The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/riscv/riscv/copyinout.S

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    1 /*-
    2  * Copyright (c) 2015-2018 Ruslan Bukin <br@bsdpad.com>
    3  * Copyright (c) 2019 Mitchell Horne
    4  * All rights reserved.
    5  *
    6  * Portions of this software were developed by SRI International and the
    7  * University of Cambridge Computer Laboratory under DARPA/AFRL contract
    8  * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
    9  *
   10  * Portions of this software were developed by the University of Cambridge
   11  * Computer Laboratory as part of the CTSRD Project, with support from the
   12  * UK Higher Education Innovation Fund (HEIF).
   13  *
   14  * Redistribution and use in source and binary forms, with or without
   15  * modification, are permitted provided that the following conditions
   16  * are met:
   17  * 1. Redistributions of source code must retain the above copyright
   18  *    notice, this list of conditions and the following disclaimer.
   19  * 2. Redistributions in binary form must reproduce the above copyright
   20  *    notice, this list of conditions and the following disclaimer in the
   21  *    documentation and/or other materials provided with the distribution.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  */
   35 
   36 #include <machine/asm.h>
   37 __FBSDID("$FreeBSD$");
   38 
   39 #include <machine/riscvreg.h>
   40 #include <sys/errno.h>
   41 
   42 #include "assym.inc"
   43 
   44 /*
   45  * Fault handler for the copy{in,out} functions below.
   46  */
   47 ENTRY(copyio_fault)
   48         SET_FAULT_HANDLER(x0, a1) /* Clear the handler */
   49         EXIT_USER_ACCESS(a1)
   50 copyio_fault_nopcb:
   51         li      a0, EFAULT
   52         ret
   53 END(copyio_fault)
   54 
   55 /*
   56  * copycommon - common copy routine
   57  *
   58  * a0 - Source address
   59  * a1 - Destination address
   60  * a2 - Size of copy
   61  */
   62         .macro copycommon
   63         la      a6, copyio_fault        /* Get the handler address */
   64         SET_FAULT_HANDLER(a6, a7)       /* Set the handler */
   65         ENTER_USER_ACCESS(a7)
   66 
   67         li      t2, XLEN_BYTES
   68         blt     a2, t2, 4f              /* Byte-copy if len < XLEN_BYTES */
   69 
   70         /*
   71          * Compare lower bits of src and dest.
   72          * If they are aligned with each other, we can do word copy.
   73          */
   74         andi    t0, a0, (XLEN_BYTES-1)  /* Low bits of src */
   75         andi    t1, a1, (XLEN_BYTES-1)  /* Low bits of dest */
   76         bne     t0, t1, 4f              /* Misaligned. Go to byte copy */
   77         beqz    t0, 2f                  /* Already word-aligned, skip ahead */
   78 
   79         /* Byte copy until the first word-aligned address */
   80 1:      lb      a4, 0(a0)               /* Load byte from src */
   81         addi    a0, a0, 1
   82         sb      a4, 0(a1)               /* Store byte in dest */
   83         addi    a1, a1, 1
   84         addi    a2, a2, -1              /* len-- */
   85         andi    t0, a0, (XLEN_BYTES-1)
   86         bnez    t0, 1b
   87         j       3f
   88 
   89         /* Copy words */
   90 2:      ld      a4, 0(a0)               /* Load word from src */
   91         addi    a0, a0, XLEN_BYTES
   92         sd      a4, 0(a1)               /* Store word in dest */
   93         addi    a1, a1, XLEN_BYTES
   94         addi    a2, a2, -XLEN_BYTES     /* len -= XLEN_BYTES */
   95 3:      bgeu    a2, t2, 2b              /* Again if len >= XLEN_BYTES */
   96 
   97         /* Check if we're finished */
   98         beqz    a2, 5f
   99 
  100         /* Copy any remaining bytes */
  101 4:      lb      a4, 0(a0)               /* Load byte from src */
  102         addi    a0, a0, 1
  103         sb      a4, 0(a1)               /* Store byte in dest */
  104         addi    a1, a1, 1
  105         addi    a2, a2, -1              /* len-- */
  106         bnez    a2, 4b
  107 
  108 5:      EXIT_USER_ACCESS(a7)
  109         SET_FAULT_HANDLER(x0, a7)       /* Clear the handler */
  110         .endm
  111 
  112 /*
  113  * Copies from a kernel to user address
  114  *
  115  * int copyout(const void *kaddr, void *udaddr, size_t len)
  116  */
  117 ENTRY(copyout)
  118         beqz    a2, copyout_end /* If len == 0 then skip loop */
  119         add     a3, a1, a2
  120         li      a4, VM_MAXUSER_ADDRESS
  121         bgt     a3, a4, copyio_fault_nopcb
  122 
  123         copycommon
  124 
  125 copyout_end:
  126         li      a0, 0           /* return 0 */
  127         ret
  128 END(copyout)
  129 
  130 /*
  131  * Copies from a user to kernel address
  132  *
  133  * int copyin(const void *uaddr, void *kaddr, size_t len)
  134  */
  135 ENTRY(copyin)
  136         beqz    a2, copyin_end  /* If len == 0 then skip loop */
  137         add     a3, a0, a2
  138         li      a4, VM_MAXUSER_ADDRESS
  139         bgt     a3, a4, copyio_fault_nopcb
  140 
  141         copycommon
  142 
  143 copyin_end:
  144         li      a0, 0           /* return 0 */
  145         ret
  146 END(copyin)
  147 
  148 /*
  149  * Copies a string from a user to kernel address
  150  *
  151  * int copyinstr(const void *udaddr, void *kaddr, size_t len, size_t *done)
  152  */
  153 ENTRY(copyinstr)
  154         mv      a5, x0          /* count = 0 */
  155         beqz    a2, 3f          /* If len == 0 then skip loop */
  156 
  157         la      a6, copyio_fault /* Get the handler address */
  158         SET_FAULT_HANDLER(a6, a7) /* Set the handler */
  159         ENTER_USER_ACCESS(a7)
  160 
  161         li      a7, VM_MAXUSER_ADDRESS
  162 1:      bgt     a0, a7, copyio_fault
  163         lb      a4, 0(a0)       /* Load from uaddr */
  164         addi    a0, a0, 1
  165         sb      a4, 0(a1)       /* Store in kaddr */
  166         addi    a1, a1, 1
  167         beqz    a4, 2f
  168         addi    a2, a2, -1      /* len-- */
  169         addi    a5, a5, 1       /* count++ */
  170         bnez    a2, 1b
  171 
  172 2:      EXIT_USER_ACCESS(a7)
  173         SET_FAULT_HANDLER(x0, a7) /* Clear the handler */
  174 
  175 3:      beqz    a3, 4f          /* Check if done != NULL */
  176         addi    a5, a5, 1       /* count++ */
  177         sd      a5, 0(a3)       /* done = count */
  178 
  179 4:      mv      a0, x0          /* return 0 */
  180         beqz    a4, 5f
  181         li      a0, ENAMETOOLONG
  182 5:
  183         ret
  184 END(copyinstr)

Cache object: 1d5d9893ed4a66b1eae70a47f7459a3c


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