This reverts commit 9da3f2b74054406f87dff7101a569217ffceb29b.

It was well-intentioned, but wrong.  Overriding the exception tables for
instructions for random reasons is just wrong, and that is what the new
code did.

It caused problems for tracing, and it caused problems for strncpy_from_user(),
because the new checks made perfectly valid use cases break, rather than
catch things that did bad things.

Unchecked user space accesses are a problem, but that's not a reason to
add invalid checks that then people have to work around with silly flags
(in this case, that 'kernel_uaccess_faults_ok' flag, which is just an
odd way to say "this commit was wrong" and was sprinked into random
places to hide the wrongness).

The real fix to unchecked user space accesses is to get rid of the
special "let's not check __get_user() and __put_user() at all" logic.
Make __{get|put}_user() be just aliases to the regular {get|put}_user()
functions, and make it impossible to access user space without having
the proper checks in places.

The raison d'être of the special double-underscore versions used to be
that the range check was expensive, and if you did multiple user
accesses, you'd do the range check up front (like the signal frame
handling code, for example).  But SMAP (on x86) and PAN (on ARM) have
made that optimization pointless, because the _real_ expense is the "set
CPU flag to allow user space access".

Do let's not break the valid cases to catch invalid cases that shouldn't
even exist.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull x86 fixes from Thomas Gleixner:
 "A few updates for x86:

   - Fix an unintended sign extension issue in the fault handling code

   - Rename the new resource control config switch so it's less
     confusing

   - Avoid setting up EFI info in kexec when the EFI runtime is
     disabled.

   - Fix the microcode version check in the AMD microcode loader so it
     only loads higher version numbers and never downgrades

   - Set EFER.LME in the 32bit trampoline before returning to long mode
     to handle older AMD/KVM behaviour properly.

   - Add Darren and Andy as x86/platform reviewers"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/resctrl: Avoid confusion over the new X86_RESCTRL config
  x86/kexec: Don't setup EFI info if EFI runtime is not enabled
  x86/microcode/amd: Don't falsely trick the late loading mechanism
  MAINTAINERS: Add Andy and Darren as arch/x86/platform/ reviewers
  x86/fault: Fix sign-extend unintended sign extension
  x86/boot/compressed/64: Set EFER.LME=1 in 32-bit trampoline before returning to long mode
  x86/cpu: Add Atom Tremont (Jacobsville)

"Resource Control" is a very broad term for this CPU feature, and a term
that is also associated with containers, cgroups etc. This can easily
cause confusion.

Make the user prompt more specific. Match the config symbol name.

 [ bp: In the future, the corresponding ARM arch-specific code will be
   under ARM_CPU_RESCTRL and the arch-agnostic bits will be carved out
   under the CPU_RESCTRL umbrella symbol. ]

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Babu Moger <Babu.Moger@amd.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linux-doc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pu Wen <puwen@hygon.cn>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190130195621.GA30653@cmpxchg.org

Pull networking fixes from David Miller:

 1) Fix regression in multi-SKB responses to RTM_GETADDR, from Arthur
    Gautier.

 2) Fix ipv6 frag parsing in openvswitch, from Yi-Hung Wei.

 3) Unbounded recursion in ipv4 and ipv6 GUE tunnels, from Stefano
    Brivio.

 4) Use after free in hns driver, from Yonglong Liu.

 5) icmp6_send() needs to handle the case of NULL skb, from Eric
    Dumazet.

 6) Missing rcu read lock in __inet6_bind() when operating on mapped
    addresses, from David Ahern.

 7) Memory leak in tipc-nl_compat_publ_dump(), from Gustavo A. R. Silva.

 8) Fix PHY vs r8169 module loading ordering issues, from Heiner
    Kallweit.

 9) Fix bridge vlan memory leak, from Ido Schimmel.

10) Dev refcount leak in AF_PACKET, from Jason Gunthorpe.

11) Infoleak in ipv6_local_error(), flow label isn't completely
    initialized. From Eric Dumazet.

12) Handle mv88e6390 errata, from Andrew Lunn.

13) Making vhost/vsock CID hashing consistent, from Zha Bin.

14) Fix lack of UMH cleanup when it unexpectedly exits, from Taehee Yoo.

15) Bridge forwarding must clear skb->tstamp, from Paolo Abeni.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (87 commits)
  bnxt_en: Fix context memory allocation.
  bnxt_en: Fix ring checking logic on 57500 chips.
  mISDN: hfcsusb: Use struct_size() in kzalloc()
  net: clear skb->tstamp in bridge forwarding path
  net: bpfilter: disallow to remove bpfilter module while being used
  net: bpfilter: restart bpfilter_umh when error occurred
  net: bpfilter: use cleanup callback to release umh_info
  umh: add exit routine for UMH process
  isdn: i4l: isdn_tty: Fix some concurrency double-free bugs
  vhost/vsock: fix vhost vsock cid hashing inconsistent
  net: stmmac: Prevent RX starvation in stmmac_napi_poll()
  net: stmmac: Fix the logic of checking if RX Watchdog must be enabled
  net: stmmac: Check if CBS is supported before configuring
  net: stmmac: dwxgmac2: Only clear interrupts that are active
  net: stmmac: Fix PCI module removal leak
  tools/bpf: fix bpftool map dump with bitfields
  tools/bpf: test btf bitfield with >=256 struct member offset
  bpf: fix bpffs bitfield pretty print
  net: ethernet: mediatek: fix warning in phy_start_aneg
  tcp: change txhash on SYN-data timeout
  ...

A UMH process which is created by the fork_usermode_blob() such as
bpfilter needs to release members of the umh_info when process is
terminated.
But the do_exit() does not release members of the umh_info. hence module
which uses UMH needs own code to detect whether UMH process is
terminated or not.
But this implementation needs extra code for checking the status of
UMH process. it eventually makes the code more complex.

The new PF_UMH flag is added and it is used to identify UMH processes.
The exit_umh() does not release members of the umh_info.
Hence umh_info->cleanup callback should release both members of the
umh_info and the private data.

Suggested-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

CONFIG_RESCTRL is too generic. The final goal is to have a generic
option called like this which is selected by the arch-specific ones
CONFIG_X86_RESCTRL and CONFIG_ARM64_RESCTRL. The generic one will
cover the resctrl filesystem and other generic and shared bits of
functionality.

Signed-off-by: Borislav Petkov <bp@suse.de>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Babu Moger <babu.moger@amd.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: James Morse <james.morse@arm.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20190108171401.GC12235@zn.tnic

Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Introduce "Energy Aware Scheduling" - by Quentin Perret.

     This is a coherent topology description of CPUs in cooperation with
     the PM subsystem, with the goal to schedule more energy-efficiently
     on asymetric SMP platform - such as waking up tasks to the more
     energy-efficient CPUs first, as long as the system isn't
     oversubscribed.

     For details of the design, see:

        https://lore.kernel.org/lkml/20180724122521.22109-1-quentin.perret@arm.com/

   - Misc cleanups and smaller enhancements"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  sched/fair: Select an energy-efficient CPU on task wake-up
  sched/fair: Introduce an energy estimation helper function
  sched/fair: Add over-utilization/tipping point indicator
  sched/fair: Clean-up update_sg_lb_stats parameters
  sched/toplogy: Introduce the 'sched_energy_present' static key
  sched/topology: Make Energy Aware Scheduling depend on schedutil
  sched/topology: Disable EAS on inappropriate platforms
  sched/topology: Add lowest CPU asymmetry sched_domain level pointer
  sched/topology: Reference the Energy Model of CPUs when available
  PM: Introduce an Energy Model management framework
  sched/cpufreq: Prepare schedutil for Energy Aware Scheduling
  sched/topology: Relocate arch_scale_cpu_capacity() to the internal header
  sched/core: Remove unnecessary unlikely() in push_*_task()
  sched/topology: Remove the ::smt_gain field from 'struct sched_domain'
  sched: Fix various typos in comments
  sched/core: Clean up the #ifdef block in add_nr_running()
  sched/fair: Make some variables static
  sched/core: Create task_has_idle_policy() helper
  sched/fair: Add lsub_positive() and use it consistently
  sched/fair: Mask UTIL_AVG_UNCHANGED usages
  ...

Pull RCU updates from Ingo Molnar:
 "The biggest RCU changes in this cycle were:

   - Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.

   - Replace calls of RCU-bh and RCU-sched update-side functions to
     their vanilla RCU counterparts. This series is a step towards
     complete removal of the RCU-bh and RCU-sched update-side functions.

     ( Note that some of these conversions are going upstream via their
       respective maintainers. )

   - Documentation updates, including a number of flavor-consolidation
     updates from Joel Fernandes.

   - Miscellaneous fixes.

   - Automate generation of the initrd filesystem used for rcutorture
     testing.

   - Convert spin_is_locked() assertions to instead use lockdep.

     ( Note that some of these conversions are going upstream via their
       respective maintainers. )

   - SRCU updates, especially including a fix from Dennis Krein for a
     bag-on-head-class bug.

   - RCU torture-test updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (112 commits)
  rcutorture: Don't do busted forward-progress testing
  rcutorture: Use 100ms buckets for forward-progress callback histograms
  rcutorture: Recover from OOM during forward-progress tests
  rcutorture: Print forward-progress test age upon failure
  rcutorture: Print time since GP end upon forward-progress failure
  rcutorture: Print histogram of CB invocation at OOM time
  rcutorture: Print GP age upon forward-progress failure
  rcu: Print per-CPU callback counts for forward-progress failures
  rcu: Account for nocb-CPU callback counts in RCU CPU stall warnings
  rcutorture: Dump grace-period diagnostics upon forward-progress OOM
  rcutorture: Prepare for asynchronous access to rcu_fwd_startat
  torture: Remove unnecessary "ret" variables
  rcutorture: Affinity forward-progress test to avoid housekeeping CPUs
  rcutorture: Break up too-long rcu_torture_fwd_prog() function
  rcutorture: Remove cbflood facility
  torture: Bring any extra CPUs online during kernel startup
  rcutorture: Add call_rcu() flooding forward-progress tests
  rcutorture/formal: Replace synchronize_sched() with synchronize_rcu()
  tools/kernel.h: Replace synchronize_sched() with synchronize_rcu()
  net/decnet: Replace rcu_barrier_bh() with rcu_barrier()
  ...

Pull x86 cache control updates from Borislav Petkov:

 - The generalization of the RDT code to accommodate the addition of
   AMD's very similar implementation of the cache monitoring feature.

   This entails a subsystem move into a separate and generic
   arch/x86/kernel/cpu/resctrl/ directory along with adding
   vendor-specific initialization and feature detection helpers.

   Ontop of that is the unification of user-visible strings, both in the
   resctrl filesystem error handling and Kconfig.

   Provided by Babu Moger and Sherry Hurwitz.

 - Code simplifications and error handling improvements by Reinette
   Chatre.

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/resctrl: Fix rdt_find_domain() return value and checks
  x86/resctrl: Remove unnecessary check for cbm_validate()
  x86/resctrl: Use rdt_last_cmd_puts() where possible
  MAINTAINERS: Update resctrl filename patterns
  Documentation: Rename and update intel_rdt_ui.txt to resctrl_ui.txt
  x86/resctrl: Introduce AMD QOS feature
  x86/resctrl: Fixup the user-visible strings
  x86/resctrl: Add AMD's X86_FEATURE_MBA to the scattered CPUID features
  x86/resctrl: Rename the config option INTEL_RDT to RESCTRL
  x86/resctrl: Add vendor check for the MBA software controller
  x86/resctrl: Bring cbm_validate() into the resource structure
  x86/resctrl: Initialize the vendor-specific resource functions
  x86/resctrl: Move all the macros to resctrl/internal.h
  x86/resctrl: Re-arrange the RDT init code
  x86/resctrl: Rename the RDT functions and definitions
  x86/resctrl: Rename and move rdt files to a separate directory

Pull RCU changes from Paul E. McKenney:

- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.

- Replace calls of RCU-bh and RCU-sched update-side functions
  to their vanilla RCU counterparts.  This series is a step
  towards complete removal of the RCU-bh and RCU-sched update-side
  functions.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- Documentation updates, including a number of flavor-consolidation
  updates from Joel Fernandes.

- Miscellaneous fixes.

- Automate generation of the initrd filesystem used for
  rcutorture testing.

- Convert spin_is_locked() assertions to instead use lockdep.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- SRCU updates, especially including a fix from Dennis Krein
  for a bag-on-head-class bug.

- RCU torture-test updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>