1 /* 2 * Copyright (C) 1994 Linus Torvalds 3 * 4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86 5 * stack - Manfred Spraul <manfred@colorfullife.com> 6 * 7 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle 8 * them correctly. Now the emulation will be in a 9 * consistent state after stackfaults - Kasper Dupont 10 * <kasperd@daimi.au.dk> 11 * 12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont 13 * <kasperd@daimi.au.dk> 14 * 15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault 16 * caused by Kasper Dupont's changes - Stas Sergeev 17 * 18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes. 19 * Kasper Dupont <kasperd@daimi.au.dk> 20 * 21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault. 22 * Kasper Dupont <kasperd@daimi.au.dk> 23 * 24 * 9 apr 2002 - Changed stack access macros to jump to a label 25 * instead of returning to userspace. This simplifies 26 * do_int, and is needed by handle_vm6_fault. Kasper 27 * Dupont <kasperd@daimi.au.dk> 28 * 29 */ 30 31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 32 33 #include <linux/capability.h> 34 #include <linux/errno.h> 35 #include <linux/interrupt.h> 36 #include <linux/syscalls.h> 37 #include <linux/sched.h> 38 #include <linux/kernel.h> 39 #include <linux/signal.h> 40 #include <linux/string.h> 41 #include <linux/mm.h> 42 #include <linux/smp.h> 43 #include <linux/highmem.h> 44 #include <linux/ptrace.h> 45 #include <linux/audit.h> 46 #include <linux/stddef.h> 47 #include <linux/slab.h> 48 #include <linux/security.h> 49 50 #include <asm/uaccess.h> 51 #include <asm/io.h> 52 #include <asm/tlbflush.h> 53 #include <asm/irq.h> 54 #include <asm/traps.h> 55 #include <asm/vm86.h> 56 57 /* 58 * Known problems: 59 * 60 * Interrupt handling is not guaranteed: 61 * - a real x86 will disable all interrupts for one instruction 62 * after a "mov ss,xx" to make stack handling atomic even without 63 * the 'lss' instruction. We can't guarantee this in v86 mode, 64 * as the next instruction might result in a page fault or similar. 65 * - a real x86 will have interrupts disabled for one instruction 66 * past the 'sti' that enables them. We don't bother with all the 67 * details yet. 68 * 69 * Let's hope these problems do not actually matter for anything. 70 */ 71 72 73 /* 74 * 8- and 16-bit register defines.. 75 */ 76 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 77 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 78 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 79 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 80 81 /* 82 * virtual flags (16 and 32-bit versions) 83 */ 84 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) 85 #define VEFLAGS (current->thread.vm86->veflags) 86 87 #define set_flags(X, new, mask) \ 88 ((X) = ((X) & ~(mask)) | ((new) & (mask))) 89 90 #define SAFE_MASK (0xDD5) 91 #define RETURN_MASK (0xDFF) 92 93 void save_v86_state(struct kernel_vm86_regs *regs, int retval) 94 { 95 struct tss_struct *tss; 96 struct task_struct *tsk = current; 97 struct vm86plus_struct __user *user; 98 struct vm86 *vm86 = current->thread.vm86; 99 long err = 0; 100 101 /* 102 * This gets called from entry.S with interrupts disabled, but 103 * from process context. Enable interrupts here, before trying 104 * to access user space. 105 */ 106 local_irq_enable(); 107 108 if (!vm86 || !vm86->user_vm86) { 109 pr_alert("no user_vm86: BAD\n"); 110 do_exit(SIGSEGV); 111 } 112 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask); 113 user = vm86->user_vm86; 114 115 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ? 116 sizeof(struct vm86plus_struct) : 117 sizeof(struct vm86_struct))) { 118 pr_alert("could not access userspace vm86 info\n"); 119 do_exit(SIGSEGV); 120 } 121 122 put_user_try { 123 put_user_ex(regs->pt.bx, &user->regs.ebx); 124 put_user_ex(regs->pt.cx, &user->regs.ecx); 125 put_user_ex(regs->pt.dx, &user->regs.edx); 126 put_user_ex(regs->pt.si, &user->regs.esi); 127 put_user_ex(regs->pt.di, &user->regs.edi); 128 put_user_ex(regs->pt.bp, &user->regs.ebp); 129 put_user_ex(regs->pt.ax, &user->regs.eax); 130 put_user_ex(regs->pt.ip, &user->regs.eip); 131 put_user_ex(regs->pt.cs, &user->regs.cs); 132 put_user_ex(regs->pt.flags, &user->regs.eflags); 133 put_user_ex(regs->pt.sp, &user->regs.esp); 134 put_user_ex(regs->pt.ss, &user->regs.ss); 135 put_user_ex(regs->es, &user->regs.es); 136 put_user_ex(regs->ds, &user->regs.ds); 137 put_user_ex(regs->fs, &user->regs.fs); 138 put_user_ex(regs->gs, &user->regs.gs); 139 140 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap); 141 } put_user_catch(err); 142 if (err) { 143 pr_alert("could not access userspace vm86 info\n"); 144 do_exit(SIGSEGV); 145 } 146 147 tss = &per_cpu(cpu_tss, get_cpu()); 148 tsk->thread.sp0 = vm86->saved_sp0; 149 tsk->thread.sysenter_cs = __KERNEL_CS; 150 load_sp0(tss, &tsk->thread); 151 vm86->saved_sp0 = 0; 152 put_cpu(); 153 154 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); 155 156 lazy_load_gs(vm86->regs32.gs); 157 158 regs->pt.ax = retval; 159 } 160 161 static void mark_screen_rdonly(struct mm_struct *mm) 162 { 163 pgd_t *pgd; 164 pud_t *pud; 165 pmd_t *pmd; 166 pte_t *pte; 167 spinlock_t *ptl; 168 int i; 169 170 down_write(&mm->mmap_sem); 171 pgd = pgd_offset(mm, 0xA0000); 172 if (pgd_none_or_clear_bad(pgd)) 173 goto out; 174 pud = pud_offset(pgd, 0xA0000); 175 if (pud_none_or_clear_bad(pud)) 176 goto out; 177 pmd = pmd_offset(pud, 0xA0000); 178 179 if (pmd_trans_huge(*pmd)) { 180 struct vm_area_struct *vma = find_vma(mm, 0xA0000); 181 split_huge_pmd(vma, pmd, 0xA0000); 182 } 183 if (pmd_none_or_clear_bad(pmd)) 184 goto out; 185 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 186 for (i = 0; i < 32; i++) { 187 if (pte_present(*pte)) 188 set_pte(pte, pte_wrprotect(*pte)); 189 pte++; 190 } 191 pte_unmap_unlock(pte, ptl); 192 out: 193 up_write(&mm->mmap_sem); 194 flush_tlb(); 195 } 196 197 198 199 static int do_vm86_irq_handling(int subfunction, int irqnumber); 200 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); 201 202 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) 203 { 204 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false); 205 } 206 207 208 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 209 { 210 switch (cmd) { 211 case VM86_REQUEST_IRQ: 212 case VM86_FREE_IRQ: 213 case VM86_GET_IRQ_BITS: 214 case VM86_GET_AND_RESET_IRQ: 215 return do_vm86_irq_handling(cmd, (int)arg); 216 case VM86_PLUS_INSTALL_CHECK: 217 /* 218 * NOTE: on old vm86 stuff this will return the error 219 * from access_ok(), because the subfunction is 220 * interpreted as (invalid) address to vm86_struct. 221 * So the installation check works. 222 */ 223 return 0; 224 } 225 226 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 227 return do_sys_vm86((struct vm86plus_struct __user *) arg, true); 228 } 229 230 231 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) 232 { 233 struct tss_struct *tss; 234 struct task_struct *tsk = current; 235 struct vm86 *vm86 = tsk->thread.vm86; 236 struct kernel_vm86_regs vm86regs; 237 struct pt_regs *regs = current_pt_regs(); 238 unsigned long err = 0; 239 240 err = security_mmap_addr(0); 241 if (err) { 242 /* 243 * vm86 cannot virtualize the address space, so vm86 users 244 * need to manage the low 1MB themselves using mmap. Given 245 * that BIOS places important data in the first page, vm86 246 * is essentially useless if mmap_min_addr != 0. DOSEMU, 247 * for example, won't even bother trying to use vm86 if it 248 * can't map a page at virtual address 0. 249 * 250 * To reduce the available kernel attack surface, simply 251 * disallow vm86(old) for users who cannot mmap at va 0. 252 * 253 * The implementation of security_mmap_addr will allow 254 * suitably privileged users to map va 0 even if 255 * vm.mmap_min_addr is set above 0, and we want this 256 * behavior for vm86 as well, as it ensures that legacy 257 * tools like vbetool will not fail just because of 258 * vm.mmap_min_addr. 259 */ 260 pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n", 261 current->comm, task_pid_nr(current), 262 from_kuid_munged(&init_user_ns, current_uid())); 263 return -EPERM; 264 } 265 266 if (!vm86) { 267 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL))) 268 return -ENOMEM; 269 tsk->thread.vm86 = vm86; 270 } 271 if (vm86->saved_sp0) 272 return -EPERM; 273 274 if (!access_ok(VERIFY_READ, user_vm86, plus ? 275 sizeof(struct vm86_struct) : 276 sizeof(struct vm86plus_struct))) 277 return -EFAULT; 278 279 memset(&vm86regs, 0, sizeof(vm86regs)); 280 get_user_try { 281 unsigned short seg; 282 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx); 283 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx); 284 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx); 285 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi); 286 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi); 287 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp); 288 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax); 289 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip); 290 get_user_ex(seg, &user_vm86->regs.cs); 291 vm86regs.pt.cs = seg; 292 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags); 293 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp); 294 get_user_ex(seg, &user_vm86->regs.ss); 295 vm86regs.pt.ss = seg; 296 get_user_ex(vm86regs.es, &user_vm86->regs.es); 297 get_user_ex(vm86regs.ds, &user_vm86->regs.ds); 298 get_user_ex(vm86regs.fs, &user_vm86->regs.fs); 299 get_user_ex(vm86regs.gs, &user_vm86->regs.gs); 300 301 get_user_ex(vm86->flags, &user_vm86->flags); 302 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap); 303 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type); 304 } get_user_catch(err); 305 if (err) 306 return err; 307 308 if (copy_from_user(&vm86->int_revectored, 309 &user_vm86->int_revectored, 310 sizeof(struct revectored_struct))) 311 return -EFAULT; 312 if (copy_from_user(&vm86->int21_revectored, 313 &user_vm86->int21_revectored, 314 sizeof(struct revectored_struct))) 315 return -EFAULT; 316 if (plus) { 317 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus, 318 sizeof(struct vm86plus_info_struct))) 319 return -EFAULT; 320 vm86->vm86plus.is_vm86pus = 1; 321 } else 322 memset(&vm86->vm86plus, 0, 323 sizeof(struct vm86plus_info_struct)); 324 325 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs)); 326 vm86->user_vm86 = user_vm86; 327 328 /* 329 * The flags register is also special: we cannot trust that the user 330 * has set it up safely, so this makes sure interrupt etc flags are 331 * inherited from protected mode. 332 */ 333 VEFLAGS = vm86regs.pt.flags; 334 vm86regs.pt.flags &= SAFE_MASK; 335 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK; 336 vm86regs.pt.flags |= X86_VM_MASK; 337 338 vm86regs.pt.orig_ax = regs->orig_ax; 339 340 switch (vm86->cpu_type) { 341 case CPU_286: 342 vm86->veflags_mask = 0; 343 break; 344 case CPU_386: 345 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 346 break; 347 case CPU_486: 348 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 349 break; 350 default: 351 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 352 break; 353 } 354 355 /* 356 * Save old state 357 */ 358 vm86->saved_sp0 = tsk->thread.sp0; 359 lazy_save_gs(vm86->regs32.gs); 360 361 tss = &per_cpu(cpu_tss, get_cpu()); 362 /* make room for real-mode segments */ 363 tsk->thread.sp0 += 16; 364 365 if (static_cpu_has(X86_FEATURE_SEP)) 366 tsk->thread.sysenter_cs = 0; 367 368 load_sp0(tss, &tsk->thread); 369 put_cpu(); 370 371 if (vm86->flags & VM86_SCREEN_BITMAP) 372 mark_screen_rdonly(tsk->mm); 373 374 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); 375 force_iret(); 376 return regs->ax; 377 } 378 379 static inline void set_IF(struct kernel_vm86_regs *regs) 380 { 381 VEFLAGS |= X86_EFLAGS_VIF; 382 } 383 384 static inline void clear_IF(struct kernel_vm86_regs *regs) 385 { 386 VEFLAGS &= ~X86_EFLAGS_VIF; 387 } 388 389 static inline void clear_TF(struct kernel_vm86_regs *regs) 390 { 391 regs->pt.flags &= ~X86_EFLAGS_TF; 392 } 393 394 static inline void clear_AC(struct kernel_vm86_regs *regs) 395 { 396 regs->pt.flags &= ~X86_EFLAGS_AC; 397 } 398 399 /* 400 * It is correct to call set_IF(regs) from the set_vflags_* 401 * functions. However someone forgot to call clear_IF(regs) 402 * in the opposite case. 403 * After the command sequence CLI PUSHF STI POPF you should 404 * end up with interrupts disabled, but you ended up with 405 * interrupts enabled. 406 * ( I was testing my own changes, but the only bug I 407 * could find was in a function I had not changed. ) 408 * [KD] 409 */ 410 411 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 412 { 413 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 414 set_flags(regs->pt.flags, flags, SAFE_MASK); 415 if (flags & X86_EFLAGS_IF) 416 set_IF(regs); 417 else 418 clear_IF(regs); 419 } 420 421 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 422 { 423 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 424 set_flags(regs->pt.flags, flags, SAFE_MASK); 425 if (flags & X86_EFLAGS_IF) 426 set_IF(regs); 427 else 428 clear_IF(regs); 429 } 430 431 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 432 { 433 unsigned long flags = regs->pt.flags & RETURN_MASK; 434 435 if (VEFLAGS & X86_EFLAGS_VIF) 436 flags |= X86_EFLAGS_IF; 437 flags |= X86_EFLAGS_IOPL; 438 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 439 } 440 441 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 442 { 443 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0" 444 :"=r" (nr) 445 :"m" (*bitmap), "r" (nr)); 446 return nr; 447 } 448 449 #define val_byte(val, n) (((__u8 *)&val)[n]) 450 451 #define pushb(base, ptr, val, err_label) \ 452 do { \ 453 __u8 __val = val; \ 454 ptr--; \ 455 if (put_user(__val, base + ptr) < 0) \ 456 goto err_label; \ 457 } while (0) 458 459 #define pushw(base, ptr, val, err_label) \ 460 do { \ 461 __u16 __val = val; \ 462 ptr--; \ 463 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 464 goto err_label; \ 465 ptr--; \ 466 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 467 goto err_label; \ 468 } while (0) 469 470 #define pushl(base, ptr, val, err_label) \ 471 do { \ 472 __u32 __val = val; \ 473 ptr--; \ 474 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 475 goto err_label; \ 476 ptr--; \ 477 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 478 goto err_label; \ 479 ptr--; \ 480 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 481 goto err_label; \ 482 ptr--; \ 483 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 484 goto err_label; \ 485 } while (0) 486 487 #define popb(base, ptr, err_label) \ 488 ({ \ 489 __u8 __res; \ 490 if (get_user(__res, base + ptr) < 0) \ 491 goto err_label; \ 492 ptr++; \ 493 __res; \ 494 }) 495 496 #define popw(base, ptr, err_label) \ 497 ({ \ 498 __u16 __res; \ 499 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 500 goto err_label; \ 501 ptr++; \ 502 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 503 goto err_label; \ 504 ptr++; \ 505 __res; \ 506 }) 507 508 #define popl(base, ptr, err_label) \ 509 ({ \ 510 __u32 __res; \ 511 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 512 goto err_label; \ 513 ptr++; \ 514 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 515 goto err_label; \ 516 ptr++; \ 517 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 518 goto err_label; \ 519 ptr++; \ 520 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 521 goto err_label; \ 522 ptr++; \ 523 __res; \ 524 }) 525 526 /* There are so many possible reasons for this function to return 527 * VM86_INTx, so adding another doesn't bother me. We can expect 528 * userspace programs to be able to handle it. (Getting a problem 529 * in userspace is always better than an Oops anyway.) [KD] 530 */ 531 static void do_int(struct kernel_vm86_regs *regs, int i, 532 unsigned char __user *ssp, unsigned short sp) 533 { 534 unsigned long __user *intr_ptr; 535 unsigned long segoffs; 536 struct vm86 *vm86 = current->thread.vm86; 537 538 if (regs->pt.cs == BIOSSEG) 539 goto cannot_handle; 540 if (is_revectored(i, &vm86->int_revectored)) 541 goto cannot_handle; 542 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 543 goto cannot_handle; 544 intr_ptr = (unsigned long __user *) (i << 2); 545 if (get_user(segoffs, intr_ptr)) 546 goto cannot_handle; 547 if ((segoffs >> 16) == BIOSSEG) 548 goto cannot_handle; 549 pushw(ssp, sp, get_vflags(regs), cannot_handle); 550 pushw(ssp, sp, regs->pt.cs, cannot_handle); 551 pushw(ssp, sp, IP(regs), cannot_handle); 552 regs->pt.cs = segoffs >> 16; 553 SP(regs) -= 6; 554 IP(regs) = segoffs & 0xffff; 555 clear_TF(regs); 556 clear_IF(regs); 557 clear_AC(regs); 558 return; 559 560 cannot_handle: 561 save_v86_state(regs, VM86_INTx + (i << 8)); 562 } 563 564 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 565 { 566 struct vm86 *vm86 = current->thread.vm86; 567 568 if (vm86->vm86plus.is_vm86pus) { 569 if ((trapno == 3) || (trapno == 1)) { 570 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 571 return 0; 572 } 573 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 574 return 0; 575 } 576 if (trapno != 1) 577 return 1; /* we let this handle by the calling routine */ 578 current->thread.trap_nr = trapno; 579 current->thread.error_code = error_code; 580 force_sig(SIGTRAP, current); 581 return 0; 582 } 583 584 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 585 { 586 unsigned char opcode; 587 unsigned char __user *csp; 588 unsigned char __user *ssp; 589 unsigned short ip, sp, orig_flags; 590 int data32, pref_done; 591 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 592 593 #define CHECK_IF_IN_TRAP \ 594 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 595 newflags |= X86_EFLAGS_TF 596 597 orig_flags = *(unsigned short *)®s->pt.flags; 598 599 csp = (unsigned char __user *) (regs->pt.cs << 4); 600 ssp = (unsigned char __user *) (regs->pt.ss << 4); 601 sp = SP(regs); 602 ip = IP(regs); 603 604 data32 = 0; 605 pref_done = 0; 606 do { 607 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 608 case 0x66: /* 32-bit data */ data32 = 1; break; 609 case 0x67: /* 32-bit address */ break; 610 case 0x2e: /* CS */ break; 611 case 0x3e: /* DS */ break; 612 case 0x26: /* ES */ break; 613 case 0x36: /* SS */ break; 614 case 0x65: /* GS */ break; 615 case 0x64: /* FS */ break; 616 case 0xf2: /* repnz */ break; 617 case 0xf3: /* rep */ break; 618 default: pref_done = 1; 619 } 620 } while (!pref_done); 621 622 switch (opcode) { 623 624 /* pushf */ 625 case 0x9c: 626 if (data32) { 627 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 628 SP(regs) -= 4; 629 } else { 630 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 631 SP(regs) -= 2; 632 } 633 IP(regs) = ip; 634 goto vm86_fault_return; 635 636 /* popf */ 637 case 0x9d: 638 { 639 unsigned long newflags; 640 if (data32) { 641 newflags = popl(ssp, sp, simulate_sigsegv); 642 SP(regs) += 4; 643 } else { 644 newflags = popw(ssp, sp, simulate_sigsegv); 645 SP(regs) += 2; 646 } 647 IP(regs) = ip; 648 CHECK_IF_IN_TRAP; 649 if (data32) 650 set_vflags_long(newflags, regs); 651 else 652 set_vflags_short(newflags, regs); 653 654 goto check_vip; 655 } 656 657 /* int xx */ 658 case 0xcd: { 659 int intno = popb(csp, ip, simulate_sigsegv); 660 IP(regs) = ip; 661 if (vmpi->vm86dbg_active) { 662 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 663 save_v86_state(regs, VM86_INTx + (intno << 8)); 664 return; 665 } 666 } 667 do_int(regs, intno, ssp, sp); 668 return; 669 } 670 671 /* iret */ 672 case 0xcf: 673 { 674 unsigned long newip; 675 unsigned long newcs; 676 unsigned long newflags; 677 if (data32) { 678 newip = popl(ssp, sp, simulate_sigsegv); 679 newcs = popl(ssp, sp, simulate_sigsegv); 680 newflags = popl(ssp, sp, simulate_sigsegv); 681 SP(regs) += 12; 682 } else { 683 newip = popw(ssp, sp, simulate_sigsegv); 684 newcs = popw(ssp, sp, simulate_sigsegv); 685 newflags = popw(ssp, sp, simulate_sigsegv); 686 SP(regs) += 6; 687 } 688 IP(regs) = newip; 689 regs->pt.cs = newcs; 690 CHECK_IF_IN_TRAP; 691 if (data32) { 692 set_vflags_long(newflags, regs); 693 } else { 694 set_vflags_short(newflags, regs); 695 } 696 goto check_vip; 697 } 698 699 /* cli */ 700 case 0xfa: 701 IP(regs) = ip; 702 clear_IF(regs); 703 goto vm86_fault_return; 704 705 /* sti */ 706 /* 707 * Damn. This is incorrect: the 'sti' instruction should actually 708 * enable interrupts after the /next/ instruction. Not good. 709 * 710 * Probably needs some horsing around with the TF flag. Aiee.. 711 */ 712 case 0xfb: 713 IP(regs) = ip; 714 set_IF(regs); 715 goto check_vip; 716 717 default: 718 save_v86_state(regs, VM86_UNKNOWN); 719 } 720 721 return; 722 723 check_vip: 724 if (VEFLAGS & X86_EFLAGS_VIP) { 725 save_v86_state(regs, VM86_STI); 726 return; 727 } 728 729 vm86_fault_return: 730 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 731 save_v86_state(regs, VM86_PICRETURN); 732 return; 733 } 734 if (orig_flags & X86_EFLAGS_TF) 735 handle_vm86_trap(regs, 0, X86_TRAP_DB); 736 return; 737 738 simulate_sigsegv: 739 /* FIXME: After a long discussion with Stas we finally 740 * agreed, that this is wrong. Here we should 741 * really send a SIGSEGV to the user program. 742 * But how do we create the correct context? We 743 * are inside a general protection fault handler 744 * and has just returned from a page fault handler. 745 * The correct context for the signal handler 746 * should be a mixture of the two, but how do we 747 * get the information? [KD] 748 */ 749 save_v86_state(regs, VM86_UNKNOWN); 750 } 751 752 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 753 754 #define VM86_IRQNAME "vm86irq" 755 756 static struct vm86_irqs { 757 struct task_struct *tsk; 758 int sig; 759 } vm86_irqs[16]; 760 761 static DEFINE_SPINLOCK(irqbits_lock); 762 static int irqbits; 763 764 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 765 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 766 | (1 << SIGUNUSED)) 767 768 static irqreturn_t irq_handler(int intno, void *dev_id) 769 { 770 int irq_bit; 771 unsigned long flags; 772 773 spin_lock_irqsave(&irqbits_lock, flags); 774 irq_bit = 1 << intno; 775 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 776 goto out; 777 irqbits |= irq_bit; 778 if (vm86_irqs[intno].sig) 779 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 780 /* 781 * IRQ will be re-enabled when user asks for the irq (whether 782 * polling or as a result of the signal) 783 */ 784 disable_irq_nosync(intno); 785 spin_unlock_irqrestore(&irqbits_lock, flags); 786 return IRQ_HANDLED; 787 788 out: 789 spin_unlock_irqrestore(&irqbits_lock, flags); 790 return IRQ_NONE; 791 } 792 793 static inline void free_vm86_irq(int irqnumber) 794 { 795 unsigned long flags; 796 797 free_irq(irqnumber, NULL); 798 vm86_irqs[irqnumber].tsk = NULL; 799 800 spin_lock_irqsave(&irqbits_lock, flags); 801 irqbits &= ~(1 << irqnumber); 802 spin_unlock_irqrestore(&irqbits_lock, flags); 803 } 804 805 void release_vm86_irqs(struct task_struct *task) 806 { 807 int i; 808 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 809 if (vm86_irqs[i].tsk == task) 810 free_vm86_irq(i); 811 } 812 813 static inline int get_and_reset_irq(int irqnumber) 814 { 815 int bit; 816 unsigned long flags; 817 int ret = 0; 818 819 if (invalid_vm86_irq(irqnumber)) return 0; 820 if (vm86_irqs[irqnumber].tsk != current) return 0; 821 spin_lock_irqsave(&irqbits_lock, flags); 822 bit = irqbits & (1 << irqnumber); 823 irqbits &= ~bit; 824 if (bit) { 825 enable_irq(irqnumber); 826 ret = 1; 827 } 828 829 spin_unlock_irqrestore(&irqbits_lock, flags); 830 return ret; 831 } 832 833 834 static int do_vm86_irq_handling(int subfunction, int irqnumber) 835 { 836 int ret; 837 switch (subfunction) { 838 case VM86_GET_AND_RESET_IRQ: { 839 return get_and_reset_irq(irqnumber); 840 } 841 case VM86_GET_IRQ_BITS: { 842 return irqbits; 843 } 844 case VM86_REQUEST_IRQ: { 845 int sig = irqnumber >> 8; 846 int irq = irqnumber & 255; 847 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 848 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 849 if (invalid_vm86_irq(irq)) return -EPERM; 850 if (vm86_irqs[irq].tsk) return -EPERM; 851 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 852 if (ret) return ret; 853 vm86_irqs[irq].sig = sig; 854 vm86_irqs[irq].tsk = current; 855 return irq; 856 } 857 case VM86_FREE_IRQ: { 858 if (invalid_vm86_irq(irqnumber)) return -EPERM; 859 if (!vm86_irqs[irqnumber].tsk) return 0; 860 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 861 free_vm86_irq(irqnumber); 862 return 0; 863 } 864 } 865 return -EINVAL; 866 } 867 868