Commit 533925cb authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'riscv-for-linus-6.5-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Palmer Dabbelt:

 - Support for ACPI

 - Various cleanups to the ISA string parsing, including making them
   case-insensitive

 - Support for the vector extension

 - Support for independent irq/softirq stacks

 - Our CPU DT binding now has "unevaluatedProperties: false"

* tag 'riscv-for-linus-6.5-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (78 commits)
  riscv: hibernate: remove WARN_ON in save_processor_state
  dt-bindings: riscv: cpus: switch to unevaluatedProperties: false
  dt-bindings: riscv: cpus: add a ref the common cpu schema
  riscv: stack: Add config of thread stack size
  riscv: stack: Support HAVE_SOFTIRQ_ON_OWN_STACK
  riscv: stack: Support HAVE_IRQ_EXIT_ON_IRQ_STACK
  RISC-V: always report presence of extensions formerly part of the base ISA
  dt-bindings: riscv: explicitly mention assumption of Zicntr & Zihpm support
  RISC-V: remove decrement/increment dance in ISA string parser
  RISC-V: rework comments in ISA string parser
  RISC-V: validate riscv,isa at boot, not during ISA string parsing
  RISC-V: split early & late of_node to hartid mapping
  RISC-V: simplify register width check in ISA string parsing
  perf: RISC-V: Limit the number of counters returned from SBI
  riscv: replace deprecated scall with ecall
  riscv: uprobes: Restore thread.bad_cause
  riscv: mm: try VMA lock-based page fault handling first
  riscv: mm: Pre-allocate PGD entries for vmalloc/modules area
  RISC-V: hwprobe: Expose Zba, Zbb, and Zbs
  RISC-V: Track ISA extensions per hart
  ...
parents d8b0bd57 488833cc
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+4 −4
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	acpi=		[HW,ACPI,X86,ARM64]
	acpi=		[HW,ACPI,X86,ARM64,RISCV64]
			Advanced Configuration and Power Interface
			Format: { force | on | off | strict | noirq | rsdt |
				  copy_dsdt }
			force -- enable ACPI if default was off
			on -- enable ACPI but allow fallback to DT [arm64]
			on -- enable ACPI but allow fallback to DT [arm64,riscv64]
			off -- disable ACPI if default was on
			noirq -- do not use ACPI for IRQ routing
			strict -- Be less tolerant of platforms that are not
				strictly ACPI specification compliant.
			rsdt -- prefer RSDT over (default) XSDT
			copy_dsdt -- copy DSDT to memory
			For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
			are available
			For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
			"acpi=force" are available

			See also Documentation/power/runtime_pm.rst, pci=noacpi

+13 −7
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@@ -23,6 +23,9 @@ description: |
  two cores, each of which has two hyperthreads, could be described as
  having four harts.

allOf:
  - $ref: /schemas/cpu.yaml#

properties:
  compatible:
    oneOf:
@@ -61,7 +64,7 @@ properties:
      hart.  These values originate from the RISC-V Privileged
      Specification document, available from
      https://riscv.org/specifications/
    $ref: "/schemas/types.yaml#/definitions/string"
    $ref: /schemas/types.yaml#/definitions/string
    enum:
      - riscv,sv32
      - riscv,sv39
@@ -89,15 +92,18 @@ properties:
      Due to revisions of the ISA specification, some deviations
      have arisen over time.
      Notably, riscv,isa was defined prior to the creation of the
      Zicsr and Zifencei extensions and thus "i" implies
      "zicsr_zifencei".
      Zicntr, Zicsr, Zifencei and Zihpm extensions and thus "i"
      implies "zicntr_zicsr_zifencei_zihpm".

      While the isa strings in ISA specification are case
      insensitive, letters in the riscv,isa string must be all
      lowercase to simplify parsing.
    $ref: "/schemas/types.yaml#/definitions/string"
      lowercase.
    $ref: /schemas/types.yaml#/definitions/string
    pattern: ^rv(?:64|32)imaf?d?q?c?b?k?j?p?v?h?(?:[hsxz](?:[a-z])+)?(?:_[hsxz](?:[a-z])+)*$

  # RISC-V has multiple properties for cache op block sizes as the sizes
  # differ between individual CBO extensions
  cache-op-block-size: false
  # RISC-V requires 'timebase-frequency' in /cpus, so disallow it here
  timebase-frequency: false

@@ -120,7 +126,7 @@ properties:
      - interrupt-controller

  cpu-idle-states:
    $ref: '/schemas/types.yaml#/definitions/phandle-array'
    $ref: /schemas/types.yaml#/definitions/phandle-array
    items:
      maxItems: 1
    description: |
@@ -137,7 +143,7 @@ required:
  - riscv,isa
  - interrupt-controller

additionalProperties: true
unevaluatedProperties: false

examples:
  - |
+13 −0
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@@ -64,6 +64,19 @@ The following keys are defined:
  * :c:macro:`RISCV_HWPROBE_IMA_C`: The C extension is supported, as defined
    by version 2.2 of the RISC-V ISA manual.

  * :c:macro:`RISCV_HWPROBE_IMA_V`: The V extension is supported, as defined by
    version 1.0 of the RISC-V Vector extension manual.

  * :c:macro:`RISCV_HWPROBE_EXT_ZBA`: The Zba address generation extension is
       supported, as defined in version 1.0 of the Bit-Manipulation ISA
       extensions.

  * :c:macro:`RISCV_HWPROBE_EXT_ZBB`: The Zbb extension is supported, as defined
       in version 1.0 of the Bit-Manipulation ISA extensions.

  * :c:macro:`RISCV_HWPROBE_EXT_ZBS`: The Zbs extension is supported, as defined
       in version 1.0 of the Bit-Manipulation ISA extensions.

* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
  information about the selected set of processors.

+1 −0
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@@ -10,6 +10,7 @@ RISC-V architecture
    hwprobe
    patch-acceptance
    uabi
    vector

    features

+132 −0
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.. SPDX-License-Identifier: GPL-2.0

=========================================
Vector Extension Support for RISC-V Linux
=========================================

This document briefly outlines the interface provided to userspace by Linux in
order to support the use of the RISC-V Vector Extension.

1.  prctl() Interface
---------------------

Two new prctl() calls are added to allow programs to manage the enablement
status for the use of Vector in userspace. The intended usage guideline for
these interfaces is to give init systems a way to modify the availability of V
for processes running under its domain. Calling thess interfaces is not
recommended in libraries routines because libraries should not override policies
configured from the parant process. Also, users must noted that these interfaces
are not portable to non-Linux, nor non-RISC-V environments, so it is discourage
to use in a portable code. To get the availability of V in an ELF program,
please read :c:macro:`COMPAT_HWCAP_ISA_V` bit of :c:macro:`ELF_HWCAP` in the
auxiliary vector.

* prctl(PR_RISCV_V_SET_CONTROL, unsigned long arg)

    Sets the Vector enablement status of the calling thread, where the control
    argument consists of two 2-bit enablement statuses and a bit for inheritance
    mode. Other threads of the calling process are unaffected.

    Enablement status is a tri-state value each occupying 2-bit of space in
    the control argument:

    * :c:macro:`PR_RISCV_V_VSTATE_CTRL_DEFAULT`: Use the system-wide default
      enablement status on execve(). The system-wide default setting can be
      controlled via sysctl interface (see sysctl section below).

    * :c:macro:`PR_RISCV_V_VSTATE_CTRL_ON`: Allow Vector to be run for the
      thread.

    * :c:macro:`PR_RISCV_V_VSTATE_CTRL_OFF`: Disallow Vector. Executing Vector
      instructions under such condition will trap and casuse the termination of the thread.

    arg: The control argument is a 5-bit value consisting of 3 parts, and
    accessed by 3 masks respectively.

    The 3 masks, PR_RISCV_V_VSTATE_CTRL_CUR_MASK,
    PR_RISCV_V_VSTATE_CTRL_NEXT_MASK, and PR_RISCV_V_VSTATE_CTRL_INHERIT
    represents bit[1:0], bit[3:2], and bit[4]. bit[1:0] accounts for the
    enablement status of current thread, and the setting at bit[3:2] takes place
    at next execve(). bit[4] defines the inheritance mode of the setting in
    bit[3:2].

        * :c:macro:`PR_RISCV_V_VSTATE_CTRL_CUR_MASK`: bit[1:0]: Account for the
          Vector enablement status for the calling thread. The calling thread is
          not able to turn off Vector once it has been enabled. The prctl() call
          fails with EPERM if the value in this mask is PR_RISCV_V_VSTATE_CTRL_OFF
          but the current enablement status is not off. Setting
          PR_RISCV_V_VSTATE_CTRL_DEFAULT here takes no effect but to set back
          the original enablement status.

        * :c:macro:`PR_RISCV_V_VSTATE_CTRL_NEXT_MASK`: bit[3:2]: Account for the
          Vector enablement setting for the calling thread at the next execve()
          system call. If PR_RISCV_V_VSTATE_CTRL_DEFAULT is used in this mask,
          then the enablement status will be decided by the system-wide
          enablement status when execve() happen.

        * :c:macro:`PR_RISCV_V_VSTATE_CTRL_INHERIT`: bit[4]: the inheritance
          mode for the setting at PR_RISCV_V_VSTATE_CTRL_NEXT_MASK. If the bit
          is set then the following execve() will not clear the setting in both
          PR_RISCV_V_VSTATE_CTRL_NEXT_MASK and PR_RISCV_V_VSTATE_CTRL_INHERIT.
          This setting persists across changes in the system-wide default value.

    Return value:
        * 0 on success;
        * EINVAL: Vector not supported, invalid enablement status for current or
          next mask;
        * EPERM: Turning off Vector in PR_RISCV_V_VSTATE_CTRL_CUR_MASK if Vector
          was enabled for the calling thread.

    On success:
        * A valid setting for PR_RISCV_V_VSTATE_CTRL_CUR_MASK takes place
          immediately. The enablement status specified in
          PR_RISCV_V_VSTATE_CTRL_NEXT_MASK happens at the next execve() call, or
          all following execve() calls if PR_RISCV_V_VSTATE_CTRL_INHERIT bit is
          set.
        * Every successful call overwrites a previous setting for the calling
          thread.

* prctl(PR_RISCV_V_GET_CONTROL)

    Gets the same Vector enablement status for the calling thread. Setting for
    next execve() call and the inheritance bit are all OR-ed together.

    Note that ELF programs are able to get the availability of V for itself by
    reading :c:macro:`COMPAT_HWCAP_ISA_V` bit of :c:macro:`ELF_HWCAP` in the
    auxiliary vector.

    Return value:
        * a nonnegative value on success;
        * EINVAL: Vector not supported.

2.  System runtime configuration (sysctl)
-----------------------------------------

To mitigate the ABI impact of expansion of the signal stack, a
policy mechanism is provided to the administrators, distro maintainers, and
developers to control the default Vector enablement status for userspace
processes in form of sysctl knob:

* /proc/sys/abi/riscv_v_default_allow

    Writing the text representation of 0 or 1 to this file sets the default
    system enablement status for new starting userspace programs. Valid values
    are:

    * 0: Do not allow Vector code to be executed as the default for new processes.
    * 1: Allow Vector code to be executed as the default for new processes.

    Reading this file returns the current system default enablement status.

    At every execve() call, a new enablement status of the new process is set to
    the system default, unless:

      * PR_RISCV_V_VSTATE_CTRL_INHERIT is set for the calling process, and the
        setting in PR_RISCV_V_VSTATE_CTRL_NEXT_MASK is not
        PR_RISCV_V_VSTATE_CTRL_DEFAULT. Or,

      * The setting in PR_RISCV_V_VSTATE_CTRL_NEXT_MASK is not
        PR_RISCV_V_VSTATE_CTRL_DEFAULT.

    Modifying the system default enablement status does not affect the enablement
    status of any existing process of thread that do not make an execve() call.
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