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/i386/i386/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: stable/10/sys/i386/i386/mem.c 309426 2016-12-02 19:02:12Z 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/sx.h>
   57 #include <sys/proc.h>
   58 #include <sys/signalvar.h>
   59 #include <sys/systm.h>
   60 #include <sys/uio.h>
   61 
   62 #include <machine/specialreg.h>
   63 
   64 #include <vm/vm.h>
   65 #include <vm/pmap.h>
   66 #include <vm/vm_extern.h>
   67 
   68 #include <machine/memdev.h>
   69 
   70 /*
   71  * Used in /dev/mem drivers and elsewhere
   72  */
   73 MALLOC_DEFINE(M_MEMDESC, "memdesc", "memory range descriptors");
   74 
   75 static struct sx memsxlock;
   76 SX_SYSINIT(memsxlockinit, &memsxlock, "/dev/mem lock");
   77 
   78 /* ARGSUSED */
   79 int
   80 memrw(struct cdev *dev, struct uio *uio, int flags)
   81 {
   82         int o;
   83         u_int c = 0;
   84         vm_paddr_t pa;
   85         struct iovec *iov;
   86         int error = 0;
   87         vm_offset_t addr;
   88 
   89         if (dev2unit(dev) != CDEV_MINOR_MEM && dev2unit(dev) != CDEV_MINOR_KMEM)
   90                 return EIO;
   91 
   92         if (dev2unit(dev) == CDEV_MINOR_KMEM && uio->uio_resid > 0) {
   93                 if (uio->uio_offset < (vm_offset_t)VADDR(PTDPTDI, 0))
   94                                 return (EFAULT);
   95 
   96                 if (!kernacc((caddr_t)(int)uio->uio_offset, uio->uio_resid,
   97                     uio->uio_rw == UIO_READ ?  VM_PROT_READ : VM_PROT_WRITE))
   98                         return (EFAULT);
   99         }
  100 
  101         while (uio->uio_resid > 0 && error == 0) {
  102                 iov = uio->uio_iov;
  103                 if (iov->iov_len == 0) {
  104                         uio->uio_iov++;
  105                         uio->uio_iovcnt--;
  106                         if (uio->uio_iovcnt < 0)
  107                                 panic("memrw");
  108                         continue;
  109                 }
  110                 if (dev2unit(dev) == CDEV_MINOR_MEM) {
  111                         if (uio->uio_offset > cpu_getmaxphyaddr()) {
  112                                 error = EFAULT;
  113                                 break;
  114                         }
  115                         pa = trunc_page(uio->uio_offset);
  116                 } else {
  117                         /*
  118                          * Extract the physical page since the mapping may
  119                          * change at any time. This avoids panics on page 
  120                          * fault in this case but will cause reading/writing
  121                          * to the wrong page.
  122                          * Hopefully an application will notice the wrong
  123                          * data on read access and refrain from writing.
  124                          * This should be replaced by a special uiomove
  125                          * type function that just returns an error if there
  126                          * is a page fault on a kernel page. 
  127                          */
  128                         addr = trunc_page(uio->uio_offset);
  129                         pa = pmap_extract(kernel_pmap, addr);
  130                         if (pa == 0) 
  131                                 return EFAULT;
  132 
  133                 }
  134                 
  135                 /* 
  136                  * XXX UPS This should just use sf_buf_alloc.
  137                  * Unfortunately sf_buf_alloc needs a vm_page
  138                  * and we may want to look at memory not covered
  139                  * by the page array.
  140                  */
  141 
  142                 sx_xlock(&memsxlock);
  143                 pmap_kenter((vm_offset_t)ptvmmap, pa);
  144                 pmap_invalidate_page(kernel_pmap,(vm_offset_t)ptvmmap);
  145 
  146                 o = (int)uio->uio_offset & PAGE_MASK;
  147                 c = PAGE_SIZE - o;
  148                 c = min(c, (u_int)iov->iov_len);
  149                 error = uiomove((caddr_t)&ptvmmap[o], (int)c, uio);
  150                 pmap_qremove((vm_offset_t)ptvmmap, 1);
  151                 sx_xunlock(&memsxlock);
  152                 
  153         }
  154 
  155         return (error);
  156 }
  157 
  158 /*
  159  * allow user processes to MMAP some memory sections
  160  * instead of going through read/write
  161  */
  162 /* ARGSUSED */
  163 int
  164 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
  165     int prot __unused, vm_memattr_t *memattr __unused)
  166 {
  167         if (dev2unit(dev) == CDEV_MINOR_MEM) {
  168                 if (offset > cpu_getmaxphyaddr())
  169                         return (-1);
  170                 *paddr = offset;
  171         } else if (dev2unit(dev) == CDEV_MINOR_KMEM)
  172                 *paddr = vtophys(offset);
  173         /* else panic! */
  174         return (0);
  175 }
  176 
  177 /*
  178  * Operations for changing memory attributes.
  179  *
  180  * This is basically just an ioctl shim for mem_range_attr_get
  181  * and mem_range_attr_set.
  182  */
  183 /* ARGSUSED */
  184 int 
  185 memioctl(struct cdev *dev __unused, u_long cmd, caddr_t data, int flags,
  186     struct thread *td)
  187 {
  188         int nd, error = 0;
  189         struct mem_range_op *mo = (struct mem_range_op *)data;
  190         struct mem_range_desc *md;
  191         
  192         /* is this for us? */
  193         if ((cmd != MEMRANGE_GET) &&
  194             (cmd != MEMRANGE_SET))
  195                 return (ENOTTY);
  196 
  197         /* any chance we can handle this? */
  198         if (mem_range_softc.mr_op == NULL)
  199                 return (EOPNOTSUPP);
  200 
  201         /* do we have any descriptors? */
  202         if (mem_range_softc.mr_ndesc == 0)
  203                 return (ENXIO);
  204 
  205         switch (cmd) {
  206         case MEMRANGE_GET:
  207                 nd = imin(mo->mo_arg[0], mem_range_softc.mr_ndesc);
  208                 if (nd > 0) {
  209                         md = (struct mem_range_desc *)
  210                                 malloc(nd * sizeof(struct mem_range_desc),
  211                                        M_MEMDESC, M_WAITOK);
  212                         error = mem_range_attr_get(md, &nd);
  213                         if (!error)
  214                                 error = copyout(md, mo->mo_desc, 
  215                                         nd * sizeof(struct mem_range_desc));
  216                         free(md, M_MEMDESC);
  217                 }
  218                 else
  219                         nd = mem_range_softc.mr_ndesc;
  220                 mo->mo_arg[0] = nd;
  221                 break;
  222                 
  223         case MEMRANGE_SET:
  224                 md = (struct mem_range_desc *)malloc(sizeof(struct mem_range_desc),
  225                                                     M_MEMDESC, M_WAITOK);
  226                 error = copyin(mo->mo_desc, md, sizeof(struct mem_range_desc));
  227                 /* clamp description string */
  228                 md->mr_owner[sizeof(md->mr_owner) - 1] = 0;
  229                 if (error == 0)
  230                         error = mem_range_attr_set(md, &mo->mo_arg[0]);
  231                 free(md, M_MEMDESC);
  232                 break;
  233         }
  234         return (error);
  235 }

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