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  * Copyright (c) 1988 University of Utah.
    3  * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
    4  * All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the Systems Programming Group of the University of Utah Computer
    8  * Science Department, and code derived from software contributed to
    9  * Berkeley by William Jolitz.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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  *      from: Utah $Hdr: mem.c 1.13 89/10/08$
   36  *      from: @(#)mem.c 7.2 (Berkeley) 5/9/91
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD: releng/11.1/sys/amd64/amd64/mem.c 312394 2017-01-18 19:38:53Z jhb $");
   41 
   42 /*
   43  * Memory special file
   44  */
   45 
   46 #include <sys/param.h>
   47 #include <sys/conf.h>
   48 #include <sys/fcntl.h>
   49 #include <sys/ioccom.h>
   50 #include <sys/kernel.h>
   51 #include <sys/lock.h>
   52 #include <sys/malloc.h>
   53 #include <sys/memrange.h>
   54 #include <sys/module.h>
   55 #include <sys/mutex.h>
   56 #include <sys/proc.h>
   57 #include <sys/signalvar.h>
   58 #include <sys/systm.h>
   59 #include <sys/uio.h>
   60 
   61 #include <machine/md_var.h>
   62 #include <machine/specialreg.h>
   63 #include <machine/vmparam.h>
   64 
   65 #include <vm/vm.h>
   66 #include <vm/pmap.h>
   67 #include <vm/vm_extern.h>
   68 
   69 #include <machine/memdev.h>
   70 
   71 /*
   72  * Used in /dev/mem drivers and elsewhere
   73  */
   74 MALLOC_DEFINE(M_MEMDESC, "memdesc", "memory range descriptors");
   75 
   76 /* ARGSUSED */
   77 int
   78 memrw(struct cdev *dev, struct uio *uio, int flags)
   79 {
   80         struct iovec *iov;
   81         void *p;
   82         ssize_t orig_resid;
   83         u_long v, vd;
   84         u_int c;
   85         int error;
   86 
   87         error = 0;
   88         orig_resid = uio->uio_resid;
   89         while (uio->uio_resid > 0 && error == 0) {
   90                 iov = uio->uio_iov;
   91                 if (iov->iov_len == 0) {
   92                         uio->uio_iov++;
   93                         uio->uio_iovcnt--;
   94                         if (uio->uio_iovcnt < 0)
   95                                 panic("memrw");
   96                         continue;
   97                 }
   98                 v = uio->uio_offset;
   99                 c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));
  100 
  101                 switch (dev2unit(dev)) {
  102                 case CDEV_MINOR_KMEM:
  103                         /*
  104                          * Since c is clamped to be less or equal than
  105                          * PAGE_SIZE, the uiomove() call does not
  106                          * access past the end of the direct map.
  107                          */
  108                         if (v >= DMAP_MIN_ADDRESS &&
  109                             v < DMAP_MIN_ADDRESS + dmaplimit) {
  110                                 error = uiomove((void *)v, c, uio);
  111                                 break;
  112                         }
  113 
  114                         if (!kernacc((void *)v, c, uio->uio_rw == UIO_READ ?
  115                             VM_PROT_READ : VM_PROT_WRITE)) {
  116                                 error = EFAULT;
  117                                 break;
  118                         }
  119 
  120                         /*
  121                          * If the extracted address is not accessible
  122                          * through the direct map, then we make a
  123                          * private (uncached) mapping because we can't
  124                          * depend on the existing kernel mapping
  125                          * remaining valid until the completion of
  126                          * uiomove().
  127                          *
  128                          * XXX We cannot provide access to the
  129                          * physical page 0 mapped into KVA.
  130                          */
  131                         v = pmap_extract(kernel_pmap, v);
  132                         if (v == 0) {
  133                                 error = EFAULT;
  134                                 break;
  135                         }
  136                         /* FALLTHROUGH */
  137                 case CDEV_MINOR_MEM:
  138                         if (v < dmaplimit) {
  139                                 vd = PHYS_TO_DMAP(v);
  140                                 error = uiomove((void *)vd, c, uio);
  141                                 break;
  142                         }
  143                         if (v > cpu_getmaxphyaddr()) {
  144                                 error = EFAULT;
  145                                 break;
  146                         }
  147                         p = pmap_mapdev(v, PAGE_SIZE);
  148                         error = uiomove(p, c, uio);
  149                         pmap_unmapdev((vm_offset_t)p, PAGE_SIZE);
  150                         break;
  151                 }
  152         }
  153         /*
  154          * Don't return error if any byte was written.  Read and write
  155          * can return error only if no i/o was performed.
  156          */
  157         if (uio->uio_resid != orig_resid)
  158                 error = 0;
  159         return (error);
  160 }
  161 
  162 /*
  163  * allow user processes to MMAP some memory sections
  164  * instead of going through read/write
  165  */
  166 /* ARGSUSED */
  167 int
  168 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
  169     int prot __unused, vm_memattr_t *memattr __unused)
  170 {
  171         if (dev2unit(dev) == CDEV_MINOR_MEM) {
  172                 if (offset > cpu_getmaxphyaddr())
  173                         return (-1);
  174                 *paddr = offset;
  175                 return (0);
  176         }
  177         return (-1);
  178 }
  179 
  180 /*
  181  * Operations for changing memory attributes.
  182  *
  183  * This is basically just an ioctl shim for mem_range_attr_get
  184  * and mem_range_attr_set.
  185  */
  186 /* ARGSUSED */
  187 int 
  188 memioctl(struct cdev *dev __unused, u_long cmd, caddr_t data, int flags,
  189     struct thread *td)
  190 {
  191         int nd, error = 0;
  192         struct mem_range_op *mo = (struct mem_range_op *)data;
  193         struct mem_range_desc *md;
  194         
  195         /* is this for us? */
  196         if ((cmd != MEMRANGE_GET) &&
  197             (cmd != MEMRANGE_SET))
  198                 return (ENOTTY);
  199 
  200         /* any chance we can handle this? */
  201         if (mem_range_softc.mr_op == NULL)
  202                 return (EOPNOTSUPP);
  203 
  204         /* do we have any descriptors? */
  205         if (mem_range_softc.mr_ndesc == 0)
  206                 return (ENXIO);
  207 
  208         switch (cmd) {
  209         case MEMRANGE_GET:
  210                 nd = imin(mo->mo_arg[0], mem_range_softc.mr_ndesc);
  211                 if (nd > 0) {
  212                         md = (struct mem_range_desc *)
  213                                 malloc(nd * sizeof(struct mem_range_desc),
  214                                        M_MEMDESC, M_WAITOK);
  215                         error = mem_range_attr_get(md, &nd);
  216                         if (!error)
  217                                 error = copyout(md, mo->mo_desc, 
  218                                         nd * sizeof(struct mem_range_desc));
  219                         free(md, M_MEMDESC);
  220                 }
  221                 else
  222                         nd = mem_range_softc.mr_ndesc;
  223                 mo->mo_arg[0] = nd;
  224                 break;
  225                 
  226         case MEMRANGE_SET:
  227                 md = (struct mem_range_desc *)malloc(sizeof(struct mem_range_desc),
  228                                                     M_MEMDESC, M_WAITOK);
  229                 error = copyin(mo->mo_desc, md, sizeof(struct mem_range_desc));
  230                 /* clamp description string */
  231                 md->mr_owner[sizeof(md->mr_owner) - 1] = 0;
  232                 if (error == 0)
  233                         error = mem_range_attr_set(md, &mo->mo_arg[0]);
  234                 free(md, M_MEMDESC);
  235                 break;
  236         }
  237         return (error);
  238 }

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