The TBI setup on arm64 is very strange: HW is set up to always do TBI,
but the kernel enforcement for system calls is purely a software
contract, and user space is supposed to mask off the top bits before the
system call.

Except all the actual brk/mmap/etc() system calls then mask it in kernel
space anyway, and accept any TBI address.

This basically unifies things and makes access_ok() also ignore it.

This is an ABI change, but the current situation is very odd, and this
change avoids the current mess and makes the kernel more permissive, and
as such is unlikely to break anything.

The way forward - for some possible future situation when people want to
use more bits - is probably to introduce a new "I actually want the full
64-bit address space" prctl.  But we should make sure that the software
and hardware rules actually match at that point.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This generates noticeably better code since we don't need to test the
error register etc, the exception just jumps to the error handling
directly.

Unlike get_user(), there's no need to worry about old compilers. All
supported compilers support the regular non-output 'asm goto', as
pointed out by Nathan Chancellor.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This generates noticeably better code with compilers that support it,
since we don't need to test the error register etc, the exception just
jumps to the error handling directly.

Note that this also marks SW_TTBR0_PAN incompatible with KCSAN support,
since KCSAN wants to save and restore the user access state.

KCSAN and SW_TTBR0_PAN were probably always incompatible, but it became
obvious only when implementing the unsafe user access functions.  At
that point the default empty user_access_save/restore() functions
weren't provided by the default fallback functions.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull parisc fix from Helge Deller:
 "On parisc we have suffered since years from random segfaults which
  seem to have been triggered due to cache inconsistencies. Those
  segfaults happened more often on machines with PA8800 and PA8900 CPUs,
  which have much bigger caches than the earlier machines.

  Dave Anglin has worked over the last few weeks to fix this bug. His
  patch has been successfully tested by various people on various
  machines and with various kernels (6.6, 6.8 and 6.9), and the debian
  buildd servers haven't shown a single random segfault with this patch.

  Since the cache handling has been reworked, the patch is slightly
  bigger than I would like in this stage, but the greatly improved
  stability IMHO justifies the inclusion now"

* tag 'parisc-for-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Try to fix random segmentation faults in package builds

Pull i2c fixes from Wolfram Sang:
 "Two fixes to correctly report i2c functionality, ensuring that
  I2C_FUNC_SLAVE is reported when a device operates solely as a slave
  interface"

* tag 'i2c-for-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: designware: Fix the functionality flags of the slave-only interface
  i2c: at91: Fix the functionality flags of the slave-only interface

Pull USB / Thunderbolt fixes from Greg KH:
 "Here are some small USB and Thunderbolt driver fixes for 6.10-rc4.
  Included in here are:

   - thunderbolt debugfs bugfix

   - USB typec bugfixes

   - kcov usb bugfix

   - xhci bugfixes

   - usb-storage bugfix

   - dt-bindings bugfix

   - cdc-wdm log message spam bugfix

  All of these, except for the last cdc-wdm log level change, have been
  in linux-next for a while with no reported problems. The cdc-wdm
  bugfix has been tested by syzbot and proved to fix the reported cpu
  lockup issues when the log is constantly spammed by a broken device"

* tag 'usb-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  USB: class: cdc-wdm: Fix CPU lockup caused by excessive log messages
  xhci: Handle TD clearing for multiple streams case
  xhci: Apply broken streams quirk to Etron EJ188 xHCI host
  xhci: Apply reset resume quirk to Etron EJ188 xHCI host
  xhci: Set correct transferred length for cancelled bulk transfers
  usb-storage: alauda: Check whether the media is initialized
  usb: typec: ucsi: Ack also failed Get Error commands
  kcov, usb: disable interrupts in kcov_remote_start_usb_softirq
  dt-bindings: usb: realtek,rts5411: Add missing "additionalProperties" on child nodes
  usb: typec: tcpm: Ignore received Hard Reset in TOGGLING state
  usb: typec: tcpm: fix use-after-free case in tcpm_register_source_caps
  USB: xen-hcd: Traverse host/ when CONFIG_USB_XEN_HCD is selected
  usb: typec: ucsi: glink: increase max ports for x1e80100
  Revert "usb: chipidea: move ci_ulpi_init after the phy initialization"
  thunderbolt: debugfs: Fix margin debugfs node creation condition

Pull tty/serial driver fixes from Greg KH:
 "Here are some small tty and serial driver fixes that resolve som
  reported problems. Included in here are:

   - n_tty lookahead buffer bugfix

   - WARN_ON() removal where it was not needed

   - 8250_dw driver bugfixes

   - 8250_pxa bugfix

   - sc16is7xx Kconfig fixes for reported build issues

  All of these have been in linux-next for over a week with no reported
  problems"

* tag 'tty-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: drop debugging WARN_ON_ONCE() from uart_write()
  serial: sc16is7xx: re-add Kconfig SPI or I2C dependency
  serial: sc16is7xx: rename Kconfig CONFIG_SERIAL_SC16IS7XX_CORE
  serial: port: Don't block system suspend even if bytes are left to xmit
  serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level
  serial: 8250_dw: Revert "Move definitions to the shared header"
  serial: 8250_dw: Don't use struct dw8250_data outside of 8250_dw
  tty: n_tty: Fix buffer offsets when lookahead is used

Pull staging driver fix from Greg KH:
 "Here is a single staging driver fix, for the vc04 driver. It resolves
  a reported problem that showed up in the merge window set of changes.

  It's been in linux-next for over a week with no reported problems"

* tag 'staging-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: vchiq_debugfs: Fix NPD in vchiq_dump_state

Pull driver core and sysfs fixes from Greg KH:
 "Here are three small changes for 6.10-rc4 that resolve reported
  problems, and finally drop an unused api call. These are:

   - removal of devm_device_add_groups(), all the callers of this are
     finally gone after the 6.10-rc1 merge (changes came in through
     different trees), so it's safe to remove.

   - much reported sysfs build error fixed up for systems that did not
     have sysfs enabled

   - driver core sync issue fix for a many reported issue over the years
     that no one really paid much attention to, until Dirk finally
     tracked down the real issue and made the "obviously correct and
     simple" fix for it.

  All of these have been in linux-next for over a week with no reported
  problems"

* tag 'driver-core-6.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  drivers: core: synchronize really_probe() and dev_uevent()
  sysfs: Unbreak the build around sysfs_bin_attr_simple_read()
  driver core: remove devm_device_add_groups()