1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
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 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_capsicum.h"
38 #include "opt_kstack_pages.h"
39
40 #include <sys/param.h>
41 #include <sys/capsicum.h>
42 #include <sys/systm.h>
43 #include <sys/lock.h>
44 #include <sys/malloc.h>
45 #include <sys/mutex.h>
46 #include <sys/priv.h>
47 #include <sys/proc.h>
48 #include <sys/smp.h>
49 #include <sys/sysproto.h>
50
51 #include <vm/vm.h>
52 #include <vm/pmap.h>
53 #include <vm/vm_map.h>
54 #include <vm/vm_extern.h>
55
56 #include <machine/atomic.h>
57 #include <machine/cpu.h>
58 #include <machine/pcb.h>
59 #include <machine/pcb_ext.h>
60 #include <machine/proc.h>
61 #include <machine/sysarch.h>
62
63 #include <security/audit/audit.h>
64
65 #include <vm/vm_kern.h> /* for kernel_map */
66
67 #define MAX_LD 8192
68 #define LD_PER_PAGE 512
69 #define NEW_MAX_LD(num) rounddown2(num + LD_PER_PAGE, LD_PER_PAGE)
70 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)
71 #define NULL_LDT_BASE ((caddr_t)NULL)
72
73 #ifdef SMP
74 static void set_user_ldt_rv(void *arg);
75 #endif
76 static int i386_set_ldt_data(struct thread *, int start, int num,
77 union descriptor *descs);
78 static int i386_ldt_grow(struct thread *td, int len);
79
80 void
81 fill_based_sd(struct segment_descriptor *sdp, uint32_t base)
82 {
83
84 sdp->sd_lobase = base & 0xffffff;
85 sdp->sd_hibase = (base >> 24) & 0xff;
86 sdp->sd_lolimit = 0xffff; /* 4GB limit, wraps around */
87 sdp->sd_hilimit = 0xf;
88 sdp->sd_type = SDT_MEMRWA;
89 sdp->sd_dpl = SEL_UPL;
90 sdp->sd_p = 1;
91 sdp->sd_xx = 0;
92 sdp->sd_def32 = 1;
93 sdp->sd_gran = 1;
94 }
95
96 /*
97 * Construct special descriptors for "base" selectors. Store them in
98 * the PCB for later use by cpu_switch(). Store them in the GDT for
99 * more immediate use. The GDT entries are part of the current
100 * context. Callers must load related segment registers to complete
101 * setting up the current context.
102 */
103 void
104 set_fsbase(struct thread *td, uint32_t base)
105 {
106 struct segment_descriptor sd;
107
108 fill_based_sd(&sd, base);
109 critical_enter();
110 td->td_pcb->pcb_fsd = sd;
111 PCPU_GET(fsgs_gdt)[0] = sd;
112 critical_exit();
113 }
114
115 void
116 set_gsbase(struct thread *td, uint32_t base)
117 {
118 struct segment_descriptor sd;
119
120 fill_based_sd(&sd, base);
121 critical_enter();
122 td->td_pcb->pcb_gsd = sd;
123 PCPU_GET(fsgs_gdt)[1] = sd;
124 critical_exit();
125 }
126
127 #ifndef _SYS_SYSPROTO_H_
128 struct sysarch_args {
129 int op;
130 char *parms;
131 };
132 #endif
133
134 int
135 sysarch(struct thread *td, struct sysarch_args *uap)
136 {
137 int error;
138 union descriptor *lp;
139 union {
140 struct i386_ldt_args largs;
141 struct i386_ioperm_args iargs;
142 struct i386_get_xfpustate xfpu;
143 } kargs;
144 uint32_t base;
145 struct segment_descriptor *sdp;
146
147 AUDIT_ARG_CMD(uap->op);
148
149 #ifdef CAPABILITY_MODE
150 /*
151 * When adding new operations, add a new case statement here to
152 * explicitly indicate whether or not the operation is safe to
153 * perform in capability mode.
154 */
155 if (IN_CAPABILITY_MODE(td)) {
156 switch (uap->op) {
157 case I386_GET_LDT:
158 case I386_SET_LDT:
159 case I386_GET_IOPERM:
160 case I386_GET_FSBASE:
161 case I386_SET_FSBASE:
162 case I386_GET_GSBASE:
163 case I386_SET_GSBASE:
164 case I386_GET_XFPUSTATE:
165 break;
166
167 case I386_SET_IOPERM:
168 default:
169 #ifdef KTRACE
170 if (KTRPOINT(td, KTR_CAPFAIL))
171 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL);
172 #endif
173 return (ECAPMODE);
174 }
175 }
176 #endif
177
178 switch (uap->op) {
179 case I386_GET_IOPERM:
180 case I386_SET_IOPERM:
181 if ((error = copyin(uap->parms, &kargs.iargs,
182 sizeof(struct i386_ioperm_args))) != 0)
183 return (error);
184 break;
185 case I386_GET_LDT:
186 case I386_SET_LDT:
187 if ((error = copyin(uap->parms, &kargs.largs,
188 sizeof(struct i386_ldt_args))) != 0)
189 return (error);
190 break;
191 case I386_GET_XFPUSTATE:
192 if ((error = copyin(uap->parms, &kargs.xfpu,
193 sizeof(struct i386_get_xfpustate))) != 0)
194 return (error);
195 break;
196 default:
197 break;
198 }
199
200 switch (uap->op) {
201 case I386_GET_LDT:
202 error = i386_get_ldt(td, &kargs.largs);
203 break;
204 case I386_SET_LDT:
205 if (kargs.largs.descs != NULL) {
206 if (kargs.largs.num > MAX_LD)
207 return (EINVAL);
208 lp = malloc(kargs.largs.num * sizeof(union descriptor),
209 M_TEMP, M_WAITOK);
210 error = copyin(kargs.largs.descs, lp,
211 kargs.largs.num * sizeof(union descriptor));
212 if (error == 0)
213 error = i386_set_ldt(td, &kargs.largs, lp);
214 free(lp, M_TEMP);
215 } else {
216 error = i386_set_ldt(td, &kargs.largs, NULL);
217 }
218 break;
219 case I386_GET_IOPERM:
220 error = i386_get_ioperm(td, &kargs.iargs);
221 if (error == 0)
222 error = copyout(&kargs.iargs, uap->parms,
223 sizeof(struct i386_ioperm_args));
224 break;
225 case I386_SET_IOPERM:
226 error = i386_set_ioperm(td, &kargs.iargs);
227 break;
228 case I386_VM86:
229 error = vm86_sysarch(td, uap->parms);
230 break;
231 case I386_GET_FSBASE:
232 sdp = &td->td_pcb->pcb_fsd;
233 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
234 error = copyout(&base, uap->parms, sizeof(base));
235 break;
236 case I386_SET_FSBASE:
237 error = copyin(uap->parms, &base, sizeof(base));
238 if (error == 0) {
239 /*
240 * Construct the special descriptor for fsbase
241 * and arrange for doreti to load its selector
242 * soon enough.
243 */
244 set_fsbase(td, base);
245 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
246 }
247 break;
248 case I386_GET_GSBASE:
249 sdp = &td->td_pcb->pcb_gsd;
250 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
251 error = copyout(&base, uap->parms, sizeof(base));
252 break;
253 case I386_SET_GSBASE:
254 error = copyin(uap->parms, &base, sizeof(base));
255 if (error == 0) {
256 /*
257 * Construct the special descriptor for gsbase.
258 * The selector is loaded immediately, since we
259 * normally only reload %gs on context switches.
260 */
261 set_gsbase(td, base);
262 load_gs(GSEL(GUGS_SEL, SEL_UPL));
263 }
264 break;
265 case I386_GET_XFPUSTATE:
266 if (kargs.xfpu.len > cpu_max_ext_state_size -
267 sizeof(union savefpu))
268 return (EINVAL);
269 npxgetregs(td);
270 error = copyout((char *)(get_pcb_user_save_td(td) + 1),
271 kargs.xfpu.addr, kargs.xfpu.len);
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 = pmap_trm_alloc(ctob(IOPAGES + 1), M_WAITOK | M_ZERO);
298 /* -16 is so we can convert a trapframe into vm86trapframe inplace */
299 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
300 /*
301 * The last byte of the i/o map must be followed by an 0xff byte.
302 * We arbitrarily allocate 16 bytes here, to keep the starting
303 * address on a doubleword boundary.
304 */
305 offset = PAGE_SIZE - 16;
306 ext->ext_tss.tss_ioopt =
307 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16;
308 ext->ext_iomap = (caddr_t)ext + offset;
309 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32;
310
311 addr = (u_long *)ext->ext_vm86.vm86_intmap;
312 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
313 *addr++ = ~0;
314
315 ssd.ssd_base = (unsigned)&ext->ext_tss;
316 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
317 ssdtosd(&ssd, &ext->ext_tssd);
318
319 KASSERT(td == curthread, ("giving TSS to !curthread"));
320 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
321
322 /* Switch to the new TSS. */
323 critical_enter();
324 ext->ext_tss.tss_esp0 = PCPU_GET(trampstk);
325 td->td_pcb->pcb_ext = ext;
326 PCPU_SET(private_tss, 1);
327 *PCPU_GET(tss_gdt) = ext->ext_tssd;
328 ltr(GSEL(GPROC0_SEL, SEL_KPL));
329 critical_exit();
330
331 return 0;
332 }
333
334 int
335 i386_set_ioperm(td, uap)
336 struct thread *td;
337 struct i386_ioperm_args *uap;
338 {
339 char *iomap;
340 u_int i;
341 int error;
342
343 if ((error = priv_check(td, PRIV_IO)) != 0)
344 return (error);
345 if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
346 return (error);
347 /*
348 * XXX
349 * While this is restricted to root, we should probably figure out
350 * whether any other driver is using this i/o address, as so not to
351 * cause confusion. This probably requires a global 'usage registry'.
352 */
353
354 if (td->td_pcb->pcb_ext == 0)
355 if ((error = i386_extend_pcb(td)) != 0)
356 return (error);
357 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
358
359 if (uap->start > uap->start + uap->length ||
360 uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
361 return (EINVAL);
362
363 for (i = uap->start; i < uap->start + uap->length; i++) {
364 if (uap->enable)
365 iomap[i >> 3] &= ~(1 << (i & 7));
366 else
367 iomap[i >> 3] |= (1 << (i & 7));
368 }
369 return (error);
370 }
371
372 int
373 i386_get_ioperm(td, uap)
374 struct thread *td;
375 struct i386_ioperm_args *uap;
376 {
377 int i, state;
378 char *iomap;
379
380 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
381 return (EINVAL);
382
383 if (td->td_pcb->pcb_ext == 0) {
384 uap->length = 0;
385 goto done;
386 }
387
388 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
389
390 i = uap->start;
391 state = (iomap[i >> 3] >> (i & 7)) & 1;
392 uap->enable = !state;
393 uap->length = 1;
394
395 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
396 if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
397 break;
398 uap->length++;
399 }
400
401 done:
402 return (0);
403 }
404
405 /*
406 * Update the GDT entry pointing to the LDT to point to the LDT of the
407 * current process. Manage dt_lock holding/unholding autonomously.
408 */
409 static void
410 set_user_ldt_locked(struct mdproc *mdp)
411 {
412 struct proc_ldt *pldt;
413 int gdt_idx;
414
415 mtx_assert(&dt_lock, MA_OWNED);
416
417 pldt = mdp->md_ldt;
418 gdt_idx = GUSERLDT_SEL;
419 gdt_idx += PCPU_GET(cpuid) * NGDT; /* always 0 on UP */
420 gdt[gdt_idx].sd = pldt->ldt_sd;
421 lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
422 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
423 }
424
425 void
426 set_user_ldt(struct mdproc *mdp)
427 {
428
429 mtx_lock_spin(&dt_lock);
430 set_user_ldt_locked(mdp);
431 mtx_unlock_spin(&dt_lock);
432 }
433
434 #ifdef SMP
435 static void
436 set_user_ldt_rv(void *arg)
437 {
438 struct proc *p;
439
440 p = curproc;
441 if (arg == p->p_vmspace)
442 set_user_ldt(&p->p_md);
443 }
444 #endif
445
446 /*
447 * dt_lock must be held. Returns with dt_lock held.
448 */
449 struct proc_ldt *
450 user_ldt_alloc(struct mdproc *mdp, int len)
451 {
452 struct proc_ldt *pldt, *new_ldt;
453
454 mtx_assert(&dt_lock, MA_OWNED);
455 mtx_unlock_spin(&dt_lock);
456 new_ldt = malloc(sizeof(struct proc_ldt), M_SUBPROC, M_WAITOK);
457
458 new_ldt->ldt_len = len = NEW_MAX_LD(len);
459 new_ldt->ldt_base = pmap_trm_alloc(len * sizeof(union descriptor),
460 M_WAITOK | M_ZERO);
461 new_ldt->ldt_refcnt = 1;
462 new_ldt->ldt_active = 0;
463
464 mtx_lock_spin(&dt_lock);
465 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base;
466 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
467 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
468
469 if ((pldt = mdp->md_ldt) != NULL) {
470 if (len > pldt->ldt_len)
471 len = pldt->ldt_len;
472 bcopy(pldt->ldt_base, new_ldt->ldt_base,
473 len * sizeof(union descriptor));
474 } else
475 bcopy(ldt, new_ldt->ldt_base, sizeof(union descriptor) * NLDT);
476
477 return (new_ldt);
478 }
479
480 /*
481 * Must be called with dt_lock held. Returns with dt_lock unheld.
482 */
483 void
484 user_ldt_free(struct thread *td)
485 {
486 struct mdproc *mdp;
487 struct proc_ldt *pldt;
488
489 mtx_assert(&dt_lock, MA_OWNED);
490 mdp = &td->td_proc->p_md;
491 if ((pldt = mdp->md_ldt) == NULL) {
492 mtx_unlock_spin(&dt_lock);
493 return;
494 }
495
496 if (td == curthread) {
497 lldt(_default_ldt);
498 PCPU_SET(currentldt, _default_ldt);
499 }
500
501 mdp->md_ldt = NULL;
502 user_ldt_deref(pldt);
503 }
504
505 void
506 user_ldt_deref(struct proc_ldt *pldt)
507 {
508
509 mtx_assert(&dt_lock, MA_OWNED);
510 if (--pldt->ldt_refcnt == 0) {
511 mtx_unlock_spin(&dt_lock);
512 pmap_trm_free(pldt->ldt_base, pldt->ldt_len *
513 sizeof(union descriptor));
514 free(pldt, M_SUBPROC);
515 } else
516 mtx_unlock_spin(&dt_lock);
517 }
518
519 /*
520 * Note for the authors of compat layers (linux, etc): copyout() in
521 * the function below is not a problem since it presents data in
522 * arch-specific format (i.e. i386-specific in this case), not in
523 * the OS-specific one.
524 */
525 int
526 i386_get_ldt(struct thread *td, struct i386_ldt_args *uap)
527 {
528 struct proc_ldt *pldt;
529 char *data;
530 u_int nldt, num;
531 int error;
532
533 #ifdef DEBUG
534 printf("i386_get_ldt: start=%u num=%u descs=%p\n",
535 uap->start, uap->num, (void *)uap->descs);
536 #endif
537
538 num = min(uap->num, MAX_LD);
539 data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK);
540 mtx_lock_spin(&dt_lock);
541 pldt = td->td_proc->p_md.md_ldt;
542 nldt = pldt != NULL ? pldt->ldt_len : NLDT;
543 if (uap->start >= nldt) {
544 num = 0;
545 } else {
546 num = min(num, nldt - uap->start);
547 bcopy(pldt != NULL ?
548 &((union descriptor *)(pldt->ldt_base))[uap->start] :
549 &ldt[uap->start], data, num * sizeof(union descriptor));
550 }
551 mtx_unlock_spin(&dt_lock);
552 error = copyout(data, uap->descs, num * sizeof(union descriptor));
553 if (error == 0)
554 td->td_retval[0] = num;
555 free(data, M_TEMP);
556 return (error);
557 }
558
559 int
560 i386_set_ldt(struct thread *td, struct i386_ldt_args *uap,
561 union descriptor *descs)
562 {
563 struct mdproc *mdp;
564 struct proc_ldt *pldt;
565 union descriptor *dp;
566 u_int largest_ld, i;
567 int error;
568
569 #ifdef DEBUG
570 printf("i386_set_ldt: start=%u num=%u descs=%p\n",
571 uap->start, uap->num, (void *)uap->descs);
572 #endif
573 error = 0;
574 mdp = &td->td_proc->p_md;
575
576 if (descs == NULL) {
577 /* Free descriptors */
578 if (uap->start == 0 && uap->num == 0) {
579 /*
580 * Treat this as a special case, so userland needn't
581 * know magic number NLDT.
582 */
583 uap->start = NLDT;
584 uap->num = MAX_LD - NLDT;
585 }
586 mtx_lock_spin(&dt_lock);
587 if ((pldt = mdp->md_ldt) == NULL ||
588 uap->start >= pldt->ldt_len) {
589 mtx_unlock_spin(&dt_lock);
590 return (0);
591 }
592 largest_ld = uap->start + uap->num;
593 if (largest_ld > pldt->ldt_len)
594 largest_ld = pldt->ldt_len;
595 for (i = uap->start; i < largest_ld; i++)
596 atomic_store_rel_64(&((uint64_t *)(pldt->ldt_base))[i],
597 0);
598 mtx_unlock_spin(&dt_lock);
599 return (0);
600 }
601
602 if (uap->start != LDT_AUTO_ALLOC || uap->num != 1) {
603 /* verify range of descriptors to modify */
604 largest_ld = uap->start + uap->num;
605 if (uap->start >= MAX_LD || largest_ld > MAX_LD)
606 return (EINVAL);
607 }
608
609 /* Check descriptors for access violations */
610 for (i = 0; i < uap->num; i++) {
611 dp = &descs[i];
612
613 switch (dp->sd.sd_type) {
614 case SDT_SYSNULL: /* system null */
615 dp->sd.sd_p = 0;
616 break;
617 case SDT_SYS286TSS: /* system 286 TSS available */
618 case SDT_SYSLDT: /* system local descriptor table */
619 case SDT_SYS286BSY: /* system 286 TSS busy */
620 case SDT_SYSTASKGT: /* system task gate */
621 case SDT_SYS286IGT: /* system 286 interrupt gate */
622 case SDT_SYS286TGT: /* system 286 trap gate */
623 case SDT_SYSNULL2: /* undefined by Intel */
624 case SDT_SYS386TSS: /* system 386 TSS available */
625 case SDT_SYSNULL3: /* undefined by Intel */
626 case SDT_SYS386BSY: /* system 386 TSS busy */
627 case SDT_SYSNULL4: /* undefined by Intel */
628 case SDT_SYS386IGT: /* system 386 interrupt gate */
629 case SDT_SYS386TGT: /* system 386 trap gate */
630 case SDT_SYS286CGT: /* system 286 call gate */
631 case SDT_SYS386CGT: /* system 386 call gate */
632 return (EACCES);
633
634 /* memory segment types */
635 case SDT_MEMEC: /* memory execute only conforming */
636 case SDT_MEMEAC: /* memory execute only accessed conforming */
637 case SDT_MEMERC: /* memory execute read conforming */
638 case SDT_MEMERAC: /* memory execute read accessed conforming */
639 /* Must be "present" if executable and conforming. */
640 if (dp->sd.sd_p == 0)
641 return (EACCES);
642 break;
643 case SDT_MEMRO: /* memory read only */
644 case SDT_MEMROA: /* memory read only accessed */
645 case SDT_MEMRW: /* memory read write */
646 case SDT_MEMRWA: /* memory read write accessed */
647 case SDT_MEMROD: /* memory read only expand dwn limit */
648 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */
649 case SDT_MEMRWD: /* memory read write expand dwn limit */
650 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */
651 case SDT_MEME: /* memory execute only */
652 case SDT_MEMEA: /* memory execute only accessed */
653 case SDT_MEMER: /* memory execute read */
654 case SDT_MEMERA: /* memory execute read accessed */
655 break;
656 default:
657 return (EINVAL);
658 }
659
660 /* Only user (ring-3) descriptors may be present. */
661 if (dp->sd.sd_p != 0 && dp->sd.sd_dpl != SEL_UPL)
662 return (EACCES);
663 }
664
665 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) {
666 /* Allocate a free slot */
667 mtx_lock_spin(&dt_lock);
668 if ((pldt = mdp->md_ldt) == NULL) {
669 if ((error = i386_ldt_grow(td, NLDT + 1))) {
670 mtx_unlock_spin(&dt_lock);
671 return (error);
672 }
673 pldt = mdp->md_ldt;
674 }
675 again:
676 /*
677 * start scanning a bit up to leave room for NVidia and
678 * Wine, which still user the "Blat" method of allocation.
679 */
680 dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
681 for (i = NLDT; i < pldt->ldt_len; ++i) {
682 if (dp->sd.sd_type == SDT_SYSNULL)
683 break;
684 dp++;
685 }
686 if (i >= pldt->ldt_len) {
687 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
688 mtx_unlock_spin(&dt_lock);
689 return (error);
690 }
691 goto again;
692 }
693 uap->start = i;
694 error = i386_set_ldt_data(td, i, 1, descs);
695 mtx_unlock_spin(&dt_lock);
696 } else {
697 largest_ld = uap->start + uap->num;
698 mtx_lock_spin(&dt_lock);
699 if (!(error = i386_ldt_grow(td, largest_ld))) {
700 error = i386_set_ldt_data(td, uap->start, uap->num,
701 descs);
702 }
703 mtx_unlock_spin(&dt_lock);
704 }
705 if (error == 0)
706 td->td_retval[0] = uap->start;
707 return (error);
708 }
709
710 static int
711 i386_set_ldt_data(struct thread *td, int start, int num,
712 union descriptor *descs)
713 {
714 struct mdproc *mdp;
715 struct proc_ldt *pldt;
716 uint64_t *dst, *src;
717 int i;
718
719 mtx_assert(&dt_lock, MA_OWNED);
720
721 mdp = &td->td_proc->p_md;
722 pldt = mdp->md_ldt;
723 dst = (uint64_t *)(pldt->ldt_base);
724 src = (uint64_t *)descs;
725
726 /*
727 * Atomic(9) is used only to get 64bit atomic store with
728 * cmpxchg8b when available. There is no op without release
729 * semantic.
730 */
731 for (i = 0; i < num; i++)
732 atomic_store_rel_64(&dst[start + i], src[i]);
733 return (0);
734 }
735
736 static int
737 i386_ldt_grow(struct thread *td, int len)
738 {
739 struct mdproc *mdp;
740 struct proc_ldt *new_ldt, *pldt;
741 caddr_t old_ldt_base;
742 int old_ldt_len;
743
744 mtx_assert(&dt_lock, MA_OWNED);
745
746 if (len > MAX_LD)
747 return (ENOMEM);
748 if (len < NLDT + 1)
749 len = NLDT + 1;
750
751 mdp = &td->td_proc->p_md;
752 old_ldt_base = NULL_LDT_BASE;
753 old_ldt_len = 0;
754
755 /* Allocate a user ldt. */
756 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
757 new_ldt = user_ldt_alloc(mdp, len);
758 if (new_ldt == NULL)
759 return (ENOMEM);
760 pldt = mdp->md_ldt;
761
762 if (pldt != NULL) {
763 if (new_ldt->ldt_len <= pldt->ldt_len) {
764 /*
765 * We just lost the race for allocation, so
766 * free the new object and return.
767 */
768 mtx_unlock_spin(&dt_lock);
769 pmap_trm_free(new_ldt->ldt_base,
770 new_ldt->ldt_len * sizeof(union descriptor));
771 free(new_ldt, M_SUBPROC);
772 mtx_lock_spin(&dt_lock);
773 return (0);
774 }
775
776 /*
777 * We have to substitute the current LDT entry for
778 * curproc with the new one since its size grew.
779 */
780 old_ldt_base = pldt->ldt_base;
781 old_ldt_len = pldt->ldt_len;
782 pldt->ldt_sd = new_ldt->ldt_sd;
783 pldt->ldt_base = new_ldt->ldt_base;
784 pldt->ldt_len = new_ldt->ldt_len;
785 } else
786 mdp->md_ldt = pldt = new_ldt;
787 #ifdef SMP
788 /*
789 * Signal other cpus to reload ldt. We need to unlock dt_lock
790 * here because other CPU will contest on it since their
791 * curthreads won't hold the lock and will block when trying
792 * to acquire it.
793 */
794 mtx_unlock_spin(&dt_lock);
795 smp_rendezvous(NULL, set_user_ldt_rv, NULL,
796 td->td_proc->p_vmspace);
797 #else
798 set_user_ldt_locked(&td->td_proc->p_md);
799 mtx_unlock_spin(&dt_lock);
800 #endif
801 if (old_ldt_base != NULL_LDT_BASE) {
802 pmap_trm_free(old_ldt_base, old_ldt_len *
803 sizeof(union descriptor));
804 free(new_ldt, M_SUBPROC);
805 }
806 mtx_lock_spin(&dt_lock);
807 }
808 return (0);
809 }
Cache object: d972b24a90ef922c638dc01bd3399401
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