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, 373 insertions, 0 deletions

diff --git a/Documentation/arch/x86/amd-debugging.rst b/Documentation/arch/x86/amd-debugging.rst
new file mode 100644
index 000000000..3176a1240
--- /dev/null
+++ b/Documentation/arch/x86/amd-debugging.rst
@@ -0,0 +1,373 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Debugging AMD Zen systems
++++++++++++++++++++++++++
+
+Introduction
+============
+
+This document describes techniques that are useful for debugging issues with
+AMD Zen systems.  It is intended for use by developers and technical users
+to help identify and resolve issues.
+
+S3 vs s2idle
+============
+
+On AMD systems, it's not possible to simultaneously support suspend-to-RAM (S3)
+and suspend-to-idle (s2idle).  To confirm which mode your system supports you
+can look at ``cat /sys/power/mem_sleep``.  If it shows ``s2idle [deep]`` then
+*S3* is supported.  If it shows ``[s2idle]`` then *s2idle* is
+supported.
+
+On systems that support *S3*, the firmware will be utilized to put all hardware into
+the appropriate low power state.
+
+On systems that support *s2idle*, the kernel will be responsible for transitioning devices
+into the appropriate low power state. When all devices are in the appropriate low
+power state, the hardware will transition into a hardware sleep state.
+
+After a suspend cycle you can tell how much time was spent in a hardware sleep
+state by looking at ``cat /sys/power/suspend_stats/last_hw_sleep``.
+
+This flowchart explains how the AMD s2idle suspend flow works.
+
+.. kernel-figure:: suspend.svg
+
+This flowchart explains how the amd s2idle resume flow works.
+
+.. kernel-figure:: resume.svg
+
+s2idle debugging tool
+=====================
+
+As there are a lot of places that problems can occur, a debugging tool has been
+created at
+`amd-debug-tools <https://git.kernel.org/pub/scm/linux/kernel/git/superm1/amd-debug-tools.git/about/>`_
+that can help test for common problems and offer suggestions.
+
+If you have an s2idle issue, it's best to start with this and follow instructions
+from its findings.  If you continue to have an issue, raise a bug with the
+report generated from this script to
+`drm/amd gitlab <https://gitlab.freedesktop.org/drm/amd/-/issues/new?issuable_template=s2idle_BUG_TEMPLATE>`_.
+
+Spurious s2idle wakeups from an IRQ
+===================================
+
+Spurious wakeups will generally have an IRQ set to ``/sys/power/pm_wakeup_irq``.
+This can be matched to ``/proc/interrupts`` to determine what device woke the system.
+
+If this isn't enough to debug the problem, then the following sysfs files
+can be set to add more verbosity to the wakeup process: ::
+
+  # echo 1 | sudo tee /sys/power/pm_debug_messages
+  # echo 1 | sudo tee /sys/power/pm_print_times
+
+After making those changes, the kernel will display messages that can
+be traced back to kernel s2idle loop code as well as display any active
+GPIO sources while waking up.
+
+If the wakeup is caused by the ACPI SCI, additional ACPI debugging may be
+needed.  These commands can enable additional trace data: ::
+
+  # echo enable | sudo tee /sys/module/acpi/parameters/trace_state
+  # echo 1 | sudo tee /sys/module/acpi/parameters/aml_debug_output
+  # echo 0x0800000f | sudo tee /sys/module/acpi/parameters/debug_level
+  # echo 0xffff0000 | sudo tee /sys/module/acpi/parameters/debug_layer
+
+Spurious s2idle wakeups from a GPIO
+===================================
+
+If a GPIO is active when waking up the system ideally you would look at the
+schematic to determine what device it is associated with. If the schematic
+is not available, another tactic is to look at the ACPI _EVT() entry
+to determine what device is notified when that GPIO is active.
+
+For a hypothetical example, say that GPIO 59 woke up the system.  You can
+look at the SSDT to determine what device is notified when GPIO 59 is active.
+
+First convert the GPIO number into hex. ::
+
+  $ python3 -c "print(hex(59))"
+  0x3b
+
+Next determine which ACPI table has the ``_EVT`` entry. For example: ::
+
+  $ sudo grep EVT /sys/firmware/acpi/tables/SSDT*
+  grep: /sys/firmware/acpi/tables/SSDT27: binary file matches
+
+Decode this table::
+
+  $ sudo cp /sys/firmware/acpi/tables/SSDT27 .
+  $ sudo iasl -d SSDT27
+
+Then look at the table and find the matching entry for GPIO 0x3b. ::
+
+  Case (0x3B)
+  {
+      M000 (0x393B)
+      M460 ("    Notify (\\_SB.PCI0.GP17.XHC1, 0x02)\n", Zero, Zero, Zero, Zero, Zero, Zero)
+      Notify (\_SB.PCI0.GP17.XHC1, 0x02) // Device Wake
+  }
+
+You can see in this case that the device ``\_SB.PCI0.GP17.XHC1`` is notified
+when GPIO 59 is active. It's obvious this is an XHCI controller, but to go a
+step further you can figure out which XHCI controller it is by matching it to
+ACPI.::
+
+  $ grep "PCI0.GP17.XHC1" /sys/bus/acpi/devices/*/path
+  /sys/bus/acpi/devices/device:2d/path:\_SB_.PCI0.GP17.XHC1
+  /sys/bus/acpi/devices/device:2e/path:\_SB_.PCI0.GP17.XHC1.RHUB
+  /sys/bus/acpi/devices/device:2f/path:\_SB_.PCI0.GP17.XHC1.RHUB.PRT1
+  /sys/bus/acpi/devices/device:30/path:\_SB_.PCI0.GP17.XHC1.RHUB.PRT1.CAM0
+  /sys/bus/acpi/devices/device:31/path:\_SB_.PCI0.GP17.XHC1.RHUB.PRT1.CAM1
+  /sys/bus/acpi/devices/device:32/path:\_SB_.PCI0.GP17.XHC1.RHUB.PRT2
+  /sys/bus/acpi/devices/LNXPOWER:0d/path:\_SB_.PCI0.GP17.XHC1.PWRS
+
+Here you can see it matches to ``device:2d``. Look at the ``physical_node``
+to determine what PCI device that actually is. ::
+
+  $ ls -l /sys/bus/acpi/devices/device:2d/physical_node
+  lrwxrwxrwx 1 root root 0 Feb 12 13:22 /sys/bus/acpi/devices/device:2d/physical_node -> ../../../../../pci0000:00/0000:00:08.1/0000:c2:00.4
+
+So there you have it: the PCI device associated with this GPIO wakeup was ``0000:c2:00.4``.
+
+The ``amd_s2idle.py`` script will capture most of these artifacts for you.
+
+s2idle PM debug messages
+========================
+
+During the s2idle flow on AMD systems, the ACPI LPS0 driver is responsible
+to check all uPEP constraints.  Failing uPEP constraints does not prevent
+s0i3 entry.  This means that if some constraints are not met, it is possible
+the kernel may attempt to enter s2idle even if there are some known issues.
+
+To activate PM debugging, either specify ``pm_debug_messagess`` kernel
+command-line option at boot or write to ``/sys/power/pm_debug_messages``.
+Unmet constraints will be displayed in the kernel log and can be
+viewed by logging tools that process kernel ring buffer like ``dmesg`` or
+``journalctl``."
+
+If the system freezes on entry/exit before these messages are flushed, a
+useful debugging tactic is to unbind the ``amd_pmc`` driver to prevent
+notification to the platform to start s0i3 entry.  This will stop the
+system from freezing on entry or exit and let you view all the failed
+constraints. ::
+
+  cd /sys/bus/platform/drivers/amd_pmc
+  ls | grep AMD | sudo tee unbind
+
+After doing this, run the suspend cycle and look specifically for errors around: ::
+
+  ACPI: LPI: Constraint not met; min power state:%s current power state:%s
+
+Historical examples of s2idle issues
+====================================
+
+To help understand the types of issues that can occur and how to debug them,
+here are some historical examples of s2idle issues that have been resolved.
+
+Core offlining
+--------------
+An end user had reported that taking a core offline would prevent the system
+from properly entering s0i3.  This was debugged using internal AMD tools
+to capture and display a stream of metrics from the hardware showing what changed
+when a core was offlined.  It was determined that the hardware didn't get
+notification the offline cores were in the deepest state, and so it prevented
+CPU from going into the deepest state. The issue was debugged to a missing
+command to put cores into C3 upon offline.
+
+`commit d6b88ce2eb9d2 ("ACPI: processor idle: Allow playing dead in C3 state") <https://git.kernel.org/torvalds/c/d6b88ce2eb9d2>`_
+
+Corruption after resume
+-----------------------
+A big problem that occurred with Rembrandt was that there was graphical
+corruption after resume.  This happened because of a misalignment of PSP
+and driver responsibility.  The PSP will save and restore DMCUB, but the
+driver assumed it needed to reset DMCUB on resume.
+This actually was a misalignment for earlier silicon as well, but was not
+observed.
+
+`commit 79d6b9351f086 ("drm/amd/display: Don't reinitialize DMCUB on s0ix resume") <https://git.kernel.org/torvalds/c/79d6b9351f086>`_
+
+Back to Back suspends fail
+--------------------------
+When using a wakeup source that triggers the IRQ to wakeup, a bug in the
+pinctrl-amd driver may capture the wrong state of the IRQ and prevent the
+system going back to sleep properly.
+
+`commit b8c824a869f22 ("pinctrl: amd: Don't save/restore interrupt status and wake status bits") <https://git.kernel.org/torvalds/c/b8c824a869f22>`_
+
+Spurious timer based wakeup after 5 minutes
+-------------------------------------------
+The HPET was being used to program the wakeup source for the system, however
+this was causing a spurious wakeup after 5 minutes.  The correct alarm to use
+was the ACPI alarm.
+
+`commit 3d762e21d5637 ("rtc: cmos: Use ACPI alarm for non-Intel x86 systems too") <https://git.kernel.org/torvalds/c/3d762e21d5637>`_
+
+Disk disappears after resume
+----------------------------
+After resuming from s2idle, the NVME disk would disappear.  This was due to the
+BIOS not specifying the _DSD StorageD3Enable property.  This caused the NVME
+driver not to put the disk into the expected state at suspend and to fail
+on resume.
+
+`commit e79a10652bbd3 ("ACPI: x86: Force StorageD3Enable on more products") <https://git.kernel.org/torvalds/c/e79a10652bbd3>`_
+
+Spurious IRQ1
+-------------
+A number of Renoir, Lucienne, Cezanne, & Barcelo platforms have a
+platform firmware bug where IRQ1 is triggered during s0i3 resume.
+
+This was fixed in the platform firmware, but a number of systems didn't
+receive any more platform firmware updates.
+
+`commit 8e60615e89321 ("platform/x86/amd: pmc: Disable IRQ1 wakeup for RN/CZN") <https://git.kernel.org/torvalds/c/8e60615e89321>`_
+
+Hardware timeout
+----------------
+The hardware performs many actions besides accepting the values from
+amd-pmc driver.  As the communication path with the hardware is a mailbox,
+it's possible that it might not respond quickly enough.
+This issue manifested as a failure to suspend: ::
+
+  PM: dpm_run_callback(): acpi_subsys_suspend_noirq+0x0/0x50 returns -110
+  amd_pmc AMDI0005:00: PM: failed to suspend noirq: error -110
+
+The timing problem was identified by comparing the values of the idle mask.
+
+`commit 3c3c8e88c8712 ("platform/x86: amd-pmc: Increase the response register timeout") <https://git.kernel.org/torvalds/c/3c3c8e88c8712>`_
+
+Failed to reach hardware sleep state with panel on
+--------------------------------------------------
+On some Strix systems certain panels were observed to block the system from
+entering a hardware sleep state if the internal panel was on during the sequence.
+
+Even though the panel got turned off during suspend it exposed a timing problem
+where an interrupt caused the display hardware to wake up and block low power
+state entry.
+
+`commit 40b8c14936bd2 ("drm/amd/display: Disable unneeded hpd interrupts during dm_init") <https://git.kernel.org/torvalds/c/40b8c14936bd2>`_
+
+Runtime power consumption issues
+================================
+
+Runtime power consumption is influenced by many factors, including but not
+limited to the configuration of the PCIe Active State Power Management (ASPM),
+the display brightness, the EPP policy of the CPU, and the power management
+of the devices.
+
+ASPM
+----
+For the best runtime power consumption, ASPM should be programmed as intended
+by the BIOS from the hardware vendor.  To accomplish this the Linux kernel
+should be compiled with ``CONFIG_PCIEASPM_DEFAULT`` set to ``y`` and the
+sysfs file ``/sys/module/pcie_aspm/parameters/policy`` should not be modified.
+
+Most notably, if L1.2 is not configured properly for any devices, the SoC
+will not be able to enter the deepest idle state.
+
+EPP Policy
+----------
+The ``energy_performance_preference`` sysfs file can be used to set a bias
+of efficiency or performance for a CPU.  This has a direct relationship on
+the battery life when more heavily biased towards performance.
+
+
+BIOS debug messages
+===================
+
+Most OEM machines don't have a serial UART for outputting kernel or BIOS
+debug messages. However BIOS debug messages are useful for understanding
+both BIOS bugs and bugs with the Linux kernel drivers that call BIOS AML.
+
+As the BIOS on most OEM AMD systems are based off an AMD reference BIOS,
+the infrastructure used for exporting debugging messages is often the same
+as AMD reference BIOS.
+
+Manually Parsing
+----------------
+There is generally an ACPI method ``\M460`` that different paths of the AML
+will call to emit a message to the BIOS serial log. This method takes
+7 arguments, with the first being a string and the rest being optional
+integers::
+
+  Method (M460, 7, Serialized)
+
+Here is an example of a string that BIOS AML may call out using ``\M460``::
+
+  M460 ("  OEM-ASL-PCIe Address (0x%X)._REG (%d %d)  PCSA = %d\n", DADR, Arg0, Arg1, PCSA, Zero, Zero)
+
+Normally when executed, the ``\M460`` method would populate the additional
+arguments into the string.  In order to get these messages from the Linux
+kernel a hook has been added into ACPICA that can capture the *arguments*
+sent to ``\M460`` and print them to the kernel ring buffer.
+For example the following message could be emitted into kernel ring buffer::
+
+  extrace-0174 ex_trace_args         :  "  OEM-ASL-PCIe Address (0x%X)._REG (%d %d)  PCSA = %d\n", ec106000, 2, 1, 1, 0, 0
+
+In order to get these messages, you need to compile with ``CONFIG_ACPI_DEBUG``
+and then turn on the following ACPICA tracing parameters.
+This can be done either on the kernel command line or at runtime:
+
+* ``acpi.trace_method_name=\M460``
+* ``acpi.trace_state=method``
+
+NOTE: These can be very noisy at bootup. If you turn these parameters on
+the kernel command, please also consider turning up ``CONFIG_LOG_BUF_SHIFT``
+to a larger size such as 17 to avoid losing early boot messages.
+
+Tool assisted Parsing
+---------------------
+As mentioned above, parsing by hand can be tedious, especially with a lot of
+messages.  To help with this, a tool has been created at
+`amd-debug-tools <https://git.kernel.org/pub/scm/linux/kernel/git/superm1/amd-debug-tools.git/about/>`_
+to help parse the messages.
+
+Random reboot issues
+====================
+
+When a random reboot occurs, the high-level reason for the reboot is stored
+in a register that will persist onto the next boot.
+
+There are 6 classes of reasons for the reboot:
+ * Software induced
+ * Power state transition
+ * Pin induced
+ * Hardware induced
+ * Remote reset
+ * Internal CPU event
+
+.. csv-table::
+   :header: "Bit", "Type", "Reason"
+   :align: left
+
+   "0",  "Pin",      "thermal pin BP_THERMTRIP_L was tripped"
+   "1",  "Pin",      "power button was pressed for 4 seconds"
+   "2",  "Pin",      "shutdown pin was tripped"
+   "4",  "Remote",   "remote ASF power off command was received"
+   "9",  "Internal", "internal CPU thermal limit was tripped"
+   "16", "Pin",      "system reset pin BP_SYS_RST_L was tripped"
+   "17", "Software", "software issued PCI reset"
+   "18", "Software", "software wrote 0x4 to reset control register 0xCF9"
+   "19", "Software", "software wrote 0x6 to reset control register 0xCF9"
+   "20", "Software", "software wrote 0xE to reset control register 0xCF9"
+   "21", "ACPI-state", "ACPI power state transition occurred"
+   "22", "Pin",      "keyboard reset pin KB_RST_L was tripped"
+   "23", "Internal", "internal CPU shutdown event occurred"
+   "24", "Hardware", "system failed to boot before failed boot timer expired"
+   "25", "Hardware", "hardware watchdog timer expired"
+   "26", "Remote",   "remote ASF reset command was received"
+   "27", "Internal", "an uncorrected error caused a data fabric sync flood event"
+   "29", "Internal", "FCH and MP1 failed warm reset handshake"
+   "30", "Internal", "a parity error occurred"
+   "31", "Internal", "a software sync flood event occurred"
+
+This information is read by the kernel at bootup and printed into
+the syslog. When a random reboot occurs this message can be helpful
+to determine the next component to debug.
+
+For example, if bit 19 was set, you will get a message like this in the log on
+next bootup::
+
+  x86/amd: Previous system reset reason [0x00080000]: software wrote 0x6 to reset control register 0xCF9