1/*- 2 * Copyright (c) 2017 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Konstantin Belousov <kib@FreeBSD.org> 6 * under sponsorship from the FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#include <sys/cdefs.h> 31__FBSDID("$FreeBSD: stable/11/lib/libc/amd64/sys/amd64_detect_rdfsgsbase.c 323538 2017-09-13 11:29:48Z kib $"); 32 33#define IN_RTLD 1 34#include <sys/param.h> 35#undef IN_RTLD 36#include <machine/cpufunc.h> 37#include <machine/specialreg.h> 38#include "amd64_detect_rdfsgsbase.h" 39#include "libc_private.h" 40 41static int state = RDFSGS_UNKNOWN; 42 43int 44amd64_detect_rdfsgsbase(void) 45{ 46 u_int p[4]; 47 48 if (__predict_true(state != RDFSGS_UNKNOWN)) 49 return (state); 50 51 if (__getosreldate() >= P_OSREL_WRFSBASE || 52 (P_OSREL_MAJOR(__getosreldate()) == 11 && __getosreldate() >= 53 P_OSREL_WRFSBASE_11)) { 54 do_cpuid(0x0, p); 55 if (p[0] >= 0x7) { 56 cpuid_count(0x7, 0x0, p); 57 if ((p[1] & CPUID_STDEXT_FSGSBASE) != 0) { 58 state = RDFSGS_SUPPORTED; 59 return (state); 60 } 61 } 62 } 63 state = RDFSGS_UNSUPPORTED; 64 return (state); 65} 66