eSDHC-A001: The data timeout counter (SYSCTL[DTOCV]) is not
reliable for DTOCV values 0x4(2^17 SD clock), 0x8(2^21 SD clock),
and 0xC(2^25 SD clock). The data timeout counter can count from
2^13–2^27, but for values 2^17, 2^21, and 2^25, the timeout
counter counts for only 2^13 SD clocks.
A-008358: The data timeout counter value loaded into the timeout
counter is less than expected and can result into early timeout
error in case of eSDHC data transactions. The table below shows
the expected vs actual timeout period for different values of
SYSCTL[DTOCV]:
these two erratum has the same quirk to control it, and set
SDHCI_QUIRK_RESET_AFTER_REQUEST to fix above issue.
Signed-off-by: Yinbo Zhu <yinbo.zhu@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Software writing to the Transfer Type configuration register
(system clock domain) can cause a setup/hold violation in the
CRC flops (card clock domain), which can cause write accesses
to be sent with corrupt CRC values. This issue occurs only for
write preceded by read. this erratum is to fix this issue.
Signed-off-by: Yinbo Zhu <yinbo.zhu@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

This patch is to add erratum A011334 support in lx2160 2.0 SoC
Signed-off-by: Yinbo Zhu <yinbo.zhu@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

As mmci_variant_init() is a local function to mmci.c, let's convert it into
static.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

It's good practice to share functions via header files, rather than from
the c-files. Therefore, let's move sdmmc_variant_init() to mmci.h.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Ludovic Barre <ludovic.barre@st.com>
Tested-by: Ludovic Barre <ludovic.barre@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

It seems a bit silly to have a header file to share only the
qcom_variant_init() function. So, let's just drop it and move the
declaration of the function into the common mmci.h instead.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Having mmci_dmae_start() to invoke the shared function, dml_start_xfer(),
explicitly for the qcom variant isn't very nice. Let's clean up this code
by moving the qcom specific parts into the qcom ->dma_start() callback and
then drop dml_start_xfer() altogether.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

There's no point clearing the variant flag in case the qcom variant fails
to setup DMA. This is because if mmci_dma_setup() fails, then the use_dma
flag remains set to false, which leads to mmci using PIO mode and not DMA.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Some of the DMA functions are shared via mmci.h, however they are not
implemented unless CONFIG_DMA_ENGINE is set. Therefore, add that constraint
to the header file as well.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Merge page ref overflow branch.

Jann Horn reported that he can overflow the page ref count with
sufficient memory (and a filesystem that is intentionally extremely
slow).

Admittedly it's not exactly easy.  To have more than four billion
references to a page requires a minimum of 32GB of kernel memory just
for the pointers to the pages, much less any metadata to keep track of
those pointers.  Jann needed a total of 140GB of memory and a specially
crafted filesystem that leaves all reads pending (in order to not ever
free the page references and just keep adding more).

Still, we have a fairly straightforward way to limit the two obvious
user-controllable sources of page references: direct-IO like page
references gotten through get_user_pages(), and the splice pipe page
duplication.  So let's just do that.

* branch page-refs:
  fs: prevent page refcount overflow in pipe_buf_get
  mm: prevent get_user_pages() from overflowing page refcount
  mm: add 'try_get_page()' helper function
  mm: make page ref count overflow check tighter and more explicit

Change pipe_buf_get() to return a bool indicating whether it succeeded
in raising the refcount of the page (if the thing in the pipe is a page).
This removes another mechanism for overflowing the page refcount.  All
callers converted to handle a failure.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If the page refcount wraps around past zero, it will be freed while
there are still four billion references to it.  One of the possible
avenues for an attacker to try to make this happen is by doing direct IO
on a page multiple times.  This patch makes get_user_pages() refuse to
take a new page reference if there are already more than two billion
references to the page.
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Matthew Wilcox <willy@infradead.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is the same as the traditional 'get_page()' function, but instead
of unconditionally incrementing the reference count of the page, it only
does so if the count was "safe".  It returns whether the reference count
was incremented (and is marked __must_check, since the caller obviously
has to be aware of it).

Also like 'get_page()', you can't use this function unless you already
had a reference to the page.  The intent is that you can use this
exactly like get_page(), but in situations where you want to limit the
maximum reference count.

The code currently does an unconditional WARN_ON_ONCE() if we ever hit
the reference count issues (either zero or negative), as a notification
that the conditional non-increment actually happened.

NOTE! The count access for the "safety" check is inherently racy, but
that doesn't matter since the buffer we use is basically half the range
of the reference count (ie we look at the sign of the count).
Acked-by: Matthew Wilcox <willy@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We have a VM_BUG_ON() to check that the page reference count doesn't
underflow (or get close to overflow) by checking the sign of the count.

That's all fine, but we actually want to allow people to use a "get page
ref unless it's already very high" helper function, and we want that one
to use the sign of the page ref (without triggering this VM_BUG_ON).

Change the VM_BUG_ON to only check for small underflows (or _very_ close
to overflowing), and ignore overflows which have strayed into negative
territory.
Acked-by: Matthew Wilcox <willy@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull block fixes from Jens Axboe:
 "Set of fixes that should go into this round. This pull is larger than
  I'd like at this time, but there's really no specific reason for that.
  Some are fixes for issues that went into this merge window, others are
  not. Anyway, this contains:

   - Hardware queue limiting for virtio-blk/scsi (Dongli)

   - Multi-page bvec fixes for lightnvm pblk

   - Multi-bio dio error fix (Jason)

   - Remove the cache hint from the io_uring tool side, since we didn't
     move forward with that (me)

   - Make io_uring SETUP_SQPOLL root restricted (me)

   - Fix leak of page in error handling for pc requests (Jérôme)

   - Fix BFQ regression introduced in this merge window (Paolo)

   - Fix break logic for bio segment iteration (Ming)

   - Fix NVMe cancel request error handling (Ming)

   - NVMe pull request with two fixes (Christoph):
       - fix the initial CSN for nvme-fc (James)
       - handle log page offsets properly in the target (Keith)"

* tag 'for-linus-20190412' of git://git.kernel.dk/linux-block:
  block: fix the return errno for direct IO
  nvmet: fix discover log page when offsets are used
  nvme-fc: correct csn initialization and increments on error
  block: do not leak memory in bio_copy_user_iov()
  lightnvm: pblk: fix crash in pblk_end_partial_read due to multipage bvecs
  nvme: cancel request synchronously
  blk-mq: introduce blk_mq_complete_request_sync()
  scsi: virtio_scsi: limit number of hw queues by nr_cpu_ids
  virtio-blk: limit number of hw queues by nr_cpu_ids
  block, bfq: fix use after free in bfq_bfqq_expire
  io_uring: restrict IORING_SETUP_SQPOLL to root
  tools/io_uring: remove IOCQE_FLAG_CACHEHIT
  block: don't use for-inside-for in bio_for_each_segment_all

Pull NFS client bugfixes from Trond Myklebust:
 "Highlights include:

  Stable fix:

   - Fix a deadlock in close() due to incorrect draining of RDMA queues

  Bugfixes:

   - Revert "SUNRPC: Micro-optimise when the task is known not to be
     sleeping" as it is causing stack overflows

   - Fix a regression where NFSv4 getacl and fs_locations stopped
     working

   - Forbid setting AF_INET6 to "struct sockaddr_in"->sin_family.

   - Fix xfstests failures due to incorrect copy_file_range() return
     values"

* tag 'nfs-for-5.1-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  Revert "SUNRPC: Micro-optimise when the task is known not to be sleeping"
  NFSv4.1 fix incorrect return value in copy_file_range
  xprtrdma: Fix helper that drains the transport
  NFS: Fix handling of reply page vector
  NFS: Forbid setting AF_INET6 to "struct sockaddr_in"->sin_family.

Pull SCSI fix from James Bottomley:
 "One obvious fix for a ciostor data corruption on error bug"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: csiostor: fix missing data copy in csio_scsi_err_handler()

Pull clk fixes from Stephen Boyd:
 "Here's more than a handful of clk driver fixes for changes that came
  in during the merge window:

   - Fix the AT91 sama5d2 programmable clk prescaler formula

   - A bunch of Amlogic meson clk driver fixes for the VPU clks

   - A DMI quirk for Intel's Bay Trail SoC's driver to properly mark pmc
     clks as critical only when really needed

   - Stop overwriting CLK_SET_RATE_PARENT flag in mediatek's clk gate
     implementation

   - Use the right structure to test for a frequency table in i.MX's
     PLL_1416x driver"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: imx: Fix PLL_1416X not rounding rates
  clk: mediatek: fix clk-gate flag setting
  platform/x86: pmc_atom: Drop __initconst on dmi table
  clk: x86: Add system specific quirk to mark clocks as critical
  clk: meson: vid-pll-div: remove warning and return 0 on invalid config
  clk: meson: pll: fix rounding and setting a rate that matches precisely
  clk: meson-g12a: fix VPU clock parents
  clk: meson: g12a: fix VPU clock muxes mask
  clk: meson-gxbb: round the vdec dividers to closest
  clk: at91: fix programmable clock for sama5d2

Pull PCI fixes from Bjorn Helgaas:

 - Add a DMA alias quirk for another Marvell SATA device (Andre
   Przywara)

 - Fix a pciehp regression that broke safe removal of devices (Sergey
   Miroshnichenko)

* tag 'pci-v5.1-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: pciehp: Ignore Link State Changes after powering off a slot
  PCI: Add function 1 DMA alias quirk for Marvell 9170 SATA controller

Pull powerpc fixes from Michael Ellerman:
 "A minor build fix for 64-bit FLATMEM configs.

  A fix for a boot failure on 32-bit powermacs.

  My commit to fix CLOCK_MONOTONIC across Y2038 broke the 32-bit VDSO on
  64-bit kernels, ie. compat mode, which is only used on big endian.

  The rewrite of the SLB code we merged in 4.20 missed the fact that the
  0x380 exception is also used with the Radix MMU to report out of range
  accesses. This could lead to an oops if userspace tried to read from
  addresses outside the user or kernel range.

  Thanks to: Aneesh Kumar K.V, Christophe Leroy, Larry Finger, Nicholas
  Piggin"

* tag 'powerpc-5.1-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm: Define MAX_PHYSMEM_BITS for all 64-bit configs
  powerpc/64s/radix: Fix radix segment exception handling
  powerpc/vdso32: fix CLOCK_MONOTONIC on PPC64
  powerpc/32: Fix early boot failure with RTAS built-in

Pull arm64 fixes from Will Deacon:
 "The main thing is a fix to our FUTEX_WAKE_OP implementation which was
  unbelievably broken, but did actually work for the one scenario that
  GLIBC used to use.

  Summary:

   - Fix stack unwinding so we ignore user stacks

   - Fix ftrace module PLT trampoline initialisation checks

   - Fix terminally broken implementation of FUTEX_WAKE_OP atomics"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: futex: Fix FUTEX_WAKE_OP atomic ops with non-zero result value
  arm64: backtrace: Don't bother trying to unwind the userspace stack
  arm64/ftrace: fix inadvertent BUG() in trampoline check

Pull x86 fixes from Ingo Molnar:
 "Fix typos in user-visible resctrl parameters, and also fix assembly
  constraint bugs that might result in miscompilation"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm: Use stricter assembly constraints in bitops
  x86/resctrl: Fix typos in the mba_sc mount option

Pull timer fix from Ingo Molnar:
 "Fix the alarm_timer_remaining() return value"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  alarmtimer: Return correct remaining time

Pull scheduler fix from Ingo Molnar:
 "Fix a NULL pointer dereference crash in certain environments"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Do not re-read ->h_load_next during hierarchical load calculation

Pull perf fixes from Ingo Molnar:
 "Six kernel side fixes: three related to NMI handling on AMD systems, a
  race fix, a kexec initialization fix and a PEBS sampling fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix perf_event_disable_inatomic() race
  x86/perf/amd: Remove need to check "running" bit in NMI handler
  x86/perf/amd: Resolve NMI latency issues for active PMCs
  x86/perf/amd: Resolve race condition when disabling PMC
  perf/x86/intel: Initialize TFA MSR
  perf/x86/intel: Fix handling of wakeup_events for multi-entry PEBS

Pull locking fix from Ingo Molnar:
 "Fixes a crash when accessing /proc/lockdep"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Zap lock classes even with lock debugging disabled

Pull irq fixes from Ingo Molnar:
 "Two genirq fixes, plus an irqchip driver error handling fix"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()
  genirq: Initialize request_mutex if CONFIG_SPARSE_IRQ=n
  irqchip/irq-ls1x: Missing error code in ls1x_intc_of_init()

Pull core fixes from Ingo Molnar:
 "Fix an objtool warning plus fix a u64_to_user_ptr() macro expansion
  bug"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add rewind_stack_do_exit() to the noreturn list
  linux/kernel.h: Use parentheses around argument in u64_to_user_ptr()

Code which initializes the "clk_init_data.ops" checks pll->rate_table
before that field is ever assigned to so it always picks
"clk_pll1416x_min_ops".

This breaks dynamic rate rounding for features such as cpufreq.

Fix by checking pll_clk->rate_table instead, here pll_clk refers to
the constant initialization data coming from per-soc clk driver.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Fixes: 8646d4dc ("clk: imx: Add PLLs driver for imx8mm soc")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

CLK_SET_RATE_PARENT would be dropped.
Merge two flag setting together to correct the error.

Fixes: 5a1cc4c2 ("clk: mediatek: Add flags to mtk_gate")
Cc: <stable@vger.kernel.org>
Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Pull dma-mapping fixes from Christoph Hellwig:
 "Fix a sparc64 sun4v_pci regression introduced in this merged window,
  and a dma-debug stracktrace regression from the big refactor last
  merge window"

* tag 'dma-mapping-5.1-1' of git://git.infradead.org/users/hch/dma-mapping:
  dma-debug: only skip one stackframe entry
  sparc64/pci_sun4v: fix ATU checks for large DMA masks

Pull IOMMU fix from Joerg Roedel:
 "Fix an AMD IOMMU issue where the driver didn't correctly setup the
  exclusion range in the hardware registers, resulting in exclusion
  ranges being one page too big.

  This can cause data corruption of the address of that last page is
  used by DMA operations"

* tag 'iommu-fix-v5.1-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/amd: Set exclusion range correctly

Pull clang-format update from Miguel Ojeda:
 "The usual roughly-per-release .clang-format macro list update"

* tag 'clang-format-for-linus-v5.1-rc5' of git://github.com/ojeda/linux:
  clang-format: Update with the latest for_each macro list

Pull MMC host fixes from Ulf Hansson:

 - alcor: Stabilize data write requests

 - sdhci-omap: Fix command error path during tuning

* tag 'mmc-v5.1-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci-omap: Don't finish_mrq() on a command error during tuning
  mmc: alcor: don't write data before command has completed

Pull sound fixes from Takashi Iwai:
 "Well, this one became unpleasantly larger than previous pull requests,
  but it's a kind of usual pattern: now it contains a collection of ASoC
  fixes, and nothing to worry too much.

  The fixes for ASoC core (DAPM, DPCM, topology) are all small and just
  covering corner cases. The rest changes are driver-specific, many of
  which are for x86 platforms and new drivers like STM32, in addition to
  the usual fixups for HD-audio"

* tag 'sound-5.1-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (66 commits)
  ASoC: wcd9335: Fix missing regmap requirement
  ALSA: hda: Fix racy display power access
  ASoC: pcm: fix error handling when try_module_get() fails.
  ASoC: stm32: sai: fix master clock management
  ASoC: Intel: kbl: fix wrong number of channels
  ALSA: hda - Add two more machines to the power_save_blacklist
  ASoC: pcm: update module refcount if module_get_upon_open is set
  ASoC: core: conditionally increase module refcount on component open
  ASoC: stm32: fix sai driver name initialisation
  ASoC: topology: Use the correct dobj to free enum control values and texts
  ALSA: seq: Fix OOB-reads from strlcpy
  ASoC: intel: skylake: add remove() callback for component driver
  ASoC: cs35l35: Disable regulators on driver removal
  ALSA: xen-front: Do not use stream buffer size before it is set
  ASoC: rockchip: pdm: change dma burst to 8
  ASoC: rockchip: pdm: fix regmap_ops hang issue
  ASoC: simple-card: don't select DPCM via simple-audio-card
  ASoC: audio-graph-card: don't select DPCM via audio-graph-card
  ASoC: tlv320aic32x4: Change author's name
  ALSA: hda/realtek - Add quirk for Tuxedo XC 1509
  ...

Pull ACPI fix from Rafael Wysocki:
 "Fix an ACPICA issue introduced during the 4.20 development cycle and
  causing some systems to crash because of leftover operation region
  data still maintained after the operation region in question has gone
  away (Erik Schmauss)"

* tag 'acpi-5.1-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Namespace: remove address node from global list after method termination

Pull drm fixes from Dave Airlie:
 "Fixes across the driver spectrum this week, the mediatek fbdev support
  might be a bit late for this round, but I looked over it and it's not
  very large and seems like a useful feature for them.

  Otherwise the main thing is a regression fix for i915 5.0 bug that
  caused black screens on a bunch of Dell XPS 15s I think, I know at
  least Fedora is waiting for this to land, and the udl fix is also for
  a regression since 5.0 where unplugging the device would end badly.

  core:
   - make atomic hooks optional

  i915:
   - Revert a 5.0 regression where some eDP panels stopped working
   - DSI related fixes for platforms up to IceLake
   - GVT (regression fix, warning fix, use-after free fix)

  amdgpu:
   - Cursor fixes
   - missing PCI ID fix for KFD
   - XGMI fix
   - shadow buffer handling after reset fix

  udl:
   - fix unplugging device crashes.

  mediatek:
   - stabilise MT2701 HDMI support
   - fbdev support

  tegra:
   - fix for build regression in rc1.

  sun4i:
   - Allwinner A6 max freq improvements
   - null ptr deref fix

  dw-hdmi:
   - SCDC configuration improvements

  omap:
   - CEC clock management policy fix"

* tag 'drm-fixes-2019-04-12' of git://anongit.freedesktop.org/drm/drm: (32 commits)
  gpu: host1x: Fix compile error when IOMMU API is not available
  drm/i915/gvt: Roundup fb->height into tile's height at calucation fb->size
  drm/i915/dp: revert back to max link rate and lane count on eDP
  drm/i915/icl: Fix port disable sequence for mipi-dsi
  drm/i915/icl: Ungate ddi clocks before IO enable
  drm/mediatek: no change parent rate in round_rate() for MT2701 hdmi phy
  drm/mediatek: using new factor for tvdpll for MT2701 hdmi phy
  drm/mediatek: remove flag CLK_SET_RATE_PARENT for MT2701 hdmi phy
  drm/mediatek: make implementation of recalc_rate() for MT2701 hdmi phy
  drm/mediatek: fix the rate and divder of hdmi phy for MT2701
  drm/mediatek: fix possible object reference leak
  drm/i915: Get power refs in encoder->get_power_domains()
  drm/i915: Fix pipe_bpp readout for BXT/GLK DSI
  drm/amd/display: Fix negative cursor pos programming (v2)
  drm/sun4i: tcon top: Fix NULL/invalid pointer dereference in sun8i_tcon_top_un/bind
  drm/udl: add a release method and delay modeset teardown
  drm/i915/gvt: Prevent use-after-free in ppgtt_free_all_spt()
  drm/i915/gvt: Annotate iomem usage
  drm/sun4i: DW HDMI: Lower max. supported rate for H6
  Revert "Documentation/gpu/meson: Remove link to meson_canvas.c"
  ...

Rather embarrassingly, our futex() FUTEX_WAKE_OP implementation doesn't
explicitly set the return value on the non-faulting path and instead
leaves it holding the result of the underlying atomic operation. This
means that any FUTEX_WAKE_OP atomic operation which computes a non-zero
value will be reported as having failed. Regrettably, I wrote the buggy
code back in 2011 and it was upstreamed as part of the initial arm64
support in 2012.

The reasons we appear to get away with this are:

  1. FUTEX_WAKE_OP is rarely used and therefore doesn't appear to get
     exercised by futex() test applications

  2. If the result of the atomic operation is zero, the system call
     behaves correctly

  3. Prior to version 2.25, the only operation used by GLIBC set the
     futex to zero, and therefore worked as expected. From 2.25 onwards,
     FUTEX_WAKE_OP is not used by GLIBC at all.

Fix the implementation by ensuring that the return value is either 0
to indicate that the atomic operation completed successfully, or -EFAULT
if we encountered a fault when accessing the user mapping.

Cc: <stable@kernel.org>
Fixes: 6170a974 ("arm64: Atomic operations")
Signed-off-by: Will Deacon <will.deacon@arm.com>