Commit 79ef0c00 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull tracing updates from Steven Rostedt:

 - kprobes: Restructured stack unwinder to show properly on x86 when a
   stack dump happens from a kretprobe callback.

 - Fix to bootconfig parsing

 - Have tracefs allow owner and group permissions by default (only
   denying others). There's been pressure to allow non root to tracefs
   in a controlled fashion, and using groups is probably the safest.

 - Bootconfig memory managament updates.

 - Bootconfig clean up to have the tools directory be less dependent on
   changes in the kernel tree.

 - Allow perf to be traced by function tracer.

 - Rewrite of function graph tracer to be a callback from the function
   tracer instead of having its own trampoline (this change will happen
   on an arch by arch basis, and currently only x86_64 implements it).

 - Allow multiple direct trampolines (bpf hooks to functions) be batched
   together in one synchronization.

 - Allow histogram triggers to add variables that can perform
   calculations against the event's fields.

 - Use the linker to determine architecture callbacks from the ftrace
   trampoline to allow for proper parameter prototypes and prevent
   warnings from the compiler.

 - Extend histogram triggers to key off of variables.

 - Have trace recursion use bit magic to determine preempt context over
   if branches.

 - Have trace recursion disable preemption as all use cases do anyway.

 - Added testing for verification of tracing utilities.

 - Various small clean ups and fixes.

* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
  tracing/histogram: Fix semicolon.cocci warnings
  tracing/histogram: Fix documentation inline emphasis warning
  tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
  tracing: Show size of requested perf buffer
  bootconfig: Initialize ret in xbc_parse_tree()
  ftrace: do CPU checking after preemption disabled
  ftrace: disable preemption when recursion locked
  tracing/histogram: Document expression arithmetic and constants
  tracing/histogram: Optimize division by a power of 2
  tracing/histogram: Covert expr to const if both operands are constants
  tracing/histogram: Simplify handling of .sym-offset in expressions
  tracing: Fix operator precedence for hist triggers expression
  tracing: Add division and multiplication support for hist triggers
  tracing: Add support for creating hist trigger variables from literal
  selftests/ftrace: Stop tracing while reading the trace file by default
  MAINTAINERS: Update KPROBES and TRACING entries
  test_kprobes: Move it from kernel/ to lib/
  docs, kprobes: Remove invalid URL and add new reference
  samples/kretprobes: Fix return value if register_kretprobe() failed
  lib/bootconfig: Fix the xbc_get_info kerneldoc
  ...
parents d54f4860 feea69ec

Documentation/trace/histogram.rst

+14 −0
Original line number Diff line number Diff line
@@ -1763,6 +1763,20 @@ using the same key and variable from yet another event:: 


  # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger



Expressions support the use of addition, subtraction, multiplication and

division operators (+-\*/).



Note that division by zero always returns -1.



Numeric constants can also be used directly in an expression::



  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/1000000 ...' >> event/trigger



or assigned to a variable and referenced in a subsequent expression::



  # echo 'hist:keys=next_pid:us_per_sec=1000000 ...' >> event/trigger

  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/$us_per_sec ...' >> event/trigger



2.2.2 Synthetic Events

----------------------

Documentation/trace/kprobes.rst

+1 −1
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@@ -784,6 +784,6 @@ References 


For additional information on Kprobes, refer to the following URLs:



- https://www.ibm.com/developerworks/library/l-kprobes/index.html

- https://lwn.net/Articles/132196/

- https://www.kernel.org/doc/ols/2006/ols2006v2-pages-109-124.pdf

Documentation/trace/timerlat-tracer.rst

+12 −12
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ Timerlat tracer 
###############



The timerlat tracer aims to help the preemptive kernel developers to

find souces of wakeup latencies of real-time threads. Like cyclictest,

find sources 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
@@ -50,14 +50,14 @@ The second is the *timer latency* observed by the thread. 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 *irq*/*thread* splitting is important to clarify in 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

delayed by hardware-related actions, such as SMIs, NMIs, IRQs,

or by 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.

postponing the scheduler execution via preempt_disable(), scheduler

execution, or masking interrupts. Threads can also be delayed by the

interference from other threads and IRQs.



Tracer options

---------------------
@@ -68,14 +68,14 @@ directory. The timerlat configs are: 


 - cpus: CPUs at which a timerlat thread will execute.

 - timerlat_period_us: the period of the timerlat thread.

 - osnoise/stop_tracing_us: stop the system tracing if a

 - stop_tracing_us: stop the system tracing if a

   timer latency at the *irq* context higher than the configured

   value happens. Writing 0 disables this option.

 - stop_tracing_total_us: stop the system tracing if a

   timer latency at the *thread* context higher than the configured

   timer latency at the *thread* context is higher than the configured

   value happens. Writing 0 disables this option.

 - print_stack: save the stack of the IRQ ocurrence, and print

   it afte the *thread context* event".

 - print_stack: save the stack of the IRQ occurrence, and print

   it after the *thread context* event".



timerlat and osnoise

----------------------------
@@ -95,7 +95,7 @@ For example:: 
      timerlat/5-1035    [005] .......   548.771104: #402268 context thread timer_latency     39960 ns



In this case, the root cause of the timer latency does not point to a

single cause, but to multiple ones. Firstly, the timer IRQ was delayed

single cause but to multiple ones. Firstly, the timer IRQ was delayed

for 13 us, which may point to a long IRQ disabled section (see IRQ

stacktrace section). Then the timer interrupt that wakes up the timerlat

thread took 7597 ns, and the qxl:21 device IRQ took 7139 ns. Finally,

MAINTAINERS

+4 −1
Original line number Diff line number Diff line
@@ -10482,10 +10482,13 @@ M: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> 
M:	"David S. Miller" <davem@davemloft.net>

M:	Masami Hiramatsu <mhiramat@kernel.org>

S:	Maintained

T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git

F:	Documentation/trace/kprobes.rst

F:	include/asm-generic/kprobes.h

F:	include/linux/kprobes.h

F:	kernel/kprobes.c

F:	lib/test_kprobes.c

F:	samples/kprobes









KS0108 LCD CONTROLLER DRIVER









M:	Miguel Ojeda <ojeda@kernel.org>








@@ -19026,7 +19029,7 @@ TRACING







M:	Steven Rostedt <rostedt@goodmis.org>









M:	Ingo Molnar <mingo@redhat.com>









S:	Maintained









T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf/core









T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git









F:	Documentation/trace/ftrace.rst









F:	arch/*/*/*/ftrace.h









F:	arch/*/kernel/ftrace.c

























arch/Kconfig



+8
−0






























Original line number
Diff line number
Diff line







@@ -191,6 +191,14 @@ config HAVE_OPTPROBES







config HAVE_KPROBES_ON_FTRACE









	bool



















config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE









	bool









	help









	  Since kretprobes modifies return address on the stack, the









	  stacktrace may see the kretprobe trampoline address instead









	  of correct one. If the architecture stacktrace code and









	  unwinder can adjust such entries, select this configuration.



















config HAVE_FUNCTION_ERROR_INJECTION









	bool