xref: /illumos-gate/usr/src/uts/intel/os/comm_page_util.c (revision 9b9d39d2a32ff806d2431dbcc50968ef1e6d46b2)
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 #if !defined(__xpv)
26 #include <sys/comm_page.h>
27 #endif /* !defined(__xpv) */
28 
29 /*
30  * Map in the comm page.
31  *
32  * The contents of the comm page are only defined on non-xpv x86 at this time.
33  * Furthermore, the data is only valid in userspace (32-bit or 64-bit) when
34  * mapped from a 64-bit kernel.
35  * See: "uts/i86pc/sys/comm_page.h"
36  */
37 caddr_t
38 comm_page_mapin()
39 {
40 #if !defined(__xpv)
41 	proc_t *p = curproc;
42 	caddr_t addr = NULL;
43 	size_t len = COMM_PAGE_SIZE;
44 	uint_t prot = PROT_USER | PROT_READ;
45 	segumap_crargs_t suarg;
46 
47 	map_addr(&addr, len, (offset_t)0, 1, 0);
48 	if (addr == NULL || valid_usr_range(addr, len, prot, p->p_as,
49 	    p->p_as->a_userlimit) != RANGE_OKAY) {
50 		return (NULL);
51 	}
52 
53 	suarg.kaddr = (caddr_t)&comm_page;
54 	suarg.prot = suarg.maxprot = prot;
55 	if (as_map(p->p_as, addr, len, segumap_create, &suarg) != 0) {
56 		return (NULL);
57 	}
58 	return (addr);
59 #else /* !defined(__xpv) */
60 	return (NULL);
61 #endif /* !defined(__xpv) */
62 }
63