Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/sys_machdep.c
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1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD: releng/5.4/sys/i386/i386/sys_machdep.c 145952 2005-05-06 02:40:49Z cperciva $"); 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/mac.h> 42 #include <sys/malloc.h> 43 #include <sys/mutex.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 <vm/vm_kern.h> /* for kernel_map */ 60 61 #define MAX_LD 8192 62 #define LD_PER_PAGE 512 63 #define NEW_MAX_LD(num) ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1)) 64 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3) 65 66 67 68 static int i386_get_ldt(struct thread *, char *); 69 static int i386_set_ldt(struct thread *, char *); 70 static int i386_set_ldt_data(struct thread *, int start, int num, 71 union descriptor *descs); 72 static int i386_ldt_grow(struct thread *td, int len); 73 static int i386_get_ioperm(struct thread *, char *); 74 static int i386_set_ioperm(struct thread *, char *); 75 #ifdef SMP 76 static void set_user_ldt_rv(struct thread *); 77 #endif 78 79 #ifndef _SYS_SYSPROTO_H_ 80 struct sysarch_args { 81 int op; 82 char *parms; 83 }; 84 #endif 85 86 int 87 sysarch(td, uap) 88 struct thread *td; 89 register struct sysarch_args *uap; 90 { 91 int error; 92 93 mtx_lock(&Giant); 94 switch(uap->op) { 95 case I386_GET_LDT: 96 error = i386_get_ldt(td, uap->parms); 97 break; 98 99 case I386_SET_LDT: 100 error = i386_set_ldt(td, uap->parms); 101 break; 102 case I386_GET_IOPERM: 103 error = i386_get_ioperm(td, uap->parms); 104 break; 105 case I386_SET_IOPERM: 106 error = i386_set_ioperm(td, uap->parms); 107 break; 108 case I386_VM86: 109 error = vm86_sysarch(td, uap->parms); 110 break; 111 default: 112 error = EINVAL; 113 break; 114 } 115 mtx_unlock(&Giant); 116 return (error); 117 } 118 119 int 120 i386_extend_pcb(struct thread *td) 121 { 122 int i, offset; 123 u_long *addr; 124 struct pcb_ext *ext; 125 struct soft_segment_descriptor ssd = { 126 0, /* segment base address (overwritten) */ 127 ctob(IOPAGES + 1) - 1, /* length */ 128 SDT_SYS386TSS, /* segment type */ 129 0, /* priority level */ 130 1, /* descriptor present */ 131 0, 0, 132 0, /* default 32 size */ 133 0 /* granularity */ 134 }; 135 136 if (td->td_proc->p_flag & P_SA) 137 return (EINVAL); /* XXXKSE */ 138 /* XXXKSE All the code below only works in 1:1 needs changing */ 139 ext = (struct pcb_ext *)kmem_alloc(kernel_map, ctob(IOPAGES+1)); 140 if (ext == 0) 141 return (ENOMEM); 142 bzero(ext, sizeof(struct pcb_ext)); 143 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 144 ext->ext_tss.tss_esp0 = td->td_kstack + ctob(KSTACK_PAGES) - 145 sizeof(struct pcb) - 16; 146 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 147 /* 148 * The last byte of the i/o map must be followed by an 0xff byte. 149 * We arbitrarily allocate 16 bytes here, to keep the starting 150 * address on a doubleword boundary. 151 */ 152 offset = PAGE_SIZE - 16; 153 ext->ext_tss.tss_ioopt = 154 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 155 ext->ext_iomap = (caddr_t)ext + offset; 156 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 157 158 addr = (u_long *)ext->ext_vm86.vm86_intmap; 159 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 160 *addr++ = ~0; 161 162 ssd.ssd_base = (unsigned)&ext->ext_tss; 163 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 164 ssdtosd(&ssd, &ext->ext_tssd); 165 166 KASSERT(td->td_proc == curthread->td_proc, ("giving TSS to !curproc")); 167 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 168 mtx_lock_spin(&sched_lock); 169 td->td_pcb->pcb_ext = ext; 170 171 /* switch to the new TSS after syscall completes */ 172 td->td_flags |= TDF_NEEDRESCHED; 173 mtx_unlock_spin(&sched_lock); 174 175 return 0; 176 } 177 178 static int 179 i386_set_ioperm(td, args) 180 struct thread *td; 181 char *args; 182 { 183 int i, error; 184 struct i386_ioperm_args ua; 185 char *iomap; 186 187 if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0) 188 return (error); 189 190 #ifdef MAC 191 if ((error = mac_check_sysarch_ioperm(td->td_ucred)) != 0) 192 return (error); 193 #endif 194 if ((error = suser(td)) != 0) 195 return (error); 196 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 197 return (error); 198 /* 199 * XXX 200 * While this is restricted to root, we should probably figure out 201 * whether any other driver is using this i/o address, as so not to 202 * cause confusion. This probably requires a global 'usage registry'. 203 */ 204 205 if (td->td_pcb->pcb_ext == 0) 206 if ((error = i386_extend_pcb(td)) != 0) 207 return (error); 208 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 209 210 if (ua.start + ua.length > IOPAGES * PAGE_SIZE * NBBY) 211 return (EINVAL); 212 213 for (i = ua.start; i < ua.start + ua.length; i++) { 214 if (ua.enable) 215 iomap[i >> 3] &= ~(1 << (i & 7)); 216 else 217 iomap[i >> 3] |= (1 << (i & 7)); 218 } 219 return (error); 220 } 221 222 static int 223 i386_get_ioperm(td, args) 224 struct thread *td; 225 char *args; 226 { 227 int i, state, error; 228 struct i386_ioperm_args ua; 229 char *iomap; 230 231 if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0) 232 return (error); 233 if (ua.start >= IOPAGES * PAGE_SIZE * NBBY) 234 return (EINVAL); 235 236 if (td->td_pcb->pcb_ext == 0) { 237 ua.length = 0; 238 goto done; 239 } 240 241 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 242 243 i = ua.start; 244 state = (iomap[i >> 3] >> (i & 7)) & 1; 245 ua.enable = !state; 246 ua.length = 1; 247 248 for (i = ua.start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 249 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 250 break; 251 ua.length++; 252 } 253 254 done: 255 error = copyout(&ua, args, sizeof(struct i386_ioperm_args)); 256 return (error); 257 } 258 259 /* 260 * Update the GDT entry pointing to the LDT to point to the LDT of the 261 * current process. 262 * 263 * This must be called with sched_lock held. Unfortunately, we can't use a 264 * mtx_assert() here because cpu_switch() calls this function after changing 265 * curproc but before sched_lock's owner is updated in mi_switch(). 266 */ 267 void 268 set_user_ldt(struct mdproc *mdp) 269 { 270 struct proc_ldt *pldt; 271 272 pldt = mdp->md_ldt; 273 #ifdef SMP 274 gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd; 275 #else 276 gdt[GUSERLDT_SEL].sd = pldt->ldt_sd; 277 #endif 278 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 279 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 280 } 281 282 #ifdef SMP 283 static void 284 set_user_ldt_rv(struct thread *td) 285 { 286 287 if (td->td_proc != curthread->td_proc) 288 return; 289 290 set_user_ldt(&td->td_proc->p_md); 291 } 292 #endif 293 294 /* 295 * Must be called with either sched_lock free or held but not recursed. 296 * If it does not return NULL, it will return with it owned. 297 */ 298 struct proc_ldt * 299 user_ldt_alloc(struct mdproc *mdp, int len) 300 { 301 struct proc_ldt *pldt, *new_ldt; 302 303 if (mtx_owned(&sched_lock)) 304 mtx_unlock_spin(&sched_lock); 305 mtx_assert(&sched_lock, MA_NOTOWNED); 306 MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt), 307 M_SUBPROC, M_WAITOK); 308 309 new_ldt->ldt_len = len = NEW_MAX_LD(len); 310 new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 311 len * sizeof(union descriptor)); 312 if (new_ldt->ldt_base == NULL) { 313 FREE(new_ldt, M_SUBPROC); 314 return NULL; 315 } 316 new_ldt->ldt_refcnt = 1; 317 new_ldt->ldt_active = 0; 318 319 mtx_lock_spin(&sched_lock); 320 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 321 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 322 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 323 324 if ((pldt = mdp->md_ldt)) { 325 if (len > pldt->ldt_len) 326 len = pldt->ldt_len; 327 bcopy(pldt->ldt_base, new_ldt->ldt_base, 328 len * sizeof(union descriptor)); 329 } else { 330 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt)); 331 } 332 return new_ldt; 333 } 334 335 /* 336 * Must be called either with sched_lock free or held but not recursed. 337 * If md_ldt is not NULL, it will return with sched_lock released. 338 */ 339 void 340 user_ldt_free(struct thread *td) 341 { 342 struct mdproc *mdp = &td->td_proc->p_md; 343 struct proc_ldt *pldt = mdp->md_ldt; 344 345 if (pldt == NULL) 346 return; 347 348 if (!mtx_owned(&sched_lock)) 349 mtx_lock_spin(&sched_lock); 350 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 351 if (td == PCPU_GET(curthread)) { 352 lldt(_default_ldt); 353 PCPU_SET(currentldt, _default_ldt); 354 } 355 356 mdp->md_ldt = NULL; 357 if (--pldt->ldt_refcnt == 0) { 358 mtx_unlock_spin(&sched_lock); 359 kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base, 360 pldt->ldt_len * sizeof(union descriptor)); 361 FREE(pldt, M_SUBPROC); 362 } else 363 mtx_unlock_spin(&sched_lock); 364 } 365 366 static int 367 i386_get_ldt(td, args) 368 struct thread *td; 369 char *args; 370 { 371 int error = 0; 372 struct proc_ldt *pldt = td->td_proc->p_md.md_ldt; 373 int nldt, num; 374 union descriptor *lp; 375 struct i386_ldt_args ua, *uap = &ua; 376 377 if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0) 378 return(error); 379 380 #ifdef DEBUG 381 printf("i386_get_ldt: start=%d num=%d descs=%p\n", 382 uap->start, uap->num, (void *)uap->descs); 383 #endif 384 385 if (pldt) { 386 nldt = pldt->ldt_len; 387 num = min(uap->num, nldt); 388 lp = &((union descriptor *)(pldt->ldt_base))[uap->start]; 389 } else { 390 nldt = sizeof(ldt)/sizeof(ldt[0]); 391 num = min(uap->num, nldt); 392 lp = &ldt[uap->start]; 393 } 394 395 if ((uap->start > (unsigned int)nldt) || 396 ((unsigned int)num > (unsigned int)nldt) || 397 ((unsigned int)(uap->start + num) > (unsigned int)nldt)) 398 return(EINVAL); 399 400 error = copyout(lp, uap->descs, num * sizeof(union descriptor)); 401 if (!error) 402 td->td_retval[0] = num; 403 404 return(error); 405 } 406 407 static int ldt_warnings; 408 #define NUM_LDT_WARNINGS 10 409 410 static int 411 i386_set_ldt(td, args) 412 struct thread *td; 413 char *args; 414 { 415 int error = 0, i; 416 int largest_ld; 417 struct mdproc *mdp = &td->td_proc->p_md; 418 struct proc_ldt *pldt = 0; 419 struct i386_ldt_args ua, *uap = &ua; 420 union descriptor *descs, *dp; 421 int descs_size; 422 423 if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0) 424 return(error); 425 426 #ifdef DEBUG 427 printf("i386_set_ldt: start=%d num=%d descs=%p\n", 428 uap->start, uap->num, (void *)uap->descs); 429 #endif 430 431 if (uap->descs == NULL) { 432 /* Free descriptors */ 433 if (uap->start == 0 && uap->num == 0) { 434 /* 435 * Treat this as a special case, so userland needn't 436 * know magic number NLDT. 437 */ 438 uap->start = NLDT; 439 uap->num = MAX_LD - NLDT; 440 } 441 if (uap->start <= LUDATA_SEL || uap->num <= 0) 442 return (EINVAL); 443 mtx_lock_spin(&sched_lock); 444 pldt = mdp->md_ldt; 445 if (pldt == NULL || uap->start >= pldt->ldt_len) { 446 mtx_unlock_spin(&sched_lock); 447 return (0); 448 } 449 largest_ld = uap->start + uap->num; 450 if (largest_ld > pldt->ldt_len) 451 largest_ld = pldt->ldt_len; 452 i = largest_ld - uap->start; 453 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start], 454 sizeof(union descriptor) * i); 455 mtx_unlock_spin(&sched_lock); 456 return (0); 457 } 458 459 if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) { 460 /* complain a for a while if using old methods */ 461 if (ldt_warnings++ < NUM_LDT_WARNINGS) { 462 printf("Warning: pid %d used static ldt allocation.\n", 463 td->td_proc->p_pid); 464 printf("See the i386_set_ldt man page for more info\n"); 465 } 466 /* verify range of descriptors to modify */ 467 largest_ld = uap->start + uap->num; 468 if (uap->start >= MAX_LD || 469 uap->num < 0 || largest_ld > MAX_LD) { 470 return (EINVAL); 471 } 472 } 473 474 descs_size = uap->num * sizeof(union descriptor); 475 descs = (union descriptor *)kmem_alloc(kernel_map, descs_size); 476 if (descs == NULL) 477 return (ENOMEM); 478 error = copyin(uap->descs, descs, descs_size); 479 if (error) { 480 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 481 return (error); 482 } 483 484 /* Check descriptors for access violations */ 485 for (i = 0; i < uap->num; i++) { 486 dp = &descs[i]; 487 488 switch (dp->sd.sd_type) { 489 case SDT_SYSNULL: /* system null */ 490 dp->sd.sd_p = 0; 491 break; 492 case SDT_SYS286TSS: /* system 286 TSS available */ 493 case SDT_SYSLDT: /* system local descriptor table */ 494 case SDT_SYS286BSY: /* system 286 TSS busy */ 495 case SDT_SYSTASKGT: /* system task gate */ 496 case SDT_SYS286IGT: /* system 286 interrupt gate */ 497 case SDT_SYS286TGT: /* system 286 trap gate */ 498 case SDT_SYSNULL2: /* undefined by Intel */ 499 case SDT_SYS386TSS: /* system 386 TSS available */ 500 case SDT_SYSNULL3: /* undefined by Intel */ 501 case SDT_SYS386BSY: /* system 386 TSS busy */ 502 case SDT_SYSNULL4: /* undefined by Intel */ 503 case SDT_SYS386IGT: /* system 386 interrupt gate */ 504 case SDT_SYS386TGT: /* system 386 trap gate */ 505 case SDT_SYS286CGT: /* system 286 call gate */ 506 case SDT_SYS386CGT: /* system 386 call gate */ 507 /* I can't think of any reason to allow a user proc 508 * to create a segment of these types. They are 509 * for OS use only. 510 */ 511 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 512 return (EACCES); 513 /*NOTREACHED*/ 514 515 /* memory segment types */ 516 case SDT_MEMEC: /* memory execute only conforming */ 517 case SDT_MEMEAC: /* memory execute only accessed conforming */ 518 case SDT_MEMERC: /* memory execute read conforming */ 519 case SDT_MEMERAC: /* memory execute read accessed conforming */ 520 /* Must be "present" if executable and conforming. */ 521 if (dp->sd.sd_p == 0) { 522 kmem_free(kernel_map, (vm_offset_t)descs, 523 descs_size); 524 return (EACCES); 525 } 526 break; 527 case SDT_MEMRO: /* memory read only */ 528 case SDT_MEMROA: /* memory read only accessed */ 529 case SDT_MEMRW: /* memory read write */ 530 case SDT_MEMRWA: /* memory read write accessed */ 531 case SDT_MEMROD: /* memory read only expand dwn limit */ 532 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 533 case SDT_MEMRWD: /* memory read write expand dwn limit */ 534 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 535 case SDT_MEME: /* memory execute only */ 536 case SDT_MEMEA: /* memory execute only accessed */ 537 case SDT_MEMER: /* memory execute read */ 538 case SDT_MEMERA: /* memory execute read accessed */ 539 break; 540 default: 541 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 542 return(EINVAL); 543 /*NOTREACHED*/ 544 } 545 546 /* Only user (ring-3) descriptors may be present. */ 547 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL)) { 548 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 549 return (EACCES); 550 } 551 } 552 553 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 554 /* Allocate a free slot */ 555 pldt = mdp->md_ldt; 556 if (pldt == NULL) { 557 error = i386_ldt_grow(td, NLDT+1); 558 if (error) { 559 kmem_free(kernel_map, (vm_offset_t)descs, 560 descs_size); 561 return (error); 562 } 563 pldt = mdp->md_ldt; 564 } 565 again: 566 mtx_lock_spin(&sched_lock); 567 /* 568 * start scanning a bit up to leave room for NVidia and 569 * Wine, which still user the "Blat" method of allocation. 570 */ 571 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 572 for (i = NLDT; i < pldt->ldt_len; ++i) { 573 if (dp->sd.sd_type == SDT_SYSNULL) 574 break; 575 dp++; 576 } 577 if (i >= pldt->ldt_len) { 578 mtx_unlock_spin(&sched_lock); 579 error = i386_ldt_grow(td, pldt->ldt_len+1); 580 if (error) { 581 kmem_free(kernel_map, (vm_offset_t)descs, 582 descs_size); 583 return (error); 584 } 585 goto again; 586 } 587 uap->start = i; 588 error = i386_set_ldt_data(td, i, 1, descs); 589 mtx_unlock_spin(&sched_lock); 590 } else { 591 largest_ld = uap->start + uap->num; 592 error = i386_ldt_grow(td, largest_ld); 593 if (error == 0) { 594 mtx_lock_spin(&sched_lock); 595 error = i386_set_ldt_data(td, uap->start, uap->num, 596 descs); 597 mtx_unlock_spin(&sched_lock); 598 } 599 } 600 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 601 if (error == 0) 602 td->td_retval[0] = uap->start; 603 return (error); 604 } 605 606 static int 607 i386_set_ldt_data(struct thread *td, int start, int num, 608 union descriptor *descs) 609 { 610 struct mdproc *mdp = &td->td_proc->p_md; 611 struct proc_ldt *pldt = mdp->md_ldt; 612 613 mtx_assert(&sched_lock, MA_OWNED); 614 615 /* Fill in range */ 616 bcopy(descs, 617 &((union descriptor *)(pldt->ldt_base))[start], 618 num * sizeof(union descriptor)); 619 return (0); 620 } 621 622 static int 623 i386_ldt_grow(struct thread *td, int len) 624 { 625 struct mdproc *mdp = &td->td_proc->p_md; 626 struct proc_ldt *pldt; 627 caddr_t old_ldt_base; 628 int old_ldt_len; 629 630 if (len > MAX_LD) 631 return (ENOMEM); 632 if (len < NLDT+1) 633 len = NLDT+1; 634 pldt = mdp->md_ldt; 635 /* allocate user ldt */ 636 if (!pldt || len > pldt->ldt_len) { 637 struct proc_ldt *new_ldt = user_ldt_alloc(mdp, len); 638 if (new_ldt == NULL) 639 return (ENOMEM); 640 pldt = mdp->md_ldt; 641 /* sched_lock was held by user_ldt_alloc */ 642 if (pldt) { 643 if (new_ldt->ldt_len > pldt->ldt_len) { 644 old_ldt_base = pldt->ldt_base; 645 old_ldt_len = pldt->ldt_len; 646 pldt->ldt_sd = new_ldt->ldt_sd; 647 pldt->ldt_base = new_ldt->ldt_base; 648 pldt->ldt_len = new_ldt->ldt_len; 649 mtx_unlock_spin(&sched_lock); 650 kmem_free(kernel_map, (vm_offset_t)old_ldt_base, 651 old_ldt_len * sizeof(union descriptor)); 652 FREE(new_ldt, M_SUBPROC); 653 mtx_lock_spin(&sched_lock); 654 } else { 655 /* 656 * If other threads already did the work, 657 * do nothing 658 */ 659 mtx_unlock_spin(&sched_lock); 660 kmem_free(kernel_map, 661 (vm_offset_t)new_ldt->ldt_base, 662 new_ldt->ldt_len * sizeof(union descriptor)); 663 FREE(new_ldt, M_SUBPROC); 664 return (0); 665 } 666 } else { 667 mdp->md_ldt = pldt = new_ldt; 668 } 669 #ifdef SMP 670 mtx_unlock_spin(&sched_lock); 671 /* signal other cpus to reload ldt */ 672 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 673 NULL, td); 674 #else 675 set_user_ldt(mdp); 676 mtx_unlock_spin(&sched_lock); 677 #endif 678 } 679 return (0); 680 }
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