The following sequence triggers a kernel stack overflow on s390x:

mount -t tracefs tracefs /sys/kernel/tracing
cd /sys/kernel/tracing
echo function_graph > current_tracer
[crash]

This is because preempt_count_{add,sub} are in the list of traced
functions, which can be demonstrated by:

echo preempt_count_add >set_ftrace_filter
echo function_graph > current_tracer
[crash]

The stack overflow happens because get_tod_clock_monotonic() gets called
by ftrace but itself calls preempt_{disable,enable}(), which leads to a
endless recursion. Fix this by using preempt_{disable,enable}_notrace().

Fixes: 011620688a71 ("s390/time: ensure get_clock_monotonic() returns monotonic values")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diag 0x44 is a voluntary undirected yield of a virtual CPU. This has
caused a lot of performance issues in the past.

There is only one caller left, and that one is only executed if diag
0x9c (directed yield) is not present. Given that all hypervisors
implement diag 0x9c anyway, remove the last diag 0x44 to avoid that
more callers will be added.

Worst case that could happen now, if diag 0x9c is not present, is that
a virtual CPU would loop a bit instead of giving its time slice up.

diag 0x44 statistics in debugfs are kept and will always be zero, so
that user space can tell that there are no calls.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

ENOTSUP is just an internal kernel error and should never reach
userspace. The return value of the share function is not exported to
userspace, but to avoid giving bad examples let us use EOPNOTSUPP:

Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Pull more powerpc updates from Michael Ellerman:
 "A few commits splitting the KASAN instrumented bitops header in three,
  to match the split of the asm-generic bitops headers.

  This is needed on powerpc because we use the generic bitops for the
  non-atomic case only, whereas the existing KASAN instrumented bitops
  assume all the underlying operations are provided by the arch as
  arch_foo() versions.

  Thanks to: Daniel Axtens & Christophe Leroy"

* tag 'powerpc-5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  docs/core-api: Remove possibly confusing sub-headings from Bit Operations
  powerpc: support KASAN instrumentation of bitops
  kasan: support instrumented bitops combined with generic bitops

Pull PCI updates from Bjorn Helgaas:
 "Enumeration:

   - Warn if a host bridge has no NUMA info (Yunsheng Lin)

   - Add PCI_STD_NUM_BARS for the number of standard BARs (Denis
     Efremov)

  Resource management:

   - Fix boot-time Embedded Controller GPE storm caused by incorrect
     resource assignment after ACPI Bus Check Notification (Mika
     Westerberg)

   - Protect pci_reassign_bridge_resources() against concurrent
     addition/removal (Benjamin Herrenschmidt)

   - Fix bridge dma_ranges resource list cleanup (Rob Herring)

   - Add "pci=hpmmiosize" and "pci=hpmmioprefsize" parameters to control
     the MMIO and prefetchable MMIO window sizes of hotplug bridges
     independently (Nicholas Johnson)

   - Fix MMIO/MMIO_PREF window assignment that assigned more space than
     desired (Nicholas Johnson)

   - Only enforce bus numbers from bridge EA if the bridge has EA
     devices downstream (Subbaraya Sundeep)

   - Consolidate DT "dma-ranges" parsing and convert all host drivers to
     use shared parsing (Rob Herring)

  Error reporting:

   - Restore AER capability after resume (Mayurkumar Patel)

   - Add PoisonTLPBlocked AER counter (Rajat Jain)

   - Use for_each_set_bit() to simplify AER code (Andy Shevchenko)

   - Fix AER kernel-doc (Andy Shevchenko)

   - Add "pcie_ports=dpc-native" parameter to allow native use of DPC
     even if platform didn't grant control over AER (Olof Johansson)

  Hotplug:

   - Avoid returning prematurely from sysfs requests to enable or
     disable a PCIe hotplug slot (Lukas Wunner)

   - Don't disable interrupts twice when suspending hotplug ports (Mika
     Westerberg)

   - Fix deadlocks when PCIe ports are hot-removed while suspended (Mika
     Westerberg)

  Power management:

   - Remove unnecessary ASPM locking (Bjorn Helgaas)

   - Add support for disabling L1 PM Substates (Heiner Kallweit)

   - Allow re-enabling Clock PM after it has been disabled (Heiner
     Kallweit)

   - Add sysfs attributes for controlling ASPM link states (Heiner
     Kallweit)

   - Remove CONFIG_PCIEASPM_DEBUG, including "link_state" and "clk_ctl"
     sysfs files (Heiner Kallweit)

   - Avoid AMD FCH XHCI USB PME# from D0 defect that prevents wakeup on
     USB 2.0 or 1.1 connect events (Kai-Heng Feng)

   - Move power state check out of pci_msi_supported() (Bjorn Helgaas)

   - Fix incorrect MSI-X masking on resume and revert related nvme quirk
     for Kingston NVME SSD running FW E8FK11.T (Jian-Hong Pan)

   - Always return devices to D0 when thawing to fix hibernation with
     drivers like mlx4 that used legacy power management (previously we
     only did it for drivers with new power management ops) (Dexuan Cui)

   - Clear PCIe PME Status even for legacy power management (Bjorn
     Helgaas)

   - Fix PCI PM documentation errors (Bjorn Helgaas)

   - Use dev_printk() for more power management messages (Bjorn Helgaas)

   - Apply D2 delay as milliseconds, not microseconds (Bjorn Helgaas)

   - Convert xen-platform from legacy to generic power management (Bjorn
     Helgaas)

   - Removed unused .resume_early() and .suspend_late() legacy power
     management hooks (Bjorn Helgaas)

   - Rearrange power management code for clarity (Rafael J. Wysocki)

   - Decode power states more clearly ("4" or "D4" really refers to
     "D3cold") (Bjorn Helgaas)

   - Notice when reading PM Control register returns an error (~0)
     instead of interpreting it as being in D3hot (Bjorn Helgaas)

   - Add missing link delays required by the PCIe spec (Mika Westerberg)

  Virtualization:

   - Move pci_prg_resp_pasid_required() to CONFIG_PCI_PRI (Bjorn
     Helgaas)

   - Allow VFs to use PRI (the PF PRI is shared by the VFs, but the code
     previously didn't recognize that) (Kuppuswamy Sathyanarayanan)

   - Allow VFs to use PASID (the PF PASID capability is shared by the
     VFs, but the code previously didn't recognize that) (Kuppuswamy
     Sathyanarayanan)

   - Disconnect PF and VF ATS enablement, since ATS in PFs and
     associated VFs can be enabled independently (Kuppuswamy
     Sathyanarayanan)

   - Cache PRI and PASID capability offsets (Kuppuswamy Sathyanarayanan)

   - Cache the PRI PRG Response PASID Required bit (Bjorn Helgaas)

   - Consolidate ATS declarations in linux/pci-ats.h (Krzysztof
     Wilczynski)

   - Remove unused PRI and PASID stubs (Bjorn Helgaas)

   - Removed unnecessary EXPORT_SYMBOL_GPL() from ATS, PRI, and PASID
     interfaces that are only used by built-in IOMMU drivers (Bjorn
     Helgaas)

   - Hide PRI and PASID state restoration functions used only inside the
     PCI core (Bjorn Helgaas)

   - Add a DMA alias quirk for the Intel VCA NTB (Slawomir Pawlowski)

   - Serialize sysfs sriov_numvfs reads vs writes (Pierre Crégut)

   - Update Cavium ACS quirk for ThunderX2 and ThunderX3 (George
     Cherian)

   - Fix the UPDCR register address in the Intel ACS quirk (Steffen
     Liebergeld)

   - Unify ACS quirk implementations (Bjorn Helgaas)

  Amlogic Meson host bridge driver:

   - Fix meson PERST# GPIO polarity problem (Remi Pommarel)

   - Add DT bindings for Amlogic Meson G12A (Neil Armstrong)

   - Fix meson clock names to match DT bindings (Neil Armstrong)

   - Add meson support for Amlogic G12A SoC with separate shared PHY
     (Neil Armstrong)

   - Add meson extended PCIe PHY functions for Amlogic G12A USB3+PCIe
     combo PHY (Neil Armstrong)

   - Add arm64 DT for Amlogic G12A PCIe controller node (Neil Armstrong)

   - Add commented-out description of VIM3 USB3/PCIe mux in arm64 DT
     (Neil Armstrong)

  Broadcom iProc host bridge driver:

   - Invalidate iProc PAXB address mapping before programming it
     (Abhishek Shah)

   - Fix iproc-msi and mvebu __iomem annotations (Ben Dooks)

  Cadence host bridge driver:

   - Refactor Cadence PCIe host controller to use as a library for both
     host and endpoint (Tom Joseph)

  Freescale Layerscape host bridge driver:

   - Add layerscape LS1028a support (Xiaowei Bao)

  Intel VMD host bridge driver:

   - Add VMD bus 224-255 restriction decode (Jon Derrick)

   - Add VMD 8086:9A0B device ID (Jon Derrick)

   - Remove Keith from VMD maintainer list (Keith Busch)

  Marvell ARMADA 3700 / Aardvark host bridge driver:

   - Use LTSSM state to build link training flag since Aardvark doesn't
     implement the Link Training bit (Remi Pommarel)

   - Delay before training Aardvark link in case PERST# was asserted
     before the driver probe (Remi Pommarel)

   - Fix Aardvark issues with Root Control reads and writes (Remi
     Pommarel)

   - Don't rely on jiffies in Aardvark config access path since
     interrupts may be disabled (Remi Pommarel)

   - Fix Aardvark big-endian support (Grzegorz Jaszczyk)

  Marvell ARMADA 370 / XP host bridge driver:

   - Make mvebu_pci_bridge_emul_ops static (Ben Dooks)

  Microsoft Hyper-V host bridge driver:

   - Add hibernation support for Hyper-V virtual PCI devices (Dexuan
     Cui)

   - Track Hyper-V pci_protocol_version per-hbus, not globally (Dexuan
     Cui)

   - Avoid kmemleak false positive on hv hbus buffer (Dexuan Cui)

  Mobiveil host bridge driver:

   - Change mobiveil csr_read()/write() function names that conflict
     with riscv arch functions (Kefeng Wang)

  NVIDIA Tegra host bridge driver:

   - Fix Tegra CLKREQ dependency programming (Vidya Sagar)

  Renesas R-Car host bridge driver:

   - Remove unnecessary header include from rcar (Andrew Murray)

   - Tighten register index checking for rcar inbound range programming
     (Marek Vasut)

   - Fix rcar inbound range alignment calculation to improve packing of
     multiple entries (Marek Vasut)

   - Update rcar MACCTLR setting to match documentation (Yoshihiro
     Shimoda)

   - Clear bit 0 of MACCTLR before PCIETCTLR.CFINIT per manual
     (Yoshihiro Shimoda)

   - Add Marek Vasut and Yoshihiro Shimoda as R-Car maintainers (Simon
     Horman)

  Rockchip host bridge driver:

   - Make rockchip 0V9 and 1V8 power regulators non-optional (Robin
     Murphy)

  Socionext UniPhier host bridge driver:

   - Set uniphier to host (RC) mode always (Kunihiko Hayashi)

  Endpoint drivers:

   - Fix endpoint driver sign extension problem when shifting page
     number to phys_addr_t (Alan Mikhak)

  Misc:

   - Add NumaChip SPDX header (Krzysztof Wilczynski)

   - Replace EXTRA_CFLAGS with ccflags-y (Krzysztof Wilczynski)

   - Remove unused includes (Krzysztof Wilczynski)

   - Removed unused sysfs attribute groups (Ben Dooks)

   - Remove PTM and ASPM dependencies on PCIEPORTBUS (Bjorn Helgaas)

   - Add PCIe Link Control 2 register field definitions to replace magic
     numbers in AMDGPU and Radeon CIK/SI (Bjorn Helgaas)

   - Fix incorrect Link Control 2 Transmit Margin usage in AMDGPU and
     Radeon CIK/SI PCIe Gen3 link training (Bjorn Helgaas)

   - Use pcie_capability_read_word() instead of pci_read_config_word()
     in AMDGPU and Radeon CIK/SI (Frederick Lawler)

   - Remove unused pci_irq_get_node() Greg Kroah-Hartman)

   - Make asm/msi.h mandatory and simplify PCI_MSI_IRQ_DOMAIN Kconfig
     (Palmer Dabbelt, Michal Simek)

   - Read all 64 bits of Switchtec part_event_bitmap (Logan Gunthorpe)

   - Fix erroneous intel-iommu dependency on CONFIG_AMD_IOMMU (Bjorn
     Helgaas)

   - Fix bridge emulation big-endian support (Grzegorz Jaszczyk)

   - Fix dwc find_next_bit() usage (Niklas Cassel)

   - Fix pcitest.c fd leak (Hewenliang)

   - Fix typos and comments (Bjorn Helgaas)

   - Fix Kconfig whitespace errors (Krzysztof Kozlowski)"

* tag 'pci-v5.5-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (160 commits)
  PCI: Remove PCI_MSI_IRQ_DOMAIN architecture whitelist
  asm-generic: Make msi.h a mandatory include/asm header
  Revert "nvme: Add quirk for Kingston NVME SSD running FW E8FK11.T"
  PCI/MSI: Fix incorrect MSI-X masking on resume
  PCI/MSI: Move power state check out of pci_msi_supported()
  PCI/MSI: Remove unused pci_irq_get_node()
  PCI: hv: Avoid a kmemleak false positive caused by the hbus buffer
  PCI: hv: Change pci_protocol_version to per-hbus
  PCI: hv: Add hibernation support
  PCI: hv: Reorganize the code in preparation of hibernation
  MAINTAINERS: Remove Keith from VMD maintainer
  PCI/ASPM: Remove PCIEASPM_DEBUG Kconfig option and related code
  PCI/ASPM: Add sysfs attributes for controlling ASPM link states
  PCI: Fix indentation
  drm/radeon: Prefer pcie_capability_read_word()
  drm/radeon: Replace numbers with PCI_EXP_LNKCTL2 definitions
  drm/radeon: Correct Transmit Margin masks
  drm/amdgpu: Prefer pcie_capability_read_word()
  PCI: uniphier: Set mode register to host mode
  drm/amdgpu: Replace numbers with PCI_EXP_LNKCTL2 definitions
  ...

Pull more s390 updates from Vasily Gorbik:

 - Make stack unwinder reliable and suitable for livepatching. Add
   unwinder testing module.

 - Fixes for CALL_ON_STACK helper used for stack switching.

 - Fix unwinding from bpf code.

 - Fix getcpu and remove compat support in vdso code.

 - Fix address space control registers initialization.

 - Save KASLR offset for early dumps.

 - Handle new FILTERED_BY_HYPERVISOR reply code in crypto code.

 - Minor perf code cleanup and potential memory leak fix.

 - Add couple of error messages for corner cases during PCI device
   creation.

* tag 's390-5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (33 commits)
  s390: remove compat vdso code
  s390/livepatch: Implement reliable stack tracing for the consistency model
  s390/unwind: add stack pointer alignment sanity checks
  s390/unwind: filter out unreliable bogus %r14
  s390/unwind: start unwinding from reliable state
  s390/test_unwind: add program check context tests
  s390/test_unwind: add irq context tests
  s390/test_unwind: print verbose unwinding results
  s390/test_unwind: add CALL_ON_STACK tests
  s390: fix register clobbering in CALL_ON_STACK
  s390/test_unwind: require that unwinding ended successfully
  s390/unwind: add a test for the internal API
  s390/unwind: always inline get_stack_pointer
  s390/pci: add error message on device number limit
  s390/pci: add error message for UID collision
  s390/cpum_sf: Check for SDBT and SDB consistency
  s390/cpum_sf: Use TEAR_REG macro consistantly
  s390/cpum_sf: Remove unnecessary check for pending SDBs
  s390/cpum_sf: Replace function name in debug statements
  s390/kaslr: store KASLR offset for early dumps
  ...

A comment in arch/s390/include/asm/unwind.h says:
> If 'first_frame' is not zero unwind_start skips unwind frames until it
> reaches the specified stack pointer.
> The end of the unwinding is indicated with unwind_done, this can be true
> right after unwind_start, e.g. with first_frame!=0 that can not be found.
> unwind_next_frame skips to the next frame.
> Once the unwind is completed unwind_error() can be used to check if there
> has been a situation where the unwinder could not correctly understand
> the tasks call chain.

With this change backchain unwinder now comply with behaviour
described. As well as matches orc unwinder implementation.  Now unwinder
starts from reliable state, i.e. __unwind_start own stack frame is
taken or stack frame generated by __switch_to (ksp) - both known to be
valid. In case of pt_regs %r15 is better match for pt_regs psw, than
sometimes random "sp" caller passed.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

CALL_ON_STACK defines and initializes register variables. Inline
assembly which follows might trigger compiler to generate memory access
for "stack" argument (e.g. in case of S390_lowcore.nodat_stack). This
memory access produces a function call under kasan with outline
instrumentation which clobbers registers.

Switch "stack" argument in CALL_ON_STACK helper to use memory reference
constraint and perform load instead.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Always inline get_stack_pointer() to avoid potential problems
due to compiler inlining decisions, i.e. getting stack pointer of
get_stack_pointer() itself which is later reused.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Replace hard coded function names in debug statements
by the "%s ...", __func__ construct suggested by checkpatch.pl
script.  Use consistent debug print format of the form variable
blank value. Also add leading 0x for all hex values.
Print allocated page addresses consistantly as hex numbers
with leading 0x.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>