/*      $NetBSD: copyoutstr.c,v 1.24 2022/10/05 08:18:00 rin Exp $      */

/*
 * Copyright 2001 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Eduardo Horvath and Simon Burge for Wasabi Systems, Inc.
 *
 * 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 for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: copyoutstr.c,v 1.24 2022/10/05 08:18:00 rin Exp $");

#include <sys/param.h>
#include <uvm/uvm_extern.h>
#include <powerpc/ibm4xx/spr.h>
#include <machine/pcb.h>

int
copyoutstr(const void *kaddr, void *uaddr, size_t len, size_t *done)
{
        struct pmap *pm = curproc->p_vmspace->vm_map.pmap;
        size_t resid;
        int rv, msr, pid, tmp, ctx;
        struct faultbuf env;

        if (__predict_false(len == 0)) {
                if (done)
                        *done = 0;
                return 0;
        }

        if ((rv = setfault(&env))) {
                curpcb->pcb_onfault = NULL;
                if (done)
                        *done = 0;
                return rv;
        }

        if (!(ctx = pm->pm_ctx)) {
                /* No context -- assign it one */
                ctx_alloc(pm);
                ctx = pm->pm_ctx;
        }

        resid = len;
        __asm volatile (
                "mtctr  %[resid];"              /* Set up counter */
                "mfmsr  %[msr];"                /* Save MSR */
                "li     %[tmp],0x20;"           /* Disable IMMU */
                "andc   %[tmp],%[msr],%[tmp];"
                "mtmsr  %[tmp];"
                "isync;"
                MFPID(%[pid])                   /* Save old PID */

        "1:"    "lbz    %[tmp],0(%[kaddr]);"    /* Load kernel byte */
                "addi   %[kaddr],%[kaddr],1;"
                "sync;"

                MTPID(%[ctx])                   /* Load user ctx */
                "isync;"
                "stb    %[tmp],0(%[uaddr]);"    /* Store byte */
                "addi   %[uaddr],%[uaddr],1;"
                "or.    %[tmp],%[tmp],%[tmp];"
                "sync;"

                MTPID(%[pid])
                "isync;"
                "bdnzf  eq,1b;"                 /* while(ctr-- && !zero) */

                "mtmsr  %[msr];"                /* Restore MSR */
                "isync;"
                "mfctr  %[resid];"              /* Restore resid */

                : [msr] "=&r" (msr), [pid] "=&r" (pid), [tmp] "=&r" (tmp),
                  [resid] "+r" (resid)
                : [ctx] "r" (ctx), [uaddr] "b" (uaddr), [kaddr] "b" (kaddr)
                : "cr0", "ctr");

        curpcb->pcb_onfault = NULL;
        if (done)
                *done = len - resid;
        if (resid == 0 && (char)tmp != '\0')
                return ENAMETOOLONG;
        else
                return 0;
}