Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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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: releng/10.0/sys/i386/i386/sys_machdep.c 255677 2013-09-18 19:26:08Z pjd $"); 34 35 #include "opt_capsicum.h" 36 #include "opt_kstack_pages.h" 37 38 #include <sys/param.h> 39 #include <sys/capability.h> 40 #include <sys/systm.h> 41 #include <sys/lock.h> 42 #include <sys/malloc.h> 43 #include <sys/mutex.h> 44 #include <sys/priv.h> 45 #include <sys/proc.h> 46 #include <sys/smp.h> 47 #include <sys/sysproto.h> 48 49 #include <vm/vm.h> 50 #include <vm/pmap.h> 51 #include <vm/vm_map.h> 52 #include <vm/vm_extern.h> 53 54 #include <machine/cpu.h> 55 #include <machine/pcb.h> 56 #include <machine/pcb_ext.h> 57 #include <machine/proc.h> 58 #include <machine/sysarch.h> 59 60 #include <security/audit/audit.h> 61 62 #ifdef XEN 63 #include <machine/xen/xenfunc.h> 64 65 void i386_reset_ldt(struct proc_ldt *pldt); 66 67 void 68 i386_reset_ldt(struct proc_ldt *pldt) 69 { 70 xen_set_ldt((vm_offset_t)pldt->ldt_base, pldt->ldt_len); 71 } 72 #else 73 #define i386_reset_ldt(x) 74 #endif 75 76 #include <vm/vm_kern.h> /* for kernel_map */ 77 78 #define MAX_LD 8192 79 #define LD_PER_PAGE 512 80 #define NEW_MAX_LD(num) ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1)) 81 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3) 82 #define NULL_LDT_BASE ((caddr_t)NULL) 83 84 #ifdef SMP 85 static void set_user_ldt_rv(struct vmspace *vmsp); 86 #endif 87 static int i386_set_ldt_data(struct thread *, int start, int num, 88 union descriptor *descs); 89 static int i386_ldt_grow(struct thread *td, int len); 90 91 #ifndef _SYS_SYSPROTO_H_ 92 struct sysarch_args { 93 int op; 94 char *parms; 95 }; 96 #endif 97 98 int 99 sysarch(td, uap) 100 struct thread *td; 101 register struct sysarch_args *uap; 102 { 103 int error; 104 union descriptor *lp; 105 union { 106 struct i386_ldt_args largs; 107 struct i386_ioperm_args iargs; 108 } kargs; 109 uint32_t base; 110 struct segment_descriptor sd, *sdp; 111 112 AUDIT_ARG_CMD(uap->op); 113 114 #ifdef CAPABILITY_MODE 115 /* 116 * When adding new operations, add a new case statement here to 117 * explicitly indicate whether or not the operation is safe to 118 * perform in capability mode. 119 */ 120 if (IN_CAPABILITY_MODE(td)) { 121 switch (uap->op) { 122 case I386_GET_LDT: 123 case I386_SET_LDT: 124 case I386_GET_IOPERM: 125 case I386_GET_FSBASE: 126 case I386_SET_FSBASE: 127 case I386_GET_GSBASE: 128 case I386_SET_GSBASE: 129 break; 130 131 case I386_SET_IOPERM: 132 default: 133 #ifdef KTRACE 134 if (KTRPOINT(td, KTR_CAPFAIL)) 135 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL); 136 #endif 137 return (ECAPMODE); 138 } 139 } 140 #endif 141 142 switch (uap->op) { 143 case I386_GET_IOPERM: 144 case I386_SET_IOPERM: 145 if ((error = copyin(uap->parms, &kargs.iargs, 146 sizeof(struct i386_ioperm_args))) != 0) 147 return (error); 148 break; 149 case I386_GET_LDT: 150 case I386_SET_LDT: 151 if ((error = copyin(uap->parms, &kargs.largs, 152 sizeof(struct i386_ldt_args))) != 0) 153 return (error); 154 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0) 155 return (EINVAL); 156 break; 157 default: 158 break; 159 } 160 161 switch(uap->op) { 162 case I386_GET_LDT: 163 error = i386_get_ldt(td, &kargs.largs); 164 break; 165 case I386_SET_LDT: 166 if (kargs.largs.descs != NULL) { 167 lp = (union descriptor *)kmem_malloc(kernel_arena, 168 kargs.largs.num * sizeof(union descriptor), 169 M_WAITOK); 170 if (lp == NULL) { 171 error = ENOMEM; 172 break; 173 } 174 error = copyin(kargs.largs.descs, lp, 175 kargs.largs.num * sizeof(union descriptor)); 176 if (error == 0) 177 error = i386_set_ldt(td, &kargs.largs, lp); 178 kmem_free(kernel_arena, (vm_offset_t)lp, 179 kargs.largs.num * sizeof(union descriptor)); 180 } else { 181 error = i386_set_ldt(td, &kargs.largs, NULL); 182 } 183 break; 184 case I386_GET_IOPERM: 185 error = i386_get_ioperm(td, &kargs.iargs); 186 if (error == 0) 187 error = copyout(&kargs.iargs, uap->parms, 188 sizeof(struct i386_ioperm_args)); 189 break; 190 case I386_SET_IOPERM: 191 error = i386_set_ioperm(td, &kargs.iargs); 192 break; 193 case I386_VM86: 194 error = vm86_sysarch(td, uap->parms); 195 break; 196 case I386_GET_FSBASE: 197 sdp = &td->td_pcb->pcb_fsd; 198 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 199 error = copyout(&base, uap->parms, sizeof(base)); 200 break; 201 case I386_SET_FSBASE: 202 error = copyin(uap->parms, &base, sizeof(base)); 203 if (!error) { 204 /* 205 * Construct a descriptor and store it in the pcb for 206 * the next context switch. Also store it in the gdt 207 * so that the load of tf_fs into %fs will activate it 208 * at return to userland. 209 */ 210 sd.sd_lobase = base & 0xffffff; 211 sd.sd_hibase = (base >> 24) & 0xff; 212 #ifdef XEN 213 /* need to do nosegneg like Linux */ 214 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff; 215 #else 216 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 217 #endif 218 sd.sd_hilimit = 0xf; 219 sd.sd_type = SDT_MEMRWA; 220 sd.sd_dpl = SEL_UPL; 221 sd.sd_p = 1; 222 sd.sd_xx = 0; 223 sd.sd_def32 = 1; 224 sd.sd_gran = 1; 225 critical_enter(); 226 td->td_pcb->pcb_fsd = sd; 227 #ifdef XEN 228 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[0]), 229 *(uint64_t *)&sd); 230 #else 231 PCPU_GET(fsgs_gdt)[0] = sd; 232 #endif 233 critical_exit(); 234 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL); 235 } 236 break; 237 case I386_GET_GSBASE: 238 sdp = &td->td_pcb->pcb_gsd; 239 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 240 error = copyout(&base, uap->parms, sizeof(base)); 241 break; 242 case I386_SET_GSBASE: 243 error = copyin(uap->parms, &base, sizeof(base)); 244 if (!error) { 245 /* 246 * Construct a descriptor and store it in the pcb for 247 * the next context switch. Also store it in the gdt 248 * because we have to do a load_gs() right now. 249 */ 250 sd.sd_lobase = base & 0xffffff; 251 sd.sd_hibase = (base >> 24) & 0xff; 252 253 #ifdef XEN 254 /* need to do nosegneg like Linux */ 255 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff; 256 #else 257 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 258 #endif 259 sd.sd_hilimit = 0xf; 260 sd.sd_type = SDT_MEMRWA; 261 sd.sd_dpl = SEL_UPL; 262 sd.sd_p = 1; 263 sd.sd_xx = 0; 264 sd.sd_def32 = 1; 265 sd.sd_gran = 1; 266 critical_enter(); 267 td->td_pcb->pcb_gsd = sd; 268 #ifdef XEN 269 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[1]), 270 *(uint64_t *)&sd); 271 #else 272 PCPU_GET(fsgs_gdt)[1] = sd; 273 #endif 274 critical_exit(); 275 load_gs(GSEL(GUGS_SEL, SEL_UPL)); 276 } 277 break; 278 default: 279 error = EINVAL; 280 break; 281 } 282 return (error); 283 } 284 285 int 286 i386_extend_pcb(struct thread *td) 287 { 288 int i, offset; 289 u_long *addr; 290 struct pcb_ext *ext; 291 struct soft_segment_descriptor ssd = { 292 0, /* segment base address (overwritten) */ 293 ctob(IOPAGES + 1) - 1, /* length */ 294 SDT_SYS386TSS, /* segment type */ 295 0, /* priority level */ 296 1, /* descriptor present */ 297 0, 0, 298 0, /* default 32 size */ 299 0 /* granularity */ 300 }; 301 302 ext = (struct pcb_ext *)kmem_malloc(kernel_arena, ctob(IOPAGES+1), 303 M_WAITOK); 304 if (ext == 0) 305 return (ENOMEM); 306 bzero(ext, sizeof(struct pcb_ext)); 307 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 308 ext->ext_tss.tss_esp0 = td->td_kstack + ctob(KSTACK_PAGES) - 309 sizeof(struct pcb) - 16; 310 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 311 /* 312 * The last byte of the i/o map must be followed by an 0xff byte. 313 * We arbitrarily allocate 16 bytes here, to keep the starting 314 * address on a doubleword boundary. 315 */ 316 offset = PAGE_SIZE - 16; 317 ext->ext_tss.tss_ioopt = 318 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 319 ext->ext_iomap = (caddr_t)ext + offset; 320 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 321 322 addr = (u_long *)ext->ext_vm86.vm86_intmap; 323 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 324 *addr++ = ~0; 325 326 ssd.ssd_base = (unsigned)&ext->ext_tss; 327 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 328 ssdtosd(&ssd, &ext->ext_tssd); 329 330 KASSERT(td == curthread, ("giving TSS to !curthread")); 331 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 332 333 /* Switch to the new TSS. */ 334 critical_enter(); 335 td->td_pcb->pcb_ext = ext; 336 PCPU_SET(private_tss, 1); 337 *PCPU_GET(tss_gdt) = ext->ext_tssd; 338 ltr(GSEL(GPROC0_SEL, SEL_KPL)); 339 critical_exit(); 340 341 return 0; 342 } 343 344 int 345 i386_set_ioperm(td, uap) 346 struct thread *td; 347 struct i386_ioperm_args *uap; 348 { 349 int i, error; 350 char *iomap; 351 352 if ((error = priv_check(td, PRIV_IO)) != 0) 353 return (error); 354 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 355 return (error); 356 /* 357 * XXX 358 * While this is restricted to root, we should probably figure out 359 * whether any other driver is using this i/o address, as so not to 360 * cause confusion. This probably requires a global 'usage registry'. 361 */ 362 363 if (td->td_pcb->pcb_ext == 0) 364 if ((error = i386_extend_pcb(td)) != 0) 365 return (error); 366 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 367 368 if (uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY) 369 return (EINVAL); 370 371 for (i = uap->start; i < uap->start + uap->length; i++) { 372 if (uap->enable) 373 iomap[i >> 3] &= ~(1 << (i & 7)); 374 else 375 iomap[i >> 3] |= (1 << (i & 7)); 376 } 377 return (error); 378 } 379 380 int 381 i386_get_ioperm(td, uap) 382 struct thread *td; 383 struct i386_ioperm_args *uap; 384 { 385 int i, state; 386 char *iomap; 387 388 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY) 389 return (EINVAL); 390 391 if (td->td_pcb->pcb_ext == 0) { 392 uap->length = 0; 393 goto done; 394 } 395 396 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 397 398 i = uap->start; 399 state = (iomap[i >> 3] >> (i & 7)) & 1; 400 uap->enable = !state; 401 uap->length = 1; 402 403 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 404 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 405 break; 406 uap->length++; 407 } 408 409 done: 410 return (0); 411 } 412 413 /* 414 * Update the GDT entry pointing to the LDT to point to the LDT of the 415 * current process. Manage dt_lock holding/unholding autonomously. 416 */ 417 void 418 set_user_ldt(struct mdproc *mdp) 419 { 420 struct proc_ldt *pldt; 421 int dtlocked; 422 423 dtlocked = 0; 424 if (!mtx_owned(&dt_lock)) { 425 mtx_lock_spin(&dt_lock); 426 dtlocked = 1; 427 } 428 429 pldt = mdp->md_ldt; 430 #ifdef XEN 431 i386_reset_ldt(pldt); 432 PCPU_SET(currentldt, (int)pldt); 433 #else 434 #ifdef SMP 435 gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd; 436 #else 437 gdt[GUSERLDT_SEL].sd = pldt->ldt_sd; 438 #endif 439 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 440 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 441 #endif /* XEN */ 442 if (dtlocked) 443 mtx_unlock_spin(&dt_lock); 444 } 445 446 #ifdef SMP 447 static void 448 set_user_ldt_rv(struct vmspace *vmsp) 449 { 450 struct thread *td; 451 452 td = curthread; 453 if (vmsp != td->td_proc->p_vmspace) 454 return; 455 456 set_user_ldt(&td->td_proc->p_md); 457 } 458 #endif 459 460 #ifdef XEN 461 462 /* 463 * dt_lock must be held. Returns with dt_lock held. 464 */ 465 struct proc_ldt * 466 user_ldt_alloc(struct mdproc *mdp, int len) 467 { 468 struct proc_ldt *pldt, *new_ldt; 469 470 mtx_assert(&dt_lock, MA_OWNED); 471 mtx_unlock_spin(&dt_lock); 472 new_ldt = malloc(sizeof(struct proc_ldt), 473 M_SUBPROC, M_WAITOK); 474 475 new_ldt->ldt_len = len = NEW_MAX_LD(len); 476 new_ldt->ldt_base = (caddr_t)kmem_malloc(kernel_arena, 477 round_page(len * sizeof(union descriptor)), M_WAITOK); 478 if (new_ldt->ldt_base == NULL) { 479 free(new_ldt, M_SUBPROC); 480 mtx_lock_spin(&dt_lock); 481 return (NULL); 482 } 483 new_ldt->ldt_refcnt = 1; 484 new_ldt->ldt_active = 0; 485 486 mtx_lock_spin(&dt_lock); 487 if ((pldt = mdp->md_ldt)) { 488 if (len > pldt->ldt_len) 489 len = pldt->ldt_len; 490 bcopy(pldt->ldt_base, new_ldt->ldt_base, 491 len * sizeof(union descriptor)); 492 } else { 493 bcopy(ldt, new_ldt->ldt_base, PAGE_SIZE); 494 } 495 mtx_unlock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 496 pmap_map_readonly(kernel_pmap, (vm_offset_t)new_ldt->ldt_base, 497 new_ldt->ldt_len*sizeof(union descriptor)); 498 mtx_lock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 499 return (new_ldt); 500 } 501 #else 502 /* 503 * dt_lock must be held. Returns with dt_lock held. 504 */ 505 struct proc_ldt * 506 user_ldt_alloc(struct mdproc *mdp, int len) 507 { 508 struct proc_ldt *pldt, *new_ldt; 509 510 mtx_assert(&dt_lock, MA_OWNED); 511 mtx_unlock_spin(&dt_lock); 512 new_ldt = malloc(sizeof(struct proc_ldt), 513 M_SUBPROC, M_WAITOK); 514 515 new_ldt->ldt_len = len = NEW_MAX_LD(len); 516 new_ldt->ldt_base = (caddr_t)kmem_malloc(kernel_arena, 517 len * sizeof(union descriptor), M_WAITOK); 518 if (new_ldt->ldt_base == NULL) { 519 free(new_ldt, M_SUBPROC); 520 mtx_lock_spin(&dt_lock); 521 return (NULL); 522 } 523 new_ldt->ldt_refcnt = 1; 524 new_ldt->ldt_active = 0; 525 526 mtx_lock_spin(&dt_lock); 527 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 528 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 529 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 530 531 if ((pldt = mdp->md_ldt) != NULL) { 532 if (len > pldt->ldt_len) 533 len = pldt->ldt_len; 534 bcopy(pldt->ldt_base, new_ldt->ldt_base, 535 len * sizeof(union descriptor)); 536 } else 537 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt)); 538 539 return (new_ldt); 540 } 541 #endif /* !XEN */ 542 543 /* 544 * Must be called with dt_lock held. Returns with dt_lock unheld. 545 */ 546 void 547 user_ldt_free(struct thread *td) 548 { 549 struct mdproc *mdp = &td->td_proc->p_md; 550 struct proc_ldt *pldt; 551 552 mtx_assert(&dt_lock, MA_OWNED); 553 if ((pldt = mdp->md_ldt) == NULL) { 554 mtx_unlock_spin(&dt_lock); 555 return; 556 } 557 558 if (td == curthread) { 559 #ifdef XEN 560 i386_reset_ldt(&default_proc_ldt); 561 PCPU_SET(currentldt, (int)&default_proc_ldt); 562 #else 563 lldt(_default_ldt); 564 PCPU_SET(currentldt, _default_ldt); 565 #endif 566 } 567 568 mdp->md_ldt = NULL; 569 user_ldt_deref(pldt); 570 } 571 572 void 573 user_ldt_deref(struct proc_ldt *pldt) 574 { 575 576 mtx_assert(&dt_lock, MA_OWNED); 577 if (--pldt->ldt_refcnt == 0) { 578 mtx_unlock_spin(&dt_lock); 579 kmem_free(kernel_arena, (vm_offset_t)pldt->ldt_base, 580 pldt->ldt_len * sizeof(union descriptor)); 581 free(pldt, M_SUBPROC); 582 } else 583 mtx_unlock_spin(&dt_lock); 584 } 585 586 /* 587 * Note for the authors of compat layers (linux, etc): copyout() in 588 * the function below is not a problem since it presents data in 589 * arch-specific format (i.e. i386-specific in this case), not in 590 * the OS-specific one. 591 */ 592 int 593 i386_get_ldt(td, uap) 594 struct thread *td; 595 struct i386_ldt_args *uap; 596 { 597 int error = 0; 598 struct proc_ldt *pldt; 599 int nldt, num; 600 union descriptor *lp; 601 602 #ifdef DEBUG 603 printf("i386_get_ldt: start=%d num=%d descs=%p\n", 604 uap->start, uap->num, (void *)uap->descs); 605 #endif 606 607 mtx_lock_spin(&dt_lock); 608 if ((pldt = td->td_proc->p_md.md_ldt) != NULL) { 609 nldt = pldt->ldt_len; 610 lp = &((union descriptor *)(pldt->ldt_base))[uap->start]; 611 mtx_unlock_spin(&dt_lock); 612 num = min(uap->num, nldt); 613 } else { 614 mtx_unlock_spin(&dt_lock); 615 nldt = sizeof(ldt)/sizeof(ldt[0]); 616 num = min(uap->num, nldt); 617 lp = &ldt[uap->start]; 618 } 619 620 if ((uap->start > (unsigned int)nldt) || 621 ((unsigned int)num > (unsigned int)nldt) || 622 ((unsigned int)(uap->start + num) > (unsigned int)nldt)) 623 return(EINVAL); 624 625 error = copyout(lp, uap->descs, num * sizeof(union descriptor)); 626 if (!error) 627 td->td_retval[0] = num; 628 629 return(error); 630 } 631 632 int 633 i386_set_ldt(td, uap, descs) 634 struct thread *td; 635 struct i386_ldt_args *uap; 636 union descriptor *descs; 637 { 638 int error = 0, i; 639 int largest_ld; 640 struct mdproc *mdp = &td->td_proc->p_md; 641 struct proc_ldt *pldt; 642 union descriptor *dp; 643 644 #ifdef DEBUG 645 printf("i386_set_ldt: start=%d num=%d descs=%p\n", 646 uap->start, uap->num, (void *)uap->descs); 647 #endif 648 649 if (descs == NULL) { 650 /* Free descriptors */ 651 if (uap->start == 0 && uap->num == 0) { 652 /* 653 * Treat this as a special case, so userland needn't 654 * know magic number NLDT. 655 */ 656 uap->start = NLDT; 657 uap->num = MAX_LD - NLDT; 658 } 659 if (uap->num == 0) 660 return (EINVAL); 661 mtx_lock_spin(&dt_lock); 662 if ((pldt = mdp->md_ldt) == NULL || 663 uap->start >= pldt->ldt_len) { 664 mtx_unlock_spin(&dt_lock); 665 return (0); 666 } 667 largest_ld = uap->start + uap->num; 668 if (largest_ld > pldt->ldt_len) 669 largest_ld = pldt->ldt_len; 670 i = largest_ld - uap->start; 671 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start], 672 sizeof(union descriptor) * i); 673 mtx_unlock_spin(&dt_lock); 674 return (0); 675 } 676 677 if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) { 678 /* verify range of descriptors to modify */ 679 largest_ld = uap->start + uap->num; 680 if (uap->start >= MAX_LD || largest_ld > MAX_LD) { 681 return (EINVAL); 682 } 683 } 684 685 /* Check descriptors for access violations */ 686 for (i = 0; i < uap->num; i++) { 687 dp = &descs[i]; 688 689 switch (dp->sd.sd_type) { 690 case SDT_SYSNULL: /* system null */ 691 dp->sd.sd_p = 0; 692 break; 693 case SDT_SYS286TSS: /* system 286 TSS available */ 694 case SDT_SYSLDT: /* system local descriptor table */ 695 case SDT_SYS286BSY: /* system 286 TSS busy */ 696 case SDT_SYSTASKGT: /* system task gate */ 697 case SDT_SYS286IGT: /* system 286 interrupt gate */ 698 case SDT_SYS286TGT: /* system 286 trap gate */ 699 case SDT_SYSNULL2: /* undefined by Intel */ 700 case SDT_SYS386TSS: /* system 386 TSS available */ 701 case SDT_SYSNULL3: /* undefined by Intel */ 702 case SDT_SYS386BSY: /* system 386 TSS busy */ 703 case SDT_SYSNULL4: /* undefined by Intel */ 704 case SDT_SYS386IGT: /* system 386 interrupt gate */ 705 case SDT_SYS386TGT: /* system 386 trap gate */ 706 case SDT_SYS286CGT: /* system 286 call gate */ 707 case SDT_SYS386CGT: /* system 386 call gate */ 708 /* I can't think of any reason to allow a user proc 709 * to create a segment of these types. They are 710 * for OS use only. 711 */ 712 return (EACCES); 713 /*NOTREACHED*/ 714 715 /* memory segment types */ 716 case SDT_MEMEC: /* memory execute only conforming */ 717 case SDT_MEMEAC: /* memory execute only accessed conforming */ 718 case SDT_MEMERC: /* memory execute read conforming */ 719 case SDT_MEMERAC: /* memory execute read accessed conforming */ 720 /* Must be "present" if executable and conforming. */ 721 if (dp->sd.sd_p == 0) 722 return (EACCES); 723 break; 724 case SDT_MEMRO: /* memory read only */ 725 case SDT_MEMROA: /* memory read only accessed */ 726 case SDT_MEMRW: /* memory read write */ 727 case SDT_MEMRWA: /* memory read write accessed */ 728 case SDT_MEMROD: /* memory read only expand dwn limit */ 729 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 730 case SDT_MEMRWD: /* memory read write expand dwn limit */ 731 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 732 case SDT_MEME: /* memory execute only */ 733 case SDT_MEMEA: /* memory execute only accessed */ 734 case SDT_MEMER: /* memory execute read */ 735 case SDT_MEMERA: /* memory execute read accessed */ 736 break; 737 default: 738 return(EINVAL); 739 /*NOTREACHED*/ 740 } 741 742 /* Only user (ring-3) descriptors may be present. */ 743 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL)) 744 return (EACCES); 745 } 746 747 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 748 /* Allocate a free slot */ 749 mtx_lock_spin(&dt_lock); 750 if ((pldt = mdp->md_ldt) == NULL) { 751 if ((error = i386_ldt_grow(td, NLDT + 1))) { 752 mtx_unlock_spin(&dt_lock); 753 return (error); 754 } 755 pldt = mdp->md_ldt; 756 } 757 again: 758 /* 759 * start scanning a bit up to leave room for NVidia and 760 * Wine, which still user the "Blat" method of allocation. 761 */ 762 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 763 for (i = NLDT; i < pldt->ldt_len; ++i) { 764 if (dp->sd.sd_type == SDT_SYSNULL) 765 break; 766 dp++; 767 } 768 if (i >= pldt->ldt_len) { 769 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) { 770 mtx_unlock_spin(&dt_lock); 771 return (error); 772 } 773 goto again; 774 } 775 uap->start = i; 776 error = i386_set_ldt_data(td, i, 1, descs); 777 mtx_unlock_spin(&dt_lock); 778 } else { 779 largest_ld = uap->start + uap->num; 780 mtx_lock_spin(&dt_lock); 781 if (!(error = i386_ldt_grow(td, largest_ld))) { 782 error = i386_set_ldt_data(td, uap->start, uap->num, 783 descs); 784 } 785 mtx_unlock_spin(&dt_lock); 786 } 787 if (error == 0) 788 td->td_retval[0] = uap->start; 789 return (error); 790 } 791 #ifdef XEN 792 static int 793 i386_set_ldt_data(struct thread *td, int start, int num, 794 union descriptor *descs) 795 { 796 struct mdproc *mdp = &td->td_proc->p_md; 797 struct proc_ldt *pldt = mdp->md_ldt; 798 799 mtx_assert(&dt_lock, MA_OWNED); 800 801 while (num) { 802 xen_update_descriptor( 803 &((union descriptor *)(pldt->ldt_base))[start], 804 descs); 805 num--; 806 start++; 807 descs++; 808 } 809 return (0); 810 } 811 #else 812 static int 813 i386_set_ldt_data(struct thread *td, int start, int num, 814 union descriptor *descs) 815 { 816 struct mdproc *mdp = &td->td_proc->p_md; 817 struct proc_ldt *pldt = mdp->md_ldt; 818 819 mtx_assert(&dt_lock, MA_OWNED); 820 821 /* Fill in range */ 822 bcopy(descs, 823 &((union descriptor *)(pldt->ldt_base))[start], 824 num * sizeof(union descriptor)); 825 return (0); 826 } 827 #endif /* !XEN */ 828 829 static int 830 i386_ldt_grow(struct thread *td, int len) 831 { 832 struct mdproc *mdp = &td->td_proc->p_md; 833 struct proc_ldt *new_ldt, *pldt; 834 caddr_t old_ldt_base = NULL_LDT_BASE; 835 int old_ldt_len = 0; 836 837 mtx_assert(&dt_lock, MA_OWNED); 838 839 if (len > MAX_LD) 840 return (ENOMEM); 841 if (len < NLDT + 1) 842 len = NLDT + 1; 843 844 /* Allocate a user ldt. */ 845 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) { 846 new_ldt = user_ldt_alloc(mdp, len); 847 if (new_ldt == NULL) 848 return (ENOMEM); 849 pldt = mdp->md_ldt; 850 851 if (pldt != NULL) { 852 if (new_ldt->ldt_len <= pldt->ldt_len) { 853 /* 854 * We just lost the race for allocation, so 855 * free the new object and return. 856 */ 857 mtx_unlock_spin(&dt_lock); 858 kmem_free(kernel_arena, 859 (vm_offset_t)new_ldt->ldt_base, 860 new_ldt->ldt_len * sizeof(union descriptor)); 861 free(new_ldt, M_SUBPROC); 862 mtx_lock_spin(&dt_lock); 863 return (0); 864 } 865 866 /* 867 * We have to substitute the current LDT entry for 868 * curproc with the new one since its size grew. 869 */ 870 old_ldt_base = pldt->ldt_base; 871 old_ldt_len = pldt->ldt_len; 872 pldt->ldt_sd = new_ldt->ldt_sd; 873 pldt->ldt_base = new_ldt->ldt_base; 874 pldt->ldt_len = new_ldt->ldt_len; 875 } else 876 mdp->md_ldt = pldt = new_ldt; 877 #ifdef SMP 878 /* 879 * Signal other cpus to reload ldt. We need to unlock dt_lock 880 * here because other CPU will contest on it since their 881 * curthreads won't hold the lock and will block when trying 882 * to acquire it. 883 */ 884 mtx_unlock_spin(&dt_lock); 885 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 886 NULL, td->td_proc->p_vmspace); 887 #else 888 set_user_ldt(&td->td_proc->p_md); 889 mtx_unlock_spin(&dt_lock); 890 #endif 891 if (old_ldt_base != NULL_LDT_BASE) { 892 kmem_free(kernel_arena, (vm_offset_t)old_ldt_base, 893 old_ldt_len * sizeof(union descriptor)); 894 free(new_ldt, M_SUBPROC); 895 } 896 mtx_lock_spin(&dt_lock); 897 } 898 return (0); 899 }
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