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 #include <machine/thread.h> 58 #include <machine/vmm.h> 59 60 /* 61 * set a TLS descriptor. For x86_64 descriptor 0 identifies %fs and 62 * descriptor 1 identifies %gs, and 0 is returned in sysmsg_result. 63 * 64 * Returns the value userland needs to load into %gs representing the 65 * TLS descriptor or -1 on error. 66 * 67 * (int which, struct tls_info *info, size_t infosize) 68 * 69 * MPSAFE 70 */ 71 int 72 sys_set_tls_area(struct set_tls_area_args *uap) 73 { 74 struct tls_info info; 75 int error; 76 int i; 77 78 /* 79 * Sanity checks 80 * 81 * which 0 == %fs, which 1 == %gs 82 */ 83 i = uap->which; 84 if (i < 0 || i > 1) 85 return (ERANGE); 86 if (uap->infosize < 0) 87 return (EINVAL); 88 89 /* 90 * Maintain forwards compatibility with future extensions. 91 */ 92 if (uap->infosize != sizeof(info)) { 93 bzero(&info, sizeof(info)); 94 error = copyin(uap->info, &info, 95 min(sizeof(info), uap->infosize)); 96 } else { 97 error = copyin(uap->info, &info, sizeof(info)); 98 } 99 if (error) 100 return (error); 101 if (info.size < -1) 102 return (EINVAL); 103 104 /* 105 * For x86_64 we can only adjust FSBASE and GSBASE 106 */ 107 curthread->td_tls.info[i] = info; 108 set_user_TLS(); 109 uap->sysmsg_result = 0; /* segment descriptor $0 */ 110 return(0); 111 } 112 113 /* 114 * Return the specified TLS descriptor to userland. 115 * 116 * Returns the value userland needs to load into %gs representing the 117 * TLS descriptor or -1 on error. 118 * 119 * (int which, struct tls_info *info, size_t infosize) 120 * 121 * MPSAFE 122 */ 123 int 124 sys_get_tls_area(struct get_tls_area_args *uap) 125 { 126 struct tls_info info; 127 int error; 128 int i; 129 130 /* 131 * Sanity checks 132 */ 133 i = uap->which; 134 if (i < 0 || i > 1) 135 return (ERANGE); 136 if (uap->infosize < 0) 137 return (EINVAL); 138 139 info = curthread->td_tls.info[i]; 140 141 error = copyout(&info, uap->info, min(sizeof(info), uap->infosize)); 142 return(error); 143 } 144 145 /* 146 * Install the TLS. 147 * 148 * It shouldn't be possible for a preemptive thread switch to do anything 149 * more than set gd_user_fs and wrmsr for us. Even though there is a window 150 * where gd_user_fs/gd_user_gs do not match the MSRs no preemptive thread 151 * switch should ever switch to any heavy weight thread other than our own. 152 * 153 * Still, use a critical section to be safe. 154 * 155 * MPSAFE 156 */ 157 void 158 set_user_TLS(void) 159 { 160 struct mdglobaldata *gd = mdcpu; 161 thread_t td = gd->mi.gd_curthread; 162 163 crit_enter_quick(td); 164 td->td_pcb->pcb_fsbase = (register_t)td->td_tls.info[0].base; 165 td->td_pcb->pcb_gsbase = (register_t)td->td_tls.info[1].base; 166 if (gd->gd_user_fs != td->td_pcb->pcb_fsbase) { 167 gd->gd_user_fs = td->td_pcb->pcb_fsbase; 168 wrmsr(MSR_FSBASE, gd->gd_user_fs); 169 } 170 if (gd->gd_user_gs != td->td_pcb->pcb_gsbase) { 171 gd->gd_user_gs = td->td_pcb->pcb_gsbase; 172 wrmsr(MSR_KGSBASE, gd->gd_user_gs); 173 } 174 175 if (td->td_vmm) { 176 vmm_vm_set_tls_area(); 177 } 178 179 clear_quickret(); 180 crit_exit_quick(td); 181 } 182 183