linux/kernel/trace/Kconfig, branch v5.14

tracing: define needed config DYNAMIC_FTRACE_WITH_ARGS

2021-08-12T17:35:57Z

Commit 2860cd8a2353 ("livepatch: Use the default ftrace_ops instead of REGS when ARGS is available") intends to enable config LIVEPATCH when ftrace with ARGS is available. However, the chain of configs to enable LIVEPATCH is incomplete, as HAVE_DYNAMIC_FTRACE_WITH_ARGS is available, but the definition of DYNAMIC_FTRACE_WITH_ARGS, combining DYNAMIC_FTRACE and HAVE_DYNAMIC_FTRACE_WITH_ARGS, needed to enable LIVEPATCH, is missing in the commit. Fortunately, ./scripts/checkkconfigsymbols.py detects this and warns: DYNAMIC_FTRACE_WITH_ARGS Referencing files: kernel/livepatch/Kconfig So, define the config DYNAMIC_FTRACE_WITH_ARGS analogously to the already existing similar configs, DYNAMIC_FTRACE_WITH_REGS and DYNAMIC_FTRACE_WITH_DIRECT_CALLS, in ./kernel/trace/Kconfig to connect the chain of configs. Link: https://lore.kernel.org/kernel-janitors/CAKXUXMwT2zS9fgyQHKUUiqo8ynZBdx2UEUu1WnV_q0OCmknqhw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210806195027.16808-1-lukas.bulwahn@gmail.com Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Peter Zijlstra Cc: Miroslav Benes Cc: stable@vger.kernel.org Fixes: 2860cd8a2353 ("livepatch: Use the default ftrace_ops instead of REGS when ARGS is available") Signed-off-by: Lukas Bulwahn Signed-off-by: Steven Rostedt (VMware)

trace: Add timerlat tracer

2021-06-25T23:57:24Z

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 # | | | |||| | | | | -0 [000] d.h1 54.029328: #1 context irq timer_latency 932 ns <...>-867 [000] .... 54.029339: #1 context thread timer_latency 11700 ns -0 [001] dNh1 54.029346: #1 context irq timer_latency 2833 ns <...>-868 [001] .... 54.029353: #1 context thread timer_latency 9820 ns -0 [000] d.h1 54.030328: #2 context irq timer_latency 769 ns <...>-867 [000] .... 54.030330: #2 context thread timer_latency 3070 ns -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 Cc: Sebastian Andrzej Siewior Cc: Kate Carcia Cc: Jonathan Corbet Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Alexandre Chartre Cc: Clark Willaims Cc: John Kacur Cc: Juri Lelli Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (VMware)

trace: Add osnoise tracer

2021-06-25T23:57:01Z

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 Cc: Sebastian Andrzej Siewior Cc: Kate Carcia Cc: Jonathan Corbet Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Alexandre Chartre Cc: Clark Willaims Cc: John Kacur Cc: Juri Lelli Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira [ 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 ] Signed-off-by: Steven Rostedt (VMware)

tracing: Fix help text of TRACEPOINT_BENCHMARK in Kconfig

2021-03-04T14:45:17Z

It's "cond_resched()" not "cond_sched()". Link: https://lkml.kernel.org/r/1863065.aFVDpXsuPd@devpool47 Signed-off-by: Rolf Eike Beer Signed-off-by: Steven Rostedt (VMware)

Merge tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2021-02-23T23:13:45Z

Pull more clang LTO updates from Kees Cook: "Clang LTO x86 enablement. Full disclosure: while this has _not_ been in linux-next (since it initially looked like the objtool dependencies weren't going to make v5.12), it has been under daily build and runtime testing by Sami for quite some time. These x86 portions have been discussed on lkml, with Peter, Josh, and others helping nail things down. The bulk of the changes are to get objtool working happily. The rest of the x86 enablement is very small. Summary: - Generate __mcount_loc in objtool (Peter Zijlstra) - Support running objtool against vmlinux.o (Sami Tolvanen) - Clang LTO enablement for x86 (Sami Tolvanen)" Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/ Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/ * tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: kbuild: lto: force rebuilds when switching CONFIG_LTO x86, build: allow LTO to be selected x86, cpu: disable LTO for cpu.c x86, vdso: disable LTO only for vDSO kbuild: lto: postpone objtool objtool: Split noinstr validation from --vmlinux x86, build: use objtool mcount tracing: add support for objtool mcount objtool: Don't autodetect vmlinux.o objtool: Fix __mcount_loc generation with Clang's assembler objtool: Add a pass for generating __mcount_loc

tracing: add support for objtool mcount

2021-02-23T20:46:57Z

This change adds build support for using objtool to generate __mcount_loc sections. Signed-off-by: Sami Tolvanen

Merge tag 'clang-lto-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2021-02-23T17:28:51Z

Pull clang LTO updates from Kees Cook: "Clang Link Time Optimization. This is built on the work done preparing for LTO by arm64 folks, tracing folks, etc. This includes the core changes as well as the remaining pieces for arm64 (LTO has been the default build method on Android for about 3 years now, as it is the prerequisite for the Control Flow Integrity protections). While x86 LTO enablement is done, it depends on some pending objtool clean-ups. It's possible that I'll send a "part 2" pull request for LTO that includes x86 support. For merge log posterity, and as detailed in commit dc5723b02e52 ("kbuild: add support for Clang LTO"), here is the lt;dr to do an LTO build: make LLVM=1 LLVM_IAS=1 defconfig scripts/config -e LTO_CLANG_THIN make LLVM=1 LLVM_IAS=1 (To do a cross-compile of arm64, add "CROSS_COMPILE=aarch64-linux-gnu-" and "ARCH=arm64" to the "make" command lines.) Summary: - Clang LTO build infrastructure and arm64-specific enablement (Sami Tolvanen) - Recursive build CC_FLAGS_LTO fix (Alexander Lobakin)" * tag 'clang-lto-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: kbuild: prevent CC_FLAGS_LTO self-bloating on recursive rebuilds arm64: allow LTO to be selected arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS arm64: vdso: disable LTO drivers/misc/lkdtm: disable LTO for rodata.o efi/libstub: disable LTO scripts/mod: disable LTO for empty.c modpost: lto: strip .lto from module names PCI: Fix PREL32 relocations for LTO init: lto: fix PREL32 relocations init: lto: ensure initcall ordering kbuild: lto: add a default list of used symbols kbuild: lto: merge module sections kbuild: lto: limit inlining kbuild: lto: fix module versioning kbuild: add support for Clang LTO tracing: move function tracer options to Kconfig

kernel: trace: preemptirq_delay_test: add cpu affinity

2021-02-02T22:02:07Z

The kernel thread executing test can run on any cpu, which might be different cpu latency tracer is running on, as a result, the big latency caused by preemptirq delay test can't be detected. Therefore, the argument cpu_affinity is added to be passed to test, ensure it's running on the same cpu with latency tracer. e.g. cyclictest -p 90 -m -c 0 -i 1000 -a 3 modprobe preemptirq_delay_test test_mode=preempt delay=500 \ burst_size=3 cpu_affinity=3 Link: https://lkml.kernel.org/r/1611797713-20965-1-git-send-email-chensong_2000@189.cn Signed-off-by: Song Chen Signed-off-by: Steven Rostedt (VMware)

tracing: Fix spelling mistake in Kconfig "infinit" -> "infinite"

2021-02-02T22:02:07Z

There is a spelling mistake in the Kconfig help text. Fix it. Link: https://lkml.kernel.org/r/20201216114051.12056-1-colin.king@canonical.com Signed-off-by: Colin Ian King Signed-off-by: Steven Rostedt (VMware)

tracing/kprobes: Do the notrace functions check without kprobes on ftrace

2021-01-11T21:09:53Z

Enable the notrace function check on the architecture which doesn't support kprobes on ftrace but support dynamic ftrace. This notrace function check is not only for the kprobes on ftrace but also sw-breakpoint based kprobes. Thus there is no reason to limit this check for the arch which supports kprobes on ftrace. This also changes the dependency of Kconfig. Because kprobe event uses the function tracer's address list for identifying notrace function, if the CONFIG_DYNAMIC_FTRACE=n, it can not check whether the target function is notrace or not. Link: https://lkml.kernel.org/r/20210105065730.2634785-1-naveen.n.rao@linux.vnet.ibm.com Link: https://lkml.kernel.org/r/161007957862.114704.4512260007555399463.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 45408c4f92506 ("tracing: kprobes: Prohibit probing on notrace function") Acked-by: Naveen N. Rao Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)