/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Ruslan Bukin <br@bsdpad.com>
 *
 * This software was developed by the University of Cambridge Computer
 * Laboratory (Department of Computer Science and Technology) under Innovate
 * UK project 105694, "Digital Security by Design (DSbD) Technology Platform
 * Prototype".
 *
 * 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 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 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 <machine/asm.h>
#include "assym.inc"

        .text

/*
 * a0 == hypctx *
 */
ENTRY(vmm_switch)
        sd      ra, (HYP_H_RA)(a0)
        sd      sp, (HYP_H_SP)(a0)
        sd      tp, (HYP_H_TP)(a0)
        sd      gp, (HYP_H_GP)(a0)
        sd      s0, (HYP_H_S + 0 * 8)(a0)
        sd      s1, (HYP_H_S + 1 * 8)(a0)
        sd      s2, (HYP_H_S + 2 * 8)(a0)
        sd      s3, (HYP_H_S + 3 * 8)(a0)
        sd      s4, (HYP_H_S + 4 * 8)(a0)
        sd      s5, (HYP_H_S + 5 * 8)(a0)
        sd      s6, (HYP_H_S + 6 * 8)(a0)
        sd      s7, (HYP_H_S + 7 * 8)(a0)
        sd      s8, (HYP_H_S + 8 * 8)(a0)
        sd      s9, (HYP_H_S + 9 * 8)(a0)
        sd      s10, (HYP_H_S + 10 * 8)(a0)
        sd      s11, (HYP_H_S + 11 * 8)(a0)

        sd      a1, (HYP_H_A + 1 * 8)(a0)
        sd      a2, (HYP_H_A + 2 * 8)(a0)
        sd      a3, (HYP_H_A + 3 * 8)(a0)
        sd      a4, (HYP_H_A + 4 * 8)(a0)
        sd      a5, (HYP_H_A + 5 * 8)(a0)
        sd      a6, (HYP_H_A + 6 * 8)(a0)
        sd      a7, (HYP_H_A + 7 * 8)(a0)

        ld      t0, (HYP_G_SSTATUS)(a0)
        ld      t1, (HYP_G_HSTATUS)(a0)
        ld      t2, (HYP_G_SCOUNTEREN)(a0)
        la      t4, .Lswitch_return
        ld      t5, (HYP_G_SEPC)(a0)

        csrrw   t0, sstatus, t0
        csrrw   t1, hstatus, t1
        csrrw   t2, scounteren, t2
        csrrw   t3, sscratch, a0
        csrrw   t4, stvec, t4
        csrw    sepc, t5

        sd      t0, (HYP_H_SSTATUS)(a0)
        sd      t1, (HYP_H_HSTATUS)(a0)
        sd      t2, (HYP_H_SCOUNTEREN)(a0)
        sd      t3, (HYP_H_SSCRATCH)(a0)
        sd      t4, (HYP_H_STVEC)(a0)

        ld      ra, (HYP_G_RA)(a0)
        ld      sp, (HYP_G_SP)(a0)
        ld      gp, (HYP_G_GP)(a0)
        ld      tp, (HYP_G_TP)(a0)
        ld      t0, (HYP_G_T + 0 * 8)(a0)
        ld      t1, (HYP_G_T + 1 * 8)(a0)
        ld      t2, (HYP_G_T + 2 * 8)(a0)
        ld      t3, (HYP_G_T + 3 * 8)(a0)
        ld      t4, (HYP_G_T + 4 * 8)(a0)
        ld      t5, (HYP_G_T + 5 * 8)(a0)
        ld      t6, (HYP_G_T + 6 * 8)(a0)
        ld      s0, (HYP_G_S + 0 * 8)(a0)
        ld      s1, (HYP_G_S + 1 * 8)(a0)
        ld      s2, (HYP_G_S + 2 * 8)(a0)
        ld      s3, (HYP_G_S + 3 * 8)(a0)
        ld      s4, (HYP_G_S + 4 * 8)(a0)
        ld      s5, (HYP_G_S + 5 * 8)(a0)
        ld      s6, (HYP_G_S + 6 * 8)(a0)
        ld      s7, (HYP_G_S + 7 * 8)(a0)
        ld      s8, (HYP_G_S + 8 * 8)(a0)
        ld      s9, (HYP_G_S + 9 * 8)(a0)
        ld      s10, (HYP_G_S + 10 * 8)(a0)
        ld      s11, (HYP_G_S + 11 * 8)(a0)
        /* skip a0 for now. */
        ld      a1, (HYP_G_A + 1 * 8)(a0)
        ld      a2, (HYP_G_A + 2 * 8)(a0)
        ld      a3, (HYP_G_A + 3 * 8)(a0)
        ld      a4, (HYP_G_A + 4 * 8)(a0)
        ld      a5, (HYP_G_A + 5 * 8)(a0)
        ld      a6, (HYP_G_A + 6 * 8)(a0)
        ld      a7, (HYP_G_A + 7 * 8)(a0)
        /* now load a0. */
        ld      a0, (HYP_G_A + 0 * 8)(a0)

        sret

        .align 2
.Lswitch_return:

        csrrw   a0, sscratch, a0
        sd      ra, (HYP_G_RA)(a0)
        sd      sp, (HYP_G_SP)(a0)
        sd      gp, (HYP_G_GP)(a0)
        sd      tp, (HYP_G_TP)(a0)
        sd      t0, (HYP_G_T + 0 * 8)(a0)
        sd      t1, (HYP_G_T + 1 * 8)(a0)
        sd      t2, (HYP_G_T + 2 * 8)(a0)
        sd      t3, (HYP_G_T + 3 * 8)(a0)
        sd      t4, (HYP_G_T + 4 * 8)(a0)
        sd      t5, (HYP_G_T + 5 * 8)(a0)
        sd      t6, (HYP_G_T + 6 * 8)(a0)
        sd      s0, (HYP_G_S + 0 * 8)(a0)
        sd      s1, (HYP_G_S + 1 * 8)(a0)
        sd      s2, (HYP_G_S + 2 * 8)(a0)
        sd      s3, (HYP_G_S + 3 * 8)(a0)
        sd      s4, (HYP_G_S + 4 * 8)(a0)
        sd      s5, (HYP_G_S + 5 * 8)(a0)
        sd      s6, (HYP_G_S + 6 * 8)(a0)
        sd      s7, (HYP_G_S + 7 * 8)(a0)
        sd      s8, (HYP_G_S + 8 * 8)(a0)
        sd      s9, (HYP_G_S + 9 * 8)(a0)
        sd      s10, (HYP_G_S + 10 * 8)(a0)
        sd      s11, (HYP_G_S + 11 * 8)(a0)
        /* skip a0 */
        sd      a1, (HYP_G_A + 1 * 8)(a0)
        sd      a2, (HYP_G_A + 2 * 8)(a0)
        sd      a3, (HYP_G_A + 3 * 8)(a0)
        sd      a4, (HYP_G_A + 4 * 8)(a0)
        sd      a5, (HYP_G_A + 5 * 8)(a0)
        sd      a6, (HYP_G_A + 6 * 8)(a0)
        sd      a7, (HYP_G_A + 7 * 8)(a0)

        ld      t1, (HYP_H_STVEC)(a0)
        ld      t2, (HYP_H_SSCRATCH)(a0)
        ld      t3, (HYP_H_SCOUNTEREN)(a0)
        ld      t4, (HYP_H_HSTATUS)(a0)
        ld      t5, (HYP_H_SSTATUS)(a0)

        csrr    t0, sepc
        csrw    stvec, t1
        csrrw   t2, sscratch, t2
        csrrw   t3, scounteren, t3
        csrrw   t4, hstatus, t4
        csrrw   t5, sstatus, t5

        sd      t0, (HYP_G_SEPC)(a0)
        sd      t2, (HYP_G_A + 0 * 8)(a0)
        sd      t3, (HYP_G_SCOUNTEREN)(a0)
        sd      t4, (HYP_G_HSTATUS)(a0)
        sd      t5, (HYP_G_SSTATUS)(a0)

        ld      ra, (HYP_H_RA)(a0)
        ld      sp, (HYP_H_SP)(a0)
        ld      tp, (HYP_H_TP)(a0)
        ld      gp, (HYP_H_GP)(a0)
        ld      s0, (HYP_H_S + 0 * 8)(a0)
        ld      s1, (HYP_H_S + 1 * 8)(a0)
        ld      s2, (HYP_H_S + 2 * 8)(a0)
        ld      s3, (HYP_H_S + 3 * 8)(a0)
        ld      s4, (HYP_H_S + 4 * 8)(a0)
        ld      s5, (HYP_H_S + 5 * 8)(a0)
        ld      s6, (HYP_H_S + 6 * 8)(a0)
        ld      s7, (HYP_H_S + 7 * 8)(a0)
        ld      s8, (HYP_H_S + 8 * 8)(a0)
        ld      s9, (HYP_H_S + 9 * 8)(a0)
        ld      s10, (HYP_H_S + 10 * 8)(a0)
        ld      s11, (HYP_H_S + 11 * 8)(a0)

        ld      a1, (HYP_H_A + 1 * 8)(a0)
        ld      a2, (HYP_H_A + 2 * 8)(a0)
        ld      a3, (HYP_H_A + 3 * 8)(a0)
        ld      a4, (HYP_H_A + 4 * 8)(a0)
        ld      a5, (HYP_H_A + 5 * 8)(a0)
        ld      a6, (HYP_H_A + 6 * 8)(a0)
        ld      a7, (HYP_H_A + 7 * 8)(a0)

        ret

END(vmm_switch)

ENTRY(vmm_unpriv_trap)
        csrr    a1, sepc
        sd      a1, HYP_TRAP_SEPC(a0)
        addi    a1, a1, 4       /* Next instruction after hlvx.hu */
        csrw    sepc, a1
        csrr    a1, scause
        sd      a1, HYP_TRAP_SCAUSE(a0)
        csrr    a1, stval
        sd      a1, HYP_TRAP_STVAL(a0)
        csrr    a1, htval
        sd      a1, HYP_TRAP_HTVAL(a0)
        csrr    a1, htinst
        sd      a1, HYP_TRAP_HTINST(a0)
        sret
END(vmm_unpriv_trap)