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