/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1982, 1986 The Regents of the University of California.
 * Copyright (c) 1989, 1990 William Jolitz
 * Copyright (c) 1994 John Dyson
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department, and William Jolitz.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *      Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/socketvar.h>
#include <sys/syscall.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/unistd.h>

#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/pcb.h>
#include <machine/sysarch.h>
#include <sys/lock.h>
#include <sys/mutex.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_param.h>
#include <vm/vm_pageout.h>
#include <vm/uma.h>
#include <vm/uma_int.h>

#include <machine/md_var.h>
#include <machine/vfp.h>

/*
 * struct switchframe and trapframe must both be a multiple of 8
 * for correct stack alignment.
 */
_Static_assert((sizeof(struct switchframe) % 8) == 0, "Bad alignment");
_Static_assert((sizeof(struct trapframe) % 8) == 0, "Bad alignment");

uint32_t initial_fpscr = VFPSCR_DN | VFPSCR_FZ;

/*
 * Finish a fork operation, with process p2 nearly set up.
 * Copy and update the pcb, set up the stack so that the child
 * ready to run and return to user mode.
 */
void
cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
{
        struct pcb *pcb2;
        struct trapframe *tf;
        struct mdproc *mdp2;

        if ((flags & RFPROC) == 0)
                return;

        /* Point the pcb to the top of the stack */
        pcb2 = (struct pcb *)
            (td2->td_kstack + td2->td_kstack_pages * PAGE_SIZE) - 1;
#ifdef VFP
        /* Store actual state of VFP */
        if (curthread == td1) {
                if ((td1->td_pcb->pcb_fpflags & PCB_FP_STARTED) != 0)
                        vfp_save_state(td1, td1->td_pcb);
        }
#endif
        td2->td_pcb = pcb2;

        /* Clone td1's pcb */
        bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));

        /* Point to mdproc and then copy over td1's contents */
        mdp2 = &p2->p_md;
        bcopy(&td1->td_proc->p_md, mdp2, sizeof(*mdp2));

        /* Point the frame to the stack in front of pcb and copy td1's frame */
        td2->td_frame = (struct trapframe *)pcb2 - 1;
        *td2->td_frame = *td1->td_frame;

        /*
         * Create a new fresh stack for the new process.
         * Copy the trap frame for the return to user mode as if from a
         * syscall.  This copies most of the user mode register values.
         */
        pmap_set_pcb_pagedir(vmspace_pmap(p2->p_vmspace), pcb2);
        pcb2->pcb_regs.sf_r4 = (register_t)fork_return;
        pcb2->pcb_regs.sf_r5 = (register_t)td2;
        pcb2->pcb_regs.sf_lr = (register_t)fork_trampoline;
        pcb2->pcb_regs.sf_sp = (register_t)STACKALIGN(td2->td_frame);
        pcb2->pcb_regs.sf_tpidrurw = (register_t)get_tls();

#ifdef VFP
        vfp_new_thread(td2, td1, true);
#endif

        tf = td2->td_frame;
        tf->tf_spsr &= ~PSR_C;
        tf->tf_r0 = 0;
        tf->tf_r1 = 0;

        /* Setup to release spin count in fork_exit(). */
        td2->td_md.md_spinlock_count = 1;
        td2->td_md.md_saved_cspr = PSR_SVC32_MODE;
}

void
cpu_set_syscall_retval(struct thread *td, int error)
{
        struct trapframe *frame;

        frame = td->td_frame;
        switch (error) {
        case 0:
                frame->tf_r0 = td->td_retval[0];
                frame->tf_r1 = td->td_retval[1];
                frame->tf_spsr &= ~PSR_C;   /* carry bit */
                break;
        case ERESTART:
                /*
                 * Reconstruct the pc to point at the swi.
                 */
                if ((frame->tf_spsr & PSR_T) != 0)
                        frame->tf_pc -= THUMB_INSN_SIZE;
                else
                        frame->tf_pc -= INSN_SIZE;
                break;
        case EJUSTRETURN:
                /* nothing to do */
                break;
        default:
                frame->tf_r0 = error;
                frame->tf_spsr |= PSR_C;    /* carry bit */
                break;
        }
}

/*
 * Initialize machine state, mostly pcb and trap frame for a new
 * thread, about to return to userspace.  Put enough state in the new
 * thread's PCB to get it to go back to the fork_return(), which
 * finalizes the thread state and handles peculiarities of the first
 * return to userspace for the new thread.
 */
void
cpu_copy_thread(struct thread *td, struct thread *td0)
{

        bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
        bcopy(td0->td_pcb, td->td_pcb, sizeof(struct pcb));

        td->td_pcb->pcb_regs.sf_r4 = (register_t)fork_return;
        td->td_pcb->pcb_regs.sf_r5 = (register_t)td;
        td->td_pcb->pcb_regs.sf_lr = (register_t)fork_trampoline;
        td->td_pcb->pcb_regs.sf_sp = (register_t)STACKALIGN(td->td_frame);

        td->td_frame->tf_spsr &= ~PSR_C;
        td->td_frame->tf_r0 = 0;

#ifdef VFP
        vfp_new_thread(td, td0, false);
#endif

        /* Setup to release spin count in fork_exit(). */
        td->td_md.md_spinlock_count = 1;
        td->td_md.md_saved_cspr = PSR_SVC32_MODE;
}

/*
 * Set that machine state for performing an upcall that starts
 * the entry function with the given argument.
 */
int
cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
        stack_t *stack)
{
        struct trapframe *tf = td->td_frame;

        tf->tf_usr_sp = STACKALIGN((int)stack->ss_sp + stack->ss_size);
        tf->tf_pc = (int)entry;
        tf->tf_r0 = (int)arg;
        tf->tf_spsr = PSR_USR32_MODE;
        if ((register_t)entry & 1)
                tf->tf_spsr |= PSR_T;
        return (0);
}

int
cpu_set_user_tls(struct thread *td, void *tls_base, int thr_flags __unused)
{

        td->td_pcb->pcb_regs.sf_tpidrurw = (register_t)tls_base;
        if (td == curthread)
                set_tls(tls_base);
        return (0);
}

void
cpu_thread_exit(struct thread *td)
{
}

void
cpu_thread_alloc(struct thread *td)
{
        td->td_pcb = (struct pcb *)(td->td_kstack + td->td_kstack_pages *
            PAGE_SIZE) - 1;
        /*
         * Ensure td_frame is aligned to an 8 byte boundary as it will be
         * placed into the stack pointer which must be 8 byte aligned in
         * the ARM EABI.
         */
        td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb) - 1;
}

void
cpu_thread_free(struct thread *td)
{
}

void
cpu_thread_clean(struct thread *td)
{
}

/*
 * Intercept the return address from a freshly forked process that has NOT
 * been scheduled yet.
 *
 * This is needed to make kernel threads stay in kernel mode.
 */
void
cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
{
        td->td_pcb->pcb_regs.sf_r4 = (register_t)func;  /* function */
        td->td_pcb->pcb_regs.sf_r5 = (register_t)arg;   /* first arg */
}

void
cpu_update_pcb(struct thread *td)
{
        MPASS(td == curthread);
        td->td_pcb->pcb_regs.sf_tpidrurw = (register_t)get_tls();
}

void
cpu_exit(struct thread *td)
{
}

bool
cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
{

        return (true);
}

int
cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
    int com __unused, void *data __unused)
{

        return (EINVAL);
}

void
cpu_sync_core(void)
{
}