, as that case also disables preemption until the ring buffer is released. Link: https://lkml.kernel.org/r/20211130024318.880190623@goodmis.org [ Fixed warning of assignment in if statement Reported-by: kernel test robot <lkp@intel.com> ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-12-06tracing: Add '__rel_loc' using trace event macrosMasami Hiramatsu1-0/+3
Add '__rel_loc' using trace event macros. These macros are usually not used in the kernel, except for testing purpose. This also add "rel_" variant of macros for dynamic_array string, and bitmask. Link: https://lkml.kernel.org/r/163757342119.510314.816029622439099016.stgit@devnote2 Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-12-06tracing: Support __rel_loc relative dynamic data location attributeMasami Hiramatsu1-0/+1
Add '__rel_loc' new dynamic data location attribute which encodes the data location from the next to the field itself. The '__data_loc' is used for encoding the dynamic data location on the trace event record. But '__data_loc' is not useful if the writer doesn't know the event header (e.g. user event), because it records the dynamic data offset from the entry of the record, not the field itself. This new '__rel_loc' attribute encodes the data location relatively from the next of the field. For example, when there is a record like below (the number in the parentheses is the size of fields) |header(N)|common(M)|fields(K)|__data_loc(4)|fields(L)|data(G)| In this case, '__data_loc' field will be __data_loc = (G << 16) | (N+M+K+4+L) If '__rel_loc' is used, this will be |header(N)|common(M)|fields(K)|__rel_loc(4)|fields(L)|data(G)| where __rel_loc = (G << 16) | (L) This case shows L bytes after the '__rel_loc' attribute field, if there is no fields after the __rel_loc field, L must be 0. This is relatively easy (and no need to consider the kernel header change) when the event data fields are composed by user who doesn't know header and common fields. Link: https://lkml.kernel.org/r/163757341258.510314.4214431827833229956.stgit@devnote2 Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-11-26tracing: Fix pid filtering when triggers are attachedSteven Rostedt (VMware)1-6/+18
If a event is filtered by pid and a trigger that requires processing of the event to happen is a attached to the event, the discard portion does not take the pid filtering into account, and the event will then be recorded when it should not have been. Cc: stable@vger.kernel.org Fixes: 3fdaf80f4a836 ("tracing: Implement event pid filtering") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-10-13tracing: in_irq() cleanupChangbin Du1-1/+1
Replace the obsolete and ambiguos macro in_irq() with new macro in_hardirq(). Link: https://lkml.kernel.org/r/20210930000342.6016-1-changbin.du@gmail.com Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-10-08tracing: Disable "other" permission bits in the tracefs filesSteven Rostedt (VMware)1-0/+3
When building the files in the tracefs file system, do not by default set any permissions for OTH (other). This will make it easier for admins who want to define a group for accessing tracefs and not having to first disable all the permission bits for "other" in the file system. As tracing can leak sensitive information, it should never by default allowing all users access. An admin can still set the permission bits for others to have access, which may be useful for creating a honeypot and seeing who takes advantage of it and roots the machine. Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-10-05tracing: Place trace_pid_list logic into abstract functionsSteven Rostedt (VMware)1-4/+10
Instead of having the logic that does trace_pid_list open coded, wrap it in abstract functions. This will allow a rewrite of the logic that implements the trace_pid_list without affecting the users. Note, this causes a change in behavior. Every time a pid is written into the set_*_pid file, it creates a new list and uses RCU to update it. If pid_max is lowered, but there was a pid currently in the list that was higher than pid_max, those pids will now be removed on updating the list. The old behavior kept that from happening. The rewrite of the pid_list logic will no longer depend on pid_max, and will return the old behavior. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-08-20tracing: Add a probe that attaches to trace eventsTzvetomir Stoyanov (VMware)1-0/+18
A new dynamic event is introduced: event probe. The event is attached to an existing tracepoint and uses its fields as arguments. The user can specify custom format string of the new event, select what tracepoint arguments will be printed and how to print them. An event probe is created by writing configuration string in 'dynamic_events' ftrace file: e[:[SNAME/]ENAME] SYSTEM/EVENT [FETCHARGS] - Set an event probe -:SNAME/ENAME - Delete an event probe Where: SNAME - System name, if omitted 'eprobes' is used. ENAME - Name of the new event in SNAME, if omitted the SYSTEM_EVENT is used. SYSTEM - Name of the system, where the tracepoint is defined, mandatory. EVENT - Name of the tracepoint event in SYSTEM, mandatory. FETCHARGS - Arguments: <name>=$<field>[:TYPE] - Fetch given filed of the tracepoint and print it as given TYPE with given name. Supported types are: (u8/u16/u32/u64/s8/s16/s32/s64), basic type (x8/x16/x32/x64), hexadecimal types "string", "ustring" and bitfield. Example, attach an event probe on openat system call and print name of the file that will be opened: echo "e:esys/eopen syscalls/sys_enter_openat file=\$filename:string" >> dynamic_events A new dynamic event is created in events/esys/eopen/ directory. It can be deleted with: echo "-:esys/eopen" >> dynamic_events Filters, triggers and histograms can be attached to the new event, it can be matched in synthetic events. There is one limitation - an event probe can not be attached to kprobe, uprobe or another event probe. Link: https://lkml.kernel.org/r/20210812145805.2292326-1-tz.stoyanov@gmail.com Link: https://lkml.kernel.org/r/20210819152825.142428383@goodmis.org Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-08-16tracing: Apply trace filters on all output channelsPingfan Liu1-32/+0
The event filters are not applied on all of the output, which results in the flood of printk when using tp_printk. Unfolding event_trigger_unlock_commit_regs() into trace_event_buffer_commit(), so the filters can be applied on every output. Link: https://lkml.kernel.org/r/20210814034538.8428-1-kernelfans@gmail.com Cc: stable@vger.kernel.org Fixes: 0daa2302968c1 ("tracing: Add tp_printk cmdline to have tracepoints go to printk()") Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-07-03Merge tag 'trace-v5.14' of ↵Linus Torvalds1-6/+29
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - Added option for per CPU threads to the hwlat tracer - Have hwlat tracer handle hotplug CPUs - New tracer: osnoise, that detects latency caused by interrupts, softirqs and scheduling of other tasks. - Added timerlat tracer that creates a thread and measures in detail what sources of latency it has for wake ups. - Removed the "success" field of the sched_wakeup trace event. This has been hardcoded as "1" since 2015, no tooling should be looking at it now. If one exists, we can revert this commit, fix that tool and try to remove it again in the future. - tgid mapping fixed to handle more than PID_MAX_DEFAULT pids/tgids. - New boot command line option "tp_printk_stop", as tp_printk causes trace events to write to console. When user space starts, this can easily live lock the system. Having a boot option to stop just after boot up is useful to prevent that from happening. - Have ftrace_dump_on_oops boot command line option take numbers that match the numbers shown in /proc/sys/kernel/ftrace_dump_on_oops. - Bootconfig clean ups, fixes and enhancements. - New ktest script that tests bootconfig options. - Add tracepoint_probe_register_may_exist() to register a tracepoint without triggering a WARN*() if it already exists. BPF has a path from user space that can do this. All other paths are considered a bug. - Small clean ups and fixes * tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (49 commits) tracing: Resize tgid_map to pid_max, not PID_MAX_DEFAULT tracing: Simplify & fix saved_tgids logic treewide: Add missing semicolons to __assign_str uses tracing: Change variable type as bool for clean-up trace/timerlat: Fix indentation on timerlat_main() trace/osnoise: Make 'noise' variable s64 in run_osnoise() tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing tracing: Fix spelling in osnoise tracer "interferences" -> "interference" Documentation: Fix a typo on trace/osnoise-tracer trace/osnoise: Fix return value on osnoise_init_hotplug_support trace/osnoise: Make interval u64 on osnoise_main trace/osnoise: Fix 'no previous prototype' warnings tracing: Have osnoise_main() add a quiescent state for task rcu seq_buf: Make trace_seq_putmem_hex() support data longer than 8 seq_buf: Fix overflow in seq_buf_putmem_hex() trace/osnoise: Support hotplug operations trace/hwlat: Support hotplug operations trace/hwlat: Protect kdata->kthread with get/put_online_cpus trace: Add timerlat tracer trace: Add osnoise tracer ...
2021-06-28once: implement DO_ONCE_LITE for non-fast-path "do once" functionalityTanner Love1-10/+3
Certain uses of "do once" functionality reside outside of fast path, and so do not require jump label patching via static keys, making existing DO_ONCE undesirable in such cases. Replace uses of __section(".data.once") with DO_ONCE_LITE(_IF)? This patch changes the return values of xfs_printk_once, printk_once, and printk_deferred_once. Before, they returned whether the print was performed, but now, they always return true. This is okay because the return values of the following macros are entirely ignored throughout the kernel: - xfs_printk_once - xfs_warn_once - xfs_notice_once - xfs_info_once - printk_once - pr_emerg_once - pr_alert_once - pr_crit_once - pr_err_once - pr_warn_once - pr_notice_once - pr_info_once - pr_devel_once - pr_debug_once - printk_deferred_once - orc_warn Changes v3: - Expand commit message to explain why changing return values of xfs_printk_once, printk_once, printk_deferred_once is benign v2: - Fix i386 build warnings Signed-off-by: Tanner Love <tannerlove@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Mahesh Bandewar <maheshb@google.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-06-25trace: Add timerlat tracerDaniel Bristot de Oliveira1-0/+2
The timerlat tracer aims to help the preemptive kernel developers to found souces of wakeup latencies of real-time threads. Like cyclictest, the tracer sets a periodic timer that wakes up a thread. The thread then computes a *wakeup latency* value as the difference between the *current time* and the *absolute time* that the timer was set to expire. The main goal of timerlat is tracing in such a way to help kernel developers. Usage Write the ASCII text "timerlat" into the current_tracer file of the tracing system (generally mounted at /sys/kernel/tracing). For example: [root@f32 ~]# cd /sys/kernel/tracing/ [root@f32 tracing]# echo timerlat > current_tracer It is possible to follow the trace by reading the trace trace file: [root@f32 tracing]# cat trace # tracer: timerlat # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # || / # |||| ACTIVATION # TASK-PID CPU# |||| TIMESTAMP ID CONTEXT LATENCY # | | | |||| | | | | <idle>-0 [000] d.h1 54.029328: #1 context irq timer_latency 932 ns <...>-867 [000] .... 54.029339: #1 context thread timer_latency 11700 ns <idle>-0 [001] dNh1 54.029346: #1 context irq timer_latency 2833 ns <...>-868 [001] .... 54.029353: #1 context thread timer_latency 9820 ns <idle>-0 [000] d.h1 54.030328: #2 context irq timer_latency 769 ns <...>-867 [000] .... 54.030330: #2 context thread timer_latency 3070 ns <idle>-0 [001] d.h1 54.030344: #2 context irq timer_latency 935 ns <...>-868 [001] .... 54.030347: #2 context thread timer_latency 4351 ns The tracer creates a per-cpu kernel thread with real-time priority that prints two lines at every activation. The first is the *timer latency* observed at the *hardirq* context before the activation of the thread. The second is the *timer latency* observed by the thread, which is the same level that cyclictest reports. The ACTIVATION ID field serves to relate the *irq* execution to its respective *thread* execution. The irq/thread splitting is important to clarify at which context the unexpected high value is coming from. The *irq* context can be delayed by hardware related actions, such as SMIs, NMIs, IRQs or by a thread masking interrupts. Once the timer happens, the delay can also be influenced by blocking caused by threads. For example, by postponing the scheduler execution via preempt_disable(), by the scheduler execution, or by masking interrupts. Threads can also be delayed by the interference from other threads and IRQs. The timerlat can also take advantage of the osnoise: traceevents. For example: [root@f32 ~]# cd /sys/kernel/tracing/ [root@f32 tracing]# echo timerlat > current_tracer [root@f32 tracing]# echo osnoise > set_event [root@f32 tracing]# echo 25 > osnoise/stop_tracing_total_us [root@f32 tracing]# tail -10 trace cc1-87882 [005] d..h... 548.771078: #402268 context irq timer_latency 1585 ns cc1-87882 [005] dNLh1.. 548.771082: irq_noise: local_timer:236 start 548.771077442 duration 4597 ns cc1-87882 [005] dNLh2.. 548.771083: irq_noise: reschedule:253 start 548.771083017 duration 56 ns cc1-87882 [005] dNLh2.. 548.771086: irq_noise: call_function_single:251 start 548.771083811 duration 2048 ns cc1-87882 [005] dNLh2.. 548.771088: irq_noise: call_function_single:251 start 548.771086814 duration 1495 ns cc1-87882 [005] dNLh2.. 548.771091: irq_noise: call_function_single:251 start 548.771089194 duration 1558 ns cc1-87882 [005] dNLh2.. 548.771094: irq_noise: call_function_single:251 start 548.771091719 duration 1932 ns cc1-87882 [005] dNLh2.. 548.771096: irq_noise: call_function_single:251 start 548.771094696 duration 1050 ns cc1-87882 [005] d...3.. 548.771101: thread_noise: cc1:87882 start 548.771078243 duration 10909 ns timerlat/5-1035 [005] ....... 548.771103: #402268 context thread timer_latency 25960 ns For further information see: Documentation/trace/timerlat-tracer.rst Link: https://lkml.kernel.org/r/71f18efc013e1194bcaea1e54db957de2b19ba62.1624372313.git.bristot@redhat.com Cc: Phil Auld <pauld@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Kate Carcia <kcarcia@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Clark Willaims <williams@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-06-25trace: Add osnoise tracerDaniel Bristot de Oliveira1-3/+6
In the context of high-performance computing (HPC), the Operating System Noise (*osnoise*) refers to the interference experienced by an application due to activities inside the operating system. In the context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread can cause noise to the system. Moreover, hardware-related jobs can also cause noise, for example, via SMIs. The osnoise tracer leverages the hwlat_detector by running a similar loop with preemption, SoftIRQs and IRQs enabled, thus allowing all the sources of *osnoise* during its execution. Using the same approach of hwlat, osnoise takes note of the entry and exit point of any source of interferences, increasing a per-cpu interference counter. The osnoise tracer also saves an interference counter for each source of interference. The interference counter for NMI, IRQs, SoftIRQs, and threads is increased anytime the tool observes these interferences' entry events. When a noise happens without any interference from the operating system level, the hardware noise counter increases, pointing to a hardware-related noise. In this way, osnoise can account for any source of interference. At the end of the period, the osnoise tracer prints the sum of all noise, the max single noise, the percentage of CPU available for the thread, and the counters for the noise sources. Usage Write the ASCII text "osnoise" into the current_tracer file of the tracing system (generally mounted at /sys/kernel/tracing). For example:: [root@f32 ~]# cd /sys/kernel/tracing/ [root@f32 tracing]# echo osnoise > current_tracer It is possible to follow the trace by reading the trace trace file:: [root@f32 tracing]# cat trace # tracer: osnoise # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth MAX # || / SINGLE Interference counters: # |||| RUNTIME NOISE % OF CPU NOISE +-----------------------------+ # TASK-PID CPU# |||| TIMESTAMP IN US IN US AVAILABLE IN US HW NMI IRQ SIRQ THREAD # | | | |||| | | | | | | | | | | <...>-859 [000] .... 81.637220: 1000000 190 99.98100 9 18 0 1007 18 1 <...>-860 [001] .... 81.638154: 1000000 656 99.93440 74 23 0 1006 16 3 <...>-861 [002] .... 81.638193: 1000000 5675 99.43250 202 6 0 1013 25 21 <...>-862 [003] .... 81.638242: 1000000 125 99.98750 45 1 0 1011 23 0 <...>-863 [004] .... 81.638260: 1000000 1721 99.82790 168 7 0 1002 49 41 <...>-864 [005] .... 81.638286: 1000000 263 99.97370 57 6 0 1006 26 2 <...>-865 [006] .... 81.638302: 1000000 109 99.98910 21 3 0 1006 18 1 <...>-866 [007] .... 81.638326: 1000000 7816 99.21840 107 8 0 1016 39 19 In addition to the regular trace fields (from TASK-PID to TIMESTAMP), the tracer prints a message at the end of each period for each CPU that is running an osnoise/CPU thread. The osnoise specific fields report: - The RUNTIME IN USE reports the amount of time in microseconds that the osnoise thread kept looping reading the time. - The NOISE IN US reports the sum of noise in microseconds observed by the osnoise tracer during the associated runtime. - The % OF CPU AVAILABLE reports the percentage of CPU available for the osnoise thread during the runtime window. - The MAX SINGLE NOISE IN US reports the maximum single noise observed during the runtime window. - The Interference counters display how many each of the respective interference happened during the runtime window. Note that the example above shows a high number of HW noise samples. The reason being is that this sample was taken on a virtual machine, and the host interference is detected as a hardware interference. Tracer options The tracer has a set of options inside the osnoise directory, they are: - osnoise/cpus: CPUs at which a osnoise thread will execute. - osnoise/period_us: the period of the osnoise thread. - osnoise/runtime_us: how long an osnoise thread will look for noise. - osnoise/stop_tracing_us: stop the system tracing if a single noise higher than the configured value happens. Writing 0 disables this option. - osnoise/stop_tracing_total_us: stop the system tracing if total noise higher than the configured value happens. Writing 0 disables this option. - tracing_threshold: the minimum delta between two time() reads to be considered as noise, in us. When set to 0, the default value will be used, which is currently 5 us. Additional Tracing In addition to the tracer, a set of tracepoints were added to facilitate the identification of the osnoise source. - osnoise:sample_threshold: printed anytime a noise is higher than the configurable tolerance_ns. - osnoise:nmi_noise: noise from NMI, including the duration. - osnoise:irq_noise: noise from an IRQ, including the duration. - osnoise:softirq_noise: noise from a SoftIRQ, including the duration. - osnoise:thread_noise: noise from a thread, including the duration. Note that all the values are *net values*. For example, if while osnoise is running, another thread preempts the osnoise thread, it will start a thread_noise duration at the start. Then, an IRQ takes place, preempting the thread_noise, starting a irq_noise. When the IRQ ends its execution, it will compute its duration, and this duration will be subtracted from the thread_noise, in such a way as to avoid the double accounting of the IRQ execution. This logic is valid for all sources of noise. Here is one example of the usage of these tracepoints:: osnoise/8-961 [008] d.h. 5789.857532: irq_noise: local_timer:236 start 5789.857529929 duration 1845 ns osnoise/8-961 [008] dNh. 5789.858408: irq_noise: local_timer:236 start 5789.858404871 duration 2848 ns migration/8-54 [008] d... 5789.858413: thread_noise: migration/8:54 start 5789.858409300 duration 3068 ns osnoise/8-961 [008] .... 5789.858413: sample_threshold: start 5789.858404555 duration 8723 ns interferences 2 In this example, a noise sample of 8 microseconds was reported in the last line, pointing to two interferences. Looking backward in the trace, the two previous entries were about the migration thread running after a timer IRQ execution. The first event is not part of the noise because it took place one millisecond before. It is worth noticing that the sum of the duration reported in the tracepoints is smaller than eight us reported in the sample_threshold. The reason roots in the overhead of the entry and exit code that happens before and after any interference execution. This justifies the dual approach: measuring thread and tracing. Link: https://lkml.kernel.org/r/e649467042d60e7b62714c9c6751a56299d15119.1624372313.git.bristot@redhat.com Cc: Phil Auld <pauld@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Kate Carcia <kcarcia@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Clark Willaims <williams@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> [ Made the following functions static: trace_irqentry_callback() trace_irqexit_callback() trace_intel_irqentry_callback() trace_intel_irqexit_callback() Added to include/trace.h: osnoise_arch_register() osnoise_arch_unregister() Fixed define logic for LATENCY_FS_NOTIFY Reported-by: kernel test robot <lkp@intel.com> ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-06-25tracing: Add LATENCY_FS_NOTIFY to define if latency_fsnotify() is definedSteven Rostedt (VMware)1-3/+3
With the coming addition of the osnoise tracer, the configs needed to include the latency_fsnotify() has become more complex, and to keep the declaration in the header file the same as in the C file, just have the logic needed to define it in one place, and that defines LATENCY_FS_NOTIFY which will be used in the C code. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-06-25trace: Add a generic function to read/write u64 values from tracefsDaniel Bristot de Oliveira1-0/+18
The hwlat detector and (in preparation for) the osnoise/timerlat tracers have a set of u64 parameters that the user can read/write via tracefs. For instance, we have hwlat_detector's window and width. To reduce the code duplication, hwlat's window and width share the same read function. However, they do not share the write functions because they do different parameter checks. For instance, the width needs to be smaller than the window, while the window needs to be larger than the window. The same pattern repeats on osnoise/timerlat, and a large portion of the code was devoted to the write function. Despite having different checks, the write functions have the same structure: read a user-space buffer take the lock that protects the value check for minimum and maximum acceptable values save the value release the lock return success or error To reduce the code duplication also in the write functions, this patch provides a generic read and write implementation for u64 values that need to be within some minimum and/or maximum parameters, while (potentially) being protected by a lock. To use this interface, the structure trace_min_max_param needs to be filled: struct trace_min_max_param { struct mutex *lock; u64 *val; u64 *min; u64 *max; }; The desired value is stored on the variable pointed by *val. If *min points to a minimum acceptable value, it will be checked during the write operation. Likewise, if *max points to a maximum allowable value, it will be checked during the write operation. Finally, if *lock points to a mutex, it will be taken at the beginning of the operation and released at the end. The definition of a trace_min_max_param needs to passed as the (private) *data for tracefs_create_file(), and the trace_min_max_fops (added by this patch) as the *fops file_operations. Link: https://lkml.kernel.org/r/3e35760a7c8b5c55f16ae5ad5fc54a0e71cbe647.1624372313.git.bristot@redhat.com Cc: Phil Auld <pauld@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Kate Carcia <kcarcia@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Clark Willaims <williams@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-04-15tracing: Add method for recording "func_repeats" eventsYordan Karadzhov (VMware)1-0/+4
This patch only provides the implementation of the method. Later we will used it in a combination with a new option for function tracing. Link: https://lkml.kernel.org/r/20210415181854.147448-5-y.karadz@gmail.com Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-04-15tracing: Add "last_func_repeats" to struct trace_arrayYordan Karadzhov (VMware)1-0/+12
The field is used to keep track of the consecutive (on the same CPU) calls of a single function. This information is needed in order to consolidate the function tracing record in the cases when a single function is called number of times. Link: https://lkml.kernel.org/r/20210415181854.147448-4-y.karadz@gmail.com Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-04-15tracing: Define new ftrace event "func_repeats"Yordan Karadzhov (VMware)1-0/+3
The event aims to consolidate the function tracing record in the cases when a single function is called number of times consecutively. while (cond) do_func(); This may happen in various scenarios (busy waiting for example). The new ftrace event can be used to show repeated function events with a single event and save space on the ring buffer Link: https://lkml.kernel.org/r/20210415181854.147448-3-y.karadz@gmail.com Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-23tracing: Fix various typos in commentsIngo Molnar1-2/+2
Fix ~59 single-word typos in the tracing code comments, and fix the grammar in a handful of places. Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-18tracing: Add a verifier to check string pointers for trace eventsSteven Rostedt (VMware)1-0/+3
It is a common mistake for someone writing a trace event to save a pointer to a string in the TP_fast_assign() and then display that string pointer in the TP_printk() with %s. The problem is that those two events may happen a long time apart, where the source of the string may no longer exist. The proper way to handle displaying any string that is not guaranteed to be in the kernel core rodata section, is to copy it into the ring buffer via the __string(), __assign_str() and __get_str() helper macros. Add a check at run time while displaying the TP_printk() of events to make sure that every %s referenced is safe to dereference, and if it is not, trigger a warning and only show the address of the pointer, and the dereferenced string if it can be safely retrieved with a strncpy_from_kernel_nofault() call. In order to not have to copy the parsing of vsnprintf() formats, or even exporting its code, the verifier relies on vsnprintf() being able to modify the va_list that is passed to it, and it remains modified after it is called. This is the case for some architectures like x86_64, but other architectures like x86_32 pass the va_list to vsnprintf() as a value not a reference, and the verifier can not use it to parse the non string arguments. Thus, at boot up, it is checked if vsnprintf() modifies the passed in va_list or not, and a static branch will disable the verifier if it's not compatible. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-18tracing: Add tracing_event_time_stamp() APISteven Rostedt (VMware)1-0/+1
Add a tracing_event_time_stamp() API that checks if the event passed in is not on the ring buffer but a pointer to the per CPU trace_buffered_event which does not have its time stamp set yet. If it is a pointer to the trace_buffered_event, then just return the current time stamp that the ring buffer would produce. Otherwise, return the time stamp from the event. Link: https://lkml.kernel.org/r/20210316164114.131996180@goodmis.org Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-18tracing: Use a no_filter_buffering_ref to stop using the filter bufferSteven Rostedt (VMware)1-2/+2
Currently, the trace histograms relies on it using absolute time stamps to trigger the tracing to not use the temp buffer if filters are set. That's because the histograms need the full timestamp that is saved in the ring buffer. That is no longer the case, as the ring_buffer_event_time_stamp() can now return the time stamp for all events without all triggering a full absolute time stamp. Now that the absolute time stamp is an unrelated dependency to not using the filters. There's nothing about having absolute timestamps to keep from using the filter buffer. Instead, change the interface to explicitly state to disable filter buffering that the histogram logic can use. Link: https://lkml.kernel.org/r/20210316164113.847886563@goodmis.org Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-18tracing: Pass buffer of event to trigger operationsSteven Rostedt (VMware)1-2/+2
The ring_buffer_event_time_stamp() is going to be updated to extract the time stamp for the event without needing it to be set to have absolute values for all events. But to do so, it needs the buffer that the event is on as the buffer saves information for the event before it is committed to the buffer. If the trace buffer is disabled, a temporary buffer is used, and there's no access to this buffer from the current histogram triggers, even though it is passed to the trace event code. Pass the buffer that the event is on all the way down to the histogram triggers. Link: https://lkml.kernel.org/r/20210316164113.542448131@goodmis.org Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-04tracing: Remove duplicate declaration from trace.hYordan Karadzhov (VMware)1-1/+0
A declaration of function "int trace_empty(struct trace_iterator *iter)" shows up twice in the header file kernel/trace/trace.h Link: https://lkml.kernel.org/r/20210304092348.208033-1-y.karadz@gmail.com Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-02-11tracing: Add ptr-hash option to show the hashed pointer valueMasami Hiramatsu1-0/+1
Add tracefs/options/hash-ptr option to show hashed pointer value by %p in event printk format string. For the security reason, normal printk will show the hashed pointer value (encrypted by random number) with %p to printk buffer to hide the real address. But the tracefs/trace always shows real address for debug. To bridge those outputs, add an option to switch the output format. Ftrace users can use it to find the hashed value corresponding to the real address in trace log. Link: https://lkml.kernel.org/r/160277372504.29307.14909828808982012211.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-02-11tracing: Show real address for trace event argumentsMasami Hiramatsu1-0/+2
To help debugging kernel, show real address for trace event arguments in tracefs/trace{,pipe} instead of hashed pointer value. Since ftrace human-readable format uses vsprintf(), all %p are translated to hash values instead of pointer address. However, when debugging the kernel, raw address value gives a hint when comparing with the memory mapping in the kernel. (Those are sometimes used with crash log, which is not hashed too) So converting %p with %px when calling trace_seq_printf(). Moreover, this is not improving the security because the tracefs can be used only by root user and the raw address values are readable from tracefs/percpu/cpu*/trace_pipe_raw file. Link: https://lkml.kernel.org/r/160277370703.29307.5134475491761971203.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-02-09tracing/dynevent: Delegate parsing to create functionMasami Hiramatsu1-2/+1
Delegate command parsing to each create function so that the command syntax can be customized. This requires changes to the kprobe/uprobe/synthetic event handling, which are also included here. Link: https://lkml.kernel.org/r/e488726f49cbdbc01568618f8680584306c4c79f.1612208610.git.zanussi@kernel.org Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> [ zanussi@kernel.org: added synthetic event modifications ] Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-02-02tracing: Inline tracing_gen_ctx_flags()Sebastian Andrzej Siewior1-19/+0
Inline tracing_gen_ctx_flags(). This allows to have one ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT. This requires to move `trace_flag_type' so tracing_gen_ctx_flags() can use it. Link: https://lkml.kernel.org/r/20210125194511.3924915-3-bigeasy@linutronix.de Suggested-by: Steven Rostedt <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/20210125140323.6b1ff20c@gandalf.local.home Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-02-02tracing: Merge irqflags + preempt counter.Sebastian Andrzej Siewior1-21/+17
The state of the interrupts (irqflags) and the preemption counter are both passed down to tracing_generic_entry_update(). Only one bit of irqflags is actually required: The on/off state. The complete 32bit of the preemption counter isn't needed. Just whether of the upper bits (softirq, hardirq and NMI) are set and the preemption depth is needed. The irqflags and the preemption counter could be evaluated early and the information stored in an integer `trace_ctx'. tracing_generic_entry_update() would use the upper bits as the TRACE_FLAG_* and the lower 8bit as the disabled-preemption depth (considering that one must be substracted from the counter in one special cases). The actual preemption value is not used except for the tracing record. The `irqflags' variable is mostly used only for the tracing record. An exception here is for instance wakeup_tracer_call() or probe_wakeup_sched_switch() which explicilty disable interrupts and use that `irqflags' to save (and restore) the IRQ state and to record the state. Struct trace_event_buffer has also the `pc' and flags' members which can be replaced with `trace_ctx' since their actual value is not used outside of trace recording. This will reduce tracing_generic_entry_update() to simply assign values to struct trace_entry. The evaluation of the TRACE_FLAG_* bits is moved to _tracing_gen_ctx_flags() which replaces preempt_count() and local_save_flags() invocations. As an example, ftrace_syscall_enter() may invoke: - trace_buffer_lock_reserve() -> … -> tracing_generic_entry_update() - event_trigger_unlock_commit() -> ftrace_trace_stack() -> … -> tracing_generic_entry_update() -> ftrace_trace_userstack() -> … -> tracing_generic_entry_update() In this case the TRACE_FLAG_* bits were evaluated three times. By using the `trace_ctx' they are evaluated once and assigned three times. A build with all tracers enabled on x86-64 with and without the patch: text data bss dec hex filename 21970669 17084168 7639260 46694097 2c87ed1 vmlinux.old 21970293 17084168 7639260 46693721 2c87d59 vmlinux.new text shrank by 379 bytes, data remained constant. Link: https://lkml.kernel.org/r/20210125194511.3924915-2-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-12-14tracing: Disable ftrace selftests when any tracer is runningMasami Hiramatsu1-0/+5
Disable ftrace selftests when any tracer (kernel command line options like ftrace=, trace_events=, kprobe_events=, and boot-time tracing) starts running because selftest can disturb it. Currently ftrace= and trace_events= are checked, but kprobe_events has a different flag, and boot-time tracing didn't checked. This unifies the disabled flag and all of those boot-time tracing features sets the flag. This also fixes warnings on kprobe-event selftest (CONFIG_FTRACE_STARTUP_TEST=y and CONFIG_KPROBE_EVENTS=y) with boot-time tracing (ftrace.event.kprobes.EVENT.probes) like below; [ 59.803496] trace_kprobe: Testing kprobe tracing: [ 59.804258] ------------[ cut here ]------------ [ 59.805682] WARNING: CPU: 3 PID: 1 at kernel/trace/trace_kprobe.c:1987 kprobe_trace_self_tests_ib [ 59.806944] Modules linked in: [ 59.807335] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.10.0-rc7+ #172 [ 59.808029] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/204 [ 59.808999] RIP: 0010:kprobe_trace_self_tests_init+0x5f/0x42b [ 59.809696] Code: e8 03 00 00 48 c7 c7 30 8e 07 82 e8 6d 3c 46 ff 48 c7 c6 00 b2 1a 81 48 c7 c7 7 [ 59.812439] RSP: 0018:ffffc90000013e78 EFLAGS: 00010282 [ 59.813038] RAX: 00000000ffffffef RBX: 0000000000000000 RCX: 0000000000049443 [ 59.813780] RDX: 0000000000049403 RSI: 0000000000049403 RDI: 000000000002deb0 [ 59.814589] RBP: ffffc90000013e90 R08: 0000000000000001 R09: 0000000000000001 [ 59.815349] R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffef [ 59.816138] R13: ffff888004613d80 R14: ffffffff82696940 R15: ffff888004429138 [ 59.816877] FS: 0000000000000000(0000) GS:ffff88807dcc0000(0000) knlGS:0000000000000000 [ 59.817772] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 59.818395] CR2: 0000000001a8dd38 CR3: 0000000002222000 CR4: 00000000000006a0 [ 59.819144] Call Trace: [ 59.819469] ? init_kprobe_trace+0x6b/0x6b [ 59.819948] do_one_initcall+0x5f/0x300 [ 59.820392] ? rcu_read_lock_sched_held+0x4f/0x80 [ 59.820916] kernel_init_freeable+0x22a/0x271 [ 59.821416] ? rest_init+0x241/0x241 [ 59.821841] kernel_init+0xe/0x10f [ 59.822251] ret_from_fork+0x22/0x30 [ 59.822683] irq event stamp: 16403349 [ 59.823121] hardirqs last enabled at (16403359): [<ffffffff810db81e>] console_unlock+0x48e/0x580 [ 59.824074] hardirqs last disabled at (16403368): [<ffffffff810db786>] console_unlock+0x3f6/0x580 [ 59.825036] softirqs last enabled at (16403200): [<ffffffff81c0033a>] __do_softirq+0x33a/0x484 [ 59.825982] softirqs last disabled at (16403087): [<ffffffff81a00f02>] asm_call_irq_on_stack+0x10 [ 59.827034] ---[ end trace 200c544775cdfeb3 ]--- [ 59.827635] trace_kprobe: error on probing function entry. Link: https://lkml.kernel.org/r/160741764955.3448999.3347769358299456915.stgit@devnote2 Fixes: 4d655281eb1b ("tracing/boot Add kprobe event support") Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-11-06ftrace: Move the recursion testing into global headersSteven Rostedt (VMware)1-177/+0
Currently, if a callback is registered to a ftrace function and its ftrace_ops does not have the RECURSION flag set, it is encapsulated in a helper function that does the recursion for it. Really, all the callbacks should have their own recursion protection for performance reasons. But they should not all implement their own. Move the recursion helpers to global headers, so that all callbacks can use them. Link: https://lkml.kernel.org/r/20201028115612.460535535@goodmis.org Link: https://lkml.kernel.org/r/20201106023546.166456258@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-11-02ftrace: Handle tracing when switching between contextSteven Rostedt (VMware)1-2/+21
When an interrupt or NMI comes in and switches the context, there's a delay from when the preempt_count() shows the update. As the preempt_count() is used to detect recursion having each context have its own bit get set when tracing starts, and if that bit is already set, it is considered a recursion and the function exits. But if this happens in that section where context has changed but preempt_count() has not been updated, this will be incorrectly flagged as a recursion. To handle this case, create another bit call TRANSITION and test it if the current context bit is already set. Flag the call as a recursion if the TRANSITION bit is already set, and if not, set it and continue. The TRANSITION bit will be cleared normally on the return of the function that set it, or if the current context bit is clear, set it and clear the TRANSITION bit to allow for another transition between the current context and an even higher one. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-11-02ftrace: Fix recursion check for NMI testSteven Rostedt (VMware)1-1/+2
The code that checks recursion will work to only do the recursion check once if there's nested checks. The top one will do the check, the other nested checks will see recursion was already checked and return zero for its "bit". On the return side, nothing will be done if the "bit" is zero. The problem is that zero is returned for the "good" bit when in NMI context. This will set the bit for NMIs making it look like *all* NMI tracing is recursing, and prevent tracing of anything in NMI context! The simple fix is to return "bit + 1" and subtract that bit on the end to get the real bit. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-10-25treewide: Convert macro and uses of __section(foo) to __section("foo")Joe Perches1-1/+1
Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Nick Desaulniers <ndesaulniers@gooogle.com> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-15tracing: Move is_good_name() from trace_probe.h to trace.hTom Zanussi1-0/+13
is_good_name() is useful for other trace infrastructure, such as synthetic events, so make it available via trace.h. Link: https://lkml.kernel.org/r/cc6d6a2d7da6957fcbe1e2922e76d18d2bb459b4.1602598160.git.zanussi@kernel.org Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-10-15tracing: Fix some typos in commentsQiujun Huang1-4/+4
s/wihin/within/ s/retrieven/retrieved/ s/suppport/support/ s/wil/will/ s/accidently/accidentally/ s/if the if the/if the/ Link: https://lkml.kernel.org/r/20201010140924.3809-1-hqjagain@gmail.com Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-09-25tracing/boot: Initialize per-instance event list in early bootMasami Hiramatsu1-0/+1
Initialize per-instance event list in early boot time (before initializing instance directory on tracefs). This fixes boot-time tracing to correctly handle the boot-time per-instance settings. Link: https://lkml.kernel.org/r/160096560826.182763.17110991546046128881.stgit@devnote2 Fixes: 4114fbfd02f1 ("tracing: Enable creating new instance early boot") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-09-21tracing: Enable creating new instance early bootMasami Hiramatsu1-0/+7
Enable creating new trace_array instance in early boot stage. If the instances directory is not created, postpone it until the tracefs is initialized. Link: https://lkml.kernel.org/r/159974154763.478751.6289753509587233103.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-09-18tracing: make tracing_init_dentry() returns an integer instead of a d_entry ↵Wei Yang1-1/+1
pointer Current tracing_init_dentry() return a d_entry pointer, while is not necessary. This function returns NULL on success or error on failure, which means there is no valid d_entry pointer return. Let's return 0 on success and negative value for error. Link: https://lkml.kernel.org/r/20200712011036.70948-5-richard.weiyang@linux.alibaba.com Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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