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  * 3. 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/11.1/sys/i386/i386/sys_machdep.c 306960 2016-10-10 11:51:47Z tijl $");
   34 
   35 #include "opt_capsicum.h"
   36 #include "opt_kstack_pages.h"
   37 
   38 #include <sys/param.h>
   39 #include <sys/capsicum.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 #include <vm/vm_kern.h>         /* for kernel_map */
   63 
   64 #define MAX_LD 8192
   65 #define LD_PER_PAGE 512
   66 #define NEW_MAX_LD(num)  rounddown2(num + LD_PER_PAGE, LD_PER_PAGE)
   67 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)
   68 #define NULL_LDT_BASE   ((caddr_t)NULL)
   69 
   70 #ifdef SMP
   71 static void set_user_ldt_rv(struct vmspace *vmsp);
   72 #endif
   73 static int i386_set_ldt_data(struct thread *, int start, int num,
   74         union descriptor *descs);
   75 static int i386_ldt_grow(struct thread *td, int len);
   76 
   77 void
   78 fill_based_sd(struct segment_descriptor *sdp, uint32_t base)
   79 {
   80 
   81         sdp->sd_lobase = base & 0xffffff;
   82         sdp->sd_hibase = (base >> 24) & 0xff;
   83         sdp->sd_lolimit = 0xffff;       /* 4GB limit, wraps around */
   84         sdp->sd_hilimit = 0xf;
   85         sdp->sd_type = SDT_MEMRWA;
   86         sdp->sd_dpl = SEL_UPL;
   87         sdp->sd_p = 1;
   88         sdp->sd_xx = 0;
   89         sdp->sd_def32 = 1;
   90         sdp->sd_gran = 1;
   91 }
   92 
   93 #ifndef _SYS_SYSPROTO_H_
   94 struct sysarch_args {
   95         int op;
   96         char *parms;
   97 };
   98 #endif
   99 
  100 int
  101 sysarch(td, uap)
  102         struct thread *td;
  103         register struct sysarch_args *uap;
  104 {
  105         int error;
  106         union descriptor *lp;
  107         union {
  108                 struct i386_ldt_args largs;
  109                 struct i386_ioperm_args iargs;
  110                 struct i386_get_xfpustate xfpu;
  111         } kargs;
  112         uint32_t base;
  113         struct segment_descriptor sd, *sdp;
  114 
  115         AUDIT_ARG_CMD(uap->op);
  116 
  117 #ifdef CAPABILITY_MODE
  118         /*
  119          * When adding new operations, add a new case statement here to
  120          * explicitly indicate whether or not the operation is safe to
  121          * perform in capability mode.
  122          */
  123         if (IN_CAPABILITY_MODE(td)) {
  124                 switch (uap->op) {
  125                 case I386_GET_LDT:
  126                 case I386_SET_LDT:
  127                 case I386_GET_IOPERM:
  128                 case I386_GET_FSBASE:
  129                 case I386_SET_FSBASE:
  130                 case I386_GET_GSBASE:
  131                 case I386_SET_GSBASE:
  132                 case I386_GET_XFPUSTATE:
  133                         break;
  134 
  135                 case I386_SET_IOPERM:
  136                 default:
  137 #ifdef KTRACE
  138                         if (KTRPOINT(td, KTR_CAPFAIL))
  139                                 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL);
  140 #endif
  141                         return (ECAPMODE);
  142                 }
  143         }
  144 #endif
  145 
  146         switch (uap->op) {
  147         case I386_GET_IOPERM:
  148         case I386_SET_IOPERM:
  149                 if ((error = copyin(uap->parms, &kargs.iargs,
  150                     sizeof(struct i386_ioperm_args))) != 0)
  151                         return (error);
  152                 break;
  153         case I386_GET_LDT:
  154         case I386_SET_LDT:
  155                 if ((error = copyin(uap->parms, &kargs.largs,
  156                     sizeof(struct i386_ldt_args))) != 0)
  157                         return (error);
  158                 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0)
  159                         return (EINVAL);
  160                 break;
  161         case I386_GET_XFPUSTATE:
  162                 if ((error = copyin(uap->parms, &kargs.xfpu,
  163                     sizeof(struct i386_get_xfpustate))) != 0)
  164                         return (error);
  165                 break;
  166         default:
  167                 break;
  168         }
  169 
  170         switch(uap->op) {
  171         case I386_GET_LDT:
  172                 error = i386_get_ldt(td, &kargs.largs);
  173                 break;
  174         case I386_SET_LDT:
  175                 if (kargs.largs.descs != NULL) {
  176                         lp = (union descriptor *)malloc(
  177                             kargs.largs.num * sizeof(union descriptor),
  178                             M_TEMP, M_WAITOK);
  179                         error = copyin(kargs.largs.descs, lp,
  180                             kargs.largs.num * sizeof(union descriptor));
  181                         if (error == 0)
  182                                 error = i386_set_ldt(td, &kargs.largs, lp);
  183                         free(lp, M_TEMP);
  184                 } else {
  185                         error = i386_set_ldt(td, &kargs.largs, NULL);
  186                 }
  187                 break;
  188         case I386_GET_IOPERM:
  189                 error = i386_get_ioperm(td, &kargs.iargs);
  190                 if (error == 0)
  191                         error = copyout(&kargs.iargs, uap->parms,
  192                             sizeof(struct i386_ioperm_args));
  193                 break;
  194         case I386_SET_IOPERM:
  195                 error = i386_set_ioperm(td, &kargs.iargs);
  196                 break;
  197         case I386_VM86:
  198                 error = vm86_sysarch(td, uap->parms);
  199                 break;
  200         case I386_GET_FSBASE:
  201                 sdp = &td->td_pcb->pcb_fsd;
  202                 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
  203                 error = copyout(&base, uap->parms, sizeof(base));
  204                 break;
  205         case I386_SET_FSBASE:
  206                 error = copyin(uap->parms, &base, sizeof(base));
  207                 if (error == 0) {
  208                         /*
  209                          * Construct a descriptor and store it in the pcb for
  210                          * the next context switch.  Also store it in the gdt
  211                          * so that the load of tf_fs into %fs will activate it
  212                          * at return to userland.
  213                          */
  214                         fill_based_sd(&sd, base);
  215                         critical_enter();
  216                         td->td_pcb->pcb_fsd = sd;
  217                         PCPU_GET(fsgs_gdt)[0] = sd;
  218                         critical_exit();
  219                         td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
  220                 }
  221                 break;
  222         case I386_GET_GSBASE:
  223                 sdp = &td->td_pcb->pcb_gsd;
  224                 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
  225                 error = copyout(&base, uap->parms, sizeof(base));
  226                 break;
  227         case I386_SET_GSBASE:
  228                 error = copyin(uap->parms, &base, sizeof(base));
  229                 if (error == 0) {
  230                         /*
  231                          * Construct a descriptor and store it in the pcb for
  232                          * the next context switch.  Also store it in the gdt
  233                          * because we have to do a load_gs() right now.
  234                          */
  235                         fill_based_sd(&sd, base);
  236                         critical_enter();
  237                         td->td_pcb->pcb_gsd = sd;
  238                         PCPU_GET(fsgs_gdt)[1] = sd;
  239                         critical_exit();
  240                         load_gs(GSEL(GUGS_SEL, SEL_UPL));
  241                 }
  242                 break;
  243         case I386_GET_XFPUSTATE:
  244                 if (kargs.xfpu.len > cpu_max_ext_state_size -
  245                     sizeof(union savefpu))
  246                         return (EINVAL);
  247                 npxgetregs(td);
  248                 error = copyout((char *)(get_pcb_user_save_td(td) + 1),
  249                     kargs.xfpu.addr, kargs.xfpu.len);
  250                 break;
  251         default:
  252                 error = EINVAL;
  253                 break;
  254         }
  255         return (error);
  256 }
  257 
  258 int
  259 i386_extend_pcb(struct thread *td)
  260 {
  261         int i, offset;
  262         u_long *addr;
  263         struct pcb_ext *ext;
  264         struct soft_segment_descriptor ssd = {
  265                 0,                      /* segment base address (overwritten) */
  266                 ctob(IOPAGES + 1) - 1,  /* length */
  267                 SDT_SYS386TSS,          /* segment type */
  268                 0,                      /* priority level */
  269                 1,                      /* descriptor present */
  270                 0, 0,
  271                 0,                      /* default 32 size */
  272                 0                       /* granularity */
  273         };
  274 
  275         ext = (struct pcb_ext *)kmem_malloc(kernel_arena, ctob(IOPAGES+1),
  276             M_WAITOK | M_ZERO);
  277         /* -16 is so we can convert a trapframe into vm86trapframe inplace */
  278         ext->ext_tss.tss_esp0 = (vm_offset_t)td->td_pcb - 16;
  279         ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
  280         /*
  281          * The last byte of the i/o map must be followed by an 0xff byte.
  282          * We arbitrarily allocate 16 bytes here, to keep the starting
  283          * address on a doubleword boundary.
  284          */
  285         offset = PAGE_SIZE - 16;
  286         ext->ext_tss.tss_ioopt = 
  287             (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16;
  288         ext->ext_iomap = (caddr_t)ext + offset;
  289         ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32;
  290 
  291         addr = (u_long *)ext->ext_vm86.vm86_intmap;
  292         for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
  293                 *addr++ = ~0;
  294 
  295         ssd.ssd_base = (unsigned)&ext->ext_tss;
  296         ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
  297         ssdtosd(&ssd, &ext->ext_tssd);
  298 
  299         KASSERT(td == curthread, ("giving TSS to !curthread"));
  300         KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
  301 
  302         /* Switch to the new TSS. */
  303         critical_enter();
  304         td->td_pcb->pcb_ext = ext;
  305         PCPU_SET(private_tss, 1);
  306         *PCPU_GET(tss_gdt) = ext->ext_tssd;
  307         ltr(GSEL(GPROC0_SEL, SEL_KPL));
  308         critical_exit();
  309 
  310         return 0;
  311 }
  312 
  313 int
  314 i386_set_ioperm(td, uap)
  315         struct thread *td;
  316         struct i386_ioperm_args *uap;
  317 {
  318         char *iomap;
  319         u_int i;
  320         int error;
  321 
  322         if ((error = priv_check(td, PRIV_IO)) != 0)
  323                 return (error);
  324         if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
  325                 return (error);
  326         /*
  327          * XXX 
  328          * While this is restricted to root, we should probably figure out
  329          * whether any other driver is using this i/o address, as so not to
  330          * cause confusion.  This probably requires a global 'usage registry'.
  331          */
  332 
  333         if (td->td_pcb->pcb_ext == 0)
  334                 if ((error = i386_extend_pcb(td)) != 0)
  335                         return (error);
  336         iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
  337 
  338         if (uap->start > uap->start + uap->length ||
  339             uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
  340                 return (EINVAL);
  341 
  342         for (i = uap->start; i < uap->start + uap->length; i++) {
  343                 if (uap->enable)
  344                         iomap[i >> 3] &= ~(1 << (i & 7));
  345                 else
  346                         iomap[i >> 3] |= (1 << (i & 7));
  347         }
  348         return (error);
  349 }
  350 
  351 int
  352 i386_get_ioperm(td, uap)
  353         struct thread *td;
  354         struct i386_ioperm_args *uap;
  355 {
  356         int i, state;
  357         char *iomap;
  358 
  359         if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
  360                 return (EINVAL);
  361 
  362         if (td->td_pcb->pcb_ext == 0) {
  363                 uap->length = 0;
  364                 goto done;
  365         }
  366 
  367         iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
  368 
  369         i = uap->start;
  370         state = (iomap[i >> 3] >> (i & 7)) & 1;
  371         uap->enable = !state;
  372         uap->length = 1;
  373 
  374         for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
  375                 if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
  376                         break;
  377                 uap->length++;
  378         }
  379 
  380 done:
  381         return (0);
  382 }
  383 
  384 /*
  385  * Update the GDT entry pointing to the LDT to point to the LDT of the
  386  * current process. Manage dt_lock holding/unholding autonomously.
  387  */   
  388 void
  389 set_user_ldt(struct mdproc *mdp)
  390 {
  391         struct proc_ldt *pldt;
  392         int dtlocked;
  393 
  394         dtlocked = 0;
  395         if (!mtx_owned(&dt_lock)) {
  396                 mtx_lock_spin(&dt_lock);
  397                 dtlocked = 1;
  398         }
  399 
  400         pldt = mdp->md_ldt;
  401 #ifdef SMP
  402         gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd;
  403 #else
  404         gdt[GUSERLDT_SEL].sd = pldt->ldt_sd;
  405 #endif
  406         lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
  407         PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
  408         if (dtlocked)
  409                 mtx_unlock_spin(&dt_lock);
  410 }
  411 
  412 #ifdef SMP
  413 static void
  414 set_user_ldt_rv(struct vmspace *vmsp)
  415 {
  416         struct thread *td;
  417 
  418         td = curthread;
  419         if (vmsp != td->td_proc->p_vmspace)
  420                 return;
  421 
  422         set_user_ldt(&td->td_proc->p_md);
  423 }
  424 #endif
  425 
  426 /*
  427  * dt_lock must be held. Returns with dt_lock held.
  428  */
  429 struct proc_ldt *
  430 user_ldt_alloc(struct mdproc *mdp, int len)
  431 {
  432         struct proc_ldt *pldt, *new_ldt;
  433 
  434         mtx_assert(&dt_lock, MA_OWNED);
  435         mtx_unlock_spin(&dt_lock);
  436         new_ldt = malloc(sizeof(struct proc_ldt),
  437                 M_SUBPROC, M_WAITOK);
  438 
  439         new_ldt->ldt_len = len = NEW_MAX_LD(len);
  440         new_ldt->ldt_base = (caddr_t)kmem_malloc(kernel_arena,
  441             len * sizeof(union descriptor), M_WAITOK | M_ZERO);
  442         new_ldt->ldt_refcnt = 1;
  443         new_ldt->ldt_active = 0;
  444 
  445         mtx_lock_spin(&dt_lock);
  446         gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base;
  447         gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
  448         ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
  449 
  450         if ((pldt = mdp->md_ldt) != NULL) {
  451                 if (len > pldt->ldt_len)
  452                         len = pldt->ldt_len;
  453                 bcopy(pldt->ldt_base, new_ldt->ldt_base,
  454                     len * sizeof(union descriptor));
  455         } else
  456                 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
  457         
  458         return (new_ldt);
  459 }
  460 
  461 /*
  462  * Must be called with dt_lock held.  Returns with dt_lock unheld.
  463  */
  464 void
  465 user_ldt_free(struct thread *td)
  466 {
  467         struct mdproc *mdp = &td->td_proc->p_md;
  468         struct proc_ldt *pldt;
  469 
  470         mtx_assert(&dt_lock, MA_OWNED);
  471         if ((pldt = mdp->md_ldt) == NULL) {
  472                 mtx_unlock_spin(&dt_lock);
  473                 return;
  474         }
  475 
  476         if (td == curthread) {
  477                 lldt(_default_ldt);
  478                 PCPU_SET(currentldt, _default_ldt);
  479         }
  480 
  481         mdp->md_ldt = NULL;
  482         user_ldt_deref(pldt);
  483 }
  484 
  485 void
  486 user_ldt_deref(struct proc_ldt *pldt)
  487 {
  488 
  489         mtx_assert(&dt_lock, MA_OWNED);
  490         if (--pldt->ldt_refcnt == 0) {
  491                 mtx_unlock_spin(&dt_lock);
  492                 kmem_free(kernel_arena, (vm_offset_t)pldt->ldt_base,
  493                         pldt->ldt_len * sizeof(union descriptor));
  494                 free(pldt, M_SUBPROC);
  495         } else
  496                 mtx_unlock_spin(&dt_lock);
  497 }
  498 
  499 /*
  500  * Note for the authors of compat layers (linux, etc): copyout() in
  501  * the function below is not a problem since it presents data in
  502  * arch-specific format (i.e. i386-specific in this case), not in
  503  * the OS-specific one.
  504  */
  505 int
  506 i386_get_ldt(td, uap)
  507         struct thread *td;
  508         struct i386_ldt_args *uap;
  509 {
  510         int error = 0;
  511         struct proc_ldt *pldt;
  512         int nldt, num;
  513         union descriptor *lp;
  514 
  515 #ifdef  DEBUG
  516         printf("i386_get_ldt: start=%d num=%d descs=%p\n",
  517             uap->start, uap->num, (void *)uap->descs);
  518 #endif
  519 
  520         mtx_lock_spin(&dt_lock);
  521         if ((pldt = td->td_proc->p_md.md_ldt) != NULL) {
  522                 nldt = pldt->ldt_len;
  523                 lp = &((union descriptor *)(pldt->ldt_base))[uap->start];
  524                 mtx_unlock_spin(&dt_lock);
  525                 num = min(uap->num, nldt);
  526         } else {
  527                 mtx_unlock_spin(&dt_lock);
  528                 nldt = sizeof(ldt)/sizeof(ldt[0]);
  529                 num = min(uap->num, nldt);
  530                 lp = &ldt[uap->start];
  531         }
  532 
  533         if ((uap->start > (unsigned int)nldt) ||
  534             ((unsigned int)num > (unsigned int)nldt) ||
  535             ((unsigned int)(uap->start + num) > (unsigned int)nldt))
  536                 return(EINVAL);
  537 
  538         error = copyout(lp, uap->descs, num * sizeof(union descriptor));
  539         if (!error)
  540                 td->td_retval[0] = num;
  541 
  542         return(error);
  543 }
  544 
  545 int
  546 i386_set_ldt(td, uap, descs)
  547         struct thread *td;
  548         struct i386_ldt_args *uap;
  549         union descriptor *descs;
  550 {
  551         int error = 0, i;
  552         int largest_ld;
  553         struct mdproc *mdp = &td->td_proc->p_md;
  554         struct proc_ldt *pldt;
  555         union descriptor *dp;
  556 
  557 #ifdef  DEBUG
  558         printf("i386_set_ldt: start=%d num=%d descs=%p\n",
  559             uap->start, uap->num, (void *)uap->descs);
  560 #endif
  561 
  562         if (descs == NULL) {
  563                 /* Free descriptors */
  564                 if (uap->start == 0 && uap->num == 0) {
  565                         /*
  566                          * Treat this as a special case, so userland needn't
  567                          * know magic number NLDT.
  568                          */
  569                         uap->start = NLDT;
  570                         uap->num = MAX_LD - NLDT;
  571                 }
  572                 if (uap->num == 0)
  573                         return (EINVAL);
  574                 mtx_lock_spin(&dt_lock);
  575                 if ((pldt = mdp->md_ldt) == NULL ||
  576                     uap->start >= pldt->ldt_len) {
  577                         mtx_unlock_spin(&dt_lock);
  578                         return (0);
  579                 }
  580                 largest_ld = uap->start + uap->num;
  581                 if (largest_ld > pldt->ldt_len)
  582                         largest_ld = pldt->ldt_len;
  583                 i = largest_ld - uap->start;
  584                 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start],
  585                     sizeof(union descriptor) * i);
  586                 mtx_unlock_spin(&dt_lock);
  587                 return (0);
  588         }
  589 
  590         if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) {
  591                 /* verify range of descriptors to modify */
  592                 largest_ld = uap->start + uap->num;
  593                 if (uap->start >= MAX_LD || largest_ld > MAX_LD) {
  594                         return (EINVAL);
  595                 }
  596         }
  597 
  598         /* Check descriptors for access violations */
  599         for (i = 0; i < uap->num; i++) {
  600                 dp = &descs[i];
  601 
  602                 switch (dp->sd.sd_type) {
  603                 case SDT_SYSNULL:       /* system null */ 
  604                         dp->sd.sd_p = 0;
  605                         break;
  606                 case SDT_SYS286TSS: /* system 286 TSS available */
  607                 case SDT_SYSLDT:    /* system local descriptor table */
  608                 case SDT_SYS286BSY: /* system 286 TSS busy */
  609                 case SDT_SYSTASKGT: /* system task gate */
  610                 case SDT_SYS286IGT: /* system 286 interrupt gate */
  611                 case SDT_SYS286TGT: /* system 286 trap gate */
  612                 case SDT_SYSNULL2:  /* undefined by Intel */ 
  613                 case SDT_SYS386TSS: /* system 386 TSS available */
  614                 case SDT_SYSNULL3:  /* undefined by Intel */
  615                 case SDT_SYS386BSY: /* system 386 TSS busy */
  616                 case SDT_SYSNULL4:  /* undefined by Intel */ 
  617                 case SDT_SYS386IGT: /* system 386 interrupt gate */
  618                 case SDT_SYS386TGT: /* system 386 trap gate */
  619                 case SDT_SYS286CGT: /* system 286 call gate */ 
  620                 case SDT_SYS386CGT: /* system 386 call gate */
  621                         /* I can't think of any reason to allow a user proc
  622                          * to create a segment of these types.  They are
  623                          * for OS use only.
  624                          */
  625                         return (EACCES);
  626                         /*NOTREACHED*/
  627 
  628                 /* memory segment types */
  629                 case SDT_MEMEC:   /* memory execute only conforming */
  630                 case SDT_MEMEAC:  /* memory execute only accessed conforming */
  631                 case SDT_MEMERC:  /* memory execute read conforming */
  632                 case SDT_MEMERAC: /* memory execute read accessed conforming */
  633                          /* Must be "present" if executable and conforming. */
  634                         if (dp->sd.sd_p == 0)
  635                                 return (EACCES);
  636                         break;
  637                 case SDT_MEMRO:   /* memory read only */
  638                 case SDT_MEMROA:  /* memory read only accessed */
  639                 case SDT_MEMRW:   /* memory read write */
  640                 case SDT_MEMRWA:  /* memory read write accessed */
  641                 case SDT_MEMROD:  /* memory read only expand dwn limit */
  642                 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */
  643                 case SDT_MEMRWD:  /* memory read write expand dwn limit */  
  644                 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */
  645                 case SDT_MEME:    /* memory execute only */ 
  646                 case SDT_MEMEA:   /* memory execute only accessed */
  647                 case SDT_MEMER:   /* memory execute read */
  648                 case SDT_MEMERA:  /* memory execute read accessed */
  649                         break;
  650                 default:
  651                         return(EINVAL);
  652                         /*NOTREACHED*/
  653                 }
  654 
  655                 /* Only user (ring-3) descriptors may be present. */
  656                 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL))
  657                         return (EACCES);
  658         }
  659 
  660         if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) {
  661                 /* Allocate a free slot */
  662                 mtx_lock_spin(&dt_lock);
  663                 if ((pldt = mdp->md_ldt) == NULL) {
  664                         if ((error = i386_ldt_grow(td, NLDT + 1))) {
  665                                 mtx_unlock_spin(&dt_lock);
  666                                 return (error);
  667                         }
  668                         pldt = mdp->md_ldt;
  669                 }
  670 again:
  671                 /*
  672                  * start scanning a bit up to leave room for NVidia and
  673                  * Wine, which still user the "Blat" method of allocation.
  674                  */
  675                 dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
  676                 for (i = NLDT; i < pldt->ldt_len; ++i) {
  677                         if (dp->sd.sd_type == SDT_SYSNULL)
  678                                 break;
  679                         dp++;
  680                 }
  681                 if (i >= pldt->ldt_len) {
  682                         if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
  683                                 mtx_unlock_spin(&dt_lock);
  684                                 return (error);
  685                         }
  686                         goto again;
  687                 }
  688                 uap->start = i;
  689                 error = i386_set_ldt_data(td, i, 1, descs);
  690                 mtx_unlock_spin(&dt_lock);
  691         } else {
  692                 largest_ld = uap->start + uap->num;
  693                 mtx_lock_spin(&dt_lock);
  694                 if (!(error = i386_ldt_grow(td, largest_ld))) {
  695                         error = i386_set_ldt_data(td, uap->start, uap->num,
  696                             descs);
  697                 }
  698                 mtx_unlock_spin(&dt_lock);
  699         }
  700         if (error == 0)
  701                 td->td_retval[0] = uap->start;
  702         return (error);
  703 }
  704 
  705 static int
  706 i386_set_ldt_data(struct thread *td, int start, int num,
  707         union descriptor *descs)
  708 {
  709         struct mdproc *mdp = &td->td_proc->p_md;
  710         struct proc_ldt *pldt = mdp->md_ldt;
  711 
  712         mtx_assert(&dt_lock, MA_OWNED);
  713 
  714         /* Fill in range */
  715         bcopy(descs,
  716             &((union descriptor *)(pldt->ldt_base))[start],
  717             num * sizeof(union descriptor));
  718         return (0);
  719 }
  720 
  721 static int
  722 i386_ldt_grow(struct thread *td, int len) 
  723 {
  724         struct mdproc *mdp = &td->td_proc->p_md;
  725         struct proc_ldt *new_ldt, *pldt;
  726         caddr_t old_ldt_base = NULL_LDT_BASE;
  727         int old_ldt_len = 0;
  728 
  729         mtx_assert(&dt_lock, MA_OWNED);
  730 
  731         if (len > MAX_LD)
  732                 return (ENOMEM);
  733         if (len < NLDT + 1)
  734                 len = NLDT + 1;
  735 
  736         /* Allocate a user ldt. */
  737         if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
  738                 new_ldt = user_ldt_alloc(mdp, len);
  739                 if (new_ldt == NULL)
  740                         return (ENOMEM);
  741                 pldt = mdp->md_ldt;
  742 
  743                 if (pldt != NULL) {
  744                         if (new_ldt->ldt_len <= pldt->ldt_len) {
  745                                 /*
  746                                  * We just lost the race for allocation, so
  747                                  * free the new object and return.
  748                                  */
  749                                 mtx_unlock_spin(&dt_lock);
  750                                 kmem_free(kernel_arena,
  751                                    (vm_offset_t)new_ldt->ldt_base,
  752                                    new_ldt->ldt_len * sizeof(union descriptor));
  753                                 free(new_ldt, M_SUBPROC);
  754                                 mtx_lock_spin(&dt_lock);
  755                                 return (0);
  756                         }
  757 
  758                         /*
  759                          * We have to substitute the current LDT entry for
  760                          * curproc with the new one since its size grew.
  761                          */
  762                         old_ldt_base = pldt->ldt_base;
  763                         old_ldt_len = pldt->ldt_len;
  764                         pldt->ldt_sd = new_ldt->ldt_sd;
  765                         pldt->ldt_base = new_ldt->ldt_base;
  766                         pldt->ldt_len = new_ldt->ldt_len;
  767                 } else
  768                         mdp->md_ldt = pldt = new_ldt;
  769 #ifdef SMP
  770                 /*
  771                  * Signal other cpus to reload ldt.  We need to unlock dt_lock
  772                  * here because other CPU will contest on it since their
  773                  * curthreads won't hold the lock and will block when trying
  774                  * to acquire it.
  775                  */
  776                 mtx_unlock_spin(&dt_lock);
  777                 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv,
  778                     NULL, td->td_proc->p_vmspace);
  779 #else
  780                 set_user_ldt(&td->td_proc->p_md);
  781                 mtx_unlock_spin(&dt_lock);
  782 #endif
  783                 if (old_ldt_base != NULL_LDT_BASE) {
  784                         kmem_free(kernel_arena, (vm_offset_t)old_ldt_base,
  785                             old_ldt_len * sizeof(union descriptor));
  786                         free(new_ldt, M_SUBPROC);
  787                 }
  788                 mtx_lock_spin(&dt_lock);
  789         }
  790         return (0);
  791 }

Cache object: 212e1e7ffbc63dfe265855211aa41a35


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