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, 263 insertions, 0 deletions

diff --git a/Documentation/driver-api/ntb.rst b/Documentation/driver-api/ntb.rst
new file mode 100644
index 000000000..a49c41383
--- /dev/null
+++ b/Documentation/driver-api/ntb.rst
@@ -0,0 +1,263 @@
+===========
+NTB Drivers
+===========
+
+NTB (Non-Transparent Bridge) is a type of PCI-Express bridge chip that connects
+the separate memory systems of two or more computers to the same PCI-Express
+fabric. Existing NTB hardware supports a common feature set: doorbell
+registers and memory translation windows, as well as non common features like
+scratchpad and message registers. Scratchpad registers are read-and-writable
+registers that are accessible from either side of the device, so that peers can
+exchange a small amount of information at a fixed address. Message registers can
+be utilized for the same purpose. Additionally they are provided with
+special status bits to make sure the information isn't rewritten by another
+peer. Doorbell registers provide a way for peers to send interrupt events.
+Memory windows allow translated read and write access to the peer memory.
+
+NTB Core Driver (ntb)
+=====================
+
+The NTB core driver defines an api wrapping the common feature set, and allows
+clients interested in NTB features to discover NTB the devices supported by
+hardware drivers.  The term "client" is used here to mean an upper layer
+component making use of the NTB api.  The term "driver," or "hardware driver,"
+is used here to mean a driver for a specific vendor and model of NTB hardware.
+
+NTB Client Drivers
+==================
+
+NTB client drivers should register with the NTB core driver.  After
+registering, the client probe and remove functions will be called appropriately
+as ntb hardware, or hardware drivers, are inserted and removed.  The
+registration uses the Linux Device framework, so it should feel familiar to
+anyone who has written a pci driver.
+
+NTB Typical client driver implementation
+----------------------------------------
+
+Primary purpose of NTB is to share some piece of memory between at least two
+systems. So the NTB device features like Scratchpad/Message registers are
+mainly used to perform the proper memory window initialization. Typically
+there are two types of memory window interfaces supported by the NTB API:
+inbound translation configured on the local ntb port and outbound translation
+configured by the peer, on the peer ntb port. The first type is
+depicted on the next figure::
+
+ Inbound translation:
+
+ Memory:              Local NTB Port:      Peer NTB Port:      Peer MMIO:
+  ____________
+ | dma-mapped |-ntb_mw_set_trans(addr)  |
+ | memory     |        _v____________   |   ______________
+ | (addr)     |<======| MW xlat addr |<====| MW base addr |<== memory-mapped IO
+ |------------|       |--------------|  |  |--------------|
+
+So typical scenario of the first type memory window initialization looks:
+1) allocate a memory region, 2) put translated address to NTB config,
+3) somehow notify a peer device of performed initialization, 4) peer device
+maps corresponding outbound memory window so to have access to the shared
+memory region.
+
+The second type of interface, that implies the shared windows being
+initialized by a peer device, is depicted on the figure::
+
+ Outbound translation:
+
+ Memory:        Local NTB Port:    Peer NTB Port:      Peer MMIO:
+  ____________                      ______________
+ | dma-mapped |                |   | MW base addr |<== memory-mapped IO
+ | memory     |                |   |--------------|
+ | (addr)     |<===================| MW xlat addr |<-ntb_peer_mw_set_trans(addr)
+ |------------|                |   |--------------|
+
+Typical scenario of the second type interface initialization would be:
+1) allocate a memory region, 2) somehow deliver a translated address to a peer
+device, 3) peer puts the translated address to NTB config, 4) peer device maps
+outbound memory window so to have access to the shared memory region.
+
+As one can see the described scenarios can be combined in one portable
+algorithm.
+
+ Local device:
+  1) Allocate memory for a shared window
+  2) Initialize memory window by translated address of the allocated region
+     (it may fail if local memory window initialization is unsupported)
+  3) Send the translated address and memory window index to a peer device
+
+ Peer device:
+  1) Initialize memory window with retrieved address of the allocated
+     by another device memory region (it may fail if peer memory window
+     initialization is unsupported)
+  2) Map outbound memory window
+
+In accordance with this scenario, the NTB Memory Window API can be used as
+follows:
+
+ Local device:
+  1) ntb_mw_count(pidx) - retrieve number of memory ranges, which can
+     be allocated for memory windows between local device and peer device
+     of port with specified index.
+  2) ntb_get_align(pidx, midx) - retrieve parameters restricting the
+     shared memory region alignment and size. Then memory can be properly
+     allocated.
+  3) Allocate physically contiguous memory region in compliance with
+     restrictions retrieved in 2).
+  4) ntb_mw_set_trans(pidx, midx) - try to set translation address of
+     the memory window with specified index for the defined peer device
+     (it may fail if local translated address setting is not supported)
+  5) Send translated base address (usually together with memory window
+     number) to the peer device using, for instance, scratchpad or message
+     registers.
+
+ Peer device:
+  1) ntb_peer_mw_set_trans(pidx, midx) - try to set received from other
+     device (related to pidx) translated address for specified memory
+     window. It may fail if retrieved address, for instance, exceeds
+     maximum possible address or isn't properly aligned.
+  2) ntb_peer_mw_get_addr(widx) - retrieve MMIO address to map the memory
+     window so to have an access to the shared memory.
+
+Also it is worth to note, that method ntb_mw_count(pidx) should return the
+same value as ntb_peer_mw_count() on the peer with port index - pidx.
+
+NTB Transport Client (ntb\_transport) and NTB Netdev (ntb\_netdev)
+------------------------------------------------------------------
+
+The primary client for NTB is the Transport client, used in tandem with NTB
+Netdev.  These drivers function together to create a logical link to the peer,
+across the ntb, to exchange packets of network data.  The Transport client
+establishes a logical link to the peer, and creates queue pairs to exchange
+messages and data.  The NTB Netdev then creates an ethernet device using a
+Transport queue pair.  Network data is copied between socket buffers and the
+Transport queue pair buffer.  The Transport client may be used for other things
+besides Netdev, however no other applications have yet been written.
+
+NTB Ping Pong Test Client (ntb\_pingpong)
+-----------------------------------------
+
+The Ping Pong test client serves as a demonstration to exercise the doorbell
+and scratchpad registers of NTB hardware, and as an example simple NTB client.
+Ping Pong enables the link when started, waits for the NTB link to come up, and
+then proceeds to read and write the doorbell scratchpad registers of the NTB.
+The peers interrupt each other using a bit mask of doorbell bits, which is
+shifted by one in each round, to test the behavior of multiple doorbell bits
+and interrupt vectors.  The Ping Pong driver also reads the first local
+scratchpad, and writes the value plus one to the first peer scratchpad, each
+round before writing the peer doorbell register.
+
+Module Parameters:
+
+* unsafe - Some hardware has known issues with scratchpad and doorbell
+	registers.  By default, Ping Pong will not attempt to exercise such
+	hardware.  You may override this behavior at your own risk by setting
+	unsafe=1.
+* delay\_ms - Specify the delay between receiving a doorbell
+	interrupt event and setting the peer doorbell register for the next
+	round.
+* init\_db - Specify the doorbell bits to start new series of rounds.  A new
+	series begins once all the doorbell bits have been shifted out of
+	range.
+* dyndbg - It is suggested to specify dyndbg=+p when loading this module, and
+	then to observe debugging output on the console.
+
+NTB Tool Test Client (ntb\_tool)
+--------------------------------
+
+The Tool test client serves for debugging, primarily, ntb hardware and drivers.
+The Tool provides access through debugfs for reading, setting, and clearing the
+NTB doorbell, and reading and writing scratchpads.
+
+The Tool does not currently have any module parameters.
+
+Debugfs Files:
+
+* *debugfs*/ntb\_tool/*hw*/
+	A directory in debugfs will be created for each
+	NTB device probed by the tool.  This directory is shortened to *hw*
+	below.
+* *hw*/db
+	This file is used to read, set, and clear the local doorbell.  Not
+	all operations may be supported by all hardware.  To read the doorbell,
+	read the file.  To set the doorbell, write `s` followed by the bits to
+	set (eg: `echo 's 0x0101' > db`).  To clear the doorbell, write `c`
+	followed by the bits to clear.
+* *hw*/mask
+	This file is used to read, set, and clear the local doorbell mask.
+	See *db* for details.
+* *hw*/peer\_db
+	This file is used to read, set, and clear the peer doorbell.
+	See *db* for details.
+* *hw*/peer\_mask
+	This file is used to read, set, and clear the peer doorbell
+	mask.  See *db* for details.
+* *hw*/spad
+	This file is used to read and write local scratchpads.  To read
+	the values of all scratchpads, read the file.  To write values, write a
+	series of pairs of scratchpad number and value
+	(eg: `echo '4 0x123 7 0xabc' > spad`
+	# to set scratchpads `4` and `7` to `0x123` and `0xabc`, respectively).
+* *hw*/peer\_spad
+	This file is used to read and write peer scratchpads.  See
+	*spad* for details.
+
+NTB MSI Test Client (ntb\_msi\_test)
+------------------------------------
+
+The MSI test client serves to test and debug the MSI library which
+allows for passing MSI interrupts across NTB memory windows. The
+test client is interacted with through the debugfs filesystem:
+
+* *debugfs*/ntb\_msi\_test/*hw*/
+	A directory in debugfs will be created for each
+	NTB device probed by the msi test.  This directory is shortened to *hw*
+	below.
+* *hw*/port
+	This file describes the local port number
+* *hw*/irq*_occurrences
+	One occurrences file exists for each interrupt and, when read,
+	returns the number of times the interrupt has been triggered.
+* *hw*/peer*/port
+	This file describes the port number for each peer
+* *hw*/peer*/count
+	This file describes the number of interrupts that can be
+	triggered on each peer
+* *hw*/peer*/trigger
+	Writing an interrupt number (any number less than the value
+	specified in count) will trigger the interrupt on the
+	specified peer. That peer's interrupt's occurrence file
+	should be incremented.
+
+NTB Hardware Drivers
+====================
+
+NTB hardware drivers should register devices with the NTB core driver.  After
+registering, clients probe and remove functions will be called.
+
+NTB Intel Hardware Driver (ntb\_hw\_intel)
+------------------------------------------
+
+The Intel hardware driver supports NTB on Xeon and Atom CPUs.
+
+Module Parameters:
+
+* b2b\_mw\_idx
+	If the peer ntb is to be accessed via a memory window, then use
+	this memory window to access the peer ntb.  A value of zero or positive
+	starts from the first mw idx, and a negative value starts from the last
+	mw idx.  Both sides MUST set the same value here!  The default value is
+	`-1`.
+* b2b\_mw\_share
+	If the peer ntb is to be accessed via a memory window, and if
+	the memory window is large enough, still allow the client to use the
+	second half of the memory window for address translation to the peer.
+* xeon\_b2b\_usd\_bar2\_addr64
+	If using B2B topology on Xeon hardware, use
+	this 64 bit address on the bus between the NTB devices for the window
+	at BAR2, on the upstream side of the link.
+* xeon\_b2b\_usd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_usd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_usd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_dsd\_bar2\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_dsd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_dsd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
+* xeon\_b2b\_dsd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*.