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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91 34 */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD: releng/5.2/sys/i386/i386/sys_machdep.c 119825 2003-09-07 05:23:28Z davidxu $"); 38 39 #include "opt_kstack_pages.h" 40 #include "opt_mac.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/lock.h> 45 #include <sys/mac.h> 46 #include <sys/malloc.h> 47 #include <sys/mutex.h> 48 #include <sys/proc.h> 49 #include <sys/smp.h> 50 #include <sys/sysproto.h> 51 #include <sys/user.h> 52 53 #include <vm/vm.h> 54 #include <vm/pmap.h> 55 #include <vm/vm_map.h> 56 #include <vm/vm_extern.h> 57 58 #include <machine/cpu.h> 59 #include <machine/pcb_ext.h> /* pcb.h included by sys/user.h */ 60 #include <machine/proc.h> 61 #include <machine/sysarch.h> 62 63 #include <vm/vm_kern.h> /* for kernel_map */ 64 65 #define MAX_LD 8192 66 #define LD_PER_PAGE 512 67 #define NEW_MAX_LD(num) ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1)) 68 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3) 69 70 71 72 static int i386_get_ldt(struct thread *, char *); 73 static int i386_set_ldt(struct thread *, char *); 74 static int i386_set_ldt_data(struct thread *, int start, int num, 75 union descriptor *descs); 76 static int i386_ldt_grow(struct thread *td, int len); 77 static int i386_get_ioperm(struct thread *, char *); 78 static int i386_set_ioperm(struct thread *, char *); 79 #ifdef SMP 80 static void set_user_ldt_rv(struct thread *); 81 #endif 82 83 #ifndef _SYS_SYSPROTO_H_ 84 struct sysarch_args { 85 int op; 86 char *parms; 87 }; 88 #endif 89 90 int 91 sysarch(td, uap) 92 struct thread *td; 93 register struct sysarch_args *uap; 94 { 95 int error; 96 97 mtx_lock(&Giant); 98 switch(uap->op) { 99 case I386_GET_LDT: 100 error = i386_get_ldt(td, uap->parms); 101 break; 102 103 case I386_SET_LDT: 104 error = i386_set_ldt(td, uap->parms); 105 break; 106 case I386_GET_IOPERM: 107 error = i386_get_ioperm(td, uap->parms); 108 break; 109 case I386_SET_IOPERM: 110 error = i386_set_ioperm(td, uap->parms); 111 break; 112 case I386_VM86: 113 error = vm86_sysarch(td, uap->parms); 114 break; 115 default: 116 error = EINVAL; 117 break; 118 } 119 mtx_unlock(&Giant); 120 return (error); 121 } 122 123 int 124 i386_extend_pcb(struct thread *td) 125 { 126 int i, offset; 127 u_long *addr; 128 struct pcb_ext *ext; 129 struct soft_segment_descriptor ssd = { 130 0, /* segment base address (overwritten) */ 131 ctob(IOPAGES + 1) - 1, /* length */ 132 SDT_SYS386TSS, /* segment type */ 133 0, /* priority level */ 134 1, /* descriptor present */ 135 0, 0, 136 0, /* default 32 size */ 137 0 /* granularity */ 138 }; 139 140 if (td->td_proc->p_flag & P_SA) 141 return (EINVAL); /* XXXKSE */ 142 /* XXXKSE All the code below only works in 1:1 needs changing */ 143 ext = (struct pcb_ext *)kmem_alloc(kernel_map, ctob(IOPAGES+1)); 144 if (ext == 0) 145 return (ENOMEM); 146 bzero(ext, sizeof(struct pcb_ext)); 147 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 148 ext->ext_tss.tss_esp0 = td->td_kstack + ctob(KSTACK_PAGES) - 149 sizeof(struct pcb) - 16; 150 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 151 /* 152 * The last byte of the i/o map must be followed by an 0xff byte. 153 * We arbitrarily allocate 16 bytes here, to keep the starting 154 * address on a doubleword boundary. 155 */ 156 offset = PAGE_SIZE - 16; 157 ext->ext_tss.tss_ioopt = 158 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 159 ext->ext_iomap = (caddr_t)ext + offset; 160 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 161 162 addr = (u_long *)ext->ext_vm86.vm86_intmap; 163 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 164 *addr++ = ~0; 165 166 ssd.ssd_base = (unsigned)&ext->ext_tss; 167 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 168 ssdtosd(&ssd, &ext->ext_tssd); 169 170 KASSERT(td->td_proc == curthread->td_proc, ("giving TSS to !curproc")); 171 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 172 mtx_lock_spin(&sched_lock); 173 td->td_pcb->pcb_ext = ext; 174 175 /* switch to the new TSS after syscall completes */ 176 td->td_flags |= TDF_NEEDRESCHED; 177 mtx_unlock_spin(&sched_lock); 178 179 return 0; 180 } 181 182 static int 183 i386_set_ioperm(td, args) 184 struct thread *td; 185 char *args; 186 { 187 int i, error; 188 struct i386_ioperm_args ua; 189 char *iomap; 190 191 if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0) 192 return (error); 193 194 #ifdef MAC 195 if ((error = mac_check_sysarch_ioperm(td->td_ucred)) != 0) 196 return (error); 197 #endif 198 if ((error = suser(td)) != 0) 199 return (error); 200 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 201 return (error); 202 /* 203 * XXX 204 * While this is restricted to root, we should probably figure out 205 * whether any other driver is using this i/o address, as so not to 206 * cause confusion. This probably requires a global 'usage registry'. 207 */ 208 209 if (td->td_pcb->pcb_ext == 0) 210 if ((error = i386_extend_pcb(td)) != 0) 211 return (error); 212 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 213 214 if (ua.start + ua.length > IOPAGES * PAGE_SIZE * NBBY) 215 return (EINVAL); 216 217 for (i = ua.start; i < ua.start + ua.length; i++) { 218 if (ua.enable) 219 iomap[i >> 3] &= ~(1 << (i & 7)); 220 else 221 iomap[i >> 3] |= (1 << (i & 7)); 222 } 223 return (error); 224 } 225 226 static int 227 i386_get_ioperm(td, args) 228 struct thread *td; 229 char *args; 230 { 231 int i, state, error; 232 struct i386_ioperm_args ua; 233 char *iomap; 234 235 if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0) 236 return (error); 237 if (ua.start >= IOPAGES * PAGE_SIZE * NBBY) 238 return (EINVAL); 239 240 if (td->td_pcb->pcb_ext == 0) { 241 ua.length = 0; 242 goto done; 243 } 244 245 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 246 247 i = ua.start; 248 state = (iomap[i >> 3] >> (i & 7)) & 1; 249 ua.enable = !state; 250 ua.length = 1; 251 252 for (i = ua.start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 253 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 254 break; 255 ua.length++; 256 } 257 258 done: 259 error = copyout(&ua, args, sizeof(struct i386_ioperm_args)); 260 return (error); 261 } 262 263 /* 264 * Update the GDT entry pointing to the LDT to point to the LDT of the 265 * current process. 266 * 267 * This must be called with sched_lock held. Unfortunately, we can't use a 268 * mtx_assert() here because cpu_switch() calls this function after changing 269 * curproc but before sched_lock's owner is updated in mi_switch(). 270 */ 271 void 272 set_user_ldt(struct mdproc *mdp) 273 { 274 struct proc_ldt *pldt; 275 276 pldt = mdp->md_ldt; 277 #ifdef SMP 278 gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd; 279 #else 280 gdt[GUSERLDT_SEL].sd = pldt->ldt_sd; 281 #endif 282 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 283 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 284 } 285 286 #ifdef SMP 287 static void 288 set_user_ldt_rv(struct thread *td) 289 { 290 291 if (td->td_proc != curthread->td_proc) 292 return; 293 294 set_user_ldt(&td->td_proc->p_md); 295 } 296 #endif 297 298 /* 299 * Must be called with either sched_lock free or held but not recursed. 300 * If it does not return NULL, it will return with it owned. 301 */ 302 struct proc_ldt * 303 user_ldt_alloc(struct mdproc *mdp, int len) 304 { 305 struct proc_ldt *pldt, *new_ldt; 306 307 if (mtx_owned(&sched_lock)) 308 mtx_unlock_spin(&sched_lock); 309 mtx_assert(&sched_lock, MA_NOTOWNED); 310 MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt), 311 M_SUBPROC, M_WAITOK); 312 313 new_ldt->ldt_len = len = NEW_MAX_LD(len); 314 new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 315 len * sizeof(union descriptor)); 316 if (new_ldt->ldt_base == NULL) { 317 FREE(new_ldt, M_SUBPROC); 318 return NULL; 319 } 320 new_ldt->ldt_refcnt = 1; 321 new_ldt->ldt_active = 0; 322 323 mtx_lock_spin(&sched_lock); 324 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 325 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 326 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 327 328 if ((pldt = mdp->md_ldt)) { 329 if (len > pldt->ldt_len) 330 len = pldt->ldt_len; 331 bcopy(pldt->ldt_base, new_ldt->ldt_base, 332 len * sizeof(union descriptor)); 333 } else { 334 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt)); 335 } 336 return new_ldt; 337 } 338 339 /* 340 * Must be called either with sched_lock free or held but not recursed. 341 * If md_ldt is not NULL, it will return with sched_lock released. 342 */ 343 void 344 user_ldt_free(struct thread *td) 345 { 346 struct mdproc *mdp = &td->td_proc->p_md; 347 struct proc_ldt *pldt = mdp->md_ldt; 348 349 if (pldt == NULL) 350 return; 351 352 if (!mtx_owned(&sched_lock)) 353 mtx_lock_spin(&sched_lock); 354 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 355 if (td == PCPU_GET(curthread)) { 356 lldt(_default_ldt); 357 PCPU_SET(currentldt, _default_ldt); 358 } 359 360 mdp->md_ldt = NULL; 361 if (--pldt->ldt_refcnt == 0) { 362 mtx_unlock_spin(&sched_lock); 363 kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base, 364 pldt->ldt_len * sizeof(union descriptor)); 365 FREE(pldt, M_SUBPROC); 366 } else 367 mtx_unlock_spin(&sched_lock); 368 } 369 370 static int 371 i386_get_ldt(td, args) 372 struct thread *td; 373 char *args; 374 { 375 int error = 0; 376 struct proc_ldt *pldt = td->td_proc->p_md.md_ldt; 377 int nldt, num; 378 union descriptor *lp; 379 struct i386_ldt_args ua, *uap = &ua; 380 381 if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0) 382 return(error); 383 384 #ifdef DEBUG 385 printf("i386_get_ldt: start=%d num=%d descs=%p\n", 386 uap->start, uap->num, (void *)uap->descs); 387 #endif 388 389 /* verify range of LDTs exist */ 390 if ((uap->start < 0) || (uap->num <= 0)) 391 return(EINVAL); 392 393 if (pldt) { 394 nldt = pldt->ldt_len; 395 num = min(uap->num, nldt); 396 lp = &((union descriptor *)(pldt->ldt_base))[uap->start]; 397 } else { 398 nldt = sizeof(ldt)/sizeof(ldt[0]); 399 num = min(uap->num, nldt); 400 lp = &ldt[uap->start]; 401 } 402 if (uap->start + num > nldt) 403 return(EINVAL); 404 405 error = copyout(lp, uap->descs, num * sizeof(union descriptor)); 406 if (!error) 407 td->td_retval[0] = num; 408 409 return(error); 410 } 411 412 static int ldt_warnings; 413 #define NUM_LDT_WARNINGS 10 414 415 static int 416 i386_set_ldt(td, args) 417 struct thread *td; 418 char *args; 419 { 420 int error = 0, i; 421 int largest_ld; 422 struct mdproc *mdp = &td->td_proc->p_md; 423 struct proc_ldt *pldt = 0; 424 struct i386_ldt_args ua, *uap = &ua; 425 union descriptor *descs, *dp; 426 int descs_size; 427 428 if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0) 429 return(error); 430 431 #ifdef DEBUG 432 printf("i386_set_ldt: start=%d num=%d descs=%p\n", 433 uap->start, uap->num, (void *)uap->descs); 434 #endif 435 436 if (uap->descs == NULL) { 437 /* Free descriptors */ 438 if (uap->start == 0 && uap->num == 0) { 439 /* 440 * Treat this as a special case, so userland needn't 441 * know magic number NLDT. 442 */ 443 uap->start = NLDT; 444 uap->num = MAX_LD - NLDT; 445 } 446 if (uap->start <= LUDATA_SEL || uap->num <= 0) 447 return (EINVAL); 448 mtx_lock_spin(&sched_lock); 449 pldt = mdp->md_ldt; 450 if (pldt == NULL || uap->start >= pldt->ldt_len) { 451 mtx_unlock_spin(&sched_lock); 452 return (0); 453 } 454 largest_ld = uap->start + uap->num; 455 if (largest_ld > pldt->ldt_len) 456 largest_ld = pldt->ldt_len; 457 i = largest_ld - uap->start; 458 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start], 459 sizeof(union descriptor) * i); 460 mtx_unlock_spin(&sched_lock); 461 return (0); 462 } 463 464 if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) { 465 /* complain a for a while if using old methods */ 466 if (ldt_warnings++ < NUM_LDT_WARNINGS) { 467 printf("Warning: pid %d used static ldt allocation.\n", 468 td->td_proc->p_pid); 469 printf("See the i386_set_ldt man page for more info\n"); 470 } 471 /* verify range of descriptors to modify */ 472 largest_ld = uap->start + uap->num; 473 if (uap->start >= MAX_LD || 474 uap->num < 0 || largest_ld > MAX_LD) { 475 return (EINVAL); 476 } 477 } 478 479 descs_size = uap->num * sizeof(union descriptor); 480 descs = (union descriptor *)kmem_alloc(kernel_map, descs_size); 481 if (descs == NULL) 482 return (ENOMEM); 483 error = copyin(uap->descs, descs, descs_size); 484 if (error) { 485 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 486 return (error); 487 } 488 489 /* Check descriptors for access violations */ 490 for (i = 0; i < uap->num; i++) { 491 dp = &descs[i]; 492 493 switch (dp->sd.sd_type) { 494 case SDT_SYSNULL: /* system null */ 495 dp->sd.sd_p = 0; 496 break; 497 case SDT_SYS286TSS: /* system 286 TSS available */ 498 case SDT_SYSLDT: /* system local descriptor table */ 499 case SDT_SYS286BSY: /* system 286 TSS busy */ 500 case SDT_SYSTASKGT: /* system task gate */ 501 case SDT_SYS286IGT: /* system 286 interrupt gate */ 502 case SDT_SYS286TGT: /* system 286 trap gate */ 503 case SDT_SYSNULL2: /* undefined by Intel */ 504 case SDT_SYS386TSS: /* system 386 TSS available */ 505 case SDT_SYSNULL3: /* undefined by Intel */ 506 case SDT_SYS386BSY: /* system 386 TSS busy */ 507 case SDT_SYSNULL4: /* undefined by Intel */ 508 case SDT_SYS386IGT: /* system 386 interrupt gate */ 509 case SDT_SYS386TGT: /* system 386 trap gate */ 510 case SDT_SYS286CGT: /* system 286 call gate */ 511 case SDT_SYS386CGT: /* system 386 call gate */ 512 /* I can't think of any reason to allow a user proc 513 * to create a segment of these types. They are 514 * for OS use only. 515 */ 516 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 517 return (EACCES); 518 /*NOTREACHED*/ 519 520 /* memory segment types */ 521 case SDT_MEMEC: /* memory execute only conforming */ 522 case SDT_MEMEAC: /* memory execute only accessed conforming */ 523 case SDT_MEMERC: /* memory execute read conforming */ 524 case SDT_MEMERAC: /* memory execute read accessed conforming */ 525 /* Must be "present" if executable and conforming. */ 526 if (dp->sd.sd_p == 0) { 527 kmem_free(kernel_map, (vm_offset_t)descs, 528 descs_size); 529 return (EACCES); 530 } 531 break; 532 case SDT_MEMRO: /* memory read only */ 533 case SDT_MEMROA: /* memory read only accessed */ 534 case SDT_MEMRW: /* memory read write */ 535 case SDT_MEMRWA: /* memory read write accessed */ 536 case SDT_MEMROD: /* memory read only expand dwn limit */ 537 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 538 case SDT_MEMRWD: /* memory read write expand dwn limit */ 539 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 540 case SDT_MEME: /* memory execute only */ 541 case SDT_MEMEA: /* memory execute only accessed */ 542 case SDT_MEMER: /* memory execute read */ 543 case SDT_MEMERA: /* memory execute read accessed */ 544 break; 545 default: 546 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 547 return(EINVAL); 548 /*NOTREACHED*/ 549 } 550 551 /* Only user (ring-3) descriptors may be present. */ 552 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL)) { 553 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 554 return (EACCES); 555 } 556 } 557 558 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 559 /* Allocate a free slot */ 560 pldt = mdp->md_ldt; 561 if (pldt == NULL) { 562 error = i386_ldt_grow(td, NLDT+1); 563 if (error) { 564 kmem_free(kernel_map, (vm_offset_t)descs, 565 descs_size); 566 return (error); 567 } 568 pldt = mdp->md_ldt; 569 } 570 again: 571 mtx_lock_spin(&sched_lock); 572 /* 573 * start scanning a bit up to leave room for NVidia and 574 * Wine, which still user the "Blat" method of allocation. 575 */ 576 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 577 for (i = NLDT; i < pldt->ldt_len; ++i) { 578 if (dp->sd.sd_type == SDT_SYSNULL) 579 break; 580 dp++; 581 } 582 if (i >= pldt->ldt_len) { 583 mtx_unlock_spin(&sched_lock); 584 error = i386_ldt_grow(td, pldt->ldt_len+1); 585 if (error) { 586 kmem_free(kernel_map, (vm_offset_t)descs, 587 descs_size); 588 return (error); 589 } 590 goto again; 591 } 592 uap->start = i; 593 error = i386_set_ldt_data(td, i, 1, descs); 594 mtx_unlock_spin(&sched_lock); 595 } else { 596 largest_ld = uap->start + uap->num; 597 error = i386_ldt_grow(td, largest_ld); 598 if (error == 0) { 599 mtx_lock_spin(&sched_lock); 600 error = i386_set_ldt_data(td, uap->start, uap->num, 601 descs); 602 mtx_unlock_spin(&sched_lock); 603 } 604 } 605 kmem_free(kernel_map, (vm_offset_t)descs, descs_size); 606 if (error == 0) 607 td->td_retval[0] = uap->start; 608 return (error); 609 } 610 611 static int 612 i386_set_ldt_data(struct thread *td, int start, int num, 613 union descriptor *descs) 614 { 615 struct mdproc *mdp = &td->td_proc->p_md; 616 struct proc_ldt *pldt = mdp->md_ldt; 617 618 mtx_assert(&sched_lock, MA_OWNED); 619 620 /* Fill in range */ 621 bcopy(descs, 622 &((union descriptor *)(pldt->ldt_base))[start], 623 num * sizeof(union descriptor)); 624 return (0); 625 } 626 627 static int 628 i386_ldt_grow(struct thread *td, int len) 629 { 630 struct mdproc *mdp = &td->td_proc->p_md; 631 struct proc_ldt *pldt; 632 caddr_t old_ldt_base; 633 int old_ldt_len; 634 635 if (len > MAX_LD) 636 return (ENOMEM); 637 if (len < NLDT+1) 638 len = NLDT+1; 639 pldt = mdp->md_ldt; 640 /* allocate user ldt */ 641 if (!pldt || len > pldt->ldt_len) { 642 struct proc_ldt *new_ldt = user_ldt_alloc(mdp, len); 643 if (new_ldt == NULL) 644 return (ENOMEM); 645 pldt = mdp->md_ldt; 646 /* sched_lock was held by user_ldt_alloc */ 647 if (pldt) { 648 if (new_ldt->ldt_len > pldt->ldt_len) { 649 old_ldt_base = pldt->ldt_base; 650 old_ldt_len = pldt->ldt_len; 651 pldt->ldt_sd = new_ldt->ldt_sd; 652 pldt->ldt_base = new_ldt->ldt_base; 653 pldt->ldt_len = new_ldt->ldt_len; 654 mtx_unlock_spin(&sched_lock); 655 kmem_free(kernel_map, (vm_offset_t)old_ldt_base, 656 old_ldt_len * sizeof(union descriptor)); 657 FREE(new_ldt, M_SUBPROC); 658 mtx_lock_spin(&sched_lock); 659 } else { 660 /* 661 * If other threads already did the work, 662 * do nothing 663 */ 664 mtx_unlock_spin(&sched_lock); 665 kmem_free(kernel_map, 666 (vm_offset_t)new_ldt->ldt_base, 667 new_ldt->ldt_len * sizeof(union descriptor)); 668 FREE(new_ldt, M_SUBPROC); 669 return (0); 670 } 671 } else { 672 mdp->md_ldt = pldt = new_ldt; 673 } 674 #ifdef SMP 675 mtx_unlock_spin(&sched_lock); 676 /* signal other cpus to reload ldt */ 677 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 678 NULL, td); 679 #else 680 set_user_ldt(mdp); 681 mtx_unlock_spin(&sched_lock); 682 #endif 683 } 684 return (0); 685 }
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