/* $OpenBSD: copy.S,v 1.10 2023/08/12 06:28:13 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 <sys/syscall.h>
#include <machine/asm.h>
#include <sys/errno.h>

        .text
        .align  2

/*
 * x0 = user space address
 * x1 = kernel space address
 * x2 = length
 *
 * Copies bytes from user space to kernel space
 */
ENTRY(copyin)
        RETGUARD_SETUP(copy, x15)
        cbnz    x2, 1f
        mov     x0, 0
        RETGUARD_CHECK(copy, x15)
        ret

1:
        /* Check whether source+len overflows. */
        adds    x3, x0, x2
        b.cs    .Laddrfault
        /* Check that source+len is in userspace. */
        tst     x3, #(1ULL << 63)
        b.ne    .Laddrfault

        mrs     x3, tpidr_el1                   // load cpuinfo
        ldr     x3, [x3, #(CI_CURPCB)]
        ldr     x4, [x3, #(PCB_ONFAULT)]
        adr     x5, .Lcopyfault
        str     x5, [x3, #(PCB_ONFAULT)]        // set handler

        cmp     x2, #16
        b.lo    .Lcopyin1
2:      ldtr    x6, [x0]
        ldtr    x7, [x0, #8]
        stp     x6, x7, [x1], #16
        add     x0, x0, #16
        sub     x2, x2, #16
        cmp     x2, #16
        b.hs    2b

.Lcopyin1:
        cbz     x2, .Lcopyin0
3:      ldtrb   w6, [x0]
        strb    w6, [x1], #1
        add     x0, x0, #1
        sub     x2, x2, #1
        cbnz    x2, 3b

.Lcopyin0:
        str     x4, [x3, #(PCB_ONFAULT)]        // clear handler
        mov     x0, xzr
        RETGUARD_CHECK(copy, x15)
        ret

.Lcopyfault:
        str     x4, [x3, #(PCB_ONFAULT)]
.Laddrfault:
        mov     x0, #EFAULT
        RETGUARD_CHECK(copy, x15)
        ret

/*
 * x0 = user space address
 * x1 = kernel space address
 *
 * Atomically copies a 32-bit word from user space to kernel space
 */
ENTRY(copyin32)
        RETGUARD_SETUP(copy, x15)

        /* Check source alignment. */
        tst     x0, #0x3
        b.ne    .Laddrfault
        /* Check that source is in userspace. */
        tst     x0, #(1ULL << 63)
        b.ne    .Laddrfault

        mrs     x3, tpidr_el1                   // load cpuinfo
        ldr     x3, [x3, #(CI_CURPCB)]
        ldr     x4, [x3, #(PCB_ONFAULT)]
        adr     x5, .Lcopyfault
        str     x5, [x3, #(PCB_ONFAULT)]        // set handler

        ldtr    w6, [x0]
        str     w6, [x1]

        str     x4, [x3, #(PCB_ONFAULT)]        // clear handler
        mov     x0, xzr
        RETGUARD_CHECK(copy, x15)
        ret

/*
 * x0 = kernel space address
 * x1 = user space address
 * x2 = length
 *
 * Copies bytes from kernel space to user space
 */

ENTRY(copyout)
        RETGUARD_SETUP(copy, x15)
        cbnz    x2, 1f
        mov     x0, 0
        RETGUARD_CHECK(copy, x15)
        ret

1:
        /* Check whether dest+len overflows. */
        adds    x3, x1, x2
        b.cs    .Laddrfault
        /* Check that dest+len is in userspace. */
        tst     x3, #(1ULL << 63)
        b.ne    .Laddrfault

        mrs     x3, tpidr_el1                   // load cpuinfo
        ldr     x3, [x3, #(CI_CURPCB)]
        ldr     x4, [x3, #(PCB_ONFAULT)]
        adr     x5, .Lcopyfault
        str     x5, [x3, #(PCB_ONFAULT)]        // set handler

        cmp     x2, #16
        b.lo    .Lcopyout1
2:      ldp     x6, x7, [x0], #16
        sttr    x6, [x1]
        sttr    x7, [x1, #8]
        add     x1, x1, #16
        sub     x2, x2, #16
        cmp     x2, #16
        b.hs    2b

.Lcopyout1:
        cbz     x2, .Lcopyout0
3:      ldrb    w6, [x0], #1
        sttrb   w6, [x1]
        add     x1, x1, #1
        sub     x2, x2, #1
        cbnz    x2, 3b

.Lcopyout0:
        str     x4, [x3, #(PCB_ONFAULT)]        // restore handler
        mov     x0, xzr
        RETGUARD_CHECK(copy, x15)
        ret

/*
 * x0 = kernel space source address
 * x1 = kernel space destination address
 * x2 = length
 *
 * Copies bytes from kernel space to kernel space, aborting on page fault
 */

ENTRY(kcopy)
        RETGUARD_SETUP(copy, x15)
        cbnz    x2, 1f
        mov     x0, 0
        RETGUARD_CHECK(copy, x15)
        ret
1:
        mrs     x3, tpidr_el1                   // load cpuinfo
        ldr     x3, [x3, #(CI_CURPCB)]
        ldr     x4, [x3, #(PCB_ONFAULT)]
        adr     x5, .Lcopyfault
        str     x5, [x3, #(PCB_ONFAULT)]        // set handler

        cmp     x2, #16
        b.lo    .Lkcopy8
2:      ldp     x6, x7, [x0], #16
        stp     x6, x7, [x1], #16
        sub     x2, x2, #16
        cmp     x2, #16
        b.hs    2b

.Lkcopy8:
        tbz     x2, #3, .Lkcopy4
        ldr     x6, [x0], #8
        str     x6, [x1], #8
        sub     x2, x2, #8

.Lkcopy4:
        tbz     x2, #2, .Lkcopy1
        ldr     w6, [x0], #4
        str     w6, [x1], #4
        sub     x2, x2, #4

.Lkcopy1:
        cbz     x2, .Lkcopy0
3:      ldrb    w6, [x0], #1
        strb    w6, [x1], #1
        sub     x2, x2, #1
        cbnz    x2, 3b

.Lkcopy0:
        str     x4, [x3, #(PCB_ONFAULT)]        // restore handler
        mov     x0, xzr
        RETGUARD_CHECK(copy, x15)
        ret