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, 178 insertions, 0 deletions

diff --git a/Documentation/gpu/tegra.rst b/Documentation/gpu/tegra.rst
new file mode 100644
index 000000000..d2ed8938c
--- /dev/null
+++ b/Documentation/gpu/tegra.rst
@@ -0,0 +1,178 @@
+===============================================
+ drm/tegra NVIDIA Tegra GPU and display driver
+===============================================
+
+NVIDIA Tegra SoCs support a set of display, graphics and video functions via
+the host1x controller. host1x supplies command streams, gathered from a push
+buffer provided directly by the CPU, to its clients via channels. Software,
+or blocks amongst themselves, can use syncpoints for synchronization.
+
+Up until, but not including, Tegra124 (aka Tegra K1) the drm/tegra driver
+supports the built-in GPU, comprised of the gr2d and gr3d engines. Starting
+with Tegra124 the GPU is based on the NVIDIA desktop GPU architecture and
+supported by the drm/nouveau driver.
+
+The drm/tegra driver supports NVIDIA Tegra SoC generations since Tegra20. It
+has three parts:
+
+  - A host1x driver that provides infrastructure and access to the host1x
+    services.
+
+  - A KMS driver that supports the display controllers as well as a number of
+    outputs, such as RGB, HDMI, DSI, and DisplayPort.
+
+  - A set of custom userspace IOCTLs that can be used to submit jobs to the
+    GPU and video engines via host1x.
+
+Driver Infrastructure
+=====================
+
+The various host1x clients need to be bound together into a logical device in
+order to expose their functionality to users. The infrastructure that supports
+this is implemented in the host1x driver. When a driver is registered with the
+infrastructure it provides a list of compatible strings specifying the devices
+that it needs. The infrastructure creates a logical device and scan the device
+tree for matching device nodes, adding the required clients to a list. Drivers
+for individual clients register with the infrastructure as well and are added
+to the logical host1x device.
+
+Once all clients are available, the infrastructure will initialize the logical
+device using a driver-provided function which will set up the bits specific to
+the subsystem and in turn initialize each of its clients.
+
+Similarly, when one of the clients is unregistered, the infrastructure will
+destroy the logical device by calling back into the driver, which ensures that
+the subsystem specific bits are torn down and the clients destroyed in turn.
+
+Host1x Infrastructure Reference
+-------------------------------
+
+.. kernel-doc:: include/linux/host1x.h
+
+.. kernel-doc:: drivers/gpu/host1x/bus.c
+   :export:
+
+Host1x Syncpoint Reference
+--------------------------
+
+.. kernel-doc:: drivers/gpu/host1x/syncpt.c
+   :export:
+
+KMS driver
+==========
+
+The display hardware has remained mostly backwards compatible over the various
+Tegra SoC generations, up until Tegra186 which introduces several changes that
+make it difficult to support with a parameterized driver.
+
+Display Controllers
+-------------------
+
+Tegra SoCs have two display controllers, each of which can be associated with
+zero or more outputs. Outputs can also share a single display controller, but
+only if they run with compatible display timings. Two display controllers can
+also share a single framebuffer, allowing cloned configurations even if modes
+on two outputs don't match. A display controller is modelled as a CRTC in KMS
+terms.
+
+On Tegra186, the number of display controllers has been increased to three. A
+display controller can no longer drive all of the outputs. While two of these
+controllers can drive both DSI outputs and both SOR outputs, the third cannot
+drive any DSI.
+
+Windows
+~~~~~~~
+
+A display controller controls a set of windows that can be used to composite
+multiple buffers onto the screen. While it is possible to assign arbitrary Z
+ordering to individual windows (by programming the corresponding blending
+registers), this is currently not supported by the driver. Instead, it will
+assume a fixed Z ordering of the windows (window A is the root window, that
+is, the lowest, while windows B and C are overlaid on top of window A). The
+overlay windows support multiple pixel formats and can automatically convert
+from YUV to RGB at scanout time. This makes them useful for displaying video
+content. In KMS, each window is modelled as a plane. Each display controller
+has a hardware cursor that is exposed as a cursor plane.
+
+Outputs
+-------
+
+The type and number of supported outputs varies between Tegra SoC generations.
+All generations support at least HDMI. While earlier generations supported the
+very simple RGB interfaces (one per display controller), recent generations no
+longer do and instead provide standard interfaces such as DSI and eDP/DP.
+
+Outputs are modelled as a composite encoder/connector pair.
+
+RGB/LVDS
+~~~~~~~~
+
+This interface is no longer available since Tegra124. It has been replaced by
+the more standard DSI and eDP interfaces.
+
+HDMI
+~~~~
+
+HDMI is supported on all Tegra SoCs. Starting with Tegra210, HDMI is provided
+by the versatile SOR output, which supports eDP, DP and HDMI. The SOR is able
+to support HDMI 2.0, though support for this is currently not merged.
+
+DSI
+~~~
+
+Although Tegra has supported DSI since Tegra30, the controller has changed in
+several ways in Tegra114. Since none of the publicly available development
+boards prior to Dalmore (Tegra114) have made use of DSI, only Tegra114 and
+later are supported by the drm/tegra driver.
+
+eDP/DP
+~~~~~~
+
+eDP was first introduced in Tegra124 where it was used to drive the display
+panel for notebook form factors. Tegra210 added support for full DisplayPort
+support, though this is currently not implemented in the drm/tegra driver.
+
+Userspace Interface
+===================
+
+The userspace interface provided by drm/tegra allows applications to create
+GEM buffers, access and control syncpoints as well as submit command streams
+to host1x.
+
+GEM Buffers
+-----------
+
+The ``DRM_IOCTL_TEGRA_GEM_CREATE`` IOCTL is used to create a GEM buffer object
+with Tegra-specific flags. This is useful for buffers that should be tiled, or
+that are to be scanned out upside down (useful for 3D content).
+
+After a GEM buffer object has been created, its memory can be mapped by an
+application using the mmap offset returned by the ``DRM_IOCTL_TEGRA_GEM_MMAP``
+IOCTL.
+
+Syncpoints
+----------
+
+The current value of a syncpoint can be obtained by executing the
+``DRM_IOCTL_TEGRA_SYNCPT_READ`` IOCTL. Incrementing the syncpoint is achieved
+using the ``DRM_IOCTL_TEGRA_SYNCPT_INCR`` IOCTL.
+
+Userspace can also request blocking on a syncpoint. To do so, it needs to
+execute the ``DRM_IOCTL_TEGRA_SYNCPT_WAIT`` IOCTL, specifying the value of
+the syncpoint to wait for. The kernel will release the application when the
+syncpoint reaches that value or after a specified timeout.
+
+Command Stream Submission
+-------------------------
+
+Before an application can submit command streams to host1x it needs to open a
+channel to an engine using the ``DRM_IOCTL_TEGRA_OPEN_CHANNEL`` IOCTL. Client
+IDs are used to identify the target of the channel. When a channel is no
+longer needed, it can be closed using the ``DRM_IOCTL_TEGRA_CLOSE_CHANNEL``
+IOCTL. To retrieve the syncpoint associated with a channel, an application
+can use the ``DRM_IOCTL_TEGRA_GET_SYNCPT``.
+
+After opening a channel, submitting command streams is easy. The application
+writes commands into the memory backing a GEM buffer object and passes these
+to the ``DRM_IOCTL_TEGRA_SUBMIT`` IOCTL along with various other parameters,
+such as the syncpoints or relocations used in the job submission.