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 * 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 if (td == curthread) 112 PCPU_GET(fsgs_gdt)[0] = sd; 113 critical_exit(); 114 } 115 116 void 117 set_gsbase(struct thread *td, uint32_t base) 118 { 119 struct segment_descriptor sd; 120 121 fill_based_sd(&sd, base); 122 critical_enter(); 123 td->td_pcb->pcb_gsd = sd; 124 if (td == curthread) 125 PCPU_GET(fsgs_gdt)[1] = sd; 126 critical_exit(); 127 } 128 129 #ifndef _SYS_SYSPROTO_H_ 130 struct sysarch_args { 131 int op; 132 char *parms; 133 }; 134 #endif 135 136 int 137 sysarch(struct thread *td, struct sysarch_args *uap) 138 { 139 int error; 140 union descriptor *lp; 141 union { 142 struct i386_ldt_args largs; 143 struct i386_ioperm_args iargs; 144 struct i386_get_xfpustate xfpu; 145 } kargs; 146 uint32_t base; 147 struct segment_descriptor *sdp; 148 149 AUDIT_ARG_CMD(uap->op); 150 151 #ifdef CAPABILITY_MODE 152 /* 153 * When adding new operations, add a new case statement here to 154 * explicitly indicate whether or not the operation is safe to 155 * perform in capability mode. 156 */ 157 if (IN_CAPABILITY_MODE(td)) { 158 switch (uap->op) { 159 case I386_GET_LDT: 160 case I386_SET_LDT: 161 case I386_GET_IOPERM: 162 case I386_GET_FSBASE: 163 case I386_SET_FSBASE: 164 case I386_GET_GSBASE: 165 case I386_SET_GSBASE: 166 case I386_GET_XFPUSTATE: 167 break; 168 169 case I386_SET_IOPERM: 170 default: 171 #ifdef KTRACE 172 if (KTRPOINT(td, KTR_CAPFAIL)) 173 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL); 174 #endif 175 return (ECAPMODE); 176 } 177 } 178 #endif 179 180 switch (uap->op) { 181 case I386_GET_IOPERM: 182 case I386_SET_IOPERM: 183 if ((error = copyin(uap->parms, &kargs.iargs, 184 sizeof(struct i386_ioperm_args))) != 0) 185 return (error); 186 break; 187 case I386_GET_LDT: 188 case I386_SET_LDT: 189 if ((error = copyin(uap->parms, &kargs.largs, 190 sizeof(struct i386_ldt_args))) != 0) 191 return (error); 192 break; 193 case I386_GET_XFPUSTATE: 194 if ((error = copyin(uap->parms, &kargs.xfpu, 195 sizeof(struct i386_get_xfpustate))) != 0) 196 return (error); 197 break; 198 default: 199 break; 200 } 201 202 switch (uap->op) { 203 case I386_GET_LDT: 204 error = i386_get_ldt(td, &kargs.largs); 205 break; 206 case I386_SET_LDT: 207 if (kargs.largs.descs != NULL) { 208 if (kargs.largs.num > MAX_LD) 209 return (EINVAL); 210 lp = malloc(kargs.largs.num * sizeof(union descriptor), 211 M_TEMP, M_WAITOK); 212 error = copyin(kargs.largs.descs, lp, 213 kargs.largs.num * sizeof(union descriptor)); 214 if (error == 0) 215 error = i386_set_ldt(td, &kargs.largs, lp); 216 free(lp, M_TEMP); 217 } else { 218 error = i386_set_ldt(td, &kargs.largs, NULL); 219 } 220 break; 221 case I386_GET_IOPERM: 222 error = i386_get_ioperm(td, &kargs.iargs); 223 if (error == 0) 224 error = copyout(&kargs.iargs, uap->parms, 225 sizeof(struct i386_ioperm_args)); 226 break; 227 case I386_SET_IOPERM: 228 error = i386_set_ioperm(td, &kargs.iargs); 229 break; 230 case I386_VM86: 231 error = vm86_sysarch(td, uap->parms); 232 break; 233 case I386_GET_FSBASE: 234 sdp = &td->td_pcb->pcb_fsd; 235 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 236 error = copyout(&base, uap->parms, sizeof(base)); 237 break; 238 case I386_SET_FSBASE: 239 error = copyin(uap->parms, &base, sizeof(base)); 240 if (error == 0) { 241 /* 242 * Construct the special descriptor for fsbase 243 * and arrange for doreti to load its selector 244 * soon enough. 245 */ 246 set_fsbase(td, base); 247 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL); 248 } 249 break; 250 case I386_GET_GSBASE: 251 sdp = &td->td_pcb->pcb_gsd; 252 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 253 error = copyout(&base, uap->parms, sizeof(base)); 254 break; 255 case I386_SET_GSBASE: 256 error = copyin(uap->parms, &base, sizeof(base)); 257 if (error == 0) { 258 /* 259 * Construct the special descriptor for gsbase. 260 * The selector is loaded immediately, since we 261 * normally only reload %gs on context switches. 262 */ 263 set_gsbase(td, base); 264 load_gs(GSEL(GUGS_SEL, SEL_UPL)); 265 } 266 break; 267 case I386_GET_XFPUSTATE: 268 if (kargs.xfpu.len > cpu_max_ext_state_size - 269 sizeof(union savefpu)) 270 return (EINVAL); 271 npxgetregs(td); 272 error = copyout((char *)(get_pcb_user_save_td(td) + 1), 273 kargs.xfpu.addr, kargs.xfpu.len); 274 break; 275 default: 276 error = EINVAL; 277 break; 278 } 279 return (error); 280 } 281 282 int 283 i386_extend_pcb(struct thread *td) 284 { 285 int i, offset; 286 u_long *addr; 287 struct pcb_ext *ext; 288 struct soft_segment_descriptor ssd = { 289 0, /* segment base address (overwritten) */ 290 ctob(IOPAGES + 1) - 1, /* length */ 291 SDT_SYS386TSS, /* segment type */ 292 0, /* priority level */ 293 1, /* descriptor present */ 294 0, 0, 295 0, /* default 32 size */ 296 0 /* granularity */ 297 }; 298 299 ext = pmap_trm_alloc(ctob(IOPAGES + 1), M_WAITOK | M_ZERO); 300 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 301 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 302 /* 303 * The last byte of the i/o map must be followed by an 0xff byte. 304 * We arbitrarily allocate 16 bytes here, to keep the starting 305 * address on a doubleword boundary. 306 */ 307 offset = PAGE_SIZE - 16; 308 ext->ext_tss.tss_ioopt = 309 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 310 ext->ext_iomap = (caddr_t)ext + offset; 311 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 312 313 addr = (u_long *)ext->ext_vm86.vm86_intmap; 314 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 315 *addr++ = ~0; 316 317 ssd.ssd_base = (unsigned)&ext->ext_tss; 318 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 319 ssdtosd(&ssd, &ext->ext_tssd); 320 321 KASSERT(td == curthread, ("giving TSS to !curthread")); 322 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 323 324 /* Switch to the new TSS. */ 325 critical_enter(); 326 ext->ext_tss.tss_esp0 = PCPU_GET(trampstk); 327 td->td_pcb->pcb_ext = ext; 328 PCPU_SET(private_tss, 1); 329 *PCPU_GET(tss_gdt) = ext->ext_tssd; 330 ltr(GSEL(GPROC0_SEL, SEL_KPL)); 331 critical_exit(); 332 333 return 0; 334 } 335 336 int 337 i386_set_ioperm(td, uap) 338 struct thread *td; 339 struct i386_ioperm_args *uap; 340 { 341 char *iomap; 342 u_int i; 343 int error; 344 345 if ((error = priv_check(td, PRIV_IO)) != 0) 346 return (error); 347 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 348 return (error); 349 /* 350 * XXX 351 * While this is restricted to root, we should probably figure out 352 * whether any other driver is using this i/o address, as so not to 353 * cause confusion. This probably requires a global 'usage registry'. 354 */ 355 356 if (td->td_pcb->pcb_ext == 0) 357 if ((error = i386_extend_pcb(td)) != 0) 358 return (error); 359 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 360 361 if (uap->start > uap->start + uap->length || 362 uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY) 363 return (EINVAL); 364 365 for (i = uap->start; i < uap->start + uap->length; i++) { 366 if (uap->enable) 367 iomap[i >> 3] &= ~(1 << (i & 7)); 368 else 369 iomap[i >> 3] |= (1 << (i & 7)); 370 } 371 return (error); 372 } 373 374 int 375 i386_get_ioperm(td, uap) 376 struct thread *td; 377 struct i386_ioperm_args *uap; 378 { 379 int i, state; 380 char *iomap; 381 382 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY) 383 return (EINVAL); 384 385 if (td->td_pcb->pcb_ext == 0) { 386 uap->length = 0; 387 goto done; 388 } 389 390 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 391 392 i = uap->start; 393 state = (iomap[i >> 3] >> (i & 7)) & 1; 394 uap->enable = !state; 395 uap->length = 1; 396 397 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 398 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 399 break; 400 uap->length++; 401 } 402 403 done: 404 return (0); 405 } 406 407 /* 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. 410 */ 411 static void 412 set_user_ldt_locked(struct mdproc *mdp) 413 { 414 struct proc_ldt *pldt; 415 int gdt_idx; 416 417 mtx_assert(&dt_lock, MA_OWNED); 418 419 pldt = mdp->md_ldt; 420 gdt_idx = GUSERLDT_SEL; 421 gdt_idx += PCPU_GET(cpuid) * NGDT; /* always 0 on UP */ 422 gdt[gdt_idx].sd = pldt->ldt_sd; 423 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 424 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 425 } 426 427 void 428 set_user_ldt(struct mdproc *mdp) 429 { 430 431 mtx_lock_spin(&dt_lock); 432 set_user_ldt_locked(mdp); 433 mtx_unlock_spin(&dt_lock); 434 } 435 436 #ifdef SMP 437 static void 438 set_user_ldt_rv(void *arg) 439 { 440 struct proc *p; 441 442 p = curproc; 443 if (arg == p->p_vmspace) 444 set_user_ldt(&p->p_md); 445 } 446 #endif 447 448 /* 449 * dt_lock must be held. Returns with dt_lock held. 450 */ 451 struct proc_ldt * 452 user_ldt_alloc(struct mdproc *mdp, int len) 453 { 454 struct proc_ldt *pldt, *new_ldt; 455 456 mtx_assert(&dt_lock, MA_OWNED); 457 mtx_unlock_spin(&dt_lock); 458 new_ldt = malloc(sizeof(struct proc_ldt), M_SUBPROC, M_WAITOK); 459 460 new_ldt->ldt_len = len = NEW_MAX_LD(len); 461 new_ldt->ldt_base = pmap_trm_alloc(len * sizeof(union descriptor), 462 M_WAITOK | M_ZERO); 463 new_ldt->ldt_refcnt = 1; 464 new_ldt->ldt_active = 0; 465 466 mtx_lock_spin(&dt_lock); 467 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 468 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 469 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 470 471 if ((pldt = mdp->md_ldt) != NULL) { 472 if (len > pldt->ldt_len) 473 len = pldt->ldt_len; 474 bcopy(pldt->ldt_base, new_ldt->ldt_base, 475 len * sizeof(union descriptor)); 476 } else 477 bcopy(ldt, new_ldt->ldt_base, sizeof(union descriptor) * NLDT); 478 479 return (new_ldt); 480 } 481 482 /* 483 * Must be called with dt_lock held. Returns with dt_lock unheld. 484 */ 485 void 486 user_ldt_free(struct thread *td) 487 { 488 struct mdproc *mdp; 489 struct proc_ldt *pldt; 490 491 mtx_assert(&dt_lock, MA_OWNED); 492 mdp = &td->td_proc->p_md; 493 if ((pldt = mdp->md_ldt) == NULL) { 494 mtx_unlock_spin(&dt_lock); 495 return; 496 } 497 498 if (td == curthread) { 499 lldt(_default_ldt); 500 PCPU_SET(currentldt, _default_ldt); 501 } 502 503 mdp->md_ldt = NULL; 504 user_ldt_deref(pldt); 505 } 506 507 void 508 user_ldt_deref(struct proc_ldt *pldt) 509 { 510 511 mtx_assert(&dt_lock, MA_OWNED); 512 if (--pldt->ldt_refcnt == 0) { 513 mtx_unlock_spin(&dt_lock); 514 pmap_trm_free(pldt->ldt_base, pldt->ldt_len * 515 sizeof(union descriptor)); 516 free(pldt, M_SUBPROC); 517 } else 518 mtx_unlock_spin(&dt_lock); 519 } 520 521 /* 522 * Note for the authors of compat layers (linux, etc): copyout() in 523 * the function below is not a problem since it presents data in 524 * arch-specific format (i.e. i386-specific in this case), not in 525 * the OS-specific one. 526 */ 527 int 528 i386_get_ldt(struct thread *td, struct i386_ldt_args *uap) 529 { 530 struct proc_ldt *pldt; 531 char *data; 532 u_int nldt, num; 533 int error; 534 535 #ifdef DEBUG 536 printf("i386_get_ldt: start=%u num=%u descs=%p\n", 537 uap->start, uap->num, (void *)uap->descs); 538 #endif 539 540 num = min(uap->num, MAX_LD); 541 data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK); 542 mtx_lock_spin(&dt_lock); 543 pldt = td->td_proc->p_md.md_ldt; 544 nldt = pldt != NULL ? pldt->ldt_len : NLDT; 545 if (uap->start >= nldt) { 546 num = 0; 547 } else { 548 num = min(num, nldt - uap->start); 549 bcopy(pldt != NULL ? 550 &((union descriptor *)(pldt->ldt_base))[uap->start] : 551 &ldt[uap->start], data, num * sizeof(union descriptor)); 552 } 553 mtx_unlock_spin(&dt_lock); 554 error = copyout(data, uap->descs, num * sizeof(union descriptor)); 555 if (error == 0) 556 td->td_retval[0] = num; 557 free(data, M_TEMP); 558 return (error); 559 } 560 561 int 562 i386_set_ldt(struct thread *td, struct i386_ldt_args *uap, 563 union descriptor *descs) 564 { 565 struct mdproc *mdp; 566 struct proc_ldt *pldt; 567 union descriptor *dp; 568 u_int largest_ld, i; 569 int error; 570 571 #ifdef DEBUG 572 printf("i386_set_ldt: start=%u num=%u descs=%p\n", 573 uap->start, uap->num, (void *)uap->descs); 574 #endif 575 error = 0; 576 mdp = &td->td_proc->p_md; 577 578 if (descs == NULL) { 579 /* Free descriptors */ 580 if (uap->start == 0 && uap->num == 0) { 581 /* 582 * Treat this as a special case, so userland needn't 583 * know magic number NLDT. 584 */ 585 uap->start = NLDT; 586 uap->num = MAX_LD - NLDT; 587 } 588 mtx_lock_spin(&dt_lock); 589 if ((pldt = mdp->md_ldt) == NULL || 590 uap->start >= pldt->ldt_len) { 591 mtx_unlock_spin(&dt_lock); 592 return (0); 593 } 594 largest_ld = uap->start + uap->num; 595 if (largest_ld > pldt->ldt_len) 596 largest_ld = pldt->ldt_len; 597 for (i = uap->start; i < largest_ld; i++) 598 atomic_store_rel_64(&((uint64_t *)(pldt->ldt_base))[i], 599 0); 600 mtx_unlock_spin(&dt_lock); 601 return (0); 602 } 603 604 if (uap->start != LDT_AUTO_ALLOC || uap->num != 1) { 605 /* verify range of descriptors to modify */ 606 largest_ld = uap->start + uap->num; 607 if (uap->start >= MAX_LD || largest_ld > MAX_LD) 608 return (EINVAL); 609 } 610 611 /* Check descriptors for access violations */ 612 for (i = 0; i < uap->num; i++) { 613 dp = &descs[i]; 614 615 switch (dp->sd.sd_type) { 616 case SDT_SYSNULL: /* system null */ 617 dp->sd.sd_p = 0; 618 break; 619 case SDT_SYS286TSS: /* system 286 TSS available */ 620 case SDT_SYSLDT: /* system local descriptor table */ 621 case SDT_SYS286BSY: /* system 286 TSS busy */ 622 case SDT_SYSTASKGT: /* system task gate */ 623 case SDT_SYS286IGT: /* system 286 interrupt gate */ 624 case SDT_SYS286TGT: /* system 286 trap gate */ 625 case SDT_SYSNULL2: /* undefined by Intel */ 626 case SDT_SYS386TSS: /* system 386 TSS available */ 627 case SDT_SYSNULL3: /* undefined by Intel */ 628 case SDT_SYS386BSY: /* system 386 TSS busy */ 629 case SDT_SYSNULL4: /* undefined by Intel */ 630 case SDT_SYS386IGT: /* system 386 interrupt gate */ 631 case SDT_SYS386TGT: /* system 386 trap gate */ 632 case SDT_SYS286CGT: /* system 286 call gate */ 633 case SDT_SYS386CGT: /* system 386 call gate */ 634 return (EACCES); 635 636 /* memory segment types */ 637 case SDT_MEMEC: /* memory execute only conforming */ 638 case SDT_MEMEAC: /* memory execute only accessed conforming */ 639 case SDT_MEMERC: /* memory execute read conforming */ 640 case SDT_MEMERAC: /* memory execute read accessed conforming */ 641 /* Must be "present" if executable and conforming. */ 642 if (dp->sd.sd_p == 0) 643 return (EACCES); 644 break; 645 case SDT_MEMRO: /* memory read only */ 646 case SDT_MEMROA: /* memory read only accessed */ 647 case SDT_MEMRW: /* memory read write */ 648 case SDT_MEMRWA: /* memory read write accessed */ 649 case SDT_MEMROD: /* memory read only expand dwn limit */ 650 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 651 case SDT_MEMRWD: /* memory read write expand dwn limit */ 652 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 653 case SDT_MEME: /* memory execute only */ 654 case SDT_MEMEA: /* memory execute only accessed */ 655 case SDT_MEMER: /* memory execute read */ 656 case SDT_MEMERA: /* memory execute read accessed */ 657 break; 658 default: 659 return (EINVAL); 660 } 661 662 /* Only user (ring-3) descriptors may be present. */ 663 if (dp->sd.sd_p != 0 && dp->sd.sd_dpl != SEL_UPL) 664 return (EACCES); 665 } 666 667 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 668 /* Allocate a free slot */ 669 mtx_lock_spin(&dt_lock); 670 if ((pldt = mdp->md_ldt) == NULL) { 671 if ((error = i386_ldt_grow(td, NLDT + 1))) { 672 mtx_unlock_spin(&dt_lock); 673 return (error); 674 } 675 pldt = mdp->md_ldt; 676 } 677 again: 678 /* 679 * start scanning a bit up to leave room for NVidia and 680 * Wine, which still user the "Blat" method of allocation. 681 */ 682 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 683 for (i = NLDT; i < pldt->ldt_len; ++i) { 684 if (dp->sd.sd_type == SDT_SYSNULL) 685 break; 686 dp++; 687 } 688 if (i >= pldt->ldt_len) { 689 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) { 690 mtx_unlock_spin(&dt_lock); 691 return (error); 692 } 693 goto again; 694 } 695 uap->start = i; 696 error = i386_set_ldt_data(td, i, 1, descs); 697 mtx_unlock_spin(&dt_lock); 698 } else { 699 largest_ld = uap->start + uap->num; 700 mtx_lock_spin(&dt_lock); 701 if (!(error = i386_ldt_grow(td, largest_ld))) { 702 error = i386_set_ldt_data(td, uap->start, uap->num, 703 descs); 704 } 705 mtx_unlock_spin(&dt_lock); 706 } 707 if (error == 0) 708 td->td_retval[0] = uap->start; 709 return (error); 710 } 711 712 static int 713 i386_set_ldt_data(struct thread *td, int start, int num, 714 union descriptor *descs) 715 { 716 struct mdproc *mdp; 717 struct proc_ldt *pldt; 718 uint64_t *dst, *src; 719 int i; 720 721 mtx_assert(&dt_lock, MA_OWNED); 722 723 mdp = &td->td_proc->p_md; 724 pldt = mdp->md_ldt; 725 dst = (uint64_t *)(pldt->ldt_base); 726 src = (uint64_t *)descs; 727 728 /* 729 * Atomic(9) is used only to get 64bit atomic store with 730 * cmpxchg8b when available. There is no op without release 731 * semantic. 732 */ 733 for (i = 0; i < num; i++) 734 atomic_store_rel_64(&dst[start + i], src[i]); 735 return (0); 736 } 737 738 static int 739 i386_ldt_grow(struct thread *td, int len) 740 { 741 struct mdproc *mdp; 742 struct proc_ldt *new_ldt, *pldt; 743 caddr_t old_ldt_base; 744 int old_ldt_len; 745 746 mtx_assert(&dt_lock, MA_OWNED); 747 748 if (len > MAX_LD) 749 return (ENOMEM); 750 if (len < NLDT + 1) 751 len = NLDT + 1; 752 753 mdp = &td->td_proc->p_md; 754 old_ldt_base = NULL_LDT_BASE; 755 old_ldt_len = 0; 756 757 /* Allocate a user ldt. */ 758 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) { 759 new_ldt = user_ldt_alloc(mdp, len); 760 if (new_ldt == NULL) 761 return (ENOMEM); 762 pldt = mdp->md_ldt; 763 764 if (pldt != NULL) { 765 if (new_ldt->ldt_len <= pldt->ldt_len) { 766 /* 767 * We just lost the race for allocation, so 768 * free the new object and return. 769 */ 770 mtx_unlock_spin(&dt_lock); 771 pmap_trm_free(new_ldt->ldt_base, 772 new_ldt->ldt_len * sizeof(union descriptor)); 773 free(new_ldt, M_SUBPROC); 774 mtx_lock_spin(&dt_lock); 775 return (0); 776 } 777 778 /* 779 * We have to substitute the current LDT entry for 780 * curproc with the new one since its size grew. 781 */ 782 old_ldt_base = pldt->ldt_base; 783 old_ldt_len = pldt->ldt_len; 784 pldt->ldt_sd = new_ldt->ldt_sd; 785 pldt->ldt_base = new_ldt->ldt_base; 786 pldt->ldt_len = new_ldt->ldt_len; 787 } else 788 mdp->md_ldt = pldt = new_ldt; 789 #ifdef SMP 790 /* 791 * Signal other cpus to reload ldt. We need to unlock dt_lock 792 * here because other CPU will contest on it since their 793 * curthreads won't hold the lock and will block when trying 794 * to acquire it. 795 */ 796 mtx_unlock_spin(&dt_lock); 797 smp_rendezvous(NULL, set_user_ldt_rv, NULL, 798 td->td_proc->p_vmspace); 799 #else 800 set_user_ldt_locked(&td->td_proc->p_md); 801 mtx_unlock_spin(&dt_lock); 802 #endif 803 if (old_ldt_base != NULL_LDT_BASE) { 804 pmap_trm_free(old_ldt_base, old_ldt_len * 805 sizeof(union descriptor)); 806 free(new_ldt, M_SUBPROC); 807 } 808 mtx_lock_spin(&dt_lock); 809 } 810 return (0); 811 }
Cache object: 24956f606524842d9d4a86ea5702b20a
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