usr/src/uts/intel/ia32/os/comm_page_util.c

   1 /*
   2  * This file and its contents are supplied under the terms of the
   3  * Common Development and Distribution License ("CDDL"), version 1.0.
   4  * You may only use this file in accordance with the terms of version
   5  * 1.0 of the CDDL.
   6  *
   7  * A full copy of the text of the CDDL should have accompanied this
   8  * source.  A copy of the CDDL is also available via the Internet at
   9  * http://www.illumos.org/license/CDDL.
  10  */
  11
  12 /*
  13  * Copyright 2016 Joyent, Inc.
  14  */
  15
  16
  17 #include <sys/types.h>
  18 #include <sys/thread.h>
  19 #include <sys/proc.h>
  20 #include <sys/mman.h>
  21 #include <sys/vmsystm.h>
  22 #include <vm/as.h>
  23 #include <vm/seg_umap.h>
  24
  25 #include <sys/comm_page.h>
  26
  27 /*
  28  * Map in the comm page.
  29  *
  30  * The contents of the comm page are only defined on non-xpv x86 at this time.
  31  * Furthermore, the data is only valid in userspace (32-bit or 64-bit) when
  32  * mapped from a 64-bit kernel.
  33  * See: "uts/i86pc/sys/comm_page.h"
  34  */
  35 caddr_t
  36 comm_page_mapin()
  37 {
  38 #if defined(__amd64) && !defined(__xpv)
  39         proc_t *p = curproc;
  40         caddr_t addr = NULL;
  41         size_t len = COMM_PAGE_SIZE;
  42         uint_t prot = PROT_USER | PROT_READ;
  43         segumap_crargs_t suarg;
  44
  45         map_addr(&addr, len, (offset_t)0, 1, 0);
  46         if (addr == NULL || valid_usr_range(addr, len, prot, p->p_as,
  47             p->p_as->a_userlimit) != RANGE_OKAY) {
  48                 return (NULL);
  49         }
  50
  51         suarg.kaddr = (caddr_t)&comm_page;
  52         suarg.prot = suarg.maxprot = prot;
  53         if (as_map(p->p_as, addr, len, segumap_create, &suarg) != 0) {
  54                 return (NULL);
  55         }
  56         return (addr);
  57 #else /* defined(__amd64) && !defined(__xpv) */
  58         return (NULL);
  59 #endif /* defined(__amd64) && !defined(__xpv) */
  60 }