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
  ...

4 files changed, 275 insertions, 0 deletions

diff --git a/Documentation/driver-api/pci/index.rst b/Documentation/driver-api/pci/index.rst
new file mode 100644
index 000000000..1abfbecf6
--- /dev/null
+++ b/Documentation/driver-api/pci/index.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================================
+The Linux PCI driver implementer's API guide
+============================================
+
+.. toctree::
+   :caption: Table of contents
+   :maxdepth: 2
+
+   pci
+   p2pdma
+   tsm
diff --git a/Documentation/driver-api/pci/p2pdma.rst b/Documentation/driver-api/pci/p2pdma.rst
new file mode 100644
index 000000000..d3f406cca
--- /dev/null
+++ b/Documentation/driver-api/pci/p2pdma.rst
@@ -0,0 +1,182 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+PCI Peer-to-Peer DMA Support
+============================
+
+The PCI bus has pretty decent support for performing DMA transfers
+between two devices on the bus. This type of transaction is henceforth
+called Peer-to-Peer (or P2P). However, there are a number of issues that
+make P2P transactions tricky to do in a perfectly safe way.
+
+For PCIe the routing of Transaction Layer Packets (TLPs) is well-defined up
+until they reach a host bridge or root port. If the path includes PCIe switches
+then based on the ACS settings the transaction can route entirely within
+the PCIe hierarchy and never reach the root port. The kernel will evaluate
+the PCIe topology and always permit P2P in these well-defined cases.
+
+However, if the P2P transaction reaches the host bridge then it might have to
+hairpin back out the same root port, be routed inside the CPU SOC to another
+PCIe root port, or routed internally to the SOC.
+
+The PCIe specification doesn't define the forwarding of transactions between
+hierarchy domains and kernel defaults to blocking such routing. There is an
+allow list to allow detecting known-good HW, in which case P2P between any
+two PCIe devices will be permitted.
+
+Since P2P inherently is doing transactions between two devices it requires two
+drivers to be co-operating inside the kernel. The providing driver has to convey
+its MMIO to the consuming driver. To meet the driver model lifecycle rules the
+MMIO must have all DMA mapping removed, all CPU accesses prevented, all page
+table mappings undone before the providing driver completes remove().
+
+This requires the providing and consuming driver to actively work together to
+guarantee that the consuming driver has stopped using the MMIO during a removal
+cycle. This is done by either a synchronous invalidation shutdown or waiting
+for all usage refcounts to reach zero.
+
+At the lowest level the P2P subsystem offers a naked struct p2p_provider that
+delegates lifecycle management to the providing driver. It is expected that
+drivers using this option will wrap their MMIO memory in DMABUF and use DMABUF
+to provide an invalidation shutdown. These MMIO addresses have no struct page, and
+if used with mmap() must create special PTEs. As such there are very few
+kernel uAPIs that can accept pointers to them; in particular they cannot be used
+with read()/write(), including O_DIRECT.
+
+Building on this, the subsystem offers a layer to wrap the MMIO in a ZONE_DEVICE
+pgmap of MEMORY_DEVICE_PCI_P2PDMA to create struct pages. The lifecycle of
+pgmap ensures that when the pgmap is destroyed all other drivers have stopped
+using the MMIO. This option works with O_DIRECT flows, in some cases, if the
+underlying subsystem supports handling MEMORY_DEVICE_PCI_P2PDMA through
+FOLL_PCI_P2PDMA. The use of FOLL_LONGTERM is prevented. As this relies on pgmap
+it also relies on architecture support along with alignment and minimum size
+limitations.
+
+
+Driver Writer's Guide
+=====================
+
+In a given P2P implementation there may be three or more different
+types of kernel drivers in play:
+
+* Provider - A driver which provides or publishes P2P resources like
+  memory or doorbell registers to other drivers.
+* Client - A driver which makes use of a resource by setting up a
+  DMA transaction to or from it.
+* Orchestrator - A driver which orchestrates the flow of data between
+  clients and providers.
+
+In many cases there could be overlap between these three types (i.e.,
+it may be typical for a driver to be both a provider and a client).
+
+For example, in the NVMe Target Copy Offload implementation:
+
+* The NVMe PCI driver is both a client, provider and orchestrator
+  in that it exposes any CMB (Controller Memory Buffer) as a P2P memory
+  resource (provider), it accepts P2P memory pages as buffers in requests
+  to be used directly (client) and it can also make use of the CMB as
+  submission queue entries (orchestrator).
+* The RDMA driver is a client in this arrangement so that an RNIC
+  can DMA directly to the memory exposed by the NVMe device.
+* The NVMe Target driver (nvmet) can orchestrate the data from the RNIC
+  to the P2P memory (CMB) and then to the NVMe device (and vice versa).
+
+This is currently the only arrangement supported by the kernel but
+one could imagine slight tweaks to this that would allow for the same
+functionality. For example, if a specific RNIC added a BAR with some
+memory behind it, its driver could add support as a P2P provider and
+then the NVMe Target could use the RNIC's memory instead of the CMB
+in cases where the NVMe cards in use do not have CMB support.
+
+
+Provider Drivers
+----------------
+
+A provider simply needs to register a BAR (or a portion of a BAR)
+as a P2P DMA resource using :c:func:`pci_p2pdma_add_resource()`.
+This will register struct pages for all the specified memory.
+
+After that it may optionally publish all of its resources as
+P2P memory using :c:func:`pci_p2pmem_publish()`. This will allow
+any orchestrator drivers to find and use the memory. When marked in
+this way, the resource must be regular memory with no side effects.
+
+For the time being this is fairly rudimentary in that all resources
+are typically going to be P2P memory. Future work will likely expand
+this to include other types of resources like doorbells.
+
+
+Client Drivers
+--------------
+
+A client driver only has to use the mapping API :c:func:`dma_map_sg()`
+and :c:func:`dma_unmap_sg()` functions as usual, and the implementation
+will do the right thing for the P2P capable memory.
+
+
+Orchestrator Drivers
+--------------------
+
+The first task an orchestrator driver must do is compile a list of
+all client devices that will be involved in a given transaction. For
+example, the NVMe Target driver creates a list including the namespace
+block device and the RNIC in use. If the orchestrator has access to
+a specific P2P provider to use it may check compatibility using
+:c:func:`pci_p2pdma_distance()` otherwise it may find a memory provider
+that's compatible with all clients using  :c:func:`pci_p2pmem_find()`.
+If more than one provider is supported, the one nearest to all the clients will
+be chosen first. If more than one provider is an equal distance away, the
+one returned will be chosen at random (it is not an arbitrary but
+truly random). This function returns the PCI device to use for the provider
+with a reference taken and therefore when it's no longer needed it should be
+returned with pci_dev_put().
+
+Once a provider is selected, the orchestrator can then use
+:c:func:`pci_alloc_p2pmem()` and :c:func:`pci_free_p2pmem()` to
+allocate P2P memory from the provider. :c:func:`pci_p2pmem_alloc_sgl()`
+and :c:func:`pci_p2pmem_free_sgl()` are convenience functions for
+allocating scatter-gather lists with P2P memory.
+
+Struct Page Caveats
+-------------------
+
+While the MEMORY_DEVICE_PCI_P2PDMA pages can be installed in VMAs,
+pin_user_pages() and related will not return them unless FOLL_PCI_P2PDMA is set.
+
+The MEMORY_DEVICE_PCI_P2PDMA pages require care to support in the kernel. The
+KVA is still MMIO and must still be accessed through the normal
+readX()/writeX()/etc helpers. Direct CPU access (e.g. memcpy) is forbidden, just
+like any other MMIO mapping. While this will actually work on some
+architectures, others will experience corruption or just crash in the kernel.
+Supporting FOLL_PCI_P2PDMA in a subsystem requires scrubbing it to ensure no CPU
+access happens.
+
+
+Usage With DMABUF
+=================
+
+DMABUF provides an alternative to the above struct page-based
+client/provider/orchestrator system and should be used when struct page
+doesn't exist. In this mode the exporting driver will wrap
+some of its MMIO in a DMABUF and give the DMABUF FD to userspace.
+
+Userspace can then pass the FD to an importing driver which will ask the
+exporting driver to map it to the importer.
+
+In this case the initiator and target pci_devices are known and the P2P subsystem
+is used to determine the mapping type. The phys_addr_t-based DMA API is used to
+establish the dma_addr_t.
+
+Lifecycle is controlled by DMABUF move_notify(). When the exporting driver wants
+to remove() it must deliver an invalidation shutdown to all DMABUF importing
+drivers through move_notify() and synchronously DMA unmap all the MMIO.
+
+No importing driver can continue to have a DMA map to the MMIO after the
+exporting driver has destroyed its p2p_provider.
+
+
+P2P DMA Support Library
+=======================
+
+.. kernel-doc:: drivers/pci/p2pdma.c
+   :export:
diff --git a/Documentation/driver-api/pci/pci.rst b/Documentation/driver-api/pci/pci.rst
new file mode 100644
index 000000000..99a1bbaae
--- /dev/null
+++ b/Documentation/driver-api/pci/pci.rst
@@ -0,0 +1,59 @@
+PCI Support Library
+-------------------
+
+.. kernel-doc:: drivers/pci/pci.c
+   :export:
+
+.. kernel-doc:: drivers/pci/iomap.c
+   :export:
+
+.. kernel-doc:: drivers/pci/devres.c
+   :export:
+
+.. kernel-doc:: drivers/pci/pci-driver.c
+   :export:
+
+.. kernel-doc:: drivers/pci/remove.c
+   :export:
+
+.. kernel-doc:: drivers/pci/search.c
+   :export:
+
+.. kernel-doc:: drivers/pci/msi/msi.c
+   :export:
+
+.. kernel-doc:: drivers/pci/bus.c
+   :export:
+
+.. kernel-doc:: drivers/pci/access.c
+   :export:
+
+.. kernel-doc:: drivers/pci/irq.c
+   :export:
+
+.. kernel-doc:: drivers/pci/probe.c
+   :export:
+
+.. kernel-doc:: drivers/pci/slot.c
+   :export:
+
+.. kernel-doc:: drivers/pci/rebar.c
+   :export:
+
+.. kernel-doc:: drivers/pci/rom.c
+   :export:
+
+.. kernel-doc:: drivers/pci/iov.c
+   :export:
+
+.. kernel-doc:: drivers/pci/pci-sysfs.c
+   :internal:
+
+.. kernel-doc:: drivers/pci/tph.c
+   :export:
+
+PCI Hotplug Support Library
+---------------------------
+
+.. kernel-doc:: drivers/pci/hotplug/pci_hotplug_core.c
+   :export:
diff --git a/Documentation/driver-api/pci/tsm.rst b/Documentation/driver-api/pci/tsm.rst
new file mode 100644
index 000000000..232b92bec
--- /dev/null
+++ b/Documentation/driver-api/pci/tsm.rst
@@ -0,0 +1,21 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+========================================================
+PCI Trusted Execution Environment Security Manager (TSM)
+========================================================
+
+Subsystem Interfaces
+====================
+
+.. kernel-doc:: include/linux/pci-ide.h
+   :internal:
+
+.. kernel-doc:: drivers/pci/ide.c
+   :export:
+
+.. kernel-doc:: include/linux/pci-tsm.h
+   :internal:
+
+.. kernel-doc:: drivers/pci/tsm.c
+   :export: