2 * Copyright (c) 1990 The Regents of the University of California.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
29 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include "opt_capsicum.h"
36 #include "opt_kstack_pages.h"
38 #include <sys/param.h>
39 #include <sys/capability.h>
40 #include <sys/systm.h>
42 #include <sys/malloc.h>
43 #include <sys/mutex.h>
47 #include <sys/sysproto.h>
51 #include <vm/vm_map.h>
52 #include <vm/vm_extern.h>
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>
60 #include <security/audit/audit.h>
63 #include <machine/xen/xenfunc.h>
65 void i386_reset_ldt(struct proc_ldt *pldt);
68 i386_reset_ldt(struct proc_ldt *pldt)
70 xen_set_ldt((vm_offset_t)pldt->ldt_base, pldt->ldt_len);
73 #define i386_reset_ldt(x)
76 #include <vm/vm_kern.h> /* for kernel_map */
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)
85 static void set_user_ldt_rv(struct vmspace *vmsp);
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);
91 #ifndef _SYS_SYSPROTO_H_
101 register struct sysarch_args *uap;
104 union descriptor *lp;
106 struct i386_ldt_args largs;
107 struct i386_ioperm_args iargs;
110 struct segment_descriptor sd, *sdp;
112 AUDIT_ARG_CMD(uap->op);
114 #ifdef CAPABILITY_MODE
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.
120 if (IN_CAPABILITY_MODE(td)) {
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:
131 case I386_SET_IOPERM:
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)
147 if ((error = copyin(uap->parms, &kargs.largs,
148 sizeof(struct i386_ldt_args))) != 0)
150 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0)
159 error = i386_get_ldt(td, &kargs.largs);
162 if (kargs.largs.descs != NULL) {
163 lp = (union descriptor *)kmem_alloc(kernel_map,
164 kargs.largs.num * sizeof(union descriptor));
169 error = copyin(kargs.largs.descs, lp,
170 kargs.largs.num * sizeof(union descriptor));
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));
176 error = i386_set_ldt(td, &kargs.largs, NULL);
179 case I386_GET_IOPERM:
180 error = i386_get_ioperm(td, &kargs.iargs);
182 error = copyout(&kargs.iargs, uap->parms,
183 sizeof(struct i386_ioperm_args));
185 case I386_SET_IOPERM:
186 error = i386_set_ioperm(td, &kargs.iargs);
189 error = vm86_sysarch(td, uap->parms);
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));
196 case I386_SET_FSBASE:
197 error = copyin(uap->parms, &base, sizeof(base));
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.
205 sd.sd_lobase = base & 0xffffff;
206 sd.sd_hibase = (base >> 24) & 0xff;
208 /* need to do nosegneg like Linux */
209 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff;
211 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
214 sd.sd_type = SDT_MEMRWA;
221 td->td_pcb->pcb_fsd = sd;
223 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[0]),
226 PCPU_GET(fsgs_gdt)[0] = sd;
229 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
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));
237 case I386_SET_GSBASE:
238 error = copyin(uap->parms, &base, sizeof(base));
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.
245 sd.sd_lobase = base & 0xffffff;
246 sd.sd_hibase = (base >> 24) & 0xff;
249 /* need to do nosegneg like Linux */
250 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff;
252 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
255 sd.sd_type = SDT_MEMRWA;
262 td->td_pcb->pcb_gsd = sd;
264 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[1]),
267 PCPU_GET(fsgs_gdt)[1] = sd;
270 load_gs(GSEL(GUGS_SEL, SEL_UPL));
281 i386_extend_pcb(struct thread *td)
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 */
293 0, /* default 32 size */
297 ext = (struct pcb_ext *)kmem_alloc(kernel_map, ctob(IOPAGES+1));
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);
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.
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;
316 addr = (u_long *)ext->ext_vm86.vm86_intmap;
317 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
320 ssd.ssd_base = (unsigned)&ext->ext_tss;
321 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
322 ssdtosd(&ssd, &ext->ext_tssd);
324 KASSERT(td == curthread, ("giving TSS to !curthread"));
325 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
327 /* Switch to the new TSS. */
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));
339 i386_set_ioperm(td, uap)
341 struct i386_ioperm_args *uap;
346 if ((error = priv_check(td, PRIV_IO)) != 0)
348 if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
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'.
357 if (td->td_pcb->pcb_ext == 0)
358 if ((error = i386_extend_pcb(td)) != 0)
360 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
362 if (uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
365 for (i = uap->start; i < uap->start + uap->length; i++) {
367 iomap[i >> 3] &= ~(1 << (i & 7));
369 iomap[i >> 3] |= (1 << (i & 7));
375 i386_get_ioperm(td, uap)
377 struct i386_ioperm_args *uap;
382 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
385 if (td->td_pcb->pcb_ext == 0) {
390 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
393 state = (iomap[i >> 3] >> (i & 7)) & 1;
394 uap->enable = !state;
397 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
398 if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
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.
412 set_user_ldt(struct mdproc *mdp)
414 struct proc_ldt *pldt;
418 if (!mtx_owned(&dt_lock)) {
419 mtx_lock_spin(&dt_lock);
425 i386_reset_ldt(pldt);
426 PCPU_SET(currentldt, (int)pldt);
429 gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd;
431 gdt[GUSERLDT_SEL].sd = pldt->ldt_sd;
433 lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
434 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
437 mtx_unlock_spin(&dt_lock);
442 set_user_ldt_rv(struct vmspace *vmsp)
447 if (vmsp != td->td_proc->p_vmspace)
450 set_user_ldt(&td->td_proc->p_md);
457 * dt_lock must be held. Returns with dt_lock held.
460 user_ldt_alloc(struct mdproc *mdp, int len)
462 struct proc_ldt *pldt, *new_ldt;
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);
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);
477 new_ldt->ldt_refcnt = 1;
478 new_ldt->ldt_active = 0;
480 mtx_lock_spin(&dt_lock);
481 if ((pldt = mdp->md_ldt)) {
482 if (len > pldt->ldt_len)
484 bcopy(pldt->ldt_base, new_ldt->ldt_base,
485 len * sizeof(union descriptor));
487 bcopy(ldt, new_ldt->ldt_base, PAGE_SIZE);
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. */
497 * dt_lock must be held. Returns with dt_lock held.
500 user_ldt_alloc(struct mdproc *mdp, int len)
502 struct proc_ldt *pldt, *new_ldt;
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);
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);
517 new_ldt->ldt_refcnt = 1;
518 new_ldt->ldt_active = 0;
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);
525 if ((pldt = mdp->md_ldt) != NULL) {
526 if (len > pldt->ldt_len)
528 bcopy(pldt->ldt_base, new_ldt->ldt_base,
529 len * sizeof(union descriptor));
531 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
538 * Must be called with dt_lock held. Returns with dt_lock unheld.
541 user_ldt_free(struct thread *td)
543 struct mdproc *mdp = &td->td_proc->p_md;
544 struct proc_ldt *pldt;
546 mtx_assert(&dt_lock, MA_OWNED);
547 if ((pldt = mdp->md_ldt) == NULL) {
548 mtx_unlock_spin(&dt_lock);
552 if (td == PCPU_GET(curthread)) {
554 i386_reset_ldt(&default_proc_ldt);
555 PCPU_SET(currentldt, (int)&default_proc_ldt);
558 PCPU_SET(currentldt, _default_ldt);
563 user_ldt_deref(pldt);
567 user_ldt_deref(struct proc_ldt *pldt)
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);
577 mtx_unlock_spin(&dt_lock);
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.
587 i386_get_ldt(td, uap)
589 struct i386_ldt_args *uap;
592 struct proc_ldt *pldt;
594 union descriptor *lp;
597 printf("i386_get_ldt: start=%d num=%d descs=%p\n",
598 uap->start, uap->num, (void *)uap->descs);
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);
608 mtx_unlock_spin(&dt_lock);
609 nldt = sizeof(ldt)/sizeof(ldt[0]);
610 num = min(uap->num, nldt);
611 lp = &ldt[uap->start];
614 if ((uap->start > (unsigned int)nldt) ||
615 ((unsigned int)num > (unsigned int)nldt) ||
616 ((unsigned int)(uap->start + num) > (unsigned int)nldt))
619 error = copyout(lp, uap->descs, num * sizeof(union descriptor));
621 td->td_retval[0] = num;
627 i386_set_ldt(td, uap, descs)
629 struct i386_ldt_args *uap;
630 union descriptor *descs;
634 struct mdproc *mdp = &td->td_proc->p_md;
635 struct proc_ldt *pldt;
636 union descriptor *dp;
639 printf("i386_set_ldt: start=%d num=%d descs=%p\n",
640 uap->start, uap->num, (void *)uap->descs);
644 /* Free descriptors */
645 if (uap->start == 0 && uap->num == 0) {
647 * Treat this as a special case, so userland needn't
648 * know magic number NLDT.
651 uap->num = MAX_LD - NLDT;
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);
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);
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) {
679 /* Check descriptors for access violations */
680 for (i = 0; i < uap->num; i++) {
683 switch (dp->sd.sd_type) {
684 case SDT_SYSNULL: /* system null */
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
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)
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 */
736 /* Only user (ring-3) descriptors may be present. */
737 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL))
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);
753 * start scanning a bit up to leave room for NVidia and
754 * Wine, which still user the "Blat" method of allocation.
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)
762 if (i >= pldt->ldt_len) {
763 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
764 mtx_unlock_spin(&dt_lock);
770 error = i386_set_ldt_data(td, i, 1, descs);
771 mtx_unlock_spin(&dt_lock);
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,
779 mtx_unlock_spin(&dt_lock);
782 td->td_retval[0] = uap->start;
787 i386_set_ldt_data(struct thread *td, int start, int num,
788 union descriptor *descs)
790 struct mdproc *mdp = &td->td_proc->p_md;
791 struct proc_ldt *pldt = mdp->md_ldt;
793 mtx_assert(&dt_lock, MA_OWNED);
796 xen_update_descriptor(
797 &((union descriptor *)(pldt->ldt_base))[start],
807 i386_set_ldt_data(struct thread *td, int start, int num,
808 union descriptor *descs)
810 struct mdproc *mdp = &td->td_proc->p_md;
811 struct proc_ldt *pldt = mdp->md_ldt;
813 mtx_assert(&dt_lock, MA_OWNED);
817 &((union descriptor *)(pldt->ldt_base))[start],
818 num * sizeof(union descriptor));
824 i386_ldt_grow(struct thread *td, int len)
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;
831 mtx_assert(&dt_lock, MA_OWNED);
838 /* Allocate a user ldt. */
839 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
840 new_ldt = user_ldt_alloc(mdp, len);
846 if (new_ldt->ldt_len <= pldt->ldt_len) {
848 * We just lost the race for allocation, so
849 * free the new object and return.
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);
861 * We have to substitute the current LDT entry for
862 * curproc with the new one since its size grew.
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;
870 mdp->md_ldt = pldt = new_ldt;
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
878 mtx_unlock_spin(&dt_lock);
879 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv,
880 NULL, td->td_proc->p_vmspace);
882 set_user_ldt(&td->td_proc->p_md);
883 mtx_unlock_spin(&dt_lock);
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);
890 mtx_lock_spin(&dt_lock);