/* $OpenBSD: copystr.S,v 1.8 2023/01/06 19:10:18 miod Exp $ */
/*
 * Copyright (c) 2015 Dale Rahn <drahn@dalerahn.com>
 * Copyright (c) 2014 Patrick Wildt <patrick@blueri.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "assym.h"
#include <machine/asm.h>
#include <sys/errno.h>

        .text
        .align  2

/*
 * x0 - user space address
 * x1 - kernel space address
 * x2 - maxlens
 * x3 - lencopied
 *
 * Copy string from user space to kernel space
 */
ENTRY(copyinstr)
        RETGUARD_SETUP(copystr, x15)
        mrs     x6, tpidr_el1                   // load curcpu
        ldr     x6, [x6, #(CI_CURPCB)]
        ldr     x5, [x6, #(PCB_ONFAULT)]
        adr     x7, .Lcopystrfault
        str     x7, [x6, #(PCB_ONFAULT)]        // set handler

        mov     x8, xzr
        cbz     x2, 2f

1:      tst     x0, #(1ULL << 63)
        b.ne    .Lcopystrfault
        ldtrb   w4, [x0]
        strb    w4, [x1], #1
        add     x0, x0, #1
        sub     x2, x2, #1
        add     x8, x8, #1
        cbz     w4, .Lcopystrsuccess
        cbnz    x2, 1b

2:
        mov     x0, #ENAMETOOLONG
        b       .Lcopystrcleanup

.Lcopystrfault:
        mov     x0, #EFAULT
        b       .Lcopystrcleanup

.Lcopystrsuccess:
        mov     x0, xzr

.Lcopystrcleanup:
        cbz     x3, 3f
        str     x8, [x3]
3:
        str     x5, [x6, #(PCB_ONFAULT)]
        RETGUARD_CHECK(copystr, x15)
        ret

/*
 * x0 - kernel space address
 * x1 - user space address
 * x2 - maxlens
 * x3 - lencopied
 *
 * Copy string from kernel space to user space
 */
ENTRY(copyoutstr)
        RETGUARD_SETUP(copystr, x15)
        mrs     x6, tpidr_el1                   // load curcpu
        ldr     x6, [x6, #(CI_CURPCB)]
        ldr     x5, [x6, #(PCB_ONFAULT)]
        adr     x7, .Lcopystrfault
        str     x7, [x6, #(PCB_ONFAULT)]        // set handler

        mov     x8, xzr
        cbz     x2, 2f

1:      tst     x1, #(1ULL << 63)
        b.ne    .Lcopystrfault
        ldrb    w4, [x0], 1
        sttrb   w4, [x1]
        add     x1, x1, #1
        sub     x2, x2, #1
        add     x8, x8, #1
        cbz     w4, .Lcopystrsuccess
        cbnz    x2, 1b

2:
        mov     x0, #ENAMETOOLONG
        b       .Lcopystrcleanup