sys/platform/vkernel/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/vkernel/i386/tls.c,v 1.3 2007/01/08 03:33:43 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/md_var.h>
  52 #include <machine/pcb_ext.h>            /* pcb.h included via sys/user.h */
  53 #include <machine/globaldata.h>         /* CPU_prvspace */
  54 #include <machine/smp.h>
  55
  56 /*
  57  * set a TLS descriptor and resync the GDT.  A descriptor may be cleared
  58  * by passing info=NULL and infosize=0.  Note that hardware limitations may
  59  * cause the size passed in tls_info to be approximated.
  60  *
  61  * Returns the value userland needs to load into %gs representing the
  62  * TLS descriptor or -1 on error.
  63  *
  64  * (struct tls_info *info, int infosize, int which)
  65  */
  66 int
  67 sys_set_tls_area(struct set_tls_area_args *uap)
  68 {
  69         struct tls_info info;
  70         struct segment_descriptor *desc;
  71         int error;
  72         int i;
  73
  74         /*
  75          * Sanity checks
  76          */
  77         i = uap->which;
  78         if (i < 0 || i >= NGTLS)
  79                 return (ERANGE);
  80         if (uap->infosize < 0)
  81                 return (EINVAL);
  82
  83         /*
  84          * Maintain forwards compatibility with future extensions.
  85          */
  86         if (uap->infosize != sizeof(info)) {
  87                 bzero(&info, sizeof(info));
  88                 error = copyin(uap->info, &info,
  89                                 min(sizeof(info), uap->infosize));
  90         } else {
  91                 error = copyin(uap->info, &info, sizeof(info));
  92         }
  93         if (error)
  94                 return (error);
  95         if (info.size < -1)
  96                 return (EINVAL);
  97         if (info.size > (1 << 20))
  98                 info.size = (info.size + PAGE_MASK) & ~PAGE_MASK;
  99
 100         /*
 101          * Load the descriptor.  A critical section is required in case
 102          * an interrupt thread comes along and switches us out and then back
 103          * in.
 104          */
 105         desc = &curthread->td_tls.tls[i];
 106         crit_enter();
 107         if (info.size == 0) {
 108                 bzero(desc, sizeof(*desc));
 109         } else {
 110                 desc->sd_lobase = (intptr_t)info.base;
 111                 desc->sd_hibase = (intptr_t)info.base >> 24;
 112                 desc->sd_def32 = 1;
 113                 desc->sd_type = SDT_MEMRWA;
 114                 desc->sd_dpl = SEL_UPL;
 115                 desc->sd_xx = 0;
 116                 desc->sd_p = 1;
 117                 if (info.size == -1) {
 118                         /*
 119                          * A descriptor size of -1 is a hack to map the
 120                          * whole address space.  This type of mapping is
 121                          * required for direct-tls accesses of variable
 122                          * data, e.g. %gs:OFFSET where OFFSET is negative.
 123                          */
 124                         desc->sd_lolimit = -1;
 125                         desc->sd_hilimit = -1;
 126                         desc->sd_gran = 1;
 127                 } else if (info.size >= (1 << 20)) {
 128                         /*
 129                          * A descriptor size greater then 1MB requires page
 130                          * granularity (the lo+hilimit field is only 20 bits)
 131                          */
 132                         desc->sd_lolimit = info.size >> PAGE_SHIFT;
 133                         desc->sd_hilimit = info.size >> (PAGE_SHIFT + 16);
 134                         desc->sd_gran = 1;
 135                 } else {
 136                         /*
 137                          * Otherwise a byte-granular size is supported.
 138                          */
 139                         desc->sd_lolimit = info.size;
 140                         desc->sd_hilimit = info.size >> 16;
 141                         desc->sd_gran = 0;
 142                 }
 143         }
 144         crit_exit();
 145         uap->sysmsg_result = GSEL(GTLS_START + i, SEL_UPL);
 146         set_user_TLS();
 147         return(0);
 148 }
 149
 150 /*
 151  * Return the specified TLS descriptor to userland.
 152  *
 153  * Returns the value userland needs to load into %gs representing the
 154  * TLS descriptor or -1 on error.
 155  *
 156  * (struct tls_info *info, int infosize, int which)
 157  */
 158 int
 159 sys_get_tls_area(struct get_tls_area_args *uap)
 160 {
 161         struct tls_info info;
 162         struct segment_descriptor *desc;
 163         int error;
 164         int i;
 165
 166         /*
 167          * Sanity checks
 168          */
 169         i = uap->which;
 170         if (i < 0 || i >= NGTLS)
 171                 return (ERANGE);
 172         if (uap->infosize < 0)
 173                 return (EINVAL);
 174
 175         /*
 176          * unpack the descriptor, ENOENT is returned for any descriptor
 177          * which has not been loaded.  uap->info may be NULL.
 178          */
 179         desc = &curthread->td_tls.tls[i];
 180         if (desc->sd_p) {
 181                 if (uap->info && uap->infosize > 0) {
 182                         bzero(&info, sizeof(info));
 183                         info.base = (void *)(intptr_t)
 184                                 ((desc->sd_hibase << 24) | desc->sd_lobase);
 185                         info.size = (desc->sd_hilimit << 16) | desc->sd_lolimit;
 186                         if (desc->sd_gran)
 187                                 info.size <<= PAGE_SHIFT;
 188                         error = copyout(&info, uap->info,
 189                                         min(sizeof(info), uap->infosize));
 190                 } else {
 191                         error = 0;
 192                 }
 193                 uap->sysmsg_result = GSEL(GTLS_START + i, SEL_UPL);
 194         } else {
 195                 error = ENOENT;
 196         }
 197         return(error);
 198 }
 199
 200 /*
 201  * This function is a NOP because the TLS segments are proactively copied
 202  * by vmspace_ctl() when we switch to the (emulated) user process.
 203  */
 204 void
 205 set_user_TLS(void)
 206 {
 207 }