The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/sys_machdep.c

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    1 /*-
    2  * Copyright (c) 1990 The Regents of the University of California.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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  *      from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/9.1/sys/i386/i386/sys_machdep.c 231150 2012-02-07 19:23:08Z jhb $");
   34 
   35 #include "opt_capsicum.h"
   36 #include "opt_kstack_pages.h"
   37 
   38 #include <sys/param.h>
   39 #include <sys/capability.h>
   40 #include <sys/systm.h>
   41 #include <sys/lock.h>
   42 #include <sys/malloc.h>
   43 #include <sys/mutex.h>
   44 #include <sys/priv.h>
   45 #include <sys/proc.h>
   46 #include <sys/smp.h>
   47 #include <sys/sysproto.h>
   48 
   49 #include <vm/vm.h>
   50 #include <vm/pmap.h>
   51 #include <vm/vm_map.h>
   52 #include <vm/vm_extern.h>
   53 
   54 #include <machine/cpu.h>
   55 #include <machine/pcb.h>
   56 #include <machine/pcb_ext.h>
   57 #include <machine/proc.h>
   58 #include <machine/sysarch.h>
   59 
   60 #include <security/audit/audit.h>
   61 
   62 #ifdef XEN 
   63 #include <machine/xen/xenfunc.h>
   64 
   65 void i386_reset_ldt(struct proc_ldt *pldt); 
   66 
   67 void 
   68 i386_reset_ldt(struct proc_ldt *pldt) 
   69 { 
   70         xen_set_ldt((vm_offset_t)pldt->ldt_base, pldt->ldt_len); 
   71 } 
   72 #else  
   73 #define i386_reset_ldt(x) 
   74 #endif 
   75 
   76 #include <vm/vm_kern.h>         /* for kernel_map */
   77 
   78 #define MAX_LD 8192
   79 #define LD_PER_PAGE 512
   80 #define NEW_MAX_LD(num)  ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1))
   81 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)
   82 #define NULL_LDT_BASE   ((caddr_t)NULL)
   83 
   84 #ifdef SMP
   85 static void set_user_ldt_rv(struct vmspace *vmsp);
   86 #endif
   87 static int i386_set_ldt_data(struct thread *, int start, int num,
   88         union descriptor *descs);
   89 static int i386_ldt_grow(struct thread *td, int len);
   90 
   91 #ifndef _SYS_SYSPROTO_H_
   92 struct sysarch_args {
   93         int op;
   94         char *parms;
   95 };
   96 #endif
   97 
   98 int
   99 sysarch(td, uap)
  100         struct thread *td;
  101         register struct sysarch_args *uap;
  102 {
  103         int error;
  104         union descriptor *lp;
  105         union {
  106                 struct i386_ldt_args largs;
  107                 struct i386_ioperm_args iargs;
  108         } kargs;
  109         uint32_t base;
  110         struct segment_descriptor sd, *sdp;
  111 
  112         AUDIT_ARG_CMD(uap->op);
  113 
  114 #ifdef CAPABILITY_MODE
  115         /*
  116          * When adding new operations, add a new case statement here to
  117          * explicitly indicate whether or not the operation is safe to
  118          * perform in capability mode.
  119          */
  120         if (IN_CAPABILITY_MODE(td)) {
  121                 switch (uap->op) {
  122                 case I386_GET_LDT:
  123                 case I386_SET_LDT:
  124                 case I386_GET_IOPERM:
  125                 case I386_GET_FSBASE:
  126                 case I386_SET_FSBASE:
  127                 case I386_GET_GSBASE:
  128                 case I386_SET_GSBASE:
  129                         break;
  130 
  131                 case I386_SET_IOPERM:
  132                 default:
  133                         return (ECAPMODE);
  134                 }
  135         }
  136 #endif
  137 
  138         switch (uap->op) {
  139         case I386_GET_IOPERM:
  140         case I386_SET_IOPERM:
  141                 if ((error = copyin(uap->parms, &kargs.iargs,
  142                     sizeof(struct i386_ioperm_args))) != 0)
  143                         return (error);
  144                 break;
  145         case I386_GET_LDT:
  146         case I386_SET_LDT:
  147                 if ((error = copyin(uap->parms, &kargs.largs,
  148                     sizeof(struct i386_ldt_args))) != 0)
  149                         return (error);
  150                 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0)
  151                         return (EINVAL);
  152                 break;
  153         default:
  154                 break;
  155         }
  156 
  157         switch(uap->op) {
  158         case I386_GET_LDT:
  159                 error = i386_get_ldt(td, &kargs.largs);
  160                 break;
  161         case I386_SET_LDT:
  162                 if (kargs.largs.descs != NULL) {
  163                         lp = (union descriptor *)kmem_alloc(kernel_map,
  164                             kargs.largs.num * sizeof(union descriptor));
  165                         if (lp == NULL) {
  166                                 error = ENOMEM;
  167                                 break;
  168                         }
  169                         error = copyin(kargs.largs.descs, lp,
  170                             kargs.largs.num * sizeof(union descriptor));
  171                         if (error == 0)
  172                                 error = i386_set_ldt(td, &kargs.largs, lp);
  173                         kmem_free(kernel_map, (vm_offset_t)lp,
  174                             kargs.largs.num * sizeof(union descriptor));
  175                 } else {
  176                         error = i386_set_ldt(td, &kargs.largs, NULL);
  177                 }
  178                 break;
  179         case I386_GET_IOPERM:
  180                 error = i386_get_ioperm(td, &kargs.iargs);
  181                 if (error == 0)
  182                         error = copyout(&kargs.iargs, uap->parms,
  183                             sizeof(struct i386_ioperm_args));
  184                 break;
  185         case I386_SET_IOPERM:
  186                 error = i386_set_ioperm(td, &kargs.iargs);
  187                 break;
  188         case I386_VM86:
  189                 error = vm86_sysarch(td, uap->parms);
  190                 break;
  191         case I386_GET_FSBASE:
  192                 sdp = &td->td_pcb->pcb_fsd;
  193                 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
  194                 error = copyout(&base, uap->parms, sizeof(base));
  195                 break;
  196         case I386_SET_FSBASE:
  197                 error = copyin(uap->parms, &base, sizeof(base));
  198                 if (!error) {
  199                         /*
  200                          * Construct a descriptor and store it in the pcb for
  201                          * the next context switch.  Also store it in the gdt
  202                          * so that the load of tf_fs into %fs will activate it
  203                          * at return to userland.
  204                          */
  205                         sd.sd_lobase = base & 0xffffff;
  206                         sd.sd_hibase = (base >> 24) & 0xff;
  207 #ifdef XEN
  208                         /* need to do nosegneg like Linux */
  209                         sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff;
  210 #else                   
  211                         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  212 #endif
  213                         sd.sd_hilimit = 0xf;
  214                         sd.sd_type  = SDT_MEMRWA;
  215                         sd.sd_dpl   = SEL_UPL;
  216                         sd.sd_p     = 1;
  217                         sd.sd_xx    = 0;
  218                         sd.sd_def32 = 1;
  219                         sd.sd_gran  = 1;
  220                         critical_enter();
  221                         td->td_pcb->pcb_fsd = sd;
  222 #ifdef XEN
  223                         HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[0]),
  224                             *(uint64_t *)&sd);
  225 #else
  226                         PCPU_GET(fsgs_gdt)[0] = sd;
  227 #endif
  228                         critical_exit();
  229                         td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
  230                 }
  231                 break;
  232         case I386_GET_GSBASE:
  233                 sdp = &td->td_pcb->pcb_gsd;
  234                 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
  235                 error = copyout(&base, uap->parms, sizeof(base));
  236                 break;
  237         case I386_SET_GSBASE:
  238                 error = copyin(uap->parms, &base, sizeof(base));
  239                 if (!error) {
  240                         /*
  241                          * Construct a descriptor and store it in the pcb for
  242                          * the next context switch.  Also store it in the gdt
  243                          * because we have to do a load_gs() right now.
  244                          */
  245                         sd.sd_lobase = base & 0xffffff;
  246                         sd.sd_hibase = (base >> 24) & 0xff;
  247 
  248 #ifdef XEN
  249                         /* need to do nosegneg like Linux */
  250                         sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff;
  251 #else   
  252                         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  253 #endif
  254                         sd.sd_hilimit = 0xf;
  255                         sd.sd_type  = SDT_MEMRWA;
  256                         sd.sd_dpl   = SEL_UPL;
  257                         sd.sd_p     = 1;
  258                         sd.sd_xx    = 0;
  259                         sd.sd_def32 = 1;
  260                         sd.sd_gran  = 1;
  261                         critical_enter();
  262                         td->td_pcb->pcb_gsd = sd;
  263 #ifdef XEN
  264                         HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[1]),
  265                             *(uint64_t *)&sd);
  266 #else                   
  267                         PCPU_GET(fsgs_gdt)[1] = sd;
  268 #endif
  269                         critical_exit();
  270                         load_gs(GSEL(GUGS_SEL, SEL_UPL));
  271                 }
  272                 break;
  273         default:
  274                 error = EINVAL;
  275                 break;
  276         }
  277         return (error);
  278 }
  279 
  280 int
  281 i386_extend_pcb(struct thread *td)
  282 {
  283         int i, offset;
  284         u_long *addr;
  285         struct pcb_ext *ext;
  286         struct soft_segment_descriptor ssd = {
  287                 0,                      /* segment base address (overwritten) */
  288                 ctob(IOPAGES + 1) - 1,  /* length */
  289                 SDT_SYS386TSS,          /* segment type */
  290                 0,                      /* priority level */
  291                 1,                      /* descriptor present */
  292                 0, 0,
  293                 0,                      /* default 32 size */
  294                 0                       /* granularity */
  295         };
  296 
  297         ext = (struct pcb_ext *)kmem_alloc(kernel_map, ctob(IOPAGES+1));
  298         if (ext == 0)
  299                 return (ENOMEM);
  300         bzero(ext, sizeof(struct pcb_ext)); 
  301         /* -16 is so we can convert a trapframe into vm86trapframe inplace */
  302         ext->ext_tss.tss_esp0 = td->td_kstack + ctob(KSTACK_PAGES) -
  303             sizeof(struct pcb) - 16;
  304         ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
  305         /*
  306          * The last byte of the i/o map must be followed by an 0xff byte.
  307          * We arbitrarily allocate 16 bytes here, to keep the starting
  308          * address on a doubleword boundary.
  309          */
  310         offset = PAGE_SIZE - 16;
  311         ext->ext_tss.tss_ioopt = 
  312             (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16;
  313         ext->ext_iomap = (caddr_t)ext + offset;
  314         ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32;
  315 
  316         addr = (u_long *)ext->ext_vm86.vm86_intmap;
  317         for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
  318                 *addr++ = ~0;
  319 
  320         ssd.ssd_base = (unsigned)&ext->ext_tss;
  321         ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
  322         ssdtosd(&ssd, &ext->ext_tssd);
  323 
  324         KASSERT(td == curthread, ("giving TSS to !curthread"));
  325         KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
  326 
  327         /* Switch to the new TSS. */
  328         critical_enter();
  329         td->td_pcb->pcb_ext = ext;
  330         PCPU_SET(private_tss, 1);
  331         *PCPU_GET(tss_gdt) = ext->ext_tssd;
  332         ltr(GSEL(GPROC0_SEL, SEL_KPL));
  333         critical_exit();
  334 
  335         return 0;
  336 }
  337 
  338 int
  339 i386_set_ioperm(td, uap)
  340         struct thread *td;
  341         struct i386_ioperm_args *uap;
  342 {
  343         int i, error;
  344         char *iomap;
  345 
  346         if ((error = priv_check(td, PRIV_IO)) != 0)
  347                 return (error);
  348         if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
  349                 return (error);
  350         /*
  351          * XXX 
  352          * While this is restricted to root, we should probably figure out
  353          * whether any other driver is using this i/o address, as so not to
  354          * cause confusion.  This probably requires a global 'usage registry'.
  355          */
  356 
  357         if (td->td_pcb->pcb_ext == 0)
  358                 if ((error = i386_extend_pcb(td)) != 0)
  359                         return (error);
  360         iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
  361 
  362         if (uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
  363                 return (EINVAL);
  364 
  365         for (i = uap->start; i < uap->start + uap->length; i++) {
  366                 if (uap->enable)
  367                         iomap[i >> 3] &= ~(1 << (i & 7));
  368                 else
  369                         iomap[i >> 3] |= (1 << (i & 7));
  370         }
  371         return (error);
  372 }
  373 
  374 int
  375 i386_get_ioperm(td, uap)
  376         struct thread *td;
  377         struct i386_ioperm_args *uap;
  378 {
  379         int i, state;
  380         char *iomap;
  381 
  382         if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
  383                 return (EINVAL);
  384 
  385         if (td->td_pcb->pcb_ext == 0) {
  386                 uap->length = 0;
  387                 goto done;
  388         }
  389 
  390         iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
  391 
  392         i = uap->start;
  393         state = (iomap[i >> 3] >> (i & 7)) & 1;
  394         uap->enable = !state;
  395         uap->length = 1;
  396 
  397         for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
  398                 if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
  399                         break;
  400                 uap->length++;
  401         }
  402 
  403 done:
  404         return (0);
  405 }
  406 
  407 /*
  408  * Update the GDT entry pointing to the LDT to point to the LDT of the
  409  * current process. Manage dt_lock holding/unholding autonomously.
  410  */   
  411 void
  412 set_user_ldt(struct mdproc *mdp)
  413 {
  414         struct proc_ldt *pldt;
  415         int dtlocked;
  416 
  417         dtlocked = 0;
  418         if (!mtx_owned(&dt_lock)) {
  419                 mtx_lock_spin(&dt_lock);
  420                 dtlocked = 1;
  421         }
  422 
  423         pldt = mdp->md_ldt;
  424 #ifdef XEN
  425         i386_reset_ldt(pldt);
  426         PCPU_SET(currentldt, (int)pldt);
  427 #else   
  428 #ifdef SMP
  429         gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd;
  430 #else
  431         gdt[GUSERLDT_SEL].sd = pldt->ldt_sd;
  432 #endif
  433         lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
  434         PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
  435 #endif /* XEN */ 
  436         if (dtlocked)
  437                 mtx_unlock_spin(&dt_lock);
  438 }
  439 
  440 #ifdef SMP
  441 static void
  442 set_user_ldt_rv(struct vmspace *vmsp)
  443 {
  444         struct thread *td;
  445 
  446         td = curthread;
  447         if (vmsp != td->td_proc->p_vmspace)
  448                 return;
  449 
  450         set_user_ldt(&td->td_proc->p_md);
  451 }
  452 #endif
  453 
  454 #ifdef XEN
  455 
  456 /* 
  457  * dt_lock must be held. Returns with dt_lock held. 
  458  */ 
  459 struct proc_ldt * 
  460 user_ldt_alloc(struct mdproc *mdp, int len) 
  461 { 
  462         struct proc_ldt *pldt, *new_ldt; 
  463  
  464         mtx_assert(&dt_lock, MA_OWNED); 
  465         mtx_unlock_spin(&dt_lock); 
  466         new_ldt = malloc(sizeof(struct proc_ldt), 
  467                 M_SUBPROC, M_WAITOK); 
  468  
  469         new_ldt->ldt_len = len = NEW_MAX_LD(len); 
  470         new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 
  471                 round_page(len * sizeof(union descriptor))); 
  472         if (new_ldt->ldt_base == NULL) { 
  473                 free(new_ldt, M_SUBPROC);
  474                 mtx_lock_spin(&dt_lock);
  475                 return (NULL);
  476         } 
  477         new_ldt->ldt_refcnt = 1; 
  478         new_ldt->ldt_active = 0; 
  479  
  480         mtx_lock_spin(&dt_lock);
  481         if ((pldt = mdp->md_ldt)) { 
  482                 if (len > pldt->ldt_len) 
  483                         len = pldt->ldt_len; 
  484                 bcopy(pldt->ldt_base, new_ldt->ldt_base, 
  485                     len * sizeof(union descriptor)); 
  486         } else { 
  487                 bcopy(ldt, new_ldt->ldt_base, PAGE_SIZE); 
  488         } 
  489         mtx_unlock_spin(&dt_lock);  /* XXX kill once pmap locking fixed. */
  490         pmap_map_readonly(kernel_pmap, (vm_offset_t)new_ldt->ldt_base, 
  491                           new_ldt->ldt_len*sizeof(union descriptor)); 
  492         mtx_lock_spin(&dt_lock);  /* XXX kill once pmap locking fixed. */
  493         return (new_ldt);
  494 } 
  495 #else
  496 /*
  497  * dt_lock must be held. Returns with dt_lock held.
  498  */
  499 struct proc_ldt *
  500 user_ldt_alloc(struct mdproc *mdp, int len)
  501 {
  502         struct proc_ldt *pldt, *new_ldt;
  503 
  504         mtx_assert(&dt_lock, MA_OWNED);
  505         mtx_unlock_spin(&dt_lock);
  506         new_ldt = malloc(sizeof(struct proc_ldt),
  507                 M_SUBPROC, M_WAITOK);
  508 
  509         new_ldt->ldt_len = len = NEW_MAX_LD(len);
  510         new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map,
  511                 len * sizeof(union descriptor));
  512         if (new_ldt->ldt_base == NULL) {
  513                 free(new_ldt, M_SUBPROC);
  514                 mtx_lock_spin(&dt_lock);
  515                 return (NULL);
  516         }
  517         new_ldt->ldt_refcnt = 1;
  518         new_ldt->ldt_active = 0;
  519 
  520         mtx_lock_spin(&dt_lock);
  521         gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base;
  522         gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
  523         ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
  524 
  525         if ((pldt = mdp->md_ldt) != NULL) {
  526                 if (len > pldt->ldt_len)
  527                         len = pldt->ldt_len;
  528                 bcopy(pldt->ldt_base, new_ldt->ldt_base,
  529                     len * sizeof(union descriptor));
  530         } else
  531                 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
  532         
  533         return (new_ldt);
  534 }
  535 #endif /* !XEN */
  536 
  537 /*
  538  * Must be called with dt_lock held.  Returns with dt_lock unheld.
  539  */
  540 void
  541 user_ldt_free(struct thread *td)
  542 {
  543         struct mdproc *mdp = &td->td_proc->p_md;
  544         struct proc_ldt *pldt;
  545 
  546         mtx_assert(&dt_lock, MA_OWNED);
  547         if ((pldt = mdp->md_ldt) == NULL) {
  548                 mtx_unlock_spin(&dt_lock);
  549                 return;
  550         }
  551 
  552         if (td == curthread) {
  553 #ifdef XEN
  554                 i386_reset_ldt(&default_proc_ldt);
  555                 PCPU_SET(currentldt, (int)&default_proc_ldt);
  556 #else
  557                 lldt(_default_ldt);
  558                 PCPU_SET(currentldt, _default_ldt);
  559 #endif
  560         }
  561 
  562         mdp->md_ldt = NULL;
  563         user_ldt_deref(pldt);
  564 }
  565 
  566 void
  567 user_ldt_deref(struct proc_ldt *pldt)
  568 {
  569 
  570         mtx_assert(&dt_lock, MA_OWNED);
  571         if (--pldt->ldt_refcnt == 0) {
  572                 mtx_unlock_spin(&dt_lock);
  573                 kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base,
  574                         pldt->ldt_len * sizeof(union descriptor));
  575                 free(pldt, M_SUBPROC);
  576         } else
  577                 mtx_unlock_spin(&dt_lock);
  578 }
  579 
  580 /*
  581  * Note for the authors of compat layers (linux, etc): copyout() in
  582  * the function below is not a problem since it presents data in
  583  * arch-specific format (i.e. i386-specific in this case), not in
  584  * the OS-specific one.
  585  */
  586 int
  587 i386_get_ldt(td, uap)
  588         struct thread *td;
  589         struct i386_ldt_args *uap;
  590 {
  591         int error = 0;
  592         struct proc_ldt *pldt;
  593         int nldt, num;
  594         union descriptor *lp;
  595 
  596 #ifdef  DEBUG
  597         printf("i386_get_ldt: start=%d num=%d descs=%p\n",
  598             uap->start, uap->num, (void *)uap->descs);
  599 #endif
  600 
  601         mtx_lock_spin(&dt_lock);
  602         if ((pldt = td->td_proc->p_md.md_ldt) != NULL) {
  603                 nldt = pldt->ldt_len;
  604                 lp = &((union descriptor *)(pldt->ldt_base))[uap->start];
  605                 mtx_unlock_spin(&dt_lock);
  606                 num = min(uap->num, nldt);
  607         } else {
  608                 mtx_unlock_spin(&dt_lock);
  609                 nldt = sizeof(ldt)/sizeof(ldt[0]);
  610                 num = min(uap->num, nldt);
  611                 lp = &ldt[uap->start];
  612         }
  613 
  614         if ((uap->start > (unsigned int)nldt) ||
  615             ((unsigned int)num > (unsigned int)nldt) ||
  616             ((unsigned int)(uap->start + num) > (unsigned int)nldt))
  617                 return(EINVAL);
  618 
  619         error = copyout(lp, uap->descs, num * sizeof(union descriptor));
  620         if (!error)
  621                 td->td_retval[0] = num;
  622 
  623         return(error);
  624 }
  625 
  626 int
  627 i386_set_ldt(td, uap, descs)
  628         struct thread *td;
  629         struct i386_ldt_args *uap;
  630         union descriptor *descs;
  631 {
  632         int error = 0, i;
  633         int largest_ld;
  634         struct mdproc *mdp = &td->td_proc->p_md;
  635         struct proc_ldt *pldt;
  636         union descriptor *dp;
  637 
  638 #ifdef  DEBUG
  639         printf("i386_set_ldt: start=%d num=%d descs=%p\n",
  640             uap->start, uap->num, (void *)uap->descs);
  641 #endif
  642 
  643         if (descs == NULL) {
  644                 /* Free descriptors */
  645                 if (uap->start == 0 && uap->num == 0) {
  646                         /*
  647                          * Treat this as a special case, so userland needn't
  648                          * know magic number NLDT.
  649                          */
  650                         uap->start = NLDT;
  651                         uap->num = MAX_LD - NLDT;
  652                 }
  653                 if (uap->num == 0)
  654                         return (EINVAL);
  655                 mtx_lock_spin(&dt_lock);
  656                 if ((pldt = mdp->md_ldt) == NULL ||
  657                     uap->start >= pldt->ldt_len) {
  658                         mtx_unlock_spin(&dt_lock);
  659                         return (0);
  660                 }
  661                 largest_ld = uap->start + uap->num;
  662                 if (largest_ld > pldt->ldt_len)
  663                         largest_ld = pldt->ldt_len;
  664                 i = largest_ld - uap->start;
  665                 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start],
  666                     sizeof(union descriptor) * i);
  667                 mtx_unlock_spin(&dt_lock);
  668                 return (0);
  669         }
  670 
  671         if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) {
  672                 /* verify range of descriptors to modify */
  673                 largest_ld = uap->start + uap->num;
  674                 if (uap->start >= MAX_LD || largest_ld > MAX_LD) {
  675                         return (EINVAL);
  676                 }
  677         }
  678 
  679         /* Check descriptors for access violations */
  680         for (i = 0; i < uap->num; i++) {
  681                 dp = &descs[i];
  682 
  683                 switch (dp->sd.sd_type) {
  684                 case SDT_SYSNULL:       /* system null */ 
  685                         dp->sd.sd_p = 0;
  686                         break;
  687                 case SDT_SYS286TSS: /* system 286 TSS available */
  688                 case SDT_SYSLDT:    /* system local descriptor table */
  689                 case SDT_SYS286BSY: /* system 286 TSS busy */
  690                 case SDT_SYSTASKGT: /* system task gate */
  691                 case SDT_SYS286IGT: /* system 286 interrupt gate */
  692                 case SDT_SYS286TGT: /* system 286 trap gate */
  693                 case SDT_SYSNULL2:  /* undefined by Intel */ 
  694                 case SDT_SYS386TSS: /* system 386 TSS available */
  695                 case SDT_SYSNULL3:  /* undefined by Intel */
  696                 case SDT_SYS386BSY: /* system 386 TSS busy */
  697                 case SDT_SYSNULL4:  /* undefined by Intel */ 
  698                 case SDT_SYS386IGT: /* system 386 interrupt gate */
  699                 case SDT_SYS386TGT: /* system 386 trap gate */
  700                 case SDT_SYS286CGT: /* system 286 call gate */ 
  701                 case SDT_SYS386CGT: /* system 386 call gate */
  702                         /* I can't think of any reason to allow a user proc
  703                          * to create a segment of these types.  They are
  704                          * for OS use only.
  705                          */
  706                         return (EACCES);
  707                         /*NOTREACHED*/
  708 
  709                 /* memory segment types */
  710                 case SDT_MEMEC:   /* memory execute only conforming */
  711                 case SDT_MEMEAC:  /* memory execute only accessed conforming */
  712                 case SDT_MEMERC:  /* memory execute read conforming */
  713                 case SDT_MEMERAC: /* memory execute read accessed conforming */
  714                          /* Must be "present" if executable and conforming. */
  715                         if (dp->sd.sd_p == 0)
  716                                 return (EACCES);
  717                         break;
  718                 case SDT_MEMRO:   /* memory read only */
  719                 case SDT_MEMROA:  /* memory read only accessed */
  720                 case SDT_MEMRW:   /* memory read write */
  721                 case SDT_MEMRWA:  /* memory read write accessed */
  722                 case SDT_MEMROD:  /* memory read only expand dwn limit */
  723                 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */
  724                 case SDT_MEMRWD:  /* memory read write expand dwn limit */  
  725                 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */
  726                 case SDT_MEME:    /* memory execute only */ 
  727                 case SDT_MEMEA:   /* memory execute only accessed */
  728                 case SDT_MEMER:   /* memory execute read */
  729                 case SDT_MEMERA:  /* memory execute read accessed */
  730                         break;
  731                 default:
  732                         return(EINVAL);
  733                         /*NOTREACHED*/
  734                 }
  735 
  736                 /* Only user (ring-3) descriptors may be present. */
  737                 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL))
  738                         return (EACCES);
  739         }
  740 
  741         if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) {
  742                 /* Allocate a free slot */
  743                 mtx_lock_spin(&dt_lock);
  744                 if ((pldt = mdp->md_ldt) == NULL) {
  745                         if ((error = i386_ldt_grow(td, NLDT + 1))) {
  746                                 mtx_unlock_spin(&dt_lock);
  747                                 return (error);
  748                         }
  749                         pldt = mdp->md_ldt;
  750                 }
  751 again:
  752                 /*
  753                  * start scanning a bit up to leave room for NVidia and
  754                  * Wine, which still user the "Blat" method of allocation.
  755                  */
  756                 dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
  757                 for (i = NLDT; i < pldt->ldt_len; ++i) {
  758                         if (dp->sd.sd_type == SDT_SYSNULL)
  759                                 break;
  760                         dp++;
  761                 }
  762                 if (i >= pldt->ldt_len) {
  763                         if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
  764                                 mtx_unlock_spin(&dt_lock);
  765                                 return (error);
  766                         }
  767                         goto again;
  768                 }
  769                 uap->start = i;
  770                 error = i386_set_ldt_data(td, i, 1, descs);
  771                 mtx_unlock_spin(&dt_lock);
  772         } else {
  773                 largest_ld = uap->start + uap->num;
  774                 mtx_lock_spin(&dt_lock);
  775                 if (!(error = i386_ldt_grow(td, largest_ld))) {
  776                         error = i386_set_ldt_data(td, uap->start, uap->num,
  777                             descs);
  778                 }
  779                 mtx_unlock_spin(&dt_lock);
  780         }
  781         if (error == 0)
  782                 td->td_retval[0] = uap->start;
  783         return (error);
  784 }
  785 #ifdef XEN
  786 static int
  787 i386_set_ldt_data(struct thread *td, int start, int num,
  788         union descriptor *descs)
  789 {
  790         struct mdproc *mdp = &td->td_proc->p_md;
  791         struct proc_ldt *pldt = mdp->md_ldt;
  792 
  793         mtx_assert(&dt_lock, MA_OWNED);
  794 
  795         while (num) {
  796                 xen_update_descriptor(
  797                     &((union descriptor *)(pldt->ldt_base))[start],
  798                     descs);
  799                 num--;
  800                 start++;
  801                 descs++;
  802         }
  803         return (0);
  804 }
  805 #else
  806 static int
  807 i386_set_ldt_data(struct thread *td, int start, int num,
  808         union descriptor *descs)
  809 {
  810         struct mdproc *mdp = &td->td_proc->p_md;
  811         struct proc_ldt *pldt = mdp->md_ldt;
  812 
  813         mtx_assert(&dt_lock, MA_OWNED);
  814 
  815         /* Fill in range */
  816         bcopy(descs,
  817             &((union descriptor *)(pldt->ldt_base))[start],
  818             num * sizeof(union descriptor));
  819         return (0);
  820 }
  821 #endif /* !XEN */
  822 
  823 static int
  824 i386_ldt_grow(struct thread *td, int len) 
  825 {
  826         struct mdproc *mdp = &td->td_proc->p_md;
  827         struct proc_ldt *new_ldt, *pldt;
  828         caddr_t old_ldt_base = NULL_LDT_BASE;
  829         int old_ldt_len = 0;
  830 
  831         mtx_assert(&dt_lock, MA_OWNED);
  832 
  833         if (len > MAX_LD)
  834                 return (ENOMEM);
  835         if (len < NLDT + 1)
  836                 len = NLDT + 1;
  837 
  838         /* Allocate a user ldt. */
  839         if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
  840                 new_ldt = user_ldt_alloc(mdp, len);
  841                 if (new_ldt == NULL)
  842                         return (ENOMEM);
  843                 pldt = mdp->md_ldt;
  844 
  845                 if (pldt != NULL) {
  846                         if (new_ldt->ldt_len <= pldt->ldt_len) {
  847                                 /*
  848                                  * We just lost the race for allocation, so
  849                                  * free the new object and return.
  850                                  */
  851                                 mtx_unlock_spin(&dt_lock);
  852                                 kmem_free(kernel_map,
  853                                    (vm_offset_t)new_ldt->ldt_base,
  854                                    new_ldt->ldt_len * sizeof(union descriptor));
  855                                 free(new_ldt, M_SUBPROC);
  856                                 mtx_lock_spin(&dt_lock);
  857                                 return (0);
  858                         }
  859 
  860                         /*
  861                          * We have to substitute the current LDT entry for
  862                          * curproc with the new one since its size grew.
  863                          */
  864                         old_ldt_base = pldt->ldt_base;
  865                         old_ldt_len = pldt->ldt_len;
  866                         pldt->ldt_sd = new_ldt->ldt_sd;
  867                         pldt->ldt_base = new_ldt->ldt_base;
  868                         pldt->ldt_len = new_ldt->ldt_len;
  869                 } else
  870                         mdp->md_ldt = pldt = new_ldt;
  871 #ifdef SMP
  872                 /*
  873                  * Signal other cpus to reload ldt.  We need to unlock dt_lock
  874                  * here because other CPU will contest on it since their
  875                  * curthreads won't hold the lock and will block when trying
  876                  * to acquire it.
  877                  */
  878                 mtx_unlock_spin(&dt_lock);
  879                 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv,
  880                     NULL, td->td_proc->p_vmspace);
  881 #else
  882                 set_user_ldt(&td->td_proc->p_md);
  883                 mtx_unlock_spin(&dt_lock);
  884 #endif
  885                 if (old_ldt_base != NULL_LDT_BASE) {
  886                         kmem_free(kernel_map, (vm_offset_t)old_ldt_base,
  887                             old_ldt_len * sizeof(union descriptor));
  888                         free(new_ldt, M_SUBPROC);
  889                 }
  890                 mtx_lock_spin(&dt_lock);
  891         }
  892         return (0);
  893 }

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