/*	$OpenBSD: vm_machdep.c,v 1.11 2023/04/11 00:45:08 jsg Exp $	*/

/*-
 * Copyright (c) 1995 Charles M. Hannum.  All rights reserved.
 * Copyright (c) 1982, 1986 The Regents of the University of California.
 * Copyright (c) 1989, 1990 William Jolitz
 * 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. 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.
 *
 *	@(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/user.h>

#include <uvm/uvm_extern.h>

#include <machine/cpu.h>

/*
 * Finish a fork operation, with process p2 nearly set up.
 * Copy and update the kernel stack and pcb, making the child
 * ready to run, and marking it so that it can return differently
 * than the parent.  Returns 1 in the child process, 0 in the parent.
 */
void
cpu_fork(struct proc *p1, struct proc *p2, void *stack, void *tcb,
    void (*func)(void *), void *arg)
{
	struct pcb *pcb = &p2->p_addr->u_pcb;
	struct pcb *pcb1 = &p1->p_addr->u_pcb;
	struct trapframe *tf;
	struct switchframe *sf;

	/* Ensure proper stack alignment. */
	CTASSERT((sizeof(struct trapframe) & STACKALIGNBYTES) == 0);
	CTASSERT((sizeof(struct switchframe) & STACKALIGNBYTES) == 0);

	/* Save FPU state to PCB if necessary. */
	if (pcb1->pcb_flags & PCB_FPU)
		fpu_save(p1, pcb1->pcb_tf);

	/* Copy the pcb. */
	*pcb = p1->p_addr->u_pcb;

	pmap_activate(p2);

	tf = (struct trapframe *)((u_long)p2->p_addr
	    + USPACE
	    - sizeof(struct trapframe)
	    - sizeof(register_t)	/* for holding curcpu */
	    - 0x10);

	tf = (struct trapframe *)STACKALIGN(tf);
	pcb->pcb_tf = tf;
	*tf = *p1->p_addr->u_pcb.pcb_tf;

	if (stack != NULL)
		tf->tf_sp = STACKALIGN(stack);
	if (tcb != NULL)
		tf->tf_tp = (register_t)tcb;

	/* Arguments for child */
	tf->tf_a[0] = 0;
	tf->tf_a[1] = 0;
	tf->tf_sstatus |= (SSTATUS_SPIE); /* Enable interrupts. */
	tf->tf_sstatus &= ~(SSTATUS_SPP); /* Enter user mode. */

	sf = (struct switchframe *)tf - 1;
	sf->sf_s[0] = 0;		/* Terminate chain of call frames. */
	sf->sf_s[1] = (uint64_t)func;
	sf->sf_s[2] = (uint64_t)arg;
	sf->sf_ra = (u_int64_t)&proc_trampoline;
	pcb->pcb_sp = (uint64_t)sf;
}

/*
 * cpu_exit is called as the last action during exit.
 *
 * We clean up a little and then call sched_exit() with the old proc as an
 * argument.
 */
void
cpu_exit(struct proc *p)
{
	pmap_deactivate(p);
	sched_exit(p);
}

struct kmem_va_mode kv_physwait = {
	.kv_map = &phys_map,
	.kv_wait = 1,
};

/*
 * Map a user I/O request into kernel virtual address space.
 * Note: the pages are already locked by uvm_vslock(), so we
 * do not need to pass an access_type to pmap_enter().
 */
void
vmapbuf(struct buf *bp, vsize_t len)
{
	vaddr_t faddr, taddr, off;
	paddr_t fpa;

	if ((bp->b_flags & B_PHYS) == 0)
		panic("vmapbuf");
	faddr = trunc_page((vaddr_t)(bp->b_saveaddr = bp->b_data));
	off = (vaddr_t)bp->b_data - faddr;
	len = round_page(off + len);
	taddr = (vaddr_t)km_alloc(len, &kv_physwait, &kp_none, &kd_waitok);
	bp->b_data = (caddr_t)(taddr + off);
	/*
	 * The region is locked, so we expect that pmap_pte() will return
	 * non-NULL.
	 * XXX: unwise to expect this in a multithreaded environment.
	 * anything can happen to a pmap between the time we lock a
	 * region, release the pmap lock, and then relock it for
	 * the pmap_extract().
	 *
	 * no need to flush TLB since we expect nothing to be mapped
	 * where we just allocated (TLB will be flushed when our
	 * mapping is removed).
	 */
	while (len) {
		(void) pmap_extract(vm_map_pmap(&bp->b_proc->p_vmspace->vm_map),
		    faddr, &fpa);
		pmap_kenter_pa(taddr, fpa, PROT_READ | PROT_WRITE);
		faddr += PAGE_SIZE;
		taddr += PAGE_SIZE;
		len -= PAGE_SIZE;
	}
	pmap_update(pmap_kernel());
}

/*
 * Unmap a previously-mapped user I/O request.
 */
void
vunmapbuf(struct buf *bp, vsize_t len)
{
	vaddr_t addr, off;

	if ((bp->b_flags & B_PHYS) == 0)
		panic("vunmapbuf");
	addr = trunc_page((vaddr_t)bp->b_data);
	off = (vaddr_t)bp->b_data - addr;
	len = round_page(off + len);
	pmap_kremove(addr, len);
	pmap_update(pmap_kernel());
	km_free((void *)addr, len, &kv_physwait, &kp_none);
	bp->b_data = bp->b_saveaddr;
	bp->b_saveaddr = NULL;
}