sys/platform/pc32/i386/tls.c

   1 /*
   2  * Copyright (c) 2003,2004 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  * $DragonFly: src/sys/platform/pc32/i386/tls.c,v 1.9 2008/06/29 19:04:01 dillon Exp $
  35  */
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/sysproto.h>
  40 #include <sys/kernel.h>
  41 #include <sys/proc.h>
  42 #include <sys/sysent.h>
  43 #include <sys/sysctl.h>
  44 #include <sys/tls.h>
  45 #include <sys/reg.h>
  46 #include <sys/thread2.h>
  47
  48 #include <machine/cpu.h>
  49 #include <machine/clock.h>
  50 #include <machine/specialreg.h>
  51 #include <machine/bootinfo.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
  57 /*
  58  * set a TLS descriptor and resync the GDT.  A descriptor may be cleared
  59  * by passing info=NULL and infosize=0.  Note that hardware limitations may
  60  * cause the size passed in tls_info to be approximated.
  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         struct segment_descriptor *desc;
  74         int error;
  75         int i;
  76
  77         /*
  78          * Sanity checks
  79          */
  80         i = uap->which;
  81         if (i < 0 || i >= NGTLS)
  82                 return (ERANGE);
  83         if (uap->infosize < 0)
  84                 return (EINVAL);
  85
  86         /*
  87          * Maintain forwards compatibility with future extensions.
  88          */
  89         if (uap->infosize != sizeof(info)) {
  90                 bzero(&info, sizeof(info));
  91                 error = copyin(uap->info, &info,
  92                                 min(sizeof(info), uap->infosize));
  93         } else {
  94                 error = copyin(uap->info, &info, sizeof(info));
  95         }
  96         if (error)
  97                 return (error);
  98         if (info.size < -1)
  99                 return (EINVAL);
 100         if (info.size > (1 << 20))
 101                 info.size = (info.size + PAGE_MASK) & ~PAGE_MASK;
 102
 103         /*
 104          * Load the descriptor.  A critical section is required in case
 105          * an interrupt thread comes along and switches us out and then back
 106          * in.
 107          */
 108         desc = &curthread->td_tls.tls[i];
 109         crit_enter();
 110         if (info.size == 0) {
 111                 bzero(desc, sizeof(*desc));
 112         } else {
 113                 desc->sd_lobase = (intptr_t)info.base;
 114                 desc->sd_hibase = (intptr_t)info.base >> 24;
 115                 desc->sd_def32 = 1;
 116                 desc->sd_type = SDT_MEMRWA;
 117                 desc->sd_dpl = SEL_UPL;
 118                 desc->sd_xx = 0;
 119                 desc->sd_p = 1;
 120                 if (info.size == -1) {
 121                         /*
 122                          * A descriptor size of -1 is a hack to map the
 123                          * whole address space.  This type of mapping is
 124                          * required for direct-tls accesses of variable
 125                          * data, e.g. %gs:OFFSET where OFFSET is negative.
 126                          */
 127                         desc->sd_lolimit = -1;
 128                         desc->sd_hilimit = -1;
 129                         desc->sd_gran = 1;
 130                 } else if (info.size >= (1 << 20)) {
 131                         /*
 132                          * A descriptor size greater then 1MB requires page
 133                          * granularity (the lo+hilimit field is only 20 bits)
 134                          */
 135                         desc->sd_lolimit = info.size >> PAGE_SHIFT;
 136                         desc->sd_hilimit = info.size >> (PAGE_SHIFT + 16);
 137                         desc->sd_gran = 1;
 138                 } else {
 139                         /*
 140                          * Otherwise a byte-granular size is supported.
 141                          */
 142                         desc->sd_lolimit = info.size;
 143                         desc->sd_hilimit = info.size >> 16;
 144                         desc->sd_gran = 0;
 145                 }
 146         }
 147         crit_exit();
 148         uap->sysmsg_result = GSEL(GTLS_START + i, SEL_UPL);
 149         set_user_TLS();
 150         return(0);
 151 }
 152
 153 /*
 154  * Return the specified TLS descriptor to userland.
 155  *
 156  * Returns the value userland needs to load into %gs representing the
 157  * TLS descriptor or -1 on error.
 158  *
 159  * (int which, struct tls_info *info, size_t infosize)
 160  *
 161  * MPSAFE
 162  */
 163 int
 164 sys_get_tls_area(struct get_tls_area_args *uap)
 165 {
 166         struct tls_info info;
 167         struct segment_descriptor *desc;
 168         int error;
 169         int i;
 170
 171         /*
 172          * Sanity checks
 173          */
 174         i = uap->which;
 175         if (i < 0 || i >= NGTLS)
 176                 return (ERANGE);
 177         if (uap->infosize < 0)
 178                 return (EINVAL);
 179
 180         /*
 181          * unpack the descriptor, ENOENT is returned for any descriptor
 182          * which has not been loaded.  uap->info may be NULL.
 183          */
 184         desc = &curthread->td_tls.tls[i];
 185         if (desc->sd_p) {
 186                 if (uap->info && uap->infosize > 0) {
 187                         bzero(&info, sizeof(info));
 188                         info.base = (void *)(intptr_t)
 189                                 ((desc->sd_hibase << 24) | desc->sd_lobase);
 190                         info.size = (desc->sd_hilimit << 16) | desc->sd_lolimit;
 191                         if (desc->sd_gran)
 192                                 info.size <<= PAGE_SHIFT;
 193                         error = copyout(&info, uap->info,
 194                                         min(sizeof(info), uap->infosize));
 195                 } else {
 196                         error = 0;
 197                 }
 198                 uap->sysmsg_result = GSEL(GTLS_START + i, SEL_UPL);
 199         } else {
 200                 error = ENOENT;
 201         }
 202         return(error);
 203 }
 204