Merge remote-tracking branch 'tip/sched/arm64' into for-next/core

* tip/sched/arm64: (785 commits)
  Documentation: arm64: describe asymmetric 32-bit support
  arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
  arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0
  arm64: Advertise CPUs capable of running 32-bit applications in sysfs
  arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system
  arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0
  arm64: Implement task_cpu_possible_mask()
  sched: Introduce dl_task_check_affinity() to check proposed affinity
  sched: Allow task CPU affinity to be restricted on asymmetric systems
  sched: Split the guts of sched_setaffinity() into a helper function
  sched: Introduce task_struct::user_cpus_ptr to track requested affinity
  sched: Reject CPU affinity changes based on task_cpu_possible_mask()
  cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
  cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()
  cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
  sched: Introduce task_cpu_possible_mask() to limit fallback rq selection
  sched: Cgroup SCHED_IDLE support
  sched/topology: Skip updating masks for non-online nodes
  Linux 5.14-rc6
  lib: use PFN_PHYS() in devmem_is_allowed()
  ...

Author: ctmarinas

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -494,6 +494,15 @@ Description:	AArch64 CPU registers
 		'identification' directory exposes the CPU ID registers for
 		identifying model and revision of the CPU.
 
+What:		/sys/devices/system/cpu/aarch32_el0
+Date:		May 2021
+Contact:	Linux ARM Kernel Mailing list <[email protected]>
+Description:	Identifies the subset of CPUs in the system that can execute
+		AArch32 (32-bit ARM) applications. If present, the same format as
+		/sys/devices/system/cpu/{offline,online,possible,present} is used.
+		If absent, then all or none of the CPUs can execute AArch32
+		applications and execve() will behave accordingly.
+
 What:		/sys/devices/system/cpu/cpu#/cpu_capacity
 Date:		December 2016
 Contact:	Linux kernel mailing list <[email protected]>

Documentation/admin-guide/kernel-parameters.txt

@@ -287,6 +287,17 @@
 			do not want to use tracing_snapshot_alloc() as it needs
 			to be done where GFP_KERNEL allocations are allowed.
 
+	allow_mismatched_32bit_el0 [ARM64]
+			Allow execve() of 32-bit applications and setting of the
+			PER_LINUX32 personality on systems where only a strict
+			subset of the CPUs support 32-bit EL0. When this
+			parameter is present, the set of CPUs supporting 32-bit
+			EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
+			and hot-unplug operations may be restricted.
+
+			See Documentation/arm64/asymmetric-32bit.rst for more
+			information.
+
 	amd_iommu=	[HW,X86-64]
 			Pass parameters to the AMD IOMMU driver in the system.
 			Possible values are:

Documentation/arm64/asymmetric-32bit.rst

@@ -0,0 +1,155 @@
+======================
+Asymmetric 32-bit SoCs
+======================
+
+Author: Will Deacon <[email protected]>
+
+This document describes the impact of asymmetric 32-bit SoCs on the
+execution of 32-bit (``AArch32``) applications.
+
+Date: 2021-05-17
+
+Introduction
+============
+
+Some Armv9 SoCs suffer from a big.LITTLE misfeature where only a subset
+of the CPUs are capable of executing 32-bit user applications. On such
+a system, Linux by default treats the asymmetry as a "mismatch" and
+disables support for both the ``PER_LINUX32`` personality and
+``execve(2)`` of 32-bit ELF binaries, with the latter returning
+``-ENOEXEC``. If the mismatch is detected during late onlining of a
+64-bit-only CPU, then the onlining operation fails and the new CPU is
+unavailable for scheduling.
+
+Surprisingly, these SoCs have been produced with the intention of
+running legacy 32-bit binaries. Unsurprisingly, that doesn't work very
+well with the default behaviour of Linux.
+
+It seems inevitable that future SoCs will drop 32-bit support
+altogether, so if you're stuck in the unenviable position of needing to
+run 32-bit code on one of these transitionary platforms then you would
+be wise to consider alternatives such as recompilation, emulation or
+retirement. If neither of those options are practical, then read on.
+
+Enabling kernel support
+=======================
+
+Since the kernel support is not completely transparent to userspace,
+allowing 32-bit tasks to run on an asymmetric 32-bit system requires an
+explicit "opt-in" and can be enabled by passing the
+``allow_mismatched_32bit_el0`` parameter on the kernel command-line.
+
+For the remainder of this document we will refer to an *asymmetric
+system* to mean an asymmetric 32-bit SoC running Linux with this kernel
+command-line option enabled.
+
+Userspace impact
+================
+
+32-bit tasks running on an asymmetric system behave in mostly the same
+way as on a homogeneous system, with a few key differences relating to
+CPU affinity.
+
+sysfs
+-----
+
+The subset of CPUs capable of running 32-bit tasks is described in
+``/sys/devices/system/cpu/aarch32_el0`` and is documented further in
+``Documentation/ABI/testing/sysfs-devices-system-cpu``.
+
+**Note:** CPUs are advertised by this file as they are detected and so
+late-onlining of 32-bit-capable CPUs can result in the file contents
+being modified by the kernel at runtime. Once advertised, CPUs are never
+removed from the file.
+
+``execve(2)``
+-------------
+
+On a homogeneous system, the CPU affinity of a task is preserved across
+``execve(2)``. This is not always possible on an asymmetric system,
+specifically when the new program being executed is 32-bit yet the
+affinity mask contains 64-bit-only CPUs. In this situation, the kernel
+determines the new affinity mask as follows:
+
+  1. If the 32-bit-capable subset of the affinity mask is not empty,
+     then the affinity is restricted to that subset and the old affinity
+     mask is saved. This saved mask is inherited over ``fork(2)`` and
+     preserved across ``execve(2)`` of 32-bit programs.
+
+     **Note:** This step does not apply to ``SCHED_DEADLINE`` tasks.
+     See `SCHED_DEADLINE`_.
+
+  2. Otherwise, the cpuset hierarchy of the task is walked until an
+     ancestor is found containing at least one 32-bit-capable CPU. The
+     affinity of the task is then changed to match the 32-bit-capable
+     subset of the cpuset determined by the walk.
+
+  3. On failure (i.e. out of memory), the affinity is changed to the set
+     of all 32-bit-capable CPUs of which the kernel is aware.
+
+A subsequent ``execve(2)`` of a 64-bit program by the 32-bit task will
+invalidate the affinity mask saved in (1) and attempt to restore the CPU
+affinity of the task using the saved mask if it was previously valid.
+This restoration may fail due to intervening changes to the deadline
+policy or cpuset hierarchy, in which case the ``execve(2)`` continues
+with the affinity unchanged.
+
+Calls to ``sched_setaffinity(2)`` for a 32-bit task will consider only
+the 32-bit-capable CPUs of the requested affinity mask. On success, the
+affinity for the task is updated and any saved mask from a prior
+``execve(2)`` is invalidated.
+
+``SCHED_DEADLINE``
+------------------
+
+Explicit admission of a 32-bit deadline task to the default root domain
+(e.g. by calling ``sched_setattr(2)``) is rejected on an asymmetric
+32-bit system unless admission control is disabled by writing -1 to
+``/proc/sys/kernel/sched_rt_runtime_us``.
+
+``execve(2)`` of a 32-bit program from a 64-bit deadline task will
+return ``-ENOEXEC`` if the root domain for the task contains any
+64-bit-only CPUs and admission control is enabled. Concurrent offlining
+of 32-bit-capable CPUs may still necessitate the procedure described in
+`execve(2)`_, in which case step (1) is skipped and a warning is
+emitted on the console.
+
+**Note:** It is recommended that a set of 32-bit-capable CPUs are placed
+into a separate root domain if ``SCHED_DEADLINE`` is to be used with
+32-bit tasks on an asymmetric system. Failure to do so is likely to
+result in missed deadlines.
+
+Cpusets
+-------
+
+The affinity of a 32-bit task on an asymmetric system may include CPUs
+that are not explicitly allowed by the cpuset to which it is attached.
+This can occur as a result of the following two situations:
+
+  - A 64-bit task attached to a cpuset which allows only 64-bit CPUs
+    executes a 32-bit program.
+
+  - All of the 32-bit-capable CPUs allowed by a cpuset containing a
+    32-bit task are offlined.
+
+In both of these cases, the new affinity is calculated according to step
+(2) of the process described in `execve(2)`_ and the cpuset hierarchy is
+unchanged irrespective of the cgroup version.
+
+CPU hotplug
+-----------
+
+On an asymmetric system, the first detected 32-bit-capable CPU is
+prevented from being offlined by userspace and any such attempt will
+return ``-EPERM``. Note that suspend is still permitted even if the
+primary CPU (i.e. CPU 0) is 64-bit-only.
+
+KVM
+---
+
+Although KVM will not advertise 32-bit EL0 support to any vCPUs on an
+asymmetric system, a broken guest at EL1 could still attempt to execute
+32-bit code at EL0. In this case, an exit from a vCPU thread in 32-bit
+mode will return to host userspace with an ``exit_reason`` of
+``KVM_EXIT_FAIL_ENTRY`` and will remain non-runnable until successfully
+re-initialised by a subsequent ``KVM_ARM_VCPU_INIT`` operation.

Documentation/arm64/index.rst

@@ -10,6 +10,7 @@ ARM64 Architecture
     acpi_object_usage
     amu
     arm-acpi
+    asymmetric-32bit
     booting
     cpu-feature-registers
     elf_hwcaps

Documentation/bpf/libbpf/libbpf_naming_convention.rst

@@ -108,7 +108,7 @@ This bump in ABI version is at most once per kernel development cycle.
 
 For example, if current state of ``libbpf.map`` is:
 
-.. code-block:: c
+.. code-block:: none
 
         LIBBPF_0.0.1 {
         	global:
@@ -121,7 +121,7 @@ For example, if current state of ``libbpf.map`` is:
 , and a new symbol ``bpf_func_c`` is being introduced, then
 ``libbpf.map`` should be changed like this:
 
-.. code-block:: c
+.. code-block:: none
 
         LIBBPF_0.0.1 {
         	global:

Documentation/devicetree/bindings/iio/st,st-sensors.yaml

@@ -152,47 +152,6 @@ allOf:
           maxItems: 1
         st,drdy-int-pin: false
 
-  - if:
-      properties:
-        compatible:
-          enum:
-            # Two intertial interrupts i.e. accelerometer/gyro interrupts
-            - st,h3lis331dl-accel
-            - st,l3g4200d-gyro
-            - st,l3g4is-gyro
-            - st,l3gd20-gyro
-            - st,l3gd20h-gyro
-            - st,lis2de12
-            - st,lis2dw12
-            - st,lis2hh12
-            - st,lis2dh12-accel
-            - st,lis331dl-accel
-            - st,lis331dlh-accel
-            - st,lis3de
-            - st,lis3dh-accel
-            - st,lis3dhh
-            - st,lis3mdl-magn
-            - st,lng2dm-accel
-            - st,lps331ap-press
-            - st,lsm303agr-accel
-            - st,lsm303dlh-accel
-            - st,lsm303dlhc-accel
-            - st,lsm303dlm-accel
-            - st,lsm330-accel
-            - st,lsm330-gyro
-            - st,lsm330d-accel
-            - st,lsm330d-gyro
-            - st,lsm330dl-accel
-            - st,lsm330dl-gyro
-            - st,lsm330dlc-accel
-            - st,lsm330dlc-gyro
-            - st,lsm9ds0-gyro
-            - st,lsm9ds1-magn
-    then:
-      properties:
-        interrupts:
-          maxItems: 2
-
 required:
   - compatible
   - reg

Documentation/gpu/rfc/i915_gem_lmem.rst

@@ -18,114 +18,5 @@ real, with all the uAPI bits is:
         * Route shmem backend over to TTM SYSTEM for discrete
         * TTM purgeable object support
         * Move i915 buddy allocator over to TTM
-        * MMAP ioctl mode(see `I915 MMAP`_)
-        * SET/GET ioctl caching(see `I915 SET/GET CACHING`_)
 * Send RFC(with mesa-dev on cc) for final sign off on the uAPI
 * Add pciid for DG1 and turn on uAPI for real
-
-New object placement and region query uAPI
-==========================================
-Starting from DG1 we need to give userspace the ability to allocate buffers from
-device local-memory. Currently the driver supports gem_create, which can place
-buffers in system memory via shmem, and the usual assortment of other
-interfaces, like dumb buffers and userptr.
-
-To support this new capability, while also providing a uAPI which will work
-beyond just DG1, we propose to offer three new bits of uAPI:
-
-DRM_I915_QUERY_MEMORY_REGIONS
------------------------------
-New query ID which allows userspace to discover the list of supported memory
-regions(like system-memory and local-memory) for a given device. We identify
-each region with a class and instance pair, which should be unique. The class
-here would be DEVICE or SYSTEM, and the instance would be zero, on platforms
-like DG1.
-
-Side note: The class/instance design is borrowed from our existing engine uAPI,
-where we describe every physical engine in terms of its class, and the
-particular instance, since we can have more than one per class.
-
-In the future we also want to expose more information which can further
-describe the capabilities of a region.
-
-.. kernel-doc:: include/uapi/drm/i915_drm.h
-        :functions: drm_i915_gem_memory_class drm_i915_gem_memory_class_instance drm_i915_memory_region_info drm_i915_query_memory_regions
-
-GEM_CREATE_EXT
---------------
-New ioctl which is basically just gem_create but now allows userspace to provide
-a chain of possible extensions. Note that if we don't provide any extensions and
-set flags=0 then we get the exact same behaviour as gem_create.
-
-Side note: We also need to support PXP[1] in the near future, which is also
-applicable to integrated platforms, and adds its own gem_create_ext extension,
-which basically lets userspace mark a buffer as "protected".
-
-.. kernel-doc:: include/uapi/drm/i915_drm.h
-        :functions: drm_i915_gem_create_ext
-
-I915_GEM_CREATE_EXT_MEMORY_REGIONS
-----------------------------------
-Implemented as an extension for gem_create_ext, we would now allow userspace to
-optionally provide an immutable list of preferred placements at creation time,
-in priority order, for a given buffer object.  For the placements we expect
-them each to use the class/instance encoding, as per the output of the regions
-query. Having the list in priority order will be useful in the future when
-placing an object, say during eviction.
-
-.. kernel-doc:: include/uapi/drm/i915_drm.h
-        :functions: drm_i915_gem_create_ext_memory_regions
-
-One fair criticism here is that this seems a little over-engineered[2]. If we
-just consider DG1 then yes, a simple gem_create.flags or something is totally
-all that's needed to tell the kernel to allocate the buffer in local-memory or
-whatever. However looking to the future we need uAPI which can also support
-upcoming Xe HP multi-tile architecture in a sane way, where there can be
-multiple local-memory instances for a given device, and so using both class and
-instance in our uAPI to describe regions is desirable, although specifically
-for DG1 it's uninteresting, since we only have a single local-memory instance.
-
-Existing uAPI issues
-====================
-Some potential issues we still need to resolve.
-
-I915 MMAP
----------
-In i915 there are multiple ways to MMAP GEM object, including mapping the same
-object using different mapping types(WC vs WB), i.e multiple active mmaps per
-object. TTM expects one MMAP at most for the lifetime of the object. If it
-turns out that we have to backpedal here, there might be some potential
-userspace fallout.
-
-I915 SET/GET CACHING
---------------------
-In i915 we have set/get_caching ioctl. TTM doesn't let us to change this, but
-DG1 doesn't support non-snooped pcie transactions, so we can just always
-allocate as WB for smem-only buffers.  If/when our hw gains support for
-non-snooped pcie transactions then we must fix this mode at allocation time as
-a new GEM extension.
-
-This is related to the mmap problem, because in general (meaning, when we're
-not running on intel cpus) the cpu mmap must not, ever, be inconsistent with
-allocation mode.
-
-Possible idea is to let the kernel picks the mmap mode for userspace from the
-following table:
-
-smem-only: WB. Userspace does not need to call clflush.
-
-smem+lmem: We only ever allow a single mode, so simply allocate this as uncached
-memory, and always give userspace a WC mapping. GPU still does snooped access
-here(assuming we can't turn it off like on DG1), which is a bit inefficient.
-
-lmem only: always WC
-
-This means on discrete you only get a single mmap mode, all others must be
-rejected. That's probably going to be a new default mode or something like
-that.
-
-Links
-=====
-[1] https://patchwork.freedesktop.org/series/86798/
-
-[2] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5599#note_553791

Documentation/i2c/index.rst

@@ -17,6 +17,7 @@ Introduction
    busses/index
    i2c-topology
    muxes/i2c-mux-gpio
+   i2c-sysfs
 
 Writing device drivers
 ======================