1 /* 2 * Copyright (c) 2003,2004,2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by David Xu <davidxu@t2t2.com> and Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 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 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/sysproto.h> 38 #include <sys/kernel.h> 39 #include <sys/proc.h> 40 #include <sys/sysent.h> 41 #include <sys/sysctl.h> 42 #include <sys/tls.h> 43 #include <sys/reg.h> 44 #include <sys/globaldata.h> 45 46 #include <sys/thread2.h> 47 48 #include <machine/cpu.h> 49 #include <machine/clock.h> 50 #include <machine/specialreg.h> 51 #include <machine/segments.h> 52 #include <machine/md_var.h> 53 #include <machine/pcb_ext.h> /* pcb.h included via sys/user.h */ 54 #include <machine/globaldata.h> /* CPU_prvspace */ 55 #include <machine/smp.h> 56 #include <machine/pcb.h> 57 58 /* 59 * set a TLS descriptor. For x86_64 descriptor 0 identifies %fs and 60 * descriptor 1 identifies %gs, and 0 is returned in sysmsg_result. 61 * 62 * Returns the value userland needs to load into %gs representing the 63 * TLS descriptor or -1 on error. 64 * 65 * (int which, struct tls_info *info, size_t infosize) 66 * 67 * MPSAFE 68 */ 69 int 70 sys_set_tls_area(struct set_tls_area_args *uap) 71 { 72 struct tls_info info; 73 int error; 74 int i; 75 76 /* 77 * Sanity checks 78 * 79 * which 0 == %fs, which 1 == %gs 80 */ 81 i = uap->which; 82 if (i < 0 || i > 1) 83 return (ERANGE); 84 if (uap->infosize < 0) 85 return (EINVAL); 86 87 /* 88 * Maintain forwards compatibility with future extensions. 89 */ 90 if (uap->infosize != sizeof(info)) { 91 bzero(&info, sizeof(info)); 92 error = copyin(uap->info, &info, 93 min(sizeof(info), uap->infosize)); 94 } else { 95 error = copyin(uap->info, &info, sizeof(info)); 96 } 97 if (error) 98 return (error); 99 if (info.size < -1) 100 return (EINVAL); 101 102 /* 103 * For x86_64 we can only adjust FSBASE and GSBASE 104 */ 105 curthread->td_tls.info[i] = info; 106 set_user_TLS(); 107 uap->sysmsg_result = 0; /* segment descriptor $0 */ 108 return(0); 109 } 110 111 /* 112 * Return the specified TLS descriptor to userland. 113 * 114 * Returns the value userland needs to load into %gs representing the 115 * TLS descriptor or -1 on error. 116 * 117 * (int which, struct tls_info *info, size_t infosize) 118 * 119 * MPSAFE 120 */ 121 int 122 sys_get_tls_area(struct get_tls_area_args *uap) 123 { 124 struct tls_info info; 125 int error; 126 int i; 127 128 /* 129 * Sanity checks 130 */ 131 i = uap->which; 132 if (i < 0 || i > 1) 133 return (ERANGE); 134 if (uap->infosize < 0) 135 return (EINVAL); 136 137 info = curthread->td_tls.info[i]; 138 139 error = copyout(&info, uap->info, min(sizeof(info), uap->infosize)); 140 return(error); 141 } 142 143 /* 144 * Install the TLS. 145 * 146 * It shouldn't be possible for a preemptive thread switch to do anything 147 * more than set gd_user_fs and wrmsr for us. Even though there is a window 148 * where gd_user_fs/gd_user_gs do not match the MSRs no preemptive thread 149 * switch should ever switch to any heavy weight thread other than our own. 150 * 151 * Still, use a critical section to be safe. 152 * 153 * MPSAFE 154 */ 155 void 156 set_user_TLS(void) 157 { 158 struct mdglobaldata *gd = mdcpu; 159 thread_t td = gd->mi.gd_curthread; 160 161 crit_enter_quick(td); 162 td->td_pcb->pcb_fsbase = (register_t)td->td_tls.info[0].base; 163 td->td_pcb->pcb_gsbase = (register_t)td->td_tls.info[1].base; 164 if (gd->gd_user_fs != td->td_pcb->pcb_fsbase) { 165 gd->gd_user_fs = td->td_pcb->pcb_fsbase; 166 wrmsr(MSR_FSBASE, gd->gd_user_fs); 167 } 168 if (gd->gd_user_gs != td->td_pcb->pcb_gsbase) { 169 gd->gd_user_gs = td->td_pcb->pcb_gsbase; 170 wrmsr(MSR_KGSBASE, gd->gd_user_gs); 171 } 172 clear_quickret(); 173 crit_exit_quick(td); 174 } 175 176