Merge tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Added new "bootconfig".

   This looks for a file appended to initrd to add boot config options,
   and has been discussed thoroughly at Linux Plumbers.

   Very useful for adding kprobes at bootup.

   Only enabled if "bootconfig" is on the real kernel command line.

 - Created dynamic event creation.

   Merges common code between creating synthetic events and kprobe
   events.

 - Rename perf "ring_buffer" structure to "perf_buffer"

 - Rename ftrace "ring_buffer" structure to "trace_buffer"

   Had to rename existing "trace_buffer" to "array_buffer"

 - Allow trace_printk() to work withing (some) tracing code.

 - Sort of tracing configs to be a little better organized

 - Fixed bug where ftrace_graph hash was not being protected properly

 - Various other small fixes and clean ups

* tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (88 commits)
  bootconfig: Show the number of nodes on boot message
  tools/bootconfig: Show the number of bootconfig nodes
  bootconfig: Add more parse error messages
  bootconfig: Use bootconfig instead of boot config
  ftrace: Protect ftrace_graph_hash with ftrace_sync
  ftrace: Add comment to why rcu_dereference_sched() is open coded
  tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu
  tracing: Annotate ftrace_graph_hash pointer with __rcu
  bootconfig: Only load bootconfig if "bootconfig" is on the kernel cmdline
  tracing: Use seq_buf for building dynevent_cmd string
  tracing: Remove useless code in dynevent_arg_pair_add()
  tracing: Remove check_arg() callbacks from dynevent args
  tracing: Consolidate some synth_event_trace code
  tracing: Fix now invalid var_ref_vals assumption in trace action
  tracing: Change trace_boot to use synth_event interface
  tracing: Move tracing selftests to bottom of menu
  tracing: Move mmio tracer config up with the other tracers
  tracing: Move tracing test module configs together
  tracing: Move all function tracing configs together
  tracing: Documentation for in-kernel synthetic event API
  ...

1 files changed, 184 insertions, 0 deletions

diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst
new file mode 100644
index 000000000000..dcb390075ca1
--- /dev/null
+++ b/Documentation/trace/boottime-trace.rst
@@ -0,0 +1,184 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Boot-time tracing
+=================
+
+:Author: Masami Hiramatsu <mhiramat@kernel.org>
+
+Overview
+========
+
+Boot-time tracing allows users to trace boot-time process including
+device initialization with full features of ftrace including per-event
+filter and actions, histograms, kprobe-events and synthetic-events,
+and trace instances.
+Since kernel command line is not enough to control these complex features,
+this uses bootconfig file to describe tracing feature programming.
+
+Options in the Boot Config
+==========================
+
+Here is the list of available options list for boot time tracing in
+boot config file [1]_. All options are under "ftrace." or "kernel."
+prefix. See kernel parameters for the options which starts
+with "kernel." prefix [2]_.
+
+.. [1] See :ref:`Documentation/admin-guide/bootconfig.rst <bootconfig>`
+.. [2] See :ref:`Documentation/admin-guide/kernel-parameters.rst <kernelparameters>`
+
+Ftrace Global Options
+---------------------
+
+Ftrace global options have "kernel." prefix in boot config, which means
+these options are passed as a part of kernel legacy command line.
+
+kernel.tp_printk
+   Output trace-event data on printk buffer too.
+
+kernel.dump_on_oops [= MODE]
+   Dump ftrace on Oops. If MODE = 1 or omitted, dump trace buffer
+   on all CPUs. If MODE = 2, dump a buffer on a CPU which kicks Oops.
+
+kernel.traceoff_on_warning
+   Stop tracing if WARN_ON() occurs.
+
+kernel.fgraph_max_depth = MAX_DEPTH
+   Set MAX_DEPTH to maximum depth of fgraph tracer.
+
+kernel.fgraph_filters = FILTER[, FILTER2...]
+   Add fgraph tracing function filters.
+
+kernel.fgraph_notraces = FILTER[, FILTER2...]
+   Add fgraph non-tracing function filters.
+
+
+Ftrace Per-instance Options
+---------------------------
+
+These options can be used for each instance including global ftrace node.
+
+ftrace.[instance.INSTANCE.]options = OPT1[, OPT2[...]]
+   Enable given ftrace options.
+
+ftrace.[instance.INSTANCE.]trace_clock = CLOCK
+   Set given CLOCK to ftrace's trace_clock.
+
+ftrace.[instance.INSTANCE.]buffer_size = SIZE
+   Configure ftrace buffer size to SIZE. You can use "KB" or "MB"
+   for that SIZE.
+
+ftrace.[instance.INSTANCE.]alloc_snapshot
+   Allocate snapshot buffer.
+
+ftrace.[instance.INSTANCE.]cpumask = CPUMASK
+   Set CPUMASK as trace cpu-mask.
+
+ftrace.[instance.INSTANCE.]events = EVENT[, EVENT2[...]]
+   Enable given events on boot. You can use a wild card in EVENT.
+
+ftrace.[instance.INSTANCE.]tracer = TRACER
+   Set TRACER to current tracer on boot. (e.g. function)
+
+ftrace.[instance.INSTANCE.]ftrace.filters
+   This will take an array of tracing function filter rules.
+
+ftrace.[instance.INSTANCE.]ftrace.notraces
+   This will take an array of NON-tracing function filter rules.
+
+
+Ftrace Per-Event Options
+------------------------
+
+These options are setting per-event options.
+
+ftrace.[instance.INSTANCE.]event.GROUP.EVENT.enable
+   Enable GROUP:EVENT tracing.
+
+ftrace.[instance.INSTANCE.]event.GROUP.EVENT.filter = FILTER
+   Set FILTER rule to the GROUP:EVENT.
+
+ftrace.[instance.INSTANCE.]event.GROUP.EVENT.actions = ACTION[, ACTION2[...]]
+   Set ACTIONs to the GROUP:EVENT.
+
+ftrace.[instance.INSTANCE.]event.kprobes.EVENT.probes = PROBE[, PROBE2[...]]
+   Defines new kprobe event based on PROBEs. It is able to define
+   multiple probes on one event, but those must have same type of
+   arguments. This option is available only for the event which
+   group name is "kprobes".
+
+ftrace.[instance.INSTANCE.]event.synthetic.EVENT.fields = FIELD[, FIELD2[...]]
+   Defines new synthetic event with FIELDs. Each field should be
+   "type varname".
+
+Note that kprobe and synthetic event definitions can be written under
+instance node, but those are also visible from other instances. So please
+take care for event name conflict.
+
+
+Examples
+========
+
+For example, to add filter and actions for each event, define kprobe
+events, and synthetic events with histogram, write a boot config like
+below::
+
+  ftrace.event {
+        task.task_newtask {
+                filter = "pid < 128"
+                enable
+        }
+        kprobes.vfs_read {
+                probes = "vfs_read $arg1 $arg2"
+                filter = "common_pid < 200"
+                enable
+        }
+        synthetic.initcall_latency {
+                fields = "unsigned long func", "u64 lat"
+                actions = "hist:keys=func.sym,lat:vals=lat:sort=lat"
+        }
+        initcall.initcall_start {
+                actions = "hist:keys=func:ts0=common_timestamp.usecs"
+        }
+        initcall.initcall_finish {
+                actions = "hist:keys=func:lat=common_timestamp.usecs-$ts0:onmatch(initcall.initcall_start).initcall_latency(func,$lat)"
+        }
+  }
+
+Also, boot-time tracing supports "instance" node, which allows us to run
+several tracers for different purpose at once. For example, one tracer
+is for tracing functions starting with "user\_", and others tracing
+"kernel\_" functions, you can write boot config as below::
+
+  ftrace.instance {
+        foo {
+                tracer = "function"
+                ftrace.filters = "user_*"
+        }
+        bar {
+                tracer = "function"
+                ftrace.filters = "kernel_*"
+        }
+  }
+
+The instance node also accepts event nodes so that each instance
+can customize its event tracing.
+
+This boot-time tracing also supports ftrace kernel parameters via boot
+config.
+For example, following kernel parameters::
+
+ trace_options=sym-addr trace_event=initcall:* tp_printk trace_buf_size=1M ftrace=function ftrace_filter="vfs*"
+
+This can be written in boot config like below::
+
+  kernel {
+        trace_options = sym-addr
+        trace_event = "initcall:*"
+        tp_printk
+        trace_buf_size = 1M
+        ftrace = function
+        ftrace_filter = "vfs*"
+  }
+
+Note that parameters start with "kernel" prefix instead of "ftrace".