Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 219 insertions, 0 deletions

diff --git a/Documentation/driver-api/reset.rst b/Documentation/driver-api/reset.rst
new file mode 100644
index 000000000..7a6571849
--- /dev/null
+++ b/Documentation/driver-api/reset.rst
@@ -0,0 +1,219 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+====================
+Reset controller API
+====================
+
+Introduction
+============
+
+Reset controllers are central units that control the reset signals to multiple
+peripherals.
+The reset controller API is split into two parts:
+the `consumer driver interface <#consumer-driver-interface>`__ (`API reference
+<#reset-consumer-api>`__), which allows peripheral drivers to request control
+over their reset input signals, and the `reset controller driver interface
+<#reset-controller-driver-interface>`__ (`API reference
+<#reset-controller-driver-api>`__), which is used by drivers for reset
+controller devices to register their reset controls to provide them to the
+consumers.
+
+While some reset controller hardware units also implement system restart
+functionality, restart handlers are out of scope for the reset controller API.
+
+Glossary
+--------
+
+The reset controller API uses these terms with a specific meaning:
+
+Reset line
+
+    Physical reset line carrying a reset signal from a reset controller
+    hardware unit to a peripheral module.
+
+Reset control
+
+    Control method that determines the state of one or multiple reset lines.
+    Most commonly this is a single bit in reset controller register space that
+    either allows direct control over the physical state of the reset line, or
+    is self-clearing and can be used to trigger a predetermined pulse on the
+    reset line.
+    In more complicated reset controls, a single trigger action can launch a
+    carefully timed sequence of pulses on multiple reset lines.
+
+Reset controller
+
+    A hardware module that provides a number of reset controls to control a
+    number of reset lines.
+
+Reset consumer
+
+    Peripheral module or external IC that is put into reset by the signal on a
+    reset line.
+
+Consumer driver interface
+=========================
+
+This interface provides an API that is similar to the kernel clock framework.
+Consumer drivers use get and put operations to acquire and release reset
+controls.
+Functions are provided to assert and deassert the controlled reset lines,
+trigger reset pulses, or to query reset line status.
+
+When requesting reset controls, consumers can use symbolic names for their
+reset inputs, which are mapped to an actual reset control on an existing reset
+controller device by the core.
+
+A stub version of this API is provided when the reset controller framework is
+not in use in order to minimize the need to use ifdefs.
+
+Shared and exclusive resets
+---------------------------
+
+The reset controller API provides either reference counted deassertion and
+assertion or direct, exclusive control.
+The distinction between shared and exclusive reset controls is made at the time
+the reset control is requested, either via devm_reset_control_get_shared() or
+via devm_reset_control_get_exclusive().
+This choice determines the behavior of the API calls made with the reset
+control.
+
+Shared resets behave similarly to clocks in the kernel clock framework.
+They provide reference counted deassertion, where only the first deassert,
+which increments the deassertion reference count to one, and the last assert
+which decrements the deassertion reference count back to zero, have a physical
+effect on the reset line.
+
+Exclusive resets on the other hand guarantee direct control.
+That is, an assert causes the reset line to be asserted immediately, and a
+deassert causes the reset line to be deasserted immediately.
+
+Assertion and deassertion
+-------------------------
+
+Consumer drivers use the reset_control_assert() and reset_control_deassert()
+functions to assert and deassert reset lines.
+For shared reset controls, calls to the two functions must be balanced.
+
+Note that since multiple consumers may be using a shared reset control, there
+is no guarantee that calling reset_control_assert() on a shared reset control
+will actually cause the reset line to be asserted.
+Consumer drivers using shared reset controls should assume that the reset line
+may be kept deasserted at all times.
+The API only guarantees that the reset line can not be asserted as long as any
+consumer has requested it to be deasserted.
+
+Triggering
+----------
+
+Consumer drivers use reset_control_reset() to trigger a reset pulse on a
+self-deasserting reset control.
+In general, these resets can not be shared between multiple consumers, since
+requesting a pulse from any consumer driver will reset all connected
+peripherals.
+
+The reset controller API allows requesting self-deasserting reset controls as
+shared, but for those only the first trigger request causes an actual pulse to
+be issued on the reset line.
+All further calls to this function have no effect until all consumers have
+called reset_control_rearm().
+For shared reset controls, calls to the two functions must be balanced.
+This allows devices that only require an initial reset at any point before the
+driver is probed or resumed to share a pulsed reset line.
+
+Querying
+--------
+
+Only some reset controllers support querying the current status of a reset
+line, via reset_control_status().
+If supported, this function returns a positive non-zero value if the given
+reset line is asserted.
+The reset_control_status() function does not accept a
+`reset control array <#reset-control-arrays>`__ handle as its input parameter.
+
+Optional resets
+---------------
+
+Often peripherals require a reset line on some platforms but not on others.
+For this, reset controls can be requested as optional using
+devm_reset_control_get_optional_exclusive() or
+devm_reset_control_get_optional_shared().
+These functions return a NULL pointer instead of an error when the requested
+reset control is not specified in the device tree.
+Passing a NULL pointer to the reset_control functions causes them to return
+quietly without an error.
+
+Reset control arrays
+--------------------
+
+Some drivers need to assert a bunch of reset lines in no particular order.
+devm_reset_control_array_get() returns an opaque reset control handle that can
+be used to assert, deassert, or trigger all specified reset controls at once.
+The reset control API does not guarantee the order in which the individual
+controls therein are handled.
+
+Reset controller driver interface
+=================================
+
+Drivers for reset controller modules provide the functionality necessary to
+assert or deassert reset signals, to trigger a reset pulse on a reset line, or
+to query its current state.
+All functions are optional.
+
+Initialization
+--------------
+
+Drivers fill a struct :c:type:`reset_controller_dev` and register it with
+reset_controller_register() in their probe function.
+The actual functionality is implemented in callback functions via a struct
+:c:type:`reset_control_ops`.
+
+API reference
+=============
+
+The reset controller API is documented here in two parts:
+the `reset consumer API <#reset-consumer-api>`__ and the `reset controller
+driver API <#reset-controller-driver-api>`__.
+
+Reset consumer API
+------------------
+
+Reset consumers can control a reset line using an opaque reset control handle,
+which can be obtained from devm_reset_control_get_exclusive() or
+devm_reset_control_get_shared().
+Given the reset control, consumers can call reset_control_assert() and
+reset_control_deassert(), trigger a reset pulse using reset_control_reset(), or
+query the reset line status using reset_control_status().
+
+.. kernel-doc:: include/linux/reset.h
+   :internal:
+
+.. kernel-doc:: drivers/reset/core.c
+   :functions: reset_control_reset
+               reset_control_assert
+               reset_control_deassert
+               reset_control_status
+               reset_control_acquire
+               reset_control_release
+               reset_control_rearm
+               reset_control_put
+               of_reset_control_get_count
+               devm_reset_control_array_get
+               reset_control_get_count
+
+Reset controller driver API
+---------------------------
+
+Reset controller drivers are supposed to implement the necessary functions in
+a static constant structure :c:type:`reset_control_ops`, allocate and fill out
+a struct :c:type:`reset_controller_dev`, and register it using
+devm_reset_controller_register().
+
+.. kernel-doc:: include/linux/reset-controller.h
+   :internal:
+
+.. kernel-doc:: drivers/reset/core.c
+   :functions: of_reset_simple_xlate
+               reset_controller_register
+               reset_controller_unregister
+               devm_reset_controller_register