Add support for 32-bit tasks on asymmetric AArch32 systems

Hi everyone,

The sun is shining and its time for your weekly dose of asymmetric
32-bit support patches, previously seen at:

  v1: https://lore.kernel.org/r/20201027215118.27003-1-will@ker...
  v2: https://lore.kernel.org/r/20201109213023.15092-1-will@ker...
  v3: https://lore.kernel.org/r/20201113093720.21106-1-will@ker...
  v4: https://lore.kernel.org/r/20201124155039.13804-1-will@ker...
  v5: https://lore.kernel.org/r/20201208132835.6151-1-will@kern...
  v6: https://lore.kernel.org/r/20210518094725.7701-1-will@kern...
  v7: https://lore.kernel.org/r/20210525151432.16875-1-will@ker...
  v8: https://lore.kernel.org/r/20210602164719.31777-1-will@ker...

There was also a nice LWN writeup in case you've forgotten what this is
about:

	https://lwn.net/Articles/838339/

Changes since v8 include:

  * Renamed task_cpus_dl_admissible() and changed return type [Daniel]
  * Renamed update_mismatched_32bit_el0_cpu_features() [Mark R]
  * Improved comments [Mark R and Valentin]
  * Cleaned up cpuset_cpus_allowed_fallback() [Valentin]
  * Remove redundant rcu_read_{lock,unlock}() in cpuset_cpus_allowed()
  * Added some more acks/reviewed-by tags

Cheers,

Will

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Qais Yousef <qais.yousef@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Quentin Perret <qperret@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kernel-team@android.com

--->8

Will Deacon (20):
  arm64: cpuinfo: Split AArch32 registers out into a separate struct
  arm64: Allow mismatched 32-bit EL0 support
  KVM: arm64: Kill 32-bit vCPUs on systems with mismatched EL0 support
  arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs
  sched: Introduce task_cpu_possible_mask() to limit fallback rq
    selection
  cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
  cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()
  cpuset: Cleanup cpuset_cpus_allowed_fallback() use in
    select_fallback_rq()
  sched: Reject CPU affinity changes based on task_cpu_possible_mask()
  sched: Introduce task_struct::user_cpus_ptr to track requested
    affinity
  sched: Split the guts of sched_setaffinity() into a helper function
  sched: Allow task CPU affinity to be restricted on asymmetric systems
  sched: Introduce dl_task_check_affinity() to check proposed affinity
  arm64: Implement task_cpu_possible_mask()
  arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit
    EL0
  arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched
    system
  arm64: Advertise CPUs capable of running 32-bit applications in sysfs
  arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0
  arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
  Documentation: arm64: describe asymmetric 32-bit support

 .../ABI/testing/sysfs-devices-system-cpu      |   9 +
 .../admin-guide/kernel-parameters.txt         |  11 +
 Documentation/arm64/asymmetric-32bit.rst      | 155 ++++++++
 Documentation/arm64/index.rst                 |   1 +
 arch/arm64/include/asm/cpu.h                  |  44 +--
 arch/arm64/include/asm/cpufeature.h           |   8 +-
 arch/arm64/include/asm/elf.h                  |   6 +-
 arch/arm64/include/asm/mmu_context.h          |  13 +
 arch/arm64/kernel/cpufeature.c                | 232 +++++++++---
 arch/arm64/kernel/cpuinfo.c                   |  53 +--
 arch/arm64/kernel/process.c                   |  44 ++-
 arch/arm64/kvm/arm.c                          |  11 +-
 arch/arm64/tools/cpucaps                      |   3 +-
 include/linux/cpuset.h                        |   8 +-
 include/linux/mmu_context.h                   |  14 +
 include/linux/sched.h                         |  21 ++
 init/init_task.c                              |   1 +
 kernel/cgroup/cpuset.c                        |  59 +--
 kernel/fork.c                                 |   2 +
 kernel/sched/core.c                           | 340 ++++++++++++++----
 kernel/sched/sched.h                          |   1 +
 21 files changed, 841 insertions(+), 195 deletions(-)
 create mode 100644 Documentation/arm64/asymmetric-32bit.rst

-- 
2.32.0.rc1.229.g3e70b5a671-goog