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