Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 390 insertions, 0 deletions

diff --git a/Documentation/loongarch/introduction.rst b/Documentation/loongarch/introduction.rst
new file mode 100644
index 000000000..49135d451
--- /dev/null
+++ b/Documentation/loongarch/introduction.rst
@@ -0,0 +1,390 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========================
+Introduction to LoongArch
+=========================
+
+LoongArch is a new RISC ISA, which is a bit like MIPS or RISC-V. There are
+currently 3 variants: a reduced 32-bit version (LA32R), a standard 32-bit
+version (LA32S) and a 64-bit version (LA64). There are 4 privilege levels
+(PLVs) defined in LoongArch: PLV0~PLV3, from high to low. Kernel runs at PLV0
+while applications run at PLV3. This document introduces the registers, basic
+instruction set, virtual memory and some other topics of LoongArch.
+
+Registers
+=========
+
+LoongArch registers include general purpose registers (GPRs), floating point
+registers (FPRs), vector registers (VRs) and control status registers (CSRs)
+used in privileged mode (PLV0).
+
+GPRs
+----
+
+LoongArch has 32 GPRs ( ``$r0`` ~ ``$r31`` ); each one is 32-bit wide in LA32
+and 64-bit wide in LA64. ``$r0`` is hard-wired to zero, and the other registers
+are not architecturally special. (Except ``$r1``, which is hard-wired as the
+link register of the BL instruction.)
+
+The kernel uses a variant of the LoongArch register convention, as described in
+the LoongArch ELF psABI spec, in :ref:`References <loongarch-references>`:
+
+================= =============== =================== ============
+Name              Alias           Usage               Preserved
+                                                      across calls
+================= =============== =================== ============
+``$r0``           ``$zero``       Constant zero       Unused
+``$r1``           ``$ra``         Return address      No
+``$r2``           ``$tp``         TLS/Thread pointer  Unused
+``$r3``           ``$sp``         Stack pointer       Yes
+``$r4``-``$r11``  ``$a0``-``$a7`` Argument registers  No
+``$r4``-``$r5``   ``$v0``-``$v1`` Return value        No
+``$r12``-``$r20`` ``$t0``-``$t8`` Temp registers      No
+``$r21``          ``$u0``         Percpu base address Unused
+``$r22``          ``$fp``         Frame pointer       Yes
+``$r23``-``$r31`` ``$s0``-``$s8`` Static registers    Yes
+================= =============== =================== ============
+
+.. Note::
+    The register ``$r21`` is reserved in the ELF psABI, but used by the Linux
+    kernel for storing the percpu base address. It normally has no ABI name,
+    but is called ``$u0`` in the kernel. You may also see ``$v0`` or ``$v1``
+    in some old code,however they are deprecated aliases of ``$a0`` and ``$a1``
+    respectively.
+
+FPRs
+----
+
+LoongArch has 32 FPRs ( ``$f0`` ~ ``$f31`` ) when FPU is present. Each one is
+64-bit wide on the LA64 cores.
+
+The floating-point register convention is the same as described in the
+LoongArch ELF psABI spec:
+
+================= ================== =================== ============
+Name              Alias              Usage               Preserved
+                                                         across calls
+================= ================== =================== ============
+``$f0``-``$f7``   ``$fa0``-``$fa7``  Argument registers  No
+``$f0``-``$f1``   ``$fv0``-``$fv1``  Return value        No
+``$f8``-``$f23``  ``$ft0``-``$ft15`` Temp registers      No
+``$f24``-``$f31`` ``$fs0``-``$fs7``  Static registers    Yes
+================= ================== =================== ============
+
+.. Note::
+    You may see ``$fv0`` or ``$fv1`` in some old code, however they are
+    deprecated aliases of ``$fa0`` and ``$fa1`` respectively.
+
+VRs
+----
+
+There are currently 2 vector extensions to LoongArch:
+
+- LSX (Loongson SIMD eXtension) with 128-bit vectors,
+- LASX (Loongson Advanced SIMD eXtension) with 256-bit vectors.
+
+LSX brings ``$v0`` ~ ``$v31`` while LASX brings ``$x0`` ~ ``$x31`` as the vector
+registers.
+
+The VRs overlap with FPRs: for example, on a core implementing LSX and LASX,
+the lower 128 bits of ``$x0`` is shared with ``$v0``, and the lower 64 bits of
+``$v0`` is shared with ``$f0``; same with all other VRs.
+
+CSRs
+----
+
+CSRs can only be accessed from privileged mode (PLV0):
+
+================= ===================================== ==============
+Address           Full Name                             Abbrev Name
+================= ===================================== ==============
+0x0               Current Mode Information              CRMD
+0x1               Pre-exception Mode Information        PRMD
+0x2               Extension Unit Enable                 EUEN
+0x3               Miscellaneous Control                 MISC
+0x4               Exception Configuration               ECFG
+0x5               Exception Status                      ESTAT
+0x6               Exception Return Address              ERA
+0x7               Bad (Faulting) Virtual Address        BADV
+0x8               Bad (Faulting) Instruction Word       BADI
+0xC               Exception Entrypoint Address          EENTRY
+0x10              TLB Index                             TLBIDX
+0x11              TLB Entry High-order Bits             TLBEHI
+0x12              TLB Entry Low-order Bits 0            TLBELO0
+0x13              TLB Entry Low-order Bits 1            TLBELO1
+0x18              Address Space Identifier              ASID
+0x19              Page Global Directory Address for     PGDL
+                  Lower-half Address Space
+0x1A              Page Global Directory Address for     PGDH
+                  Higher-half Address Space
+0x1B              Page Global Directory Address         PGD
+0x1C              Page Walk Control for Lower-          PWCL
+                  half Address Space
+0x1D              Page Walk Control for Higher-         PWCH
+                  half Address Space
+0x1E              STLB Page Size                        STLBPS
+0x1F              Reduced Virtual Address Configuration RVACFG
+0x20              CPU Identifier                        CPUID
+0x21              Privileged Resource Configuration 1   PRCFG1
+0x22              Privileged Resource Configuration 2   PRCFG2
+0x23              Privileged Resource Configuration 3   PRCFG3
+0x30+n (0≤n≤15)   Saved Data register                   SAVEn
+0x40              Timer Identifier                      TID
+0x41              Timer Configuration                   TCFG
+0x42              Timer Value                           TVAL
+0x43              Compensation of Timer Count           CNTC
+0x44              Timer Interrupt Clearing              TICLR
+0x60              LLBit Control                         LLBCTL
+0x80              Implementation-specific Control 1     IMPCTL1
+0x81              Implementation-specific Control 2     IMPCTL2
+0x88              TLB Refill Exception Entrypoint       TLBRENTRY
+                  Address
+0x89              TLB Refill Exception BAD (Faulting)   TLBRBADV
+                  Virtual Address
+0x8A              TLB Refill Exception Return Address   TLBRERA
+0x8B              TLB Refill Exception Saved Data       TLBRSAVE
+                  Register
+0x8C              TLB Refill Exception Entry Low-order  TLBRELO0
+                  Bits 0
+0x8D              TLB Refill Exception Entry Low-order  TLBRELO1
+                  Bits 1
+0x8E              TLB Refill Exception Entry High-order TLBEHI
+                  Bits
+0x8F              TLB Refill Exception Pre-exception    TLBRPRMD
+                  Mode Information
+0x90              Machine Error Control                 MERRCTL
+0x91              Machine Error Information 1           MERRINFO1
+0x92              Machine Error Information 2           MERRINFO2
+0x93              Machine Error Exception Entrypoint    MERRENTRY
+                  Address
+0x94              Machine Error Exception Return        MERRERA
+                  Address
+0x95              Machine Error Exception Saved Data    MERRSAVE
+                  Register
+0x98              Cache TAGs                            CTAG
+0x180+n (0≤n≤3)   Direct Mapping Configuration Window n DMWn
+0x200+2n (0≤n≤31) Performance Monitor Configuration n   PMCFGn
+0x201+2n (0≤n≤31) Performance Monitor Overall Counter n PMCNTn
+0x300             Memory Load/Store WatchPoint          MWPC
+                  Overall Control
+0x301             Memory Load/Store WatchPoint          MWPS
+                  Overall Status
+0x310+8n (0≤n≤7)  Memory Load/Store WatchPoint n        MWPnCFG1
+                  Configuration 1
+0x311+8n (0≤n≤7)  Memory Load/Store WatchPoint n        MWPnCFG2
+                  Configuration 2
+0x312+8n (0≤n≤7)  Memory Load/Store WatchPoint n        MWPnCFG3
+                  Configuration 3
+0x313+8n (0≤n≤7)  Memory Load/Store WatchPoint n        MWPnCFG4
+                  Configuration 4
+0x380             Instruction Fetch WatchPoint          FWPC
+                  Overall Control
+0x381             Instruction Fetch WatchPoint          FWPS
+                  Overall Status
+0x390+8n (0≤n≤7)  Instruction Fetch WatchPoint n        FWPnCFG1
+                  Configuration 1
+0x391+8n (0≤n≤7)  Instruction Fetch WatchPoint n        FWPnCFG2
+                  Configuration 2
+0x392+8n (0≤n≤7)  Instruction Fetch WatchPoint n        FWPnCFG3
+                  Configuration 3
+0x393+8n (0≤n≤7)  Instruction Fetch WatchPoint n        FWPnCFG4
+                  Configuration 4
+0x500             Debug Register                        DBG
+0x501             Debug Exception Return Address        DERA
+0x502             Debug Exception Saved Data Register   DSAVE
+================= ===================================== ==============
+
+ERA, TLBRERA, MERRERA and DERA are sometimes also known as EPC, TLBREPC, MERREPC
+and DEPC respectively.
+
+Basic Instruction Set
+=====================
+
+Instruction formats
+-------------------
+
+LoongArch instructions are 32 bits wide, belonging to 9 basic instruction
+formats (and variants of them):
+
+=========== ==========================
+Format name Composition
+=========== ==========================
+2R          Opcode + Rj + Rd
+3R          Opcode + Rk + Rj + Rd
+4R          Opcode + Ra + Rk + Rj + Rd
+2RI8        Opcode + I8 + Rj + Rd
+2RI12       Opcode + I12 + Rj + Rd
+2RI14       Opcode + I14 + Rj + Rd
+2RI16       Opcode + I16 + Rj + Rd
+1RI21       Opcode + I21L + Rj + I21H
+I26         Opcode + I26L + I26H
+=========== ==========================
+
+Rd is the destination register operand, while Rj, Rk and Ra ("a" stands for
+"additional") are the source register operands. I8/I12/I14/I16/I21/I26 are
+immediate operands of respective width. The longer I21 and I26 are stored
+in separate higher and lower parts in the instruction word, denoted by the "L"
+and "H" suffixes.
+
+List of Instructions
+--------------------
+
+For brevity, only instruction names (mnemonics) are listed here; please see the
+:ref:`References <loongarch-references>` for details.
+
+
+1. Arithmetic Instructions::
+
+    ADD.W SUB.W ADDI.W ADD.D SUB.D ADDI.D
+    SLT SLTU SLTI SLTUI
+    AND OR NOR XOR ANDN ORN ANDI ORI XORI
+    MUL.W MULH.W MULH.WU DIV.W DIV.WU MOD.W MOD.WU
+    MUL.D MULH.D MULH.DU DIV.D DIV.DU MOD.D MOD.DU
+    PCADDI PCADDU12I PCADDU18I
+    LU12I.W LU32I.D LU52I.D ADDU16I.D
+
+2. Bit-shift Instructions::
+
+    SLL.W SRL.W SRA.W ROTR.W SLLI.W SRLI.W SRAI.W ROTRI.W
+    SLL.D SRL.D SRA.D ROTR.D SLLI.D SRLI.D SRAI.D ROTRI.D
+
+3. Bit-manipulation Instructions::
+
+    EXT.W.B EXT.W.H CLO.W CLO.D SLZ.W CLZ.D CTO.W CTO.D CTZ.W CTZ.D
+    BYTEPICK.W BYTEPICK.D BSTRINS.W BSTRINS.D BSTRPICK.W BSTRPICK.D
+    REVB.2H REVB.4H REVB.2W REVB.D REVH.2W REVH.D BITREV.4B BITREV.8B BITREV.W BITREV.D
+    MASKEQZ MASKNEZ
+
+4. Branch Instructions::
+
+    BEQ BNE BLT BGE BLTU BGEU BEQZ BNEZ B BL JIRL
+
+5. Load/Store Instructions::
+
+    LD.B LD.BU LD.H LD.HU LD.W LD.WU LD.D ST.B ST.H ST.W ST.D
+    LDX.B LDX.BU LDX.H LDX.HU LDX.W LDX.WU LDX.D STX.B STX.H STX.W STX.D
+    LDPTR.W LDPTR.D STPTR.W STPTR.D
+    PRELD PRELDX
+
+6. Atomic Operation Instructions::
+
+    LL.W SC.W LL.D SC.D
+    AMSWAP.W AMSWAP.D AMADD.W AMADD.D AMAND.W AMAND.D AMOR.W AMOR.D AMXOR.W AMXOR.D
+    AMMAX.W AMMAX.D AMMIN.W AMMIN.D
+
+7. Barrier Instructions::
+
+    IBAR DBAR
+
+8. Special Instructions::
+
+    SYSCALL BREAK CPUCFG NOP IDLE ERTN(ERET) DBCL(DBGCALL) RDTIMEL.W RDTIMEH.W RDTIME.D
+    ASRTLE.D ASRTGT.D
+
+9. Privileged Instructions::
+
+    CSRRD CSRWR CSRXCHG
+    IOCSRRD.B IOCSRRD.H IOCSRRD.W IOCSRRD.D IOCSRWR.B IOCSRWR.H IOCSRWR.W IOCSRWR.D
+    CACOP TLBP(TLBSRCH) TLBRD TLBWR TLBFILL TLBCLR TLBFLUSH INVTLB LDDIR LDPTE
+
+Virtual Memory
+==============
+
+LoongArch supports direct-mapped virtual memory and page-mapped virtual memory.
+
+Direct-mapped virtual memory is configured by CSR.DMWn (n=0~3), it has a simple
+relationship between virtual address (VA) and physical address (PA)::
+
+ VA = PA + FixedOffset
+
+Page-mapped virtual memory has arbitrary relationship between VA and PA, which
+is recorded in TLB and page tables. LoongArch's TLB includes a fully-associative
+MTLB (Multiple Page Size TLB) and set-associative STLB (Single Page Size TLB).
+
+By default, the whole virtual address space of LA32 is configured like this:
+
+============ =========================== =============================
+Name         Address Range               Attributes
+============ =========================== =============================
+``UVRANGE``  ``0x00000000 - 0x7FFFFFFF`` Page-mapped, Cached, PLV0~3
+``KPRANGE0`` ``0x80000000 - 0x9FFFFFFF`` Direct-mapped, Uncached, PLV0
+``KPRANGE1`` ``0xA0000000 - 0xBFFFFFFF`` Direct-mapped, Cached, PLV0
+``KVRANGE``  ``0xC0000000 - 0xFFFFFFFF`` Page-mapped, Cached, PLV0
+============ =========================== =============================
+
+User mode (PLV3) can only access UVRANGE. For direct-mapped KPRANGE0 and
+KPRANGE1, PA is equal to VA with bit30~31 cleared. For example, the uncached
+direct-mapped VA of 0x00001000 is 0x80001000, and the cached direct-mapped
+VA of 0x00001000 is 0xA0001000.
+
+By default, the whole virtual address space of LA64 is configured like this:
+
+============ ====================== ======================================
+Name         Address Range          Attributes
+============ ====================== ======================================
+``XUVRANGE`` ``0x0000000000000000 - Page-mapped, Cached, PLV0~3
+             0x3FFFFFFFFFFFFFFF``
+``XSPRANGE`` ``0x4000000000000000 - Direct-mapped, Cached / Uncached, PLV0
+             0x7FFFFFFFFFFFFFFF``
+``XKPRANGE`` ``0x8000000000000000 - Direct-mapped, Cached / Uncached, PLV0
+             0xBFFFFFFFFFFFFFFF``
+``XKVRANGE`` ``0xC000000000000000 - Page-mapped, Cached, PLV0
+             0xFFFFFFFFFFFFFFFF``
+============ ====================== ======================================
+
+User mode (PLV3) can only access XUVRANGE. For direct-mapped XSPRANGE and
+XKPRANGE, PA is equal to VA with bits 60~63 cleared, and the cache attribute
+is configured by bits 60~61 in VA: 0 is for strongly-ordered uncached, 1 is
+for coherent cached, and 2 is for weakly-ordered uncached.
+
+Currently we only use XKPRANGE for direct mapping and XSPRANGE is reserved.
+
+To put this in action: the strongly-ordered uncached direct-mapped VA (in
+XKPRANGE) of 0x00000000_00001000 is 0x80000000_00001000, the coherent cached
+direct-mapped VA (in XKPRANGE) of 0x00000000_00001000 is 0x90000000_00001000,
+and the weakly-ordered uncached direct-mapped VA (in XKPRANGE) of 0x00000000
+_00001000 is 0xA0000000_00001000.
+
+Relationship of Loongson and LoongArch
+======================================
+
+LoongArch is a RISC ISA which is different from any other existing ones, while
+Loongson is a family of processors. Loongson includes 3 series: Loongson-1 is
+the 32-bit processor series, Loongson-2 is the low-end 64-bit processor series,
+and Loongson-3 is the high-end 64-bit processor series. Old Loongson is based on
+MIPS, while New Loongson is based on LoongArch. Take Loongson-3 as an example:
+Loongson-3A1000/3B1500/3A2000/3A3000/3A4000 are MIPS-compatible, while Loongson-
+3A5000 (and future revisions) are all based on LoongArch.
+
+.. _loongarch-references:
+
+References
+==========
+
+Official web site of Loongson Technology Corp. Ltd.:
+
+  http://www.loongson.cn/
+
+Developer web site of Loongson and LoongArch (Software and Documentation):
+
+  http://www.loongnix.cn/
+
+  https://github.com/loongson/
+
+  https://loongson.github.io/LoongArch-Documentation/
+
+Documentation of LoongArch ISA:
+
+  https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.02-CN.pdf (in Chinese)
+
+  https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.02-EN.pdf (in English)
+
+Documentation of LoongArch ELF psABI:
+
+  https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-ELF-ABI-v2.00-CN.pdf (in Chinese)
+
+  https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-ELF-ABI-v2.00-EN.pdf (in English)
+
+Linux kernel repository of Loongson and LoongArch:
+
+  https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git