Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/sys_machdep.c
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1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_kstack_pages.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/lock.h> 40 #include <sys/malloc.h> 41 #include <sys/mutex.h> 42 #include <sys/priv.h> 43 #include <sys/proc.h> 44 #include <sys/smp.h> 45 #include <sys/sysproto.h> 46 47 #include <vm/vm.h> 48 #include <vm/pmap.h> 49 #include <vm/vm_map.h> 50 #include <vm/vm_extern.h> 51 52 #include <machine/cpu.h> 53 #include <machine/pcb.h> 54 #include <machine/pcb_ext.h> 55 #include <machine/proc.h> 56 #include <machine/sysarch.h> 57 58 #include <security/audit/audit.h> 59 60 #ifdef XEN 61 #include <machine/xen/xenfunc.h> 62 63 void i386_reset_ldt(struct proc_ldt *pldt); 64 65 void 66 i386_reset_ldt(struct proc_ldt *pldt) 67 { 68 xen_set_ldt((vm_offset_t)pldt->ldt_base, pldt->ldt_len); 69 } 70 #else 71 #define i386_reset_ldt(x) 72 #endif 73 74 #include <vm/vm_kern.h> /* for kernel_map */ 75 76 #define MAX_LD 8192 77 #define LD_PER_PAGE 512 78 #define NEW_MAX_LD(num) ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1)) 79 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3) 80 #define NULL_LDT_BASE ((caddr_t)NULL) 81 82 #ifdef SMP 83 static void set_user_ldt_rv(struct vmspace *vmsp); 84 #endif 85 static int i386_set_ldt_data(struct thread *, int start, int num, 86 union descriptor *descs); 87 static int i386_ldt_grow(struct thread *td, int len); 88 89 #ifndef _SYS_SYSPROTO_H_ 90 struct sysarch_args { 91 int op; 92 char *parms; 93 }; 94 #endif 95 96 int 97 sysarch(td, uap) 98 struct thread *td; 99 register struct sysarch_args *uap; 100 { 101 int error; 102 union descriptor *lp; 103 union { 104 struct i386_ldt_args largs; 105 struct i386_ioperm_args iargs; 106 } kargs; 107 uint32_t base; 108 struct segment_descriptor sd, *sdp; 109 110 AUDIT_ARG_CMD(uap->op); 111 switch (uap->op) { 112 case I386_GET_IOPERM: 113 case I386_SET_IOPERM: 114 if ((error = copyin(uap->parms, &kargs.iargs, 115 sizeof(struct i386_ioperm_args))) != 0) 116 return (error); 117 break; 118 case I386_GET_LDT: 119 case I386_SET_LDT: 120 if ((error = copyin(uap->parms, &kargs.largs, 121 sizeof(struct i386_ldt_args))) != 0) 122 return (error); 123 if (kargs.largs.num > MAX_LD || kargs.largs.num <= 0) 124 return (EINVAL); 125 break; 126 default: 127 break; 128 } 129 130 switch(uap->op) { 131 case I386_GET_LDT: 132 error = i386_get_ldt(td, &kargs.largs); 133 break; 134 case I386_SET_LDT: 135 if (kargs.largs.descs != NULL) { 136 lp = (union descriptor *)kmem_alloc(kernel_map, 137 kargs.largs.num * sizeof(union descriptor)); 138 if (lp == NULL) { 139 error = ENOMEM; 140 break; 141 } 142 error = copyin(kargs.largs.descs, lp, 143 kargs.largs.num * sizeof(union descriptor)); 144 if (error == 0) 145 error = i386_set_ldt(td, &kargs.largs, lp); 146 kmem_free(kernel_map, (vm_offset_t)lp, 147 kargs.largs.num * sizeof(union descriptor)); 148 } else { 149 error = i386_set_ldt(td, &kargs.largs, NULL); 150 } 151 break; 152 case I386_GET_IOPERM: 153 error = i386_get_ioperm(td, &kargs.iargs); 154 if (error == 0) 155 error = copyout(&kargs.iargs, uap->parms, 156 sizeof(struct i386_ioperm_args)); 157 break; 158 case I386_SET_IOPERM: 159 error = i386_set_ioperm(td, &kargs.iargs); 160 break; 161 case I386_VM86: 162 error = vm86_sysarch(td, uap->parms); 163 break; 164 case I386_GET_FSBASE: 165 sdp = &td->td_pcb->pcb_fsd; 166 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 167 error = copyout(&base, uap->parms, sizeof(base)); 168 break; 169 case I386_SET_FSBASE: 170 error = copyin(uap->parms, &base, sizeof(base)); 171 if (!error) { 172 /* 173 * Construct a descriptor and store it in the pcb for 174 * the next context switch. Also store it in the gdt 175 * so that the load of tf_fs into %fs will activate it 176 * at return to userland. 177 */ 178 sd.sd_lobase = base & 0xffffff; 179 sd.sd_hibase = (base >> 24) & 0xff; 180 #ifdef XEN 181 /* need to do nosegneg like Linux */ 182 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff; 183 #else 184 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 185 #endif 186 sd.sd_hilimit = 0xf; 187 sd.sd_type = SDT_MEMRWA; 188 sd.sd_dpl = SEL_UPL; 189 sd.sd_p = 1; 190 sd.sd_xx = 0; 191 sd.sd_def32 = 1; 192 sd.sd_gran = 1; 193 critical_enter(); 194 td->td_pcb->pcb_fsd = sd; 195 #ifdef XEN 196 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[0]), 197 *(uint64_t *)&sd); 198 #else 199 PCPU_GET(fsgs_gdt)[0] = sd; 200 #endif 201 critical_exit(); 202 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL); 203 } 204 break; 205 case I386_GET_GSBASE: 206 sdp = &td->td_pcb->pcb_gsd; 207 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 208 error = copyout(&base, uap->parms, sizeof(base)); 209 break; 210 case I386_SET_GSBASE: 211 error = copyin(uap->parms, &base, sizeof(base)); 212 if (!error) { 213 /* 214 * Construct a descriptor and store it in the pcb for 215 * the next context switch. Also store it in the gdt 216 * because we have to do a load_gs() right now. 217 */ 218 sd.sd_lobase = base & 0xffffff; 219 sd.sd_hibase = (base >> 24) & 0xff; 220 221 #ifdef XEN 222 /* need to do nosegneg like Linux */ 223 sd.sd_lolimit = (HYPERVISOR_VIRT_START >> 12) & 0xffff; 224 #else 225 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 226 #endif 227 sd.sd_hilimit = 0xf; 228 sd.sd_type = SDT_MEMRWA; 229 sd.sd_dpl = SEL_UPL; 230 sd.sd_p = 1; 231 sd.sd_xx = 0; 232 sd.sd_def32 = 1; 233 sd.sd_gran = 1; 234 critical_enter(); 235 td->td_pcb->pcb_gsd = sd; 236 #ifdef XEN 237 HYPERVISOR_update_descriptor(vtomach(&PCPU_GET(fsgs_gdt)[1]), 238 *(uint64_t *)&sd); 239 #else 240 PCPU_GET(fsgs_gdt)[1] = sd; 241 #endif 242 critical_exit(); 243 load_gs(GSEL(GUGS_SEL, SEL_UPL)); 244 } 245 break; 246 default: 247 error = EINVAL; 248 break; 249 } 250 return (error); 251 } 252 253 int 254 i386_extend_pcb(struct thread *td) 255 { 256 int i, offset; 257 u_long *addr; 258 struct pcb_ext *ext; 259 struct soft_segment_descriptor ssd = { 260 0, /* segment base address (overwritten) */ 261 ctob(IOPAGES + 1) - 1, /* length */ 262 SDT_SYS386TSS, /* segment type */ 263 0, /* priority level */ 264 1, /* descriptor present */ 265 0, 0, 266 0, /* default 32 size */ 267 0 /* granularity */ 268 }; 269 270 ext = (struct pcb_ext *)kmem_alloc(kernel_map, ctob(IOPAGES+1)); 271 if (ext == 0) 272 return (ENOMEM); 273 bzero(ext, sizeof(struct pcb_ext)); 274 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 275 ext->ext_tss.tss_esp0 = td->td_kstack + ctob(KSTACK_PAGES) - 276 sizeof(struct pcb) - 16; 277 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 278 /* 279 * The last byte of the i/o map must be followed by an 0xff byte. 280 * We arbitrarily allocate 16 bytes here, to keep the starting 281 * address on a doubleword boundary. 282 */ 283 offset = PAGE_SIZE - 16; 284 ext->ext_tss.tss_ioopt = 285 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 286 ext->ext_iomap = (caddr_t)ext + offset; 287 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 288 289 addr = (u_long *)ext->ext_vm86.vm86_intmap; 290 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 291 *addr++ = ~0; 292 293 ssd.ssd_base = (unsigned)&ext->ext_tss; 294 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 295 ssdtosd(&ssd, &ext->ext_tssd); 296 297 KASSERT(td == curthread, ("giving TSS to !curthread")); 298 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 299 300 /* Switch to the new TSS. */ 301 critical_enter(); 302 td->td_pcb->pcb_ext = ext; 303 PCPU_SET(private_tss, 1); 304 *PCPU_GET(tss_gdt) = ext->ext_tssd; 305 ltr(GSEL(GPROC0_SEL, SEL_KPL)); 306 critical_exit(); 307 308 return 0; 309 } 310 311 int 312 i386_set_ioperm(td, uap) 313 struct thread *td; 314 struct i386_ioperm_args *uap; 315 { 316 int i, error; 317 char *iomap; 318 319 if ((error = priv_check(td, PRIV_IO)) != 0) 320 return (error); 321 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 322 return (error); 323 /* 324 * XXX 325 * While this is restricted to root, we should probably figure out 326 * whether any other driver is using this i/o address, as so not to 327 * cause confusion. This probably requires a global 'usage registry'. 328 */ 329 330 if (td->td_pcb->pcb_ext == 0) 331 if ((error = i386_extend_pcb(td)) != 0) 332 return (error); 333 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 334 335 if (uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY) 336 return (EINVAL); 337 338 for (i = uap->start; i < uap->start + uap->length; i++) { 339 if (uap->enable) 340 iomap[i >> 3] &= ~(1 << (i & 7)); 341 else 342 iomap[i >> 3] |= (1 << (i & 7)); 343 } 344 return (error); 345 } 346 347 int 348 i386_get_ioperm(td, uap) 349 struct thread *td; 350 struct i386_ioperm_args *uap; 351 { 352 int i, state; 353 char *iomap; 354 355 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY) 356 return (EINVAL); 357 358 if (td->td_pcb->pcb_ext == 0) { 359 uap->length = 0; 360 goto done; 361 } 362 363 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 364 365 i = uap->start; 366 state = (iomap[i >> 3] >> (i & 7)) & 1; 367 uap->enable = !state; 368 uap->length = 1; 369 370 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 371 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 372 break; 373 uap->length++; 374 } 375 376 done: 377 return (0); 378 } 379 380 /* 381 * Update the GDT entry pointing to the LDT to point to the LDT of the 382 * current process. Manage dt_lock holding/unholding autonomously. 383 */ 384 void 385 set_user_ldt(struct mdproc *mdp) 386 { 387 struct proc_ldt *pldt; 388 int dtlocked; 389 390 dtlocked = 0; 391 if (!mtx_owned(&dt_lock)) { 392 mtx_lock_spin(&dt_lock); 393 dtlocked = 1; 394 } 395 396 pldt = mdp->md_ldt; 397 #ifdef XEN 398 i386_reset_ldt(pldt); 399 PCPU_SET(currentldt, (int)pldt); 400 #else 401 #ifdef SMP 402 gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd; 403 #else 404 gdt[GUSERLDT_SEL].sd = pldt->ldt_sd; 405 #endif 406 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 407 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 408 #endif /* XEN */ 409 if (dtlocked) 410 mtx_unlock_spin(&dt_lock); 411 } 412 413 #ifdef SMP 414 static void 415 set_user_ldt_rv(struct vmspace *vmsp) 416 { 417 struct thread *td; 418 419 td = curthread; 420 if (vmsp != td->td_proc->p_vmspace) 421 return; 422 423 set_user_ldt(&td->td_proc->p_md); 424 } 425 #endif 426 427 #ifdef XEN 428 429 /* 430 * dt_lock must be held. Returns with dt_lock held. 431 */ 432 struct proc_ldt * 433 user_ldt_alloc(struct mdproc *mdp, int len) 434 { 435 struct proc_ldt *pldt, *new_ldt; 436 437 mtx_assert(&dt_lock, MA_OWNED); 438 mtx_unlock_spin(&dt_lock); 439 new_ldt = malloc(sizeof(struct proc_ldt), 440 M_SUBPROC, M_WAITOK); 441 442 new_ldt->ldt_len = len = NEW_MAX_LD(len); 443 new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 444 round_page(len * sizeof(union descriptor))); 445 if (new_ldt->ldt_base == NULL) { 446 free(new_ldt, M_SUBPROC); 447 mtx_lock_spin(&dt_lock); 448 return (NULL); 449 } 450 new_ldt->ldt_refcnt = 1; 451 new_ldt->ldt_active = 0; 452 453 mtx_lock_spin(&dt_lock); 454 if ((pldt = mdp->md_ldt)) { 455 if (len > pldt->ldt_len) 456 len = pldt->ldt_len; 457 bcopy(pldt->ldt_base, new_ldt->ldt_base, 458 len * sizeof(union descriptor)); 459 } else { 460 bcopy(ldt, new_ldt->ldt_base, PAGE_SIZE); 461 } 462 mtx_unlock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 463 pmap_map_readonly(kernel_pmap, (vm_offset_t)new_ldt->ldt_base, 464 new_ldt->ldt_len*sizeof(union descriptor)); 465 mtx_lock_spin(&dt_lock); /* XXX kill once pmap locking fixed. */ 466 return (new_ldt); 467 } 468 #else 469 /* 470 * dt_lock must be held. Returns with dt_lock held. 471 */ 472 struct proc_ldt * 473 user_ldt_alloc(struct mdproc *mdp, int len) 474 { 475 struct proc_ldt *pldt, *new_ldt; 476 477 mtx_assert(&dt_lock, MA_OWNED); 478 mtx_unlock_spin(&dt_lock); 479 new_ldt = malloc(sizeof(struct proc_ldt), 480 M_SUBPROC, M_WAITOK); 481 482 new_ldt->ldt_len = len = NEW_MAX_LD(len); 483 new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 484 len * sizeof(union descriptor)); 485 if (new_ldt->ldt_base == NULL) { 486 free(new_ldt, M_SUBPROC); 487 mtx_lock_spin(&dt_lock); 488 return (NULL); 489 } 490 new_ldt->ldt_refcnt = 1; 491 new_ldt->ldt_active = 0; 492 493 mtx_lock_spin(&dt_lock); 494 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 495 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 496 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 497 498 if ((pldt = mdp->md_ldt) != NULL) { 499 if (len > pldt->ldt_len) 500 len = pldt->ldt_len; 501 bcopy(pldt->ldt_base, new_ldt->ldt_base, 502 len * sizeof(union descriptor)); 503 } else 504 bcopy(ldt, new_ldt->ldt_base, sizeof(ldt)); 505 506 return (new_ldt); 507 } 508 #endif /* !XEN */ 509 510 /* 511 * Must be called with dt_lock held. Returns with dt_lock unheld. 512 */ 513 void 514 user_ldt_free(struct thread *td) 515 { 516 struct mdproc *mdp = &td->td_proc->p_md; 517 struct proc_ldt *pldt; 518 519 mtx_assert(&dt_lock, MA_OWNED); 520 if ((pldt = mdp->md_ldt) == NULL) { 521 mtx_unlock_spin(&dt_lock); 522 return; 523 } 524 525 if (td == curthread) { 526 #ifdef XEN 527 i386_reset_ldt(&default_proc_ldt); 528 PCPU_SET(currentldt, (int)&default_proc_ldt); 529 #else 530 lldt(_default_ldt); 531 PCPU_SET(currentldt, _default_ldt); 532 #endif 533 } 534 535 mdp->md_ldt = NULL; 536 user_ldt_deref(pldt); 537 } 538 539 void 540 user_ldt_deref(struct proc_ldt *pldt) 541 { 542 543 mtx_assert(&dt_lock, MA_OWNED); 544 if (--pldt->ldt_refcnt == 0) { 545 mtx_unlock_spin(&dt_lock); 546 kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base, 547 pldt->ldt_len * sizeof(union descriptor)); 548 free(pldt, M_SUBPROC); 549 } else 550 mtx_unlock_spin(&dt_lock); 551 } 552 553 /* 554 * Note for the authors of compat layers (linux, etc): copyout() in 555 * the function below is not a problem since it presents data in 556 * arch-specific format (i.e. i386-specific in this case), not in 557 * the OS-specific one. 558 */ 559 int 560 i386_get_ldt(td, uap) 561 struct thread *td; 562 struct i386_ldt_args *uap; 563 { 564 int error = 0; 565 struct proc_ldt *pldt; 566 int nldt, num; 567 union descriptor *lp; 568 569 #ifdef DEBUG 570 printf("i386_get_ldt: start=%d num=%d descs=%p\n", 571 uap->start, uap->num, (void *)uap->descs); 572 #endif 573 574 mtx_lock_spin(&dt_lock); 575 if ((pldt = td->td_proc->p_md.md_ldt) != NULL) { 576 nldt = pldt->ldt_len; 577 lp = &((union descriptor *)(pldt->ldt_base))[uap->start]; 578 mtx_unlock_spin(&dt_lock); 579 num = min(uap->num, nldt); 580 } else { 581 mtx_unlock_spin(&dt_lock); 582 nldt = sizeof(ldt)/sizeof(ldt[0]); 583 num = min(uap->num, nldt); 584 lp = &ldt[uap->start]; 585 } 586 587 if ((uap->start > (unsigned int)nldt) || 588 ((unsigned int)num > (unsigned int)nldt) || 589 ((unsigned int)(uap->start + num) > (unsigned int)nldt)) 590 return(EINVAL); 591 592 error = copyout(lp, uap->descs, num * sizeof(union descriptor)); 593 if (!error) 594 td->td_retval[0] = num; 595 596 return(error); 597 } 598 599 int 600 i386_set_ldt(td, uap, descs) 601 struct thread *td; 602 struct i386_ldt_args *uap; 603 union descriptor *descs; 604 { 605 int error = 0, i; 606 int largest_ld; 607 struct mdproc *mdp = &td->td_proc->p_md; 608 struct proc_ldt *pldt; 609 union descriptor *dp; 610 611 #ifdef DEBUG 612 printf("i386_set_ldt: start=%d num=%d descs=%p\n", 613 uap->start, uap->num, (void *)uap->descs); 614 #endif 615 616 if (descs == NULL) { 617 /* Free descriptors */ 618 if (uap->start == 0 && uap->num == 0) { 619 /* 620 * Treat this as a special case, so userland needn't 621 * know magic number NLDT. 622 */ 623 uap->start = NLDT; 624 uap->num = MAX_LD - NLDT; 625 } 626 if (uap->num <= 0) 627 return (EINVAL); 628 mtx_lock_spin(&dt_lock); 629 if ((pldt = mdp->md_ldt) == NULL || 630 uap->start >= pldt->ldt_len) { 631 mtx_unlock_spin(&dt_lock); 632 return (0); 633 } 634 largest_ld = uap->start + uap->num; 635 if (largest_ld > pldt->ldt_len) 636 largest_ld = pldt->ldt_len; 637 i = largest_ld - uap->start; 638 bzero(&((union descriptor *)(pldt->ldt_base))[uap->start], 639 sizeof(union descriptor) * i); 640 mtx_unlock_spin(&dt_lock); 641 return (0); 642 } 643 644 if (!(uap->start == LDT_AUTO_ALLOC && uap->num == 1)) { 645 /* verify range of descriptors to modify */ 646 largest_ld = uap->start + uap->num; 647 if (uap->start >= MAX_LD || 648 uap->num < 0 || largest_ld > MAX_LD) { 649 return (EINVAL); 650 } 651 } 652 653 /* Check descriptors for access violations */ 654 for (i = 0; i < uap->num; i++) { 655 dp = &descs[i]; 656 657 switch (dp->sd.sd_type) { 658 case SDT_SYSNULL: /* system null */ 659 dp->sd.sd_p = 0; 660 break; 661 case SDT_SYS286TSS: /* system 286 TSS available */ 662 case SDT_SYSLDT: /* system local descriptor table */ 663 case SDT_SYS286BSY: /* system 286 TSS busy */ 664 case SDT_SYSTASKGT: /* system task gate */ 665 case SDT_SYS286IGT: /* system 286 interrupt gate */ 666 case SDT_SYS286TGT: /* system 286 trap gate */ 667 case SDT_SYSNULL2: /* undefined by Intel */ 668 case SDT_SYS386TSS: /* system 386 TSS available */ 669 case SDT_SYSNULL3: /* undefined by Intel */ 670 case SDT_SYS386BSY: /* system 386 TSS busy */ 671 case SDT_SYSNULL4: /* undefined by Intel */ 672 case SDT_SYS386IGT: /* system 386 interrupt gate */ 673 case SDT_SYS386TGT: /* system 386 trap gate */ 674 case SDT_SYS286CGT: /* system 286 call gate */ 675 case SDT_SYS386CGT: /* system 386 call gate */ 676 /* I can't think of any reason to allow a user proc 677 * to create a segment of these types. They are 678 * for OS use only. 679 */ 680 return (EACCES); 681 /*NOTREACHED*/ 682 683 /* memory segment types */ 684 case SDT_MEMEC: /* memory execute only conforming */ 685 case SDT_MEMEAC: /* memory execute only accessed conforming */ 686 case SDT_MEMERC: /* memory execute read conforming */ 687 case SDT_MEMERAC: /* memory execute read accessed conforming */ 688 /* Must be "present" if executable and conforming. */ 689 if (dp->sd.sd_p == 0) 690 return (EACCES); 691 break; 692 case SDT_MEMRO: /* memory read only */ 693 case SDT_MEMROA: /* memory read only accessed */ 694 case SDT_MEMRW: /* memory read write */ 695 case SDT_MEMRWA: /* memory read write accessed */ 696 case SDT_MEMROD: /* memory read only expand dwn limit */ 697 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 698 case SDT_MEMRWD: /* memory read write expand dwn limit */ 699 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 700 case SDT_MEME: /* memory execute only */ 701 case SDT_MEMEA: /* memory execute only accessed */ 702 case SDT_MEMER: /* memory execute read */ 703 case SDT_MEMERA: /* memory execute read accessed */ 704 break; 705 default: 706 return(EINVAL); 707 /*NOTREACHED*/ 708 } 709 710 /* Only user (ring-3) descriptors may be present. */ 711 if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL)) 712 return (EACCES); 713 } 714 715 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 716 /* Allocate a free slot */ 717 mtx_lock_spin(&dt_lock); 718 if ((pldt = mdp->md_ldt) == NULL) { 719 if ((error = i386_ldt_grow(td, NLDT + 1))) { 720 mtx_unlock_spin(&dt_lock); 721 return (error); 722 } 723 pldt = mdp->md_ldt; 724 } 725 again: 726 /* 727 * start scanning a bit up to leave room for NVidia and 728 * Wine, which still user the "Blat" method of allocation. 729 */ 730 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 731 for (i = NLDT; i < pldt->ldt_len; ++i) { 732 if (dp->sd.sd_type == SDT_SYSNULL) 733 break; 734 dp++; 735 } 736 if (i >= pldt->ldt_len) { 737 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) { 738 mtx_unlock_spin(&dt_lock); 739 return (error); 740 } 741 goto again; 742 } 743 uap->start = i; 744 error = i386_set_ldt_data(td, i, 1, descs); 745 mtx_unlock_spin(&dt_lock); 746 } else { 747 largest_ld = uap->start + uap->num; 748 mtx_lock_spin(&dt_lock); 749 if (!(error = i386_ldt_grow(td, largest_ld))) { 750 error = i386_set_ldt_data(td, uap->start, uap->num, 751 descs); 752 } 753 mtx_unlock_spin(&dt_lock); 754 } 755 if (error == 0) 756 td->td_retval[0] = uap->start; 757 return (error); 758 } 759 #ifdef XEN 760 static int 761 i386_set_ldt_data(struct thread *td, int start, int num, 762 union descriptor *descs) 763 { 764 struct mdproc *mdp = &td->td_proc->p_md; 765 struct proc_ldt *pldt = mdp->md_ldt; 766 767 mtx_assert(&dt_lock, MA_OWNED); 768 769 while (num) { 770 xen_update_descriptor( 771 &((union descriptor *)(pldt->ldt_base))[start], 772 descs); 773 num--; 774 start++; 775 descs++; 776 } 777 return (0); 778 } 779 #else 780 static int 781 i386_set_ldt_data(struct thread *td, int start, int num, 782 union descriptor *descs) 783 { 784 struct mdproc *mdp = &td->td_proc->p_md; 785 struct proc_ldt *pldt = mdp->md_ldt; 786 787 mtx_assert(&dt_lock, MA_OWNED); 788 789 /* Fill in range */ 790 bcopy(descs, 791 &((union descriptor *)(pldt->ldt_base))[start], 792 num * sizeof(union descriptor)); 793 return (0); 794 } 795 #endif /* !XEN */ 796 797 static int 798 i386_ldt_grow(struct thread *td, int len) 799 { 800 struct mdproc *mdp = &td->td_proc->p_md; 801 struct proc_ldt *new_ldt, *pldt; 802 caddr_t old_ldt_base = NULL_LDT_BASE; 803 int old_ldt_len = 0; 804 805 mtx_assert(&dt_lock, MA_OWNED); 806 807 if (len > MAX_LD) 808 return (ENOMEM); 809 if (len < NLDT + 1) 810 len = NLDT + 1; 811 812 /* Allocate a user ldt. */ 813 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) { 814 new_ldt = user_ldt_alloc(mdp, len); 815 if (new_ldt == NULL) 816 return (ENOMEM); 817 pldt = mdp->md_ldt; 818 819 if (pldt != NULL) { 820 if (new_ldt->ldt_len <= pldt->ldt_len) { 821 /* 822 * We just lost the race for allocation, so 823 * free the new object and return. 824 */ 825 mtx_unlock_spin(&dt_lock); 826 kmem_free(kernel_map, 827 (vm_offset_t)new_ldt->ldt_base, 828 new_ldt->ldt_len * sizeof(union descriptor)); 829 free(new_ldt, M_SUBPROC); 830 mtx_lock_spin(&dt_lock); 831 return (0); 832 } 833 834 /* 835 * We have to substitute the current LDT entry for 836 * curproc with the new one since its size grew. 837 */ 838 old_ldt_base = pldt->ldt_base; 839 old_ldt_len = pldt->ldt_len; 840 pldt->ldt_sd = new_ldt->ldt_sd; 841 pldt->ldt_base = new_ldt->ldt_base; 842 pldt->ldt_len = new_ldt->ldt_len; 843 } else 844 mdp->md_ldt = pldt = new_ldt; 845 #ifdef SMP 846 /* 847 * Signal other cpus to reload ldt. We need to unlock dt_lock 848 * here because other CPU will contest on it since their 849 * curthreads won't hold the lock and will block when trying 850 * to acquire it. 851 */ 852 mtx_unlock_spin(&dt_lock); 853 smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 854 NULL, td->td_proc->p_vmspace); 855 #else 856 set_user_ldt(&td->td_proc->p_md); 857 mtx_unlock_spin(&dt_lock); 858 #endif 859 if (old_ldt_base != NULL_LDT_BASE) { 860 kmem_free(kernel_map, (vm_offset_t)old_ldt_base, 861 old_ldt_len * sizeof(union descriptor)); 862 free(new_ldt, M_SUBPROC); 863 } 864 mtx_lock_spin(&dt_lock); 865 } 866 return (0); 867 }
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