/*-
 * Copyright (c) 2026 Ruslan Bukin <br@bsdpad.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/proc.h>

#include <vm/uma.h>

#include <machine/vector.h>
#include <machine/pcb.h>
#include <machine/reg.h>
#include <machine/md_var.h>

static MALLOC_DEFINE(M_RVV_CTX, "rvv_ctx", "Contexts for user Vector state");

static void
vector_enable(void)
{
        uint64_t reg;

        reg = SSTATUS_VS_CLEAN;

        csr_set(sstatus, reg);
}

static void
vector_disable(void)
{
        uint64_t mask;

        mask = SSTATUS_VS_MASK;

        csr_clear(sstatus, mask);
}

static void
vector_state_store_common(struct pcb *p, void *datap)
{
        uint64_t vl;

        vector_enable();

        /* Store vector CSRs. */
        __asm __volatile(
                "csrr   %0, vstart\n\t"
                "csrr   %1, vtype\n\t"
                "csrr   %2, vl\n\t"
                "csrr   %3, vcsr\n\t"
                : "=r" (p->pcb_vstart), "=r" (p->pcb_vtype),
                  "=r" (p->pcb_vl), "=r" (p->pcb_vcsr) ::);

        if (datap == NULL)
                goto done;

        /* Store vector registers. */
        __asm __volatile(
                ".option push\n\t"
                ".option arch, +zve32x\n\t"
                "vsetvli        %0, x0, e8, m8, ta, ma\n\t"
                "vse8.v         v0, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vse8.v         v8, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vse8.v         v16, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vse8.v         v24, (%1)\n\t"
                ".option pop\n\t"
                : "=&r" (vl) : "r" (datap) : "memory");

done:
        vector_disable();
}

void
vector_state_store_savectx(struct pcb *p)
{

        if (!has_vector)
                return;

        /*
         * savectx() will be called on panic with dumppcb as an argument.
         * Save the vector CSR registers, but ignore the vector data.
         */

        vector_state_store_common(p, NULL);
}

void
vector_state_store(struct thread *td)
{
        struct pcb *p;
        void *datap;

        p = td->td_pcb;

        KASSERT(p->pcb_vsaved != NULL, ("VS area is NULL"));

        datap = p->pcb_vsaved;

        vector_state_store_common(p, datap);
}

void
vector_state_restore(struct thread *td)
{
        struct pcb *p;
        void *datap;
        uint64_t vl;

        p = td->td_pcb;

        KASSERT(p->pcb_vsaved != NULL, ("VS area is NULL"));

        datap = p->pcb_vsaved;

        vector_enable();

        /* Restore vector registers. */
        __asm __volatile(
                ".option push\n\t"
                ".option arch, +zve32x\n\t"
                "vsetvli        %0, x0, e8, m8, ta, ma\n\t"
                "vle8.v         v0, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vle8.v         v8, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vle8.v         v16, (%1)\n\t"
                "add            %1, %1, %0\n\t"
                "vle8.v         v24, (%1)\n\t"
                ".option pop\n\t"
                : "=&r" (vl) : "r" (datap) : "memory");

        /* Restore vector CSRs. */
        __asm __volatile(
                ".option push\n\t"
                ".option arch, +zve32x\n\t"
                "vsetvl x0, %2, %1\n\t"
                ".option pop\n\t"
                "csrw   vstart, %0\n\t"
                "csrw   vcsr, %3\n\t"
                :: "r" (p->pcb_vstart), "r" (p->pcb_vtype),
                   "r" (p->pcb_vl), "r" (p->pcb_vcsr));

        vector_disable();
}

int
vector_get_size(void)
{
        int len;

        /* RISC-V has 32 vector registers of vlenb size each. */

        vector_enable();
        len = csr_read(vlenb) * 32;
        vector_disable();

        return (len);
}

void
vector_state_init(struct thread *td)
{
        struct pcb *p;
        int len;

        p = td->td_pcb;

        KASSERT(p->pcb_vsaved == NULL, ("vsaved is already initialized"));

        len = vector_get_size();

        p->pcb_vsaved = malloc(len, M_RVV_CTX, M_WAITOK | M_ZERO);
}

void
vector_copy_thread(struct thread *td1, struct thread *td2)
{
        struct pcb *p1;
        struct pcb *p2;
        int len;

        /* Struct pcb already copied, now init the vector save area. */

        p1 = td1->td_pcb;
        p2 = td2->td_pcb;
        p2->pcb_vsaved = NULL;

        vector_state_init(td2);

        len = vector_get_size();

        memcpy(p2->pcb_vsaved, p1->pcb_vsaved, len);
}

static void
vector_thread_dtor(void *arg __unused, struct thread *td)
{
        void *datap;

        datap = td->td_pcb->pcb_vsaved;

        free(datap, M_RVV_CTX);
}

static void
vector_init(const void *dummy __unused)
{

        EVENTHANDLER_REGISTER(thread_dtor, vector_thread_dtor, NULL,
            EVENTHANDLER_PRI_ANY);
}

SYSINIT(vector, SI_SUB_SMP, SI_ORDER_ANY, vector_init, NULL);