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/sched/task_stack.h> 39 #include <linux/kernel.h> 40 #include <linux/signal.h> 41 #include <linux/string.h> 42 #include <linux/mm.h> 43 #include <linux/smp.h> 44 #include <linux/highmem.h> 45 #include <linux/ptrace.h> 46 #include <linux/audit.h> 47 #include <linux/stddef.h> 48 #include <linux/slab.h> 49 #include <linux/security.h> 50 51 #include <linux/uaccess.h> 52 #include <asm/io.h> 53 #include <asm/tlbflush.h> 54 #include <asm/irq.h> 55 #include <asm/traps.h> 56 #include <asm/vm86.h> 57 58 /* 59 * Known problems: 60 * 61 * Interrupt handling is not guaranteed: 62 * - a real x86 will disable all interrupts for one instruction 63 * after a "mov ss,xx" to make stack handling atomic even without 64 * the 'lss' instruction. We can't guarantee this in v86 mode, 65 * as the next instruction might result in a page fault or similar. 66 * - a real x86 will have interrupts disabled for one instruction 67 * past the 'sti' that enables them. We don't bother with all the 68 * details yet. 69 * 70 * Let's hope these problems do not actually matter for anything. 71 */ 72 73 74 /* 75 * 8- and 16-bit register defines.. 76 */ 77 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 78 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 79 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 80 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 81 82 /* 83 * virtual flags (16 and 32-bit versions) 84 */ 85 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) 86 #define VEFLAGS (current->thread.vm86->veflags) 87 88 #define set_flags(X, new, mask) \ 89 ((X) = ((X) & ~(mask)) | ((new) & (mask))) 90 91 #define SAFE_MASK (0xDD5) 92 #define RETURN_MASK (0xDFF) 93 94 void save_v86_state(struct kernel_vm86_regs *regs, int retval) 95 { 96 struct tss_struct *tss; 97 struct task_struct *tsk = current; 98 struct vm86plus_struct __user *user; 99 struct vm86 *vm86 = current->thread.vm86; 100 long err = 0; 101 102 /* 103 * This gets called from entry.S with interrupts disabled, but 104 * from process context. Enable interrupts here, before trying 105 * to access user space. 106 */ 107 local_irq_enable(); 108 109 if (!vm86 || !vm86->user_vm86) { 110 pr_alert("no user_vm86: BAD\n"); 111 do_exit(SIGSEGV); 112 } 113 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask); 114 user = vm86->user_vm86; 115 116 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ? 117 sizeof(struct vm86plus_struct) : 118 sizeof(struct vm86_struct))) { 119 pr_alert("could not access userspace vm86 info\n"); 120 do_exit(SIGSEGV); 121 } 122 123 put_user_try { 124 put_user_ex(regs->pt.bx, &user->regs.ebx); 125 put_user_ex(regs->pt.cx, &user->regs.ecx); 126 put_user_ex(regs->pt.dx, &user->regs.edx); 127 put_user_ex(regs->pt.si, &user->regs.esi); 128 put_user_ex(regs->pt.di, &user->regs.edi); 129 put_user_ex(regs->pt.bp, &user->regs.ebp); 130 put_user_ex(regs->pt.ax, &user->regs.eax); 131 put_user_ex(regs->pt.ip, &user->regs.eip); 132 put_user_ex(regs->pt.cs, &user->regs.cs); 133 put_user_ex(regs->pt.flags, &user->regs.eflags); 134 put_user_ex(regs->pt.sp, &user->regs.esp); 135 put_user_ex(regs->pt.ss, &user->regs.ss); 136 put_user_ex(regs->es, &user->regs.es); 137 put_user_ex(regs->ds, &user->regs.ds); 138 put_user_ex(regs->fs, &user->regs.fs); 139 put_user_ex(regs->gs, &user->regs.gs); 140 141 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap); 142 } put_user_catch(err); 143 if (err) { 144 pr_alert("could not access userspace vm86 info\n"); 145 do_exit(SIGSEGV); 146 } 147 148 tss = &per_cpu(cpu_tss, get_cpu()); 149 tsk->thread.sp0 = vm86->saved_sp0; 150 tsk->thread.sysenter_cs = __KERNEL_CS; 151 load_sp0(tss, &tsk->thread); 152 vm86->saved_sp0 = 0; 153 put_cpu(); 154 155 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); 156 157 lazy_load_gs(vm86->regs32.gs); 158 159 regs->pt.ax = retval; 160 } 161 162 static void mark_screen_rdonly(struct mm_struct *mm) 163 { 164 struct vm_area_struct *vma; 165 spinlock_t *ptl; 166 pgd_t *pgd; 167 p4d_t *p4d; 168 pud_t *pud; 169 pmd_t *pmd; 170 pte_t *pte; 171 int i; 172 173 down_write(&mm->mmap_sem); 174 pgd = pgd_offset(mm, 0xA0000); 175 if (pgd_none_or_clear_bad(pgd)) 176 goto out; 177 p4d = p4d_offset(pgd, 0xA0000); 178 if (p4d_none_or_clear_bad(p4d)) 179 goto out; 180 pud = pud_offset(p4d, 0xA0000); 181 if (pud_none_or_clear_bad(pud)) 182 goto out; 183 pmd = pmd_offset(pud, 0xA0000); 184 185 if (pmd_trans_huge(*pmd)) { 186 vma = find_vma(mm, 0xA0000); 187 split_huge_pmd(vma, pmd, 0xA0000); 188 } 189 if (pmd_none_or_clear_bad(pmd)) 190 goto out; 191 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 192 for (i = 0; i < 32; i++) { 193 if (pte_present(*pte)) 194 set_pte(pte, pte_wrprotect(*pte)); 195 pte++; 196 } 197 pte_unmap_unlock(pte, ptl); 198 out: 199 up_write(&mm->mmap_sem); 200 flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL); 201 } 202 203 204 205 static int do_vm86_irq_handling(int subfunction, int irqnumber); 206 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); 207 208 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) 209 { 210 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false); 211 } 212 213 214 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 215 { 216 switch (cmd) { 217 case VM86_REQUEST_IRQ: 218 case VM86_FREE_IRQ: 219 case VM86_GET_IRQ_BITS: 220 case VM86_GET_AND_RESET_IRQ: 221 return do_vm86_irq_handling(cmd, (int)arg); 222 case VM86_PLUS_INSTALL_CHECK: 223 /* 224 * NOTE: on old vm86 stuff this will return the error 225 * from access_ok(), because the subfunction is 226 * interpreted as (invalid) address to vm86_struct. 227 * So the installation check works. 228 */ 229 return 0; 230 } 231 232 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 233 return do_sys_vm86((struct vm86plus_struct __user *) arg, true); 234 } 235 236 237 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) 238 { 239 struct tss_struct *tss; 240 struct task_struct *tsk = current; 241 struct vm86 *vm86 = tsk->thread.vm86; 242 struct kernel_vm86_regs vm86regs; 243 struct pt_regs *regs = current_pt_regs(); 244 unsigned long err = 0; 245 246 err = security_mmap_addr(0); 247 if (err) { 248 /* 249 * vm86 cannot virtualize the address space, so vm86 users 250 * need to manage the low 1MB themselves using mmap. Given 251 * that BIOS places important data in the first page, vm86 252 * is essentially useless if mmap_min_addr != 0. DOSEMU, 253 * for example, won't even bother trying to use vm86 if it 254 * can't map a page at virtual address 0. 255 * 256 * To reduce the available kernel attack surface, simply 257 * disallow vm86(old) for users who cannot mmap at va 0. 258 * 259 * The implementation of security_mmap_addr will allow 260 * suitably privileged users to map va 0 even if 261 * vm.mmap_min_addr is set above 0, and we want this 262 * behavior for vm86 as well, as it ensures that legacy 263 * tools like vbetool will not fail just because of 264 * vm.mmap_min_addr. 265 */ 266 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", 267 current->comm, task_pid_nr(current), 268 from_kuid_munged(&init_user_ns, current_uid())); 269 return -EPERM; 270 } 271 272 if (!vm86) { 273 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL))) 274 return -ENOMEM; 275 tsk->thread.vm86 = vm86; 276 } 277 if (vm86->saved_sp0) 278 return -EPERM; 279 280 if (!access_ok(VERIFY_READ, user_vm86, plus ? 281 sizeof(struct vm86_struct) : 282 sizeof(struct vm86plus_struct))) 283 return -EFAULT; 284 285 memset(&vm86regs, 0, sizeof(vm86regs)); 286 get_user_try { 287 unsigned short seg; 288 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx); 289 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx); 290 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx); 291 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi); 292 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi); 293 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp); 294 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax); 295 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip); 296 get_user_ex(seg, &user_vm86->regs.cs); 297 vm86regs.pt.cs = seg; 298 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags); 299 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp); 300 get_user_ex(seg, &user_vm86->regs.ss); 301 vm86regs.pt.ss = seg; 302 get_user_ex(vm86regs.es, &user_vm86->regs.es); 303 get_user_ex(vm86regs.ds, &user_vm86->regs.ds); 304 get_user_ex(vm86regs.fs, &user_vm86->regs.fs); 305 get_user_ex(vm86regs.gs, &user_vm86->regs.gs); 306 307 get_user_ex(vm86->flags, &user_vm86->flags); 308 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap); 309 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type); 310 } get_user_catch(err); 311 if (err) 312 return err; 313 314 if (copy_from_user(&vm86->int_revectored, 315 &user_vm86->int_revectored, 316 sizeof(struct revectored_struct))) 317 return -EFAULT; 318 if (copy_from_user(&vm86->int21_revectored, 319 &user_vm86->int21_revectored, 320 sizeof(struct revectored_struct))) 321 return -EFAULT; 322 if (plus) { 323 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus, 324 sizeof(struct vm86plus_info_struct))) 325 return -EFAULT; 326 vm86->vm86plus.is_vm86pus = 1; 327 } else 328 memset(&vm86->vm86plus, 0, 329 sizeof(struct vm86plus_info_struct)); 330 331 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs)); 332 vm86->user_vm86 = user_vm86; 333 334 /* 335 * The flags register is also special: we cannot trust that the user 336 * has set it up safely, so this makes sure interrupt etc flags are 337 * inherited from protected mode. 338 */ 339 VEFLAGS = vm86regs.pt.flags; 340 vm86regs.pt.flags &= SAFE_MASK; 341 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK; 342 vm86regs.pt.flags |= X86_VM_MASK; 343 344 vm86regs.pt.orig_ax = regs->orig_ax; 345 346 switch (vm86->cpu_type) { 347 case CPU_286: 348 vm86->veflags_mask = 0; 349 break; 350 case CPU_386: 351 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 352 break; 353 case CPU_486: 354 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 355 break; 356 default: 357 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 358 break; 359 } 360 361 /* 362 * Save old state 363 */ 364 vm86->saved_sp0 = tsk->thread.sp0; 365 lazy_save_gs(vm86->regs32.gs); 366 367 tss = &per_cpu(cpu_tss, get_cpu()); 368 /* make room for real-mode segments */ 369 tsk->thread.sp0 += 16; 370 371 if (static_cpu_has(X86_FEATURE_SEP)) 372 tsk->thread.sysenter_cs = 0; 373 374 load_sp0(tss, &tsk->thread); 375 put_cpu(); 376 377 if (vm86->flags & VM86_SCREEN_BITMAP) 378 mark_screen_rdonly(tsk->mm); 379 380 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); 381 force_iret(); 382 return regs->ax; 383 } 384 385 static inline void set_IF(struct kernel_vm86_regs *regs) 386 { 387 VEFLAGS |= X86_EFLAGS_VIF; 388 } 389 390 static inline void clear_IF(struct kernel_vm86_regs *regs) 391 { 392 VEFLAGS &= ~X86_EFLAGS_VIF; 393 } 394 395 static inline void clear_TF(struct kernel_vm86_regs *regs) 396 { 397 regs->pt.flags &= ~X86_EFLAGS_TF; 398 } 399 400 static inline void clear_AC(struct kernel_vm86_regs *regs) 401 { 402 regs->pt.flags &= ~X86_EFLAGS_AC; 403 } 404 405 /* 406 * It is correct to call set_IF(regs) from the set_vflags_* 407 * functions. However someone forgot to call clear_IF(regs) 408 * in the opposite case. 409 * After the command sequence CLI PUSHF STI POPF you should 410 * end up with interrupts disabled, but you ended up with 411 * interrupts enabled. 412 * ( I was testing my own changes, but the only bug I 413 * could find was in a function I had not changed. ) 414 * [KD] 415 */ 416 417 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 418 { 419 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 420 set_flags(regs->pt.flags, flags, SAFE_MASK); 421 if (flags & X86_EFLAGS_IF) 422 set_IF(regs); 423 else 424 clear_IF(regs); 425 } 426 427 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 428 { 429 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 430 set_flags(regs->pt.flags, flags, SAFE_MASK); 431 if (flags & X86_EFLAGS_IF) 432 set_IF(regs); 433 else 434 clear_IF(regs); 435 } 436 437 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 438 { 439 unsigned long flags = regs->pt.flags & RETURN_MASK; 440 441 if (VEFLAGS & X86_EFLAGS_VIF) 442 flags |= X86_EFLAGS_IF; 443 flags |= X86_EFLAGS_IOPL; 444 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 445 } 446 447 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 448 { 449 return test_bit(nr, bitmap->__map); 450 } 451 452 #define val_byte(val, n) (((__u8 *)&val)[n]) 453 454 #define pushb(base, ptr, val, err_label) \ 455 do { \ 456 __u8 __val = val; \ 457 ptr--; \ 458 if (put_user(__val, base + ptr) < 0) \ 459 goto err_label; \ 460 } while (0) 461 462 #define pushw(base, ptr, val, err_label) \ 463 do { \ 464 __u16 __val = val; \ 465 ptr--; \ 466 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 467 goto err_label; \ 468 ptr--; \ 469 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 470 goto err_label; \ 471 } while (0) 472 473 #define pushl(base, ptr, val, err_label) \ 474 do { \ 475 __u32 __val = val; \ 476 ptr--; \ 477 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 478 goto err_label; \ 479 ptr--; \ 480 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 481 goto err_label; \ 482 ptr--; \ 483 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 484 goto err_label; \ 485 ptr--; \ 486 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 487 goto err_label; \ 488 } while (0) 489 490 #define popb(base, ptr, err_label) \ 491 ({ \ 492 __u8 __res; \ 493 if (get_user(__res, base + ptr) < 0) \ 494 goto err_label; \ 495 ptr++; \ 496 __res; \ 497 }) 498 499 #define popw(base, ptr, err_label) \ 500 ({ \ 501 __u16 __res; \ 502 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 503 goto err_label; \ 504 ptr++; \ 505 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 506 goto err_label; \ 507 ptr++; \ 508 __res; \ 509 }) 510 511 #define popl(base, ptr, err_label) \ 512 ({ \ 513 __u32 __res; \ 514 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 515 goto err_label; \ 516 ptr++; \ 517 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 518 goto err_label; \ 519 ptr++; \ 520 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 521 goto err_label; \ 522 ptr++; \ 523 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 524 goto err_label; \ 525 ptr++; \ 526 __res; \ 527 }) 528 529 /* There are so many possible reasons for this function to return 530 * VM86_INTx, so adding another doesn't bother me. We can expect 531 * userspace programs to be able to handle it. (Getting a problem 532 * in userspace is always better than an Oops anyway.) [KD] 533 */ 534 static void do_int(struct kernel_vm86_regs *regs, int i, 535 unsigned char __user *ssp, unsigned short sp) 536 { 537 unsigned long __user *intr_ptr; 538 unsigned long segoffs; 539 struct vm86 *vm86 = current->thread.vm86; 540 541 if (regs->pt.cs == BIOSSEG) 542 goto cannot_handle; 543 if (is_revectored(i, &vm86->int_revectored)) 544 goto cannot_handle; 545 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 546 goto cannot_handle; 547 intr_ptr = (unsigned long __user *) (i << 2); 548 if (get_user(segoffs, intr_ptr)) 549 goto cannot_handle; 550 if ((segoffs >> 16) == BIOSSEG) 551 goto cannot_handle; 552 pushw(ssp, sp, get_vflags(regs), cannot_handle); 553 pushw(ssp, sp, regs->pt.cs, cannot_handle); 554 pushw(ssp, sp, IP(regs), cannot_handle); 555 regs->pt.cs = segoffs >> 16; 556 SP(regs) -= 6; 557 IP(regs) = segoffs & 0xffff; 558 clear_TF(regs); 559 clear_IF(regs); 560 clear_AC(regs); 561 return; 562 563 cannot_handle: 564 save_v86_state(regs, VM86_INTx + (i << 8)); 565 } 566 567 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 568 { 569 struct vm86 *vm86 = current->thread.vm86; 570 571 if (vm86->vm86plus.is_vm86pus) { 572 if ((trapno == 3) || (trapno == 1)) { 573 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 574 return 0; 575 } 576 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 577 return 0; 578 } 579 if (trapno != 1) 580 return 1; /* we let this handle by the calling routine */ 581 current->thread.trap_nr = trapno; 582 current->thread.error_code = error_code; 583 force_sig(SIGTRAP, current); 584 return 0; 585 } 586 587 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 588 { 589 unsigned char opcode; 590 unsigned char __user *csp; 591 unsigned char __user *ssp; 592 unsigned short ip, sp, orig_flags; 593 int data32, pref_done; 594 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 595 596 #define CHECK_IF_IN_TRAP \ 597 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 598 newflags |= X86_EFLAGS_TF 599 600 orig_flags = *(unsigned short *)®s->pt.flags; 601 602 csp = (unsigned char __user *) (regs->pt.cs << 4); 603 ssp = (unsigned char __user *) (regs->pt.ss << 4); 604 sp = SP(regs); 605 ip = IP(regs); 606 607 data32 = 0; 608 pref_done = 0; 609 do { 610 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 611 case 0x66: /* 32-bit data */ data32 = 1; break; 612 case 0x67: /* 32-bit address */ break; 613 case 0x2e: /* CS */ break; 614 case 0x3e: /* DS */ break; 615 case 0x26: /* ES */ break; 616 case 0x36: /* SS */ break; 617 case 0x65: /* GS */ break; 618 case 0x64: /* FS */ break; 619 case 0xf2: /* repnz */ break; 620 case 0xf3: /* rep */ break; 621 default: pref_done = 1; 622 } 623 } while (!pref_done); 624 625 switch (opcode) { 626 627 /* pushf */ 628 case 0x9c: 629 if (data32) { 630 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 631 SP(regs) -= 4; 632 } else { 633 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 634 SP(regs) -= 2; 635 } 636 IP(regs) = ip; 637 goto vm86_fault_return; 638 639 /* popf */ 640 case 0x9d: 641 { 642 unsigned long newflags; 643 if (data32) { 644 newflags = popl(ssp, sp, simulate_sigsegv); 645 SP(regs) += 4; 646 } else { 647 newflags = popw(ssp, sp, simulate_sigsegv); 648 SP(regs) += 2; 649 } 650 IP(regs) = ip; 651 CHECK_IF_IN_TRAP; 652 if (data32) 653 set_vflags_long(newflags, regs); 654 else 655 set_vflags_short(newflags, regs); 656 657 goto check_vip; 658 } 659 660 /* int xx */ 661 case 0xcd: { 662 int intno = popb(csp, ip, simulate_sigsegv); 663 IP(regs) = ip; 664 if (vmpi->vm86dbg_active) { 665 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 666 save_v86_state(regs, VM86_INTx + (intno << 8)); 667 return; 668 } 669 } 670 do_int(regs, intno, ssp, sp); 671 return; 672 } 673 674 /* iret */ 675 case 0xcf: 676 { 677 unsigned long newip; 678 unsigned long newcs; 679 unsigned long newflags; 680 if (data32) { 681 newip = popl(ssp, sp, simulate_sigsegv); 682 newcs = popl(ssp, sp, simulate_sigsegv); 683 newflags = popl(ssp, sp, simulate_sigsegv); 684 SP(regs) += 12; 685 } else { 686 newip = popw(ssp, sp, simulate_sigsegv); 687 newcs = popw(ssp, sp, simulate_sigsegv); 688 newflags = popw(ssp, sp, simulate_sigsegv); 689 SP(regs) += 6; 690 } 691 IP(regs) = newip; 692 regs->pt.cs = newcs; 693 CHECK_IF_IN_TRAP; 694 if (data32) { 695 set_vflags_long(newflags, regs); 696 } else { 697 set_vflags_short(newflags, regs); 698 } 699 goto check_vip; 700 } 701 702 /* cli */ 703 case 0xfa: 704 IP(regs) = ip; 705 clear_IF(regs); 706 goto vm86_fault_return; 707 708 /* sti */ 709 /* 710 * Damn. This is incorrect: the 'sti' instruction should actually 711 * enable interrupts after the /next/ instruction. Not good. 712 * 713 * Probably needs some horsing around with the TF flag. Aiee.. 714 */ 715 case 0xfb: 716 IP(regs) = ip; 717 set_IF(regs); 718 goto check_vip; 719 720 default: 721 save_v86_state(regs, VM86_UNKNOWN); 722 } 723 724 return; 725 726 check_vip: 727 if (VEFLAGS & X86_EFLAGS_VIP) { 728 save_v86_state(regs, VM86_STI); 729 return; 730 } 731 732 vm86_fault_return: 733 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 734 save_v86_state(regs, VM86_PICRETURN); 735 return; 736 } 737 if (orig_flags & X86_EFLAGS_TF) 738 handle_vm86_trap(regs, 0, X86_TRAP_DB); 739 return; 740 741 simulate_sigsegv: 742 /* FIXME: After a long discussion with Stas we finally 743 * agreed, that this is wrong. Here we should 744 * really send a SIGSEGV to the user program. 745 * But how do we create the correct context? We 746 * are inside a general protection fault handler 747 * and has just returned from a page fault handler. 748 * The correct context for the signal handler 749 * should be a mixture of the two, but how do we 750 * get the information? [KD] 751 */ 752 save_v86_state(regs, VM86_UNKNOWN); 753 } 754 755 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 756 757 #define VM86_IRQNAME "vm86irq" 758 759 static struct vm86_irqs { 760 struct task_struct *tsk; 761 int sig; 762 } vm86_irqs[16]; 763 764 static DEFINE_SPINLOCK(irqbits_lock); 765 static int irqbits; 766 767 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 768 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 769 | (1 << SIGUNUSED)) 770 771 static irqreturn_t irq_handler(int intno, void *dev_id) 772 { 773 int irq_bit; 774 unsigned long flags; 775 776 spin_lock_irqsave(&irqbits_lock, flags); 777 irq_bit = 1 << intno; 778 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 779 goto out; 780 irqbits |= irq_bit; 781 if (vm86_irqs[intno].sig) 782 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 783 /* 784 * IRQ will be re-enabled when user asks for the irq (whether 785 * polling or as a result of the signal) 786 */ 787 disable_irq_nosync(intno); 788 spin_unlock_irqrestore(&irqbits_lock, flags); 789 return IRQ_HANDLED; 790 791 out: 792 spin_unlock_irqrestore(&irqbits_lock, flags); 793 return IRQ_NONE; 794 } 795 796 static inline void free_vm86_irq(int irqnumber) 797 { 798 unsigned long flags; 799 800 free_irq(irqnumber, NULL); 801 vm86_irqs[irqnumber].tsk = NULL; 802 803 spin_lock_irqsave(&irqbits_lock, flags); 804 irqbits &= ~(1 << irqnumber); 805 spin_unlock_irqrestore(&irqbits_lock, flags); 806 } 807 808 void release_vm86_irqs(struct task_struct *task) 809 { 810 int i; 811 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 812 if (vm86_irqs[i].tsk == task) 813 free_vm86_irq(i); 814 } 815 816 static inline int get_and_reset_irq(int irqnumber) 817 { 818 int bit; 819 unsigned long flags; 820 int ret = 0; 821 822 if (invalid_vm86_irq(irqnumber)) return 0; 823 if (vm86_irqs[irqnumber].tsk != current) return 0; 824 spin_lock_irqsave(&irqbits_lock, flags); 825 bit = irqbits & (1 << irqnumber); 826 irqbits &= ~bit; 827 if (bit) { 828 enable_irq(irqnumber); 829 ret = 1; 830 } 831 832 spin_unlock_irqrestore(&irqbits_lock, flags); 833 return ret; 834 } 835 836 837 static int do_vm86_irq_handling(int subfunction, int irqnumber) 838 { 839 int ret; 840 switch (subfunction) { 841 case VM86_GET_AND_RESET_IRQ: { 842 return get_and_reset_irq(irqnumber); 843 } 844 case VM86_GET_IRQ_BITS: { 845 return irqbits; 846 } 847 case VM86_REQUEST_IRQ: { 848 int sig = irqnumber >> 8; 849 int irq = irqnumber & 255; 850 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 851 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 852 if (invalid_vm86_irq(irq)) return -EPERM; 853 if (vm86_irqs[irq].tsk) return -EPERM; 854 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 855 if (ret) return ret; 856 vm86_irqs[irq].sig = sig; 857 vm86_irqs[irq].tsk = current; 858 return irq; 859 } 860 case VM86_FREE_IRQ: { 861 if (invalid_vm86_irq(irqnumber)) return -EPERM; 862 if (!vm86_irqs[irqnumber].tsk) return 0; 863 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 864 free_vm86_irq(irqnumber); 865 return 0; 866 } 867 } 868 return -EINVAL; 869 } 870 871