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("$FreeBSD$"); 34 35 #include "opt_capsicum.h" 36 #include "opt_kstack_pages.h" 37 38 #include <sys/param.h> 39 #include <sys/capsicum.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 void 92 fill_based_sd(struct segment_descriptor *sdp, uint32_t base) 93 { 94 95 sdp->sd_lobase = base & 0xffffff; 96 sdp->sd_hibase = (base >> 24) & 0xff; 97 #ifdef XEN 98 /* need to do nosegneg like Linux */ 99 sdp->sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff; 100 #else 101 sdp->sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 102 #endif 103 sdp->sd_hilimit = 0xf; 104 sdp->sd_type = SDT_MEMRWA; 105 sdp->sd_dpl = SEL_UPL; 106 sdp->sd_p = 1; 107 sdp->sd_xx = 0; 108 sdp->sd_def32 = 1; 109 sdp->sd_gran = 1; 110 } 111 112 #ifndef _SYS_SYSPROTO_H_ 113 struct sysarch_args { 114 int op; 115 char *parms; 116 }; 117 #endif 118 119 int 120 sysarch(td, uap) 121 struct thread *td; 122 register struct sysarch_args *uap; 123 { 124 int error; 125 union descriptor *lp; 126 union { 127 struct i386_ldt_args largs; 128 struct i386_ioperm_args iargs; 129 struct i386_get_xfpustate xfpu; 130 } kargs; 131 uint32_t base; 132 struct segment_descriptor sd, *sdp; 133 134 AUDIT_ARG_CMD(uap->op); 135 136 #ifdef CAPABILITY_MODE 137 /* 138 * When adding new operations, add a new case statement here to 139 * explicitly indicate whether or not the operation is safe to 140 * perform in capability mode. 141 */ 142 if (IN_CAPABILITY_MODE(td)) { 143 switch (uap->op) { 144 case I386_GET_LDT: 145 case I386_SET_LDT: 146 case I386_GET_IOPERM: 147 case I386_GET_FSBASE: 148 case I386_SET_FSBASE: 149 case I386_GET_GSBASE: 150 case I386_SET_GSBASE: 151 case I386_GET_XFPUSTATE: 152 break; 153 154 case I386_SET_IOPERM: 155 default: 156 #ifdef KTRACE 157 if (KTRPOINT(td, KTR_CAPFAIL)) 158 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL); 159 #endif 160 return (ECAPMODE); 161 } 162 } 163 #endif 164 165 switch (uap->op) { 166 case I386_GET_IOPERM: 167 case I386_SET_IOPERM: 168 if ((error = copyin(uap->parms, &kargs.iargs, 169 sizeof(struct i386_ioperm_args))) != 0) 170 return (error); 171 break; 172 case I386_GET_LDT: 173 case I386_SET_LDT: 174 if ((error = copyin(uap->parms, &kargs.largs, 175 sizeof(struct i386_ldt_args))) != 0) 176 return (error); 177 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0) 178 return (EINVAL); 179 break; 180 case I386_GET_XFPUSTATE: 181 if ((error = copyin(uap->parms, &kargs.xfpu, 182 sizeof(struct i386_get_xfpustate))) != 0) 183 return (error); 184 break; 185 default: 186 break; 187 } 188 189 switch(uap->op) { 190 case I386_GET_LDT: 191 error = i386_get_ldt(td, &kargs.largs); 192 break; 193 case I386_SET_LDT: 194 if (kargs.largs.descs != NULL) { 195 lp = (union descriptor *)malloc( 196 kargs.largs.num * sizeof(union descriptor), 197 M_TEMP, M_WAITOK); 198 error = copyin(kargs.largs.descs, lp, 199 kargs.largs.num * sizeof(union descriptor)); 200 if (error == 0) 201 error = i386_set_ldt(td, &kargs.largs, lp); 202 free(lp, M_TEMP); 203 } else { 204 error = i386_set_ldt(td, &kargs.largs, NULL); 205 } 206 break; 207 case I386_GET_IOPERM: 208 error = i386_get_ioperm(td, &kargs.iargs); 209 if (error == 0) 210 error = copyout(&kargs.iargs, uap->parms, 211 sizeof(struct i386_ioperm_args)); 212 break; 213 case I386_SET_IOPERM: 214 error = i386_set_ioperm(td, &kargs.iargs); 215 break; 216 case I386_VM86: 217 error = vm86_sysarch(td, uap->parms); 218 break; 219 case I386_GET_FSBASE: 220 sdp = &td->td_pcb->pcb_fsd; 221 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 222 error = copyout(&base, uap->parms, sizeof(base)); 223 break; 224 case I386_SET_FSBASE: 225 error = copyin(uap->parms, &base, sizeof(base)); 226 if (error == 0) { 227 /* 228 * Construct a descriptor and store it in the pcb for 229 * the next context switch. Also store it in the gdt 230 * so that the load of tf_fs into %fs will activate it 231 * at return to userland. 232 */ 233 fill_based_sd(&sd, base); 234 critical_enter(); 235 td->td_pcb->pcb_fsd = sd; 236 #ifdef XEN 237 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[0]), 238 *(uint64_t *)&sd); 239 #else 240 PCPU_GET(fsgs_gdt)[0] = sd; 241 #endif 242 critical_exit(); 243 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL); 244 } 245 break; 246 case I386_GET_GSBASE: 247 sdp = &td->td_pcb->pcb_gsd; 248 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 249 error = copyout(&base, uap->parms, sizeof(base)); 250 break; 251 case I386_SET_GSBASE: 252 error = copyin(uap->parms, &base, sizeof(base)); 253 if (error == 0) { 254 /* 255 * Construct a descriptor and store it in the pcb for 256 * the next context switch. Also store it in the gdt 257 * because we have to do a load_gs() right now. 258 */ 259 fill_based_sd(&sd, base); 260 critical_enter(); 261 td->td_pcb->pcb_gsd = sd; 262 #ifdef XEN 263 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[1]), 264 *(uint64_t *)&sd); 265 #else 266 PCPU_GET(fsgs_gdt)[1] = sd; 267 #endif 268 critical_exit(); 269 load_gs(GSEL(GUGS_SEL, SEL_UPL)); 270 } 271 break; 272 case I386_GET_XFPUSTATE: 273 if (kargs.xfpu.len > cpu_max_ext_state_size - 274 sizeof(union savefpu)) 275 return (EINVAL); 276 npxgetregs(td); 277 error = copyout((char *)(get_pcb_user_save_td(td) + 1), 278 kargs.xfpu.addr, kargs.xfpu.len); 279 break; 280 default: 281 error = EINVAL; 282 break; 283 } 284 return (error); 285 } 286 287 int 288 i386_extend_pcb(struct thread *td) 289 { 290 int i, offset; 291 u_long *addr; 292 struct pcb_ext *ext; 293 struct soft_segment_descriptor ssd = { 294 0, /* segment base address (overwritten) */ 295 ctob(IOPAGES + 1) - 1, /* length */ 296 SDT_SYS386TSS, /* segment type */ 297 0, /* priority level */ 298 1, /* descriptor present */ 299 0, 0, 300 0, /* default 32 size */ 301 0 /* granularity */ 302 }; 303 304 ext = (struct pcb_ext *)kmem_malloc(kernel_arena, ctob(IOPAGES+1), 305 M_WAITOK | M_ZERO); 306 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 307 ext->ext_tss.tss_esp0 = (vm_offset_t)td->td_pcb - 16; 308 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 309 /* 310 * The last byte of the i/o map must be followed by an 0xff byte. 311 * We arbitrarily allocate 16 bytes here, to keep the starting 312 * address on a doubleword boundary. 313 */ 314 offset = PAGE_SIZE - 16; 315 ext->ext_tss.tss_ioopt = 316 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 317 ext->ext_iomap = (caddr_t)ext + offset; 318 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 319 320 addr = (u_long *)ext->ext_vm86.vm86_intmap; 321 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 322 *addr++ = ~0; 323 324 ssd.ssd_base = (unsigned)&ext->ext_tss; 325 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 326 ssdtosd(&ssd, &ext->ext_tssd); 327 328 KASSERT(td == curthread, ("giving TSS to !curthread")); 329 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 330 331 /* Switch to the new TSS. */ 332 critical_enter(); 333 td->td_pcb->pcb_ext = ext; 334 PCPU_SET(private_tss, 1); 335 *PCPU_GET(tss_gdt) = ext->ext_tssd; 336 ltr(GSEL(GPROC0_SEL, SEL_KPL)); 337 critical_exit(); 338 339 return 0; 340 } 341 342 int 343 i386_set_ioperm(td, uap) 344 struct thread *td; 345 struct i386_ioperm_args *uap; 346 { 347 char *iomap; 348 u_int i; 349 int error; 350 351 if ((error = priv_check(td, PRIV_IO)) != 0) 352 return (error); 353 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 354 return (error); 355 /* 356 * XXX 357 * While this is restricted to root, we should probably figure out 358 * whether any other driver is using this i/o address, as so not to 359 * cause confusion. This probably requires a global 'usage registry'. 360 */ 361 362 if (td->td_pcb->pcb_ext == 0) 363 if ((error = i386_extend_pcb(td)) != 0) 364 return (error); 365 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 366 367 if (uap->start > uap->start + uap->length || 368 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 new_ldt->ldt_refcnt = 1; 479 new_ldt->ldt_active = 0; 480 481 mtx_lock_spin(&dt_lock); 482 if ((pldt = mdp->md_ldt)) { 483 if (len > pldt->ldt_len) 484 len = pldt->ldt_len; 485 bcopy(pldt->ldt_base, new_ldt->ldt_base, 486 len * sizeof(union descriptor)); 487 } else { 488 bcopy(ldt, new_ldt->ldt_base, PAGE_SIZE); 489 } 490 mtx_unlock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 491 pmap_map_readonly(kernel_pmap, (vm_offset_t)new_ldt->ldt_base, 492 new_ldt->ldt_len*sizeof(union descriptor)); 493 mtx_lock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 494 return (new_ldt); 495 } 496 #else 497 /* 498 * dt_lock must be held. Returns with dt_lock held. 499 */ 500 struct proc_ldt * 501 user_ldt_alloc(struct mdproc *mdp, int len) 502 { 503 struct proc_ldt *pldt, *new_ldt; 504 505 mtx_assert(&dt_lock, MA_OWNED); 506 mtx_unlock_spin(&dt_lock); 507 new_ldt = malloc(sizeof(struct proc_ldt), 508 M_SUBPROC, M_WAITOK); 509 510 new_ldt->ldt_len = len = NEW_MAX_LD(len); 511 new_ldt->ldt_base = (caddr_t)kmem_malloc(kernel_arena, 512 len * sizeof(union descriptor), M_WAITOK | M_ZERO); 513 new_ldt->ldt_refcnt = 1; 514 new_ldt->ldt_active = 0; 515 516 mtx_lock_spin(&dt_lock); 517 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 518 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 519 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 520 521 if ((pldt = mdp->md_ldt) != NULL) { 522 if (len > pldt->ldt_len) 523 len = pldt->ldt_len; 524 bcopy(pldt->ldt_base, new_ldt->ldt_base, 525 len * sizeof(union descriptor)); 526 } else 527 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt)); 528 529 return (new_ldt); 530 } 531 #endif /* !XEN */ 532 533 /* 534 * Must be called with dt_lock held. Returns with dt_lock unheld. 535 */ 536 void 537 user_ldt_free(struct thread *td) 538 { 539 struct mdproc *mdp = &td->td_proc->p_md; 540 struct proc_ldt *pldt; 541 542 mtx_assert(&dt_lock, MA_OWNED); 543 if ((pldt = mdp->md_ldt) == NULL) { 544 mtx_unlock_spin(&dt_lock); 545 return; 546 } 547 548 if (td == curthread) { 549 #ifdef XEN 550 i386_reset_ldt(&default_proc_ldt); 551 PCPU_SET(currentldt, (int)&default_proc_ldt); 552 #else 553 lldt(_default_ldt); 554 PCPU_SET(currentldt, _default_ldt); 555 #endif 556 } 557 558 mdp->md_ldt = NULL; 559 user_ldt_deref(pldt); 560 } 561 562 void 563 user_ldt_deref(struct proc_ldt *pldt) 564 { 565 566 mtx_assert(&dt_lock, MA_OWNED); 567 if (--pldt->ldt_refcnt == 0) { 568 mtx_unlock_spin(&dt_lock); 569 kmem_free(kernel_arena, (vm_offset_t)pldt->ldt_base, 570 pldt->ldt_len * sizeof(union descriptor)); 571 free(pldt, M_SUBPROC); 572 } else 573 mtx_unlock_spin(&dt_lock); 574 } 575 576 /* 577 * Note for the authors of compat layers (linux, etc): copyout() in 578 * the function below is not a problem since it presents data in 579 * arch-specific format (i.e. i386-specific in this case), not in 580 * the OS-specific one. 581 */ 582 int 583 i386_get_ldt(td, uap) 584 struct thread *td; 585 struct i386_ldt_args *uap; 586 { 587 int error = 0; 588 struct proc_ldt *pldt; 589 int nldt, num; 590 union descriptor *lp; 591 592 #ifdef DEBUG 593 printf("i386_get_ldt: start=%d num=%d descs=%p\n", 594 uap->start, uap->num, (void *)uap->descs); 595 #endif 596 597 mtx_lock_spin(&dt_lock); 598 if ((pldt = td->td_proc->p_md.md_ldt) != NULL) { 599 nldt = pldt->ldt_len; 600 lp = &((union descriptor *)(pldt->ldt_base))[uap->start]; 601 mtx_unlock_spin(&dt_lock); 602 num = min(uap->num, nldt); 603 } else { 604 mtx_unlock_spin(&dt_lock); 605 nldt = sizeof(ldt)/sizeof(ldt[0]); 606 num = min(uap->num, nldt); 607 lp = &ldt[uap->start]; 608 } 609 610 if ((uap->start > (unsigned int)nldt) || 611 ((unsigned int)num > (unsigned int)nldt) || 612 ((unsigned int)(uap->start + num) > (unsigned int)nldt)) 613 return(EINVAL); 614 615 error = copyout(lp, uap->descs, num * sizeof(union descriptor)); 616 if (!error) 617 td->td_retval[0] = num; 618 619 return(error); 620 } 621 622 int 623 i386_set_ldt(td, uap, descs) 624 struct thread *td; 625 struct i386_ldt_args *uap; 626 union descriptor *descs; 627 { 628 int error = 0, i; 629 int largest_ld; 630 struct mdproc *mdp = &td->td_proc->p_md; 631 struct proc_ldt *pldt; 632 union descriptor *dp; 633 634 #ifdef DEBUG 635 printf("i386_set_ldt: start=%d num=%d descs=%p\n", 636 uap->start, uap->num, (void *)uap->descs); 637 #endif 638 639 if (descs == NULL) { 640 /* Free descriptors */ 641 if (uap->start == 0 && uap->num == 0) { 642 /* 643 * Treat this as a special case, so userland needn't 644 * know magic number NLDT. 645 */ 646 uap->start = NLDT; 647 uap->num = MAX_LD - NLDT; 648 } 649 if (uap->num == 0) 650 return (EINVAL); 651 mtx_lock_spin(&dt_lock); 652 if ((pldt = mdp->md_ldt) == NULL || 653 uap->start >= pldt->ldt_len) { 654 mtx_unlock_spin(&dt_lock); 655 return (0); 656 } 657 largest_ld = uap->start + uap->num; 658 if (largest_ld > pldt->ldt_len) 659 largest_ld = pldt->ldt_len; 660 i = largest_ld - uap->start; 661 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start], 662 sizeof(union descriptor) * i); 663 mtx_unlock_spin(&dt_lock); 664 return (0); 665 } 666 667 if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) { 668 /* verify range of descriptors to modify */ 669 largest_ld = uap->start + uap->num; 670 if (uap->start >= MAX_LD || largest_ld > MAX_LD) { 671 return (EINVAL); 672 } 673 } 674 675 /* Check descriptors for access violations */ 676 for (i = 0; i < uap->num; i++) { 677 dp = &descs[i]; 678 679 switch (dp->sd.sd_type) { 680 case SDT_SYSNULL: /* system null */ 681 dp->sd.sd_p = 0; 682 break; 683 case SDT_SYS286TSS: /* system 286 TSS available */ 684 case SDT_SYSLDT: /* system local descriptor table */ 685 case SDT_SYS286BSY: /* system 286 TSS busy */ 686 case SDT_SYSTASKGT: /* system task gate */ 687 case SDT_SYS286IGT: /* system 286 interrupt gate */ 688 case SDT_SYS286TGT: /* system 286 trap gate */ 689 case SDT_SYSNULL2: /* undefined by Intel */ 690 case SDT_SYS386TSS: /* system 386 TSS available */ 691 case SDT_SYSNULL3: /* undefined by Intel */ 692 case SDT_SYS386BSY: /* system 386 TSS busy */ 693 case SDT_SYSNULL4: /* undefined by Intel */ 694 case SDT_SYS386IGT: /* system 386 interrupt gate */ 695 case SDT_SYS386TGT: /* system 386 trap gate */ 696 case SDT_SYS286CGT: /* system 286 call gate */ 697 case SDT_SYS386CGT: /* system 386 call gate */ 698 /* I can't think of any reason to allow a user proc 699 * to create a segment of these types. They are 700 * for OS use only. 701 */ 702 return (EACCES); 703 /*NOTREACHED*/ 704 705 /* memory segment types */ 706 case SDT_MEMEC: /* memory execute only conforming */ 707 case SDT_MEMEAC: /* memory execute only accessed conforming */ 708 case SDT_MEMERC: /* memory execute read conforming */ 709 case SDT_MEMERAC: /* memory execute read accessed conforming */ 710 /* Must be "present" if executable and conforming. */ 711 if (dp->sd.sd_p == 0) 712 return (EACCES); 713 break; 714 case SDT_MEMRO: /* memory read only */ 715 case SDT_MEMROA: /* memory read only accessed */ 716 case SDT_MEMRW: /* memory read write */ 717 case SDT_MEMRWA: /* memory read write accessed */ 718 case SDT_MEMROD: /* memory read only expand dwn limit */ 719 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 720 case SDT_MEMRWD: /* memory read write expand dwn limit */ 721 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 722 case SDT_MEME: /* memory execute only */ 723 case SDT_MEMEA: /* memory execute only accessed */ 724 case SDT_MEMER: /* memory execute read */ 725 case SDT_MEMERA: /* memory execute read accessed */ 726 break; 727 default: 728 return(EINVAL); 729 /*NOTREACHED*/ 730 } 731 732 /* Only user (ring-3) descriptors may be present. */ 733 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL)) 734 return (EACCES); 735 } 736 737 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 738 /* Allocate a free slot */ 739 mtx_lock_spin(&dt_lock); 740 if ((pldt = mdp->md_ldt) == NULL) { 741 if ((error = i386_ldt_grow(td, NLDT + 1))) { 742 mtx_unlock_spin(&dt_lock); 743 return (error); 744 } 745 pldt = mdp->md_ldt; 746 } 747 again: 748 /* 749 * start scanning a bit up to leave room for NVidia and 750 * Wine, which still user the "Blat" method of allocation. 751 */ 752 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 753 for (i = NLDT; i < pldt->ldt_len; ++i) { 754 if (dp->sd.sd_type == SDT_SYSNULL) 755 break; 756 dp++; 757 } 758 if (i >= pldt->ldt_len) { 759 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) { 760 mtx_unlock_spin(&dt_lock); 761 return (error); 762 } 763 goto again; 764 } 765 uap->start = i; 766 error = i386_set_ldt_data(td, i, 1, descs); 767 mtx_unlock_spin(&dt_lock); 768 } else { 769 largest_ld = uap->start + uap->num; 770 mtx_lock_spin(&dt_lock); 771 if (!(error = i386_ldt_grow(td, largest_ld))) { 772 error = i386_set_ldt_data(td, uap->start, uap->num, 773 descs); 774 } 775 mtx_unlock_spin(&dt_lock); 776 } 777 if (error == 0) 778 td->td_retval[0] = uap->start; 779 return (error); 780 } 781 #ifdef XEN 782 static int 783 i386_set_ldt_data(struct thread *td, int start, int num, 784 union descriptor *descs) 785 { 786 struct mdproc *mdp = &td->td_proc->p_md; 787 struct proc_ldt *pldt = mdp->md_ldt; 788 789 mtx_assert(&dt_lock, MA_OWNED); 790 791 while (num) { 792 xen_update_descriptor( 793 &((union descriptor *)(pldt->ldt_base))[start], 794 descs); 795 num--; 796 start++; 797 descs++; 798 } 799 return (0); 800 } 801 #else 802 static int 803 i386_set_ldt_data(struct thread *td, int start, int num, 804 union descriptor *descs) 805 { 806 struct mdproc *mdp = &td->td_proc->p_md; 807 struct proc_ldt *pldt = mdp->md_ldt; 808 809 mtx_assert(&dt_lock, MA_OWNED); 810 811 /* Fill in range */ 812 bcopy(descs, 813 &((union descriptor *)(pldt->ldt_base))[start], 814 num * sizeof(union descriptor)); 815 return (0); 816 } 817 #endif /* !XEN */ 818 819 static int 820 i386_ldt_grow(struct thread *td, int len) 821 { 822 struct mdproc *mdp = &td->td_proc->p_md; 823 struct proc_ldt *new_ldt, *pldt; 824 caddr_t old_ldt_base = NULL_LDT_BASE; 825 int old_ldt_len = 0; 826 827 mtx_assert(&dt_lock, MA_OWNED); 828 829 if (len > MAX_LD) 830 return (ENOMEM); 831 if (len < NLDT + 1) 832 len = NLDT + 1; 833 834 /* Allocate a user ldt. */ 835 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) { 836 new_ldt = user_ldt_alloc(mdp, len); 837 if (new_ldt == NULL) 838 return (ENOMEM); 839 pldt = mdp->md_ldt; 840 841 if (pldt != NULL) { 842 if (new_ldt->ldt_len <= pldt->ldt_len) { 843 /* 844 * We just lost the race for allocation, so 845 * free the new object and return. 846 */ 847 mtx_unlock_spin(&dt_lock); 848 kmem_free(kernel_arena, 849 (vm_offset_t)new_ldt->ldt_base, 850 new_ldt->ldt_len * sizeof(union descriptor)); 851 free(new_ldt, M_SUBPROC); 852 mtx_lock_spin(&dt_lock); 853 return (0); 854 } 855 856 /* 857 * We have to substitute the current LDT entry for 858 * curproc with the new one since its size grew. 859 */ 860 old_ldt_base = pldt->ldt_base; 861 old_ldt_len = pldt->ldt_len; 862 pldt->ldt_sd = new_ldt->ldt_sd; 863 pldt->ldt_base = new_ldt->ldt_base; 864 pldt->ldt_len = new_ldt->ldt_len; 865 } else 866 mdp->md_ldt = pldt = new_ldt; 867 #ifdef SMP 868 /* 869 * Signal other cpus to reload ldt. We need to unlock dt_lock 870 * here because other CPU will contest on it since their 871 * curthreads won't hold the lock and will block when trying 872 * to acquire it. 873 */ 874 mtx_unlock_spin(&dt_lock); 875 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 876 NULL, td->td_proc->p_vmspace); 877 #else 878 set_user_ldt(&td->td_proc->p_md); 879 mtx_unlock_spin(&dt_lock); 880 #endif 881 if (old_ldt_base != NULL_LDT_BASE) { 882 kmem_free(kernel_arena, (vm_offset_t)old_ldt_base, 883 old_ldt_len * sizeof(union descriptor)); 884 free(new_ldt, M_SUBPROC); 885 } 886 mtx_lock_spin(&dt_lock); 887 } 888 return (0); 889 }
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