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/amd64/amd64/mem.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1988 University of Utah.
    5  * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
    6  * All rights reserved.
    7  *
    8  * This code is derived from software contributed to Berkeley by
    9  * the Systems Programming Group of the University of Utah Computer
   10  * Science Department, and code derived from software contributed to
   11  * Berkeley by William Jolitz.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      from: Utah $Hdr: mem.c 1.13 89/10/08$
   38  *      from: @(#)mem.c 7.2 (Berkeley) 5/9/91
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/12.0/sys/amd64/amd64/mem.c 326023 2017-11-20 19:43:44Z pfg $");
   43 
   44 /*
   45  * Memory special file
   46  */
   47 
   48 #include <sys/param.h>
   49 #include <sys/conf.h>
   50 #include <sys/fcntl.h>
   51 #include <sys/ioccom.h>
   52 #include <sys/kernel.h>
   53 #include <sys/lock.h>
   54 #include <sys/malloc.h>
   55 #include <sys/memrange.h>
   56 #include <sys/module.h>
   57 #include <sys/mutex.h>
   58 #include <sys/proc.h>
   59 #include <sys/signalvar.h>
   60 #include <sys/systm.h>
   61 #include <sys/uio.h>
   62 
   63 #include <machine/md_var.h>
   64 #include <machine/specialreg.h>
   65 #include <machine/vmparam.h>
   66 
   67 #include <vm/vm.h>
   68 #include <vm/pmap.h>
   69 #include <vm/vm_extern.h>
   70 
   71 #include <machine/memdev.h>
   72 
   73 /*
   74  * Used in /dev/mem drivers and elsewhere
   75  */
   76 MALLOC_DEFINE(M_MEMDESC, "memdesc", "memory range descriptors");
   77 
   78 /* ARGSUSED */
   79 int
   80 memrw(struct cdev *dev, struct uio *uio, int flags)
   81 {
   82         struct iovec *iov;
   83         void *p;
   84         ssize_t orig_resid;
   85         u_long v, vd;
   86         u_int c;
   87         int error;
   88 
   89         error = 0;
   90         orig_resid = uio->uio_resid;
   91         while (uio->uio_resid > 0 && error == 0) {
   92                 iov = uio->uio_iov;
   93                 if (iov->iov_len == 0) {
   94                         uio->uio_iov++;
   95                         uio->uio_iovcnt--;
   96                         if (uio->uio_iovcnt < 0)
   97                                 panic("memrw");
   98                         continue;
   99                 }
  100                 v = uio->uio_offset;
  101                 c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));
  102 
  103                 switch (dev2unit(dev)) {
  104                 case CDEV_MINOR_KMEM:
  105                         /*
  106                          * Since c is clamped to be less or equal than
  107                          * PAGE_SIZE, the uiomove() call does not
  108                          * access past the end of the direct map.
  109                          */
  110                         if (v >= DMAP_MIN_ADDRESS &&
  111                             v < DMAP_MIN_ADDRESS + dmaplimit) {
  112                                 error = uiomove((void *)v, c, uio);
  113                                 break;
  114                         }
  115 
  116                         if (!kernacc((void *)v, c, uio->uio_rw == UIO_READ ?
  117                             VM_PROT_READ : VM_PROT_WRITE)) {
  118                                 error = EFAULT;
  119                                 break;
  120                         }
  121 
  122                         /*
  123                          * If the extracted address is not accessible
  124                          * through the direct map, then we make a
  125                          * private (uncached) mapping because we can't
  126                          * depend on the existing kernel mapping
  127                          * remaining valid until the completion of
  128                          * uiomove().
  129                          *
  130                          * XXX We cannot provide access to the
  131                          * physical page 0 mapped into KVA.
  132                          */
  133                         v = pmap_extract(kernel_pmap, v);
  134                         if (v == 0) {
  135                                 error = EFAULT;
  136                                 break;
  137                         }
  138                         /* FALLTHROUGH */
  139                 case CDEV_MINOR_MEM:
  140                         if (v < dmaplimit) {
  141                                 vd = PHYS_TO_DMAP(v);
  142                                 error = uiomove((void *)vd, c, uio);
  143                                 break;
  144                         }
  145                         if (v > cpu_getmaxphyaddr()) {
  146                                 error = EFAULT;
  147                                 break;
  148                         }
  149                         p = pmap_mapdev(v, PAGE_SIZE);
  150                         error = uiomove(p, c, uio);
  151                         pmap_unmapdev((vm_offset_t)p, PAGE_SIZE);
  152                         break;
  153                 }
  154         }
  155         /*
  156          * Don't return error if any byte was written.  Read and write
  157          * can return error only if no i/o was performed.
  158          */
  159         if (uio->uio_resid != orig_resid)
  160                 error = 0;
  161         return (error);
  162 }
  163 
  164 /*
  165  * allow user processes to MMAP some memory sections
  166  * instead of going through read/write
  167  */
  168 /* ARGSUSED */
  169 int
  170 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
  171     int prot __unused, vm_memattr_t *memattr __unused)
  172 {
  173         if (dev2unit(dev) == CDEV_MINOR_MEM) {
  174                 if (offset > cpu_getmaxphyaddr())
  175                         return (-1);
  176                 *paddr = offset;
  177                 return (0);
  178         }
  179         return (-1);
  180 }
  181 
  182 /*
  183  * Operations for changing memory attributes.
  184  *
  185  * This is basically just an ioctl shim for mem_range_attr_get
  186  * and mem_range_attr_set.
  187  */
  188 /* ARGSUSED */
  189 int 
  190 memioctl(struct cdev *dev __unused, u_long cmd, caddr_t data, int flags,
  191     struct thread *td)
  192 {
  193         int nd, error = 0;
  194         struct mem_range_op *mo = (struct mem_range_op *)data;
  195         struct mem_range_desc *md;
  196         
  197         /* is this for us? */
  198         if ((cmd != MEMRANGE_GET) &&
  199             (cmd != MEMRANGE_SET))
  200                 return (ENOTTY);
  201 
  202         /* any chance we can handle this? */
  203         if (mem_range_softc.mr_op == NULL)
  204                 return (EOPNOTSUPP);
  205 
  206         /* do we have any descriptors? */
  207         if (mem_range_softc.mr_ndesc == 0)
  208                 return (ENXIO);
  209 
  210         switch (cmd) {
  211         case MEMRANGE_GET:
  212                 nd = imin(mo->mo_arg[0], mem_range_softc.mr_ndesc);
  213                 if (nd > 0) {
  214                         md = (struct mem_range_desc *)
  215                                 malloc(nd * sizeof(struct mem_range_desc),
  216                                        M_MEMDESC, M_WAITOK);
  217                         error = mem_range_attr_get(md, &nd);
  218                         if (!error)
  219                                 error = copyout(md, mo->mo_desc, 
  220                                         nd * sizeof(struct mem_range_desc));
  221                         free(md, M_MEMDESC);
  222                 }
  223                 else
  224                         nd = mem_range_softc.mr_ndesc;
  225                 mo->mo_arg[0] = nd;
  226                 break;
  227                 
  228         case MEMRANGE_SET:
  229                 md = (struct mem_range_desc *)malloc(sizeof(struct mem_range_desc),
  230                                                     M_MEMDESC, M_WAITOK);
  231                 error = copyin(mo->mo_desc, md, sizeof(struct mem_range_desc));
  232                 /* clamp description string */
  233                 md->mr_owner[sizeof(md->mr_owner) - 1] = 0;
  234                 if (error == 0)
  235                         error = mem_range_attr_set(md, &mo->mo_arg[0]);
  236                 free(md, M_MEMDESC);
  237                 break;
  238         }
  239         return (error);
  240 }

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