Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 174 insertions, 0 deletions

diff --git a/Documentation/wmi/acpi-interface.rst b/Documentation/wmi/acpi-interface.rst
new file mode 100644
index 000000000..4657101c5
--- /dev/null
+++ b/Documentation/wmi/acpi-interface.rst
@@ -0,0 +1,174 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==================
+ACPI WMI interface
+==================
+
+The ACPI WMI interface is a proprietary extension of the ACPI specification made
+by Microsoft to allow hardware vendors to embed WMI (Windows Management Instrumentation)
+objects inside their ACPI firmware. Typical functions implemented over ACPI WMI
+are hotkey events on modern notebooks and configuration of BIOS options.
+
+PNP0C14 ACPI device
+-------------------
+
+Discovery of WMI objects is handled by defining ACPI devices with a PNP ID
+of ``PNP0C14``. These devices will contain a set of ACPI buffers and methods
+used for mapping and execution of WMI methods and/or queries. If there exist
+multiple of such devices, then each device is required to have a
+unique ACPI UID.
+
+_WDG buffer
+-----------
+
+The ``_WDG`` buffer is used to discover WMI objects and is required to be
+static. Its internal structure consists of data blocks with a size of 20 bytes,
+containing the following data:
+
+======= =============== =====================================================
+Offset  Size (in bytes) Content
+======= =============== =====================================================
+0x00    16              128 bit Variant 2 object GUID.
+0x10    2               2 character method ID or single byte notification ID.
+0x12    1               Object instance count.
+0x13    1               Object flags.
+======= =============== =====================================================
+
+The WMI object flags control whether the method or notification ID is used:
+
+- 0x1: Data block is expensive to collect.
+- 0x2: Data block contains WMI methods.
+- 0x4: Data block contains ASCIZ string.
+- 0x8: Data block describes a WMI event, use notification ID instead
+  of method ID.
+
+Each WMI object GUID can appear multiple times inside a system.
+The method/notification ID is used to construct the ACPI method names used for
+interacting with the WMI object.
+
+WQxx ACPI methods
+-----------------
+
+If a data block does not contain WMI methods, then its content can be retrieved
+by this required ACPI method. The last two characters of the ACPI method name
+are the method ID of the data block to query. Their single parameter is an
+integer describing the instance which should be queried. This parameter can be
+omitted if the data block contains only a single instance.
+
+WSxx ACPI methods
+-----------------
+
+Similar to the ``WQxx`` ACPI methods, except that it is optional and takes an
+additional buffer as its second argument. The instance argument also cannot
+be omitted.
+
+WMxx ACPI methods
+-----------------
+
+Used for executing WMI methods associated with a data block. The last two
+characters of the ACPI method name are the method ID of the data block
+containing the WMI methods. Their first parameter is a integer describing the
+instance which methods should be executed. The second parameter is an integer
+describing the WMI method ID to execute, and the third parameter is a buffer
+containing the WMI method parameters. If the data block is marked as containing
+an ASCIZ string, then this buffer should contain an ASCIZ string. The ACPI
+method will return the result of the executed WMI method.
+
+WExx ACPI methods
+-----------------
+
+Used for optionally enabling/disabling WMI events, the last two characters of
+the ACPI method are the notification ID of the data block describing the WMI
+event as hexadecimal value. Their first parameter is an integer with a value
+of 0 if the WMI event should be disabled, other values will enable
+the WMI event.
+
+Those ACPI methods are always called even for WMI events not registered as
+being expensive to collect to match the behavior of the Windows driver.
+
+WCxx ACPI methods
+-----------------
+Similar to the ``WExx`` ACPI methods, except that instead of WMI events it controls
+data collection of data blocks registered as being expensive to collect. Thus the
+last two characters of the ACPI method name are the method ID of the data block
+to enable/disable.
+
+Those ACPI methods are also called before setting data blocks to match the
+behavior of the Windows driver.
+
+_WED ACPI method
+----------------
+
+Used to retrieve additional WMI event data, its single parameter is a integer
+holding the notification ID of the event. This method should be evaluated every
+time an ACPI notification is received, since some ACPI implementations use a
+queue to store WMI event data items. This queue will overflow after a couple
+of WMI events are received without retrieving the associated WMI event data.
+
+Conversion rules for ACPI data types
+------------------------------------
+
+Consumers of the ACPI-WMI interface use binary buffers to exchange data with the WMI driver core,
+with the internal structure of the buffer being only know to the consumers. The WMI driver core is
+thus responsible for converting the data inside the buffer into an appropriate ACPI data type for
+consumption by the ACPI firmware. Additionally, any data returned by the various ACPI methods needs
+to be converted back into a binary buffer.
+
+The layout of said buffers is defined by the MOF description of the WMI method or data block in
+question [1]_:
+
+=============== ======================================================================= =========
+Data Type       Layout                                                                  Alignment
+=============== ======================================================================= =========
+``string``      Starts with an unsigned 16-bit little endian integer specifying         2 bytes
+                the length of the string data in bytes, followed by the string data
+                encoded as UTF-16LE with **optional** NULL termination and padding.
+                Keep in mind that some firmware implementations might depend on the
+                terminating NULL character to be present. Also the padding should
+                always be performed with NULL characters.
+``boolean``     Single byte where 0 means ``false`` and nonzero means ``true``.         1 byte
+``sint8``       Signed 8-bit integer.                                                   1 byte
+``uint8``       Unsigned 8-bit integer.                                                 1 byte
+``sint16``      Signed 16-bit little endian integer.                                    2 bytes
+``uint16``      Unsigned 16-bit little endian integer.                                  2 bytes
+``sint32``      Signed 32-bit little endian integer.                                    4 bytes
+``uint32``      Unsigned 32-bit little endian integer.                                  4 bytes
+``sint64``      Signed 64-bit little endian integer.                                    8 bytes
+``uint64``      Unsigned 64-bit little endian integer.                                  8 bytes
+``datetime``    A fixed-length 25-character UTF-16LE string with the format             2 bytes
+                *yyyymmddhhmmss.mmmmmmsutc* where *yyyy* is the 4-digit year, *mm* is
+                the 2-digit month, *dd* is the 2-digit day, *hh* is the 2-digit hour
+                based on a 24-hour clock, *mm* is the 2-digit minute, *ss* is the
+                2-digit second, *mmmmmm* is the 6-digit microsecond, *s* is a plus or
+                minus character depending on whether *utc* is a positive or negative
+                offset from UTC (or a colon if the date is an interval). Unpopulated
+                fields should be filled with asterisks.
+=============== ======================================================================= =========
+
+Arrays should be aligned based on the alignment of their base type, while objects should be
+aligned based on the largest alignment of an element inside them.
+
+All buffers returned by the WMI driver core are 8-byte aligned. When converting ACPI data types
+into such buffers the following conversion rules apply:
+
+=============== ============================================================
+ACPI Data Type  Converted into
+=============== ============================================================
+Buffer          Copied as-is.
+Integer         Converted into a ``uint32``.
+String          Converted into a ``string`` with a terminating NULL character
+                to match the behavior the of the Windows driver.
+Package         Each element inside the package is converted with alignment
+                of the resulting data types being respected. Nested packages
+                are not allowed.
+=============== ============================================================
+
+The Windows driver does attempt to handle nested packages, but this results in internal data
+structures (``_ACPI_METHOD_ARGUMENT_V1``) erroneously being copied into the resulting buffer.
+ACPI firmware implementations should thus not return nested packages from ACPI methods
+associated with the ACPI-WMI interface.
+
+References
+==========
+
+.. [1] https://learn.microsoft.com/en-us/windows-hardware/drivers/kernel/driver-defined-wmi-data-items