1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 Peter Wemm
5 * Copyright (c) 2017, 2018 The FreeBSD Foundation
6 * All rights reserved.
7 *
8 * Portions of this software were developed by Konstantin Belousov
9 * under sponsorship from the FreeBSD Foundation.
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 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD: stable/12/lib/libc/amd64/sys/amd64_get_gsbase.c 340608 2018-11-19 05:56:46Z kib $");
35
36 #define IN_RTLD 1
37 #include <sys/param.h>
38 #undef IN_RTLD
39 #include <machine/cpufunc.h>
40 #include <machine/specialreg.h>
41 #include <machine/sysarch.h>
42 #include <x86/ifunc.h>
43 #include "libc_private.h"
44
45 static int
amd64_get_gsbase_cpu(void ** addr)46 amd64_get_gsbase_cpu(void **addr)
47 {
48
49 *addr = (void *)rdgsbase();
50 return (0);
51 }
52
53 static int
amd64_get_gsbase_syscall(void ** addr)54 amd64_get_gsbase_syscall(void **addr)
55 {
56
57 return (sysarch(AMD64_GET_GSBASE, addr));
58 }
59
60 DEFINE_UIFUNC(, int, amd64_get_gsbase, (void **), static)
61 {
62
63 if (__getosreldate() >= P_OSREL_WRFSBASE &&
64 (cpu_stdext_feature & CPUID_STDEXT_FSGSBASE) != 0)
65 return (amd64_get_gsbase_cpu);
66 return (amd64_get_gsbase_syscall);
67 }
68