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, 509 insertions, 0 deletions

diff --git a/lib/mpi/mpih-mul.c b/lib/mpi/mpih-mul.c
new file mode 100644
index 000000000..e5f1c84e3
--- /dev/null
+++ b/lib/mpi/mpih-mul.c
@@ -0,0 +1,509 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* mpihelp-mul.c  -  MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 1999,
+ *               2000 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ *	 The GNU MP Library itself is published under the LGPL;
+ *	 however I decided to publish this code under the plain GPL.
+ */
+
+#include <linux/string.h>
+#include "mpi-internal.h"
+#include "longlong.h"
+
+#define MPN_MUL_N_RECURSE(prodp, up, vp, size, tspace)		\
+	do {							\
+		if ((size) < KARATSUBA_THRESHOLD)		\
+			mul_n_basecase(prodp, up, vp, size);	\
+		else						\
+			mul_n(prodp, up, vp, size, tspace);	\
+	} while (0);
+
+#define MPN_SQR_N_RECURSE(prodp, up, size, tspace)		\
+	do {							\
+		if ((size) < KARATSUBA_THRESHOLD)		\
+			mpih_sqr_n_basecase(prodp, up, size);	\
+		else						\
+			mpih_sqr_n(prodp, up, size, tspace);	\
+	} while (0);
+
+/* Multiply the natural numbers u (pointed to by UP) and v (pointed to by VP),
+ * both with SIZE limbs, and store the result at PRODP.  2 * SIZE limbs are
+ * always stored.  Return the most significant limb.
+ *
+ * Argument constraints:
+ * 1. PRODP != UP and PRODP != VP, i.e. the destination
+ *    must be distinct from the multiplier and the multiplicand.
+ *
+ *
+ * Handle simple cases with traditional multiplication.
+ *
+ * This is the most critical code of multiplication.  All multiplies rely
+ * on this, both small and huge.  Small ones arrive here immediately.  Huge
+ * ones arrive here as this is the base case for Karatsuba's recursive
+ * algorithm below.
+ */
+
+static mpi_limb_t
+mul_n_basecase(mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size)
+{
+	mpi_size_t i;
+	mpi_limb_t cy;
+	mpi_limb_t v_limb;
+
+	/* Multiply by the first limb in V separately, as the result can be
+	 * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+	v_limb = vp[0];
+	if (v_limb <= 1) {
+		if (v_limb == 1)
+			MPN_COPY(prodp, up, size);
+		else
+			MPN_ZERO(prodp, size);
+		cy = 0;
+	} else
+		cy = mpihelp_mul_1(prodp, up, size, v_limb);
+
+	prodp[size] = cy;
+	prodp++;
+
+	/* For each iteration in the outer loop, multiply one limb from
+	 * U with one limb from V, and add it to PROD.  */
+	for (i = 1; i < size; i++) {
+		v_limb = vp[i];
+		if (v_limb <= 1) {
+			cy = 0;
+			if (v_limb == 1)
+				cy = mpihelp_add_n(prodp, prodp, up, size);
+		} else
+			cy = mpihelp_addmul_1(prodp, up, size, v_limb);
+
+		prodp[size] = cy;
+		prodp++;
+	}
+
+	return cy;
+}
+
+static void
+mul_n(mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp,
+		mpi_size_t size, mpi_ptr_t tspace)
+{
+	if (size & 1) {
+		/* The size is odd, and the code below doesn't handle that.
+		 * Multiply the least significant (size - 1) limbs with a recursive
+		 * call, and handle the most significant limb of S1 and S2
+		 * separately.
+		 * A slightly faster way to do this would be to make the Karatsuba
+		 * code below behave as if the size were even, and let it check for
+		 * odd size in the end.  I.e., in essence move this code to the end.
+		 * Doing so would save us a recursive call, and potentially make the
+		 * stack grow a lot less.
+		 */
+		mpi_size_t esize = size - 1;	/* even size */
+		mpi_limb_t cy_limb;
+
+		MPN_MUL_N_RECURSE(prodp, up, vp, esize, tspace);
+		cy_limb = mpihelp_addmul_1(prodp + esize, up, esize, vp[esize]);
+		prodp[esize + esize] = cy_limb;
+		cy_limb = mpihelp_addmul_1(prodp + esize, vp, size, up[esize]);
+		prodp[esize + size] = cy_limb;
+	} else {
+		/* Anatolij Alekseevich Karatsuba's divide-and-conquer algorithm.
+		 *
+		 * Split U in two pieces, U1 and U0, such that
+		 * U = U0 + U1*(B**n),
+		 * and V in V1 and V0, such that
+		 * V = V0 + V1*(B**n).
+		 *
+		 * UV is then computed recursively using the identity
+		 *
+		 *        2n   n          n                     n
+		 * UV = (B  + B )U V  +  B (U -U )(V -V )  +  (B + 1)U V
+		 *                1 1        1  0   0  1              0 0
+		 *
+		 * Where B = 2**BITS_PER_MP_LIMB.
+		 */
+		mpi_size_t hsize = size >> 1;
+		mpi_limb_t cy;
+		int negflg;
+
+		/* Product H.      ________________  ________________
+		 *                |_____U1 x V1____||____U0 x V0_____|
+		 * Put result in upper part of PROD and pass low part of TSPACE
+		 * as new TSPACE.
+		 */
+		MPN_MUL_N_RECURSE(prodp + size, up + hsize, vp + hsize, hsize,
+				  tspace);
+
+		/* Product M.      ________________
+		 *                |_(U1-U0)(V0-V1)_|
+		 */
+		if (mpihelp_cmp(up + hsize, up, hsize) >= 0) {
+			mpihelp_sub_n(prodp, up + hsize, up, hsize);
+			negflg = 0;
+		} else {
+			mpihelp_sub_n(prodp, up, up + hsize, hsize);
+			negflg = 1;
+		}
+		if (mpihelp_cmp(vp + hsize, vp, hsize) >= 0) {
+			mpihelp_sub_n(prodp + hsize, vp + hsize, vp, hsize);
+			negflg ^= 1;
+		} else {
+			mpihelp_sub_n(prodp + hsize, vp, vp + hsize, hsize);
+			/* No change of NEGFLG.  */
+		}
+		/* Read temporary operands from low part of PROD.
+		 * Put result in low part of TSPACE using upper part of TSPACE
+		 * as new TSPACE.
+		 */
+		MPN_MUL_N_RECURSE(tspace, prodp, prodp + hsize, hsize,
+				  tspace + size);
+
+		/* Add/copy product H. */
+		MPN_COPY(prodp + hsize, prodp + size, hsize);
+		cy = mpihelp_add_n(prodp + size, prodp + size,
+				   prodp + size + hsize, hsize);
+
+		/* Add product M (if NEGFLG M is a negative number) */
+		if (negflg)
+			cy -=
+			    mpihelp_sub_n(prodp + hsize, prodp + hsize, tspace,
+					  size);
+		else
+			cy +=
+			    mpihelp_add_n(prodp + hsize, prodp + hsize, tspace,
+					  size);
+
+		/* Product L.      ________________  ________________
+		 *                |________________||____U0 x V0_____|
+		 * Read temporary operands from low part of PROD.
+		 * Put result in low part of TSPACE using upper part of TSPACE
+		 * as new TSPACE.
+		 */
+		MPN_MUL_N_RECURSE(tspace, up, vp, hsize, tspace + size);
+
+		/* Add/copy Product L (twice) */
+
+		cy += mpihelp_add_n(prodp + hsize, prodp + hsize, tspace, size);
+		if (cy)
+			mpihelp_add_1(prodp + hsize + size,
+				      prodp + hsize + size, hsize, cy);
+
+		MPN_COPY(prodp, tspace, hsize);
+		cy = mpihelp_add_n(prodp + hsize, prodp + hsize, tspace + hsize,
+				   hsize);
+		if (cy)
+			mpihelp_add_1(prodp + size, prodp + size, size, 1);
+	}
+}
+
+void mpih_sqr_n_basecase(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t size)
+{
+	mpi_size_t i;
+	mpi_limb_t cy_limb;
+	mpi_limb_t v_limb;
+
+	/* Multiply by the first limb in V separately, as the result can be
+	 * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+	v_limb = up[0];
+	if (v_limb <= 1) {
+		if (v_limb == 1)
+			MPN_COPY(prodp, up, size);
+		else
+			MPN_ZERO(prodp, size);
+		cy_limb = 0;
+	} else
+		cy_limb = mpihelp_mul_1(prodp, up, size, v_limb);
+
+	prodp[size] = cy_limb;
+	prodp++;
+
+	/* For each iteration in the outer loop, multiply one limb from
+	 * U with one limb from V, and add it to PROD.  */
+	for (i = 1; i < size; i++) {
+		v_limb = up[i];
+		if (v_limb <= 1) {
+			cy_limb = 0;
+			if (v_limb == 1)
+				cy_limb = mpihelp_add_n(prodp, prodp, up, size);
+		} else
+			cy_limb = mpihelp_addmul_1(prodp, up, size, v_limb);
+
+		prodp[size] = cy_limb;
+		prodp++;
+	}
+}
+
+void
+mpih_sqr_n(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t size, mpi_ptr_t tspace)
+{
+	if (size & 1) {
+		/* The size is odd, and the code below doesn't handle that.
+		 * Multiply the least significant (size - 1) limbs with a recursive
+		 * call, and handle the most significant limb of S1 and S2
+		 * separately.
+		 * A slightly faster way to do this would be to make the Karatsuba
+		 * code below behave as if the size were even, and let it check for
+		 * odd size in the end.  I.e., in essence move this code to the end.
+		 * Doing so would save us a recursive call, and potentially make the
+		 * stack grow a lot less.
+		 */
+		mpi_size_t esize = size - 1;	/* even size */
+		mpi_limb_t cy_limb;
+
+		MPN_SQR_N_RECURSE(prodp, up, esize, tspace);
+		cy_limb = mpihelp_addmul_1(prodp + esize, up, esize, up[esize]);
+		prodp[esize + esize] = cy_limb;
+		cy_limb = mpihelp_addmul_1(prodp + esize, up, size, up[esize]);
+
+		prodp[esize + size] = cy_limb;
+	} else {
+		mpi_size_t hsize = size >> 1;
+		mpi_limb_t cy;
+
+		/* Product H.      ________________  ________________
+		 *                |_____U1 x U1____||____U0 x U0_____|
+		 * Put result in upper part of PROD and pass low part of TSPACE
+		 * as new TSPACE.
+		 */
+		MPN_SQR_N_RECURSE(prodp + size, up + hsize, hsize, tspace);
+
+		/* Product M.      ________________
+		 *                |_(U1-U0)(U0-U1)_|
+		 */
+		if (mpihelp_cmp(up + hsize, up, hsize) >= 0)
+			mpihelp_sub_n(prodp, up + hsize, up, hsize);
+		else
+			mpihelp_sub_n(prodp, up, up + hsize, hsize);
+
+		/* Read temporary operands from low part of PROD.
+		 * Put result in low part of TSPACE using upper part of TSPACE
+		 * as new TSPACE.  */
+		MPN_SQR_N_RECURSE(tspace, prodp, hsize, tspace + size);
+
+		/* Add/copy product H  */
+		MPN_COPY(prodp + hsize, prodp + size, hsize);
+		cy = mpihelp_add_n(prodp + size, prodp + size,
+				   prodp + size + hsize, hsize);
+
+		/* Add product M (if NEGFLG M is a negative number).  */
+		cy -= mpihelp_sub_n(prodp + hsize, prodp + hsize, tspace, size);
+
+		/* Product L.      ________________  ________________
+		 *                |________________||____U0 x U0_____|
+		 * Read temporary operands from low part of PROD.
+		 * Put result in low part of TSPACE using upper part of TSPACE
+		 * as new TSPACE.  */
+		MPN_SQR_N_RECURSE(tspace, up, hsize, tspace + size);
+
+		/* Add/copy Product L (twice).  */
+		cy += mpihelp_add_n(prodp + hsize, prodp + hsize, tspace, size);
+		if (cy)
+			mpihelp_add_1(prodp + hsize + size,
+				      prodp + hsize + size, hsize, cy);
+
+		MPN_COPY(prodp, tspace, hsize);
+		cy = mpihelp_add_n(prodp + hsize, prodp + hsize, tspace + hsize,
+				   hsize);
+		if (cy)
+			mpihelp_add_1(prodp + size, prodp + size, size, 1);
+	}
+}
+
+
+void mpihelp_mul_n(mpi_ptr_t prodp,
+		mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size)
+{
+	if (up == vp) {
+		if (size < KARATSUBA_THRESHOLD)
+			mpih_sqr_n_basecase(prodp, up, size);
+		else {
+			mpi_ptr_t tspace;
+			tspace = mpi_alloc_limb_space(2 * size);
+			mpih_sqr_n(prodp, up, size, tspace);
+			mpi_free_limb_space(tspace);
+		}
+	} else {
+		if (size < KARATSUBA_THRESHOLD)
+			mul_n_basecase(prodp, up, vp, size);
+		else {
+			mpi_ptr_t tspace;
+			tspace = mpi_alloc_limb_space(2 * size);
+			mul_n(prodp, up, vp, size, tspace);
+			mpi_free_limb_space(tspace);
+		}
+	}
+}
+
+int
+mpihelp_mul_karatsuba_case(mpi_ptr_t prodp,
+			   mpi_ptr_t up, mpi_size_t usize,
+			   mpi_ptr_t vp, mpi_size_t vsize,
+			   struct karatsuba_ctx *ctx)
+{
+	mpi_limb_t cy;
+
+	if (!ctx->tspace || ctx->tspace_size < vsize) {
+		if (ctx->tspace)
+			mpi_free_limb_space(ctx->tspace);
+		ctx->tspace = mpi_alloc_limb_space(2 * vsize);
+		if (!ctx->tspace)
+			return -ENOMEM;
+		ctx->tspace_size = vsize;
+	}
+
+	MPN_MUL_N_RECURSE(prodp, up, vp, vsize, ctx->tspace);
+
+	prodp += vsize;
+	up += vsize;
+	usize -= vsize;
+	if (usize >= vsize) {
+		if (!ctx->tp || ctx->tp_size < vsize) {
+			if (ctx->tp)
+				mpi_free_limb_space(ctx->tp);
+			ctx->tp = mpi_alloc_limb_space(2 * vsize);
+			if (!ctx->tp) {
+				if (ctx->tspace)
+					mpi_free_limb_space(ctx->tspace);
+				ctx->tspace = NULL;
+				return -ENOMEM;
+			}
+			ctx->tp_size = vsize;
+		}
+
+		do {
+			MPN_MUL_N_RECURSE(ctx->tp, up, vp, vsize, ctx->tspace);
+			cy = mpihelp_add_n(prodp, prodp, ctx->tp, vsize);
+			mpihelp_add_1(prodp + vsize, ctx->tp + vsize, vsize,
+				      cy);
+			prodp += vsize;
+			up += vsize;
+			usize -= vsize;
+		} while (usize >= vsize);
+	}
+
+	if (usize) {
+		if (usize < KARATSUBA_THRESHOLD) {
+			mpi_limb_t tmp;
+			if (mpihelp_mul(ctx->tspace, vp, vsize, up, usize, &tmp)
+			    < 0)
+				return -ENOMEM;
+		} else {
+			if (!ctx->next) {
+				ctx->next = kzalloc(sizeof *ctx, GFP_KERNEL);
+				if (!ctx->next)
+					return -ENOMEM;
+			}
+			if (mpihelp_mul_karatsuba_case(ctx->tspace,
+						       vp, vsize,
+						       up, usize,
+						       ctx->next) < 0)
+				return -ENOMEM;
+		}
+
+		cy = mpihelp_add_n(prodp, prodp, ctx->tspace, vsize);
+		mpihelp_add_1(prodp + vsize, ctx->tspace + vsize, usize, cy);
+	}
+
+	return 0;
+}
+
+void mpihelp_release_karatsuba_ctx(struct karatsuba_ctx *ctx)
+{
+	struct karatsuba_ctx *ctx2;
+
+	if (ctx->tp)
+		mpi_free_limb_space(ctx->tp);
+	if (ctx->tspace)
+		mpi_free_limb_space(ctx->tspace);
+	for (ctx = ctx->next; ctx; ctx = ctx2) {
+		ctx2 = ctx->next;
+		if (ctx->tp)
+			mpi_free_limb_space(ctx->tp);
+		if (ctx->tspace)
+			mpi_free_limb_space(ctx->tspace);
+		kfree(ctx);
+	}
+}
+
+/* Multiply the natural numbers u (pointed to by UP, with USIZE limbs)
+ * and v (pointed to by VP, with VSIZE limbs), and store the result at
+ * PRODP.  USIZE + VSIZE limbs are always stored, but if the input
+ * operands are normalized.  Return the most significant limb of the
+ * result.
+ *
+ * NOTE: The space pointed to by PRODP is overwritten before finished
+ * with U and V, so overlap is an error.
+ *
+ * Argument constraints:
+ * 1. USIZE >= VSIZE.
+ * 2. PRODP != UP and PRODP != VP, i.e. the destination
+ *    must be distinct from the multiplier and the multiplicand.
+ */
+
+int
+mpihelp_mul(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t usize,
+	    mpi_ptr_t vp, mpi_size_t vsize, mpi_limb_t *_result)
+{
+	mpi_ptr_t prod_endp = prodp + usize + vsize - 1;
+	mpi_limb_t cy;
+	struct karatsuba_ctx ctx;
+
+	if (vsize < KARATSUBA_THRESHOLD) {
+		mpi_size_t i;
+		mpi_limb_t v_limb;
+
+		if (!vsize) {
+			*_result = 0;
+			return 0;
+		}
+
+		/* Multiply by the first limb in V separately, as the result can be
+		 * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+		v_limb = vp[0];
+		if (v_limb <= 1) {
+			if (v_limb == 1)
+				MPN_COPY(prodp, up, usize);
+			else
+				MPN_ZERO(prodp, usize);
+			cy = 0;
+		} else
+			cy = mpihelp_mul_1(prodp, up, usize, v_limb);
+
+		prodp[usize] = cy;
+		prodp++;
+
+		/* For each iteration in the outer loop, multiply one limb from
+		 * U with one limb from V, and add it to PROD.  */
+		for (i = 1; i < vsize; i++) {
+			v_limb = vp[i];
+			if (v_limb <= 1) {
+				cy = 0;
+				if (v_limb == 1)
+					cy = mpihelp_add_n(prodp, prodp, up,
+							   usize);
+			} else
+				cy = mpihelp_addmul_1(prodp, up, usize, v_limb);
+
+			prodp[usize] = cy;
+			prodp++;
+		}
+
+		*_result = cy;
+		return 0;
+	}
+
+	memset(&ctx, 0, sizeof ctx);
+	if (mpihelp_mul_karatsuba_case(prodp, up, usize, vp, vsize, &ctx) < 0)
+		return -ENOMEM;
+	mpihelp_release_karatsuba_ctx(&ctx);
+	*_result = *prod_endp;
+	return 0;
+}