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 return test_bit(nr, bitmap->__map); 444 } 445 446 #define val_byte(val, n) (((__u8 *)&val)[n]) 447 448 #define pushb(base, ptr, val, err_label) \ 449 do { \ 450 __u8 __val = val; \ 451 ptr--; \ 452 if (put_user(__val, base + ptr) < 0) \ 453 goto err_label; \ 454 } while (0) 455 456 #define pushw(base, ptr, val, err_label) \ 457 do { \ 458 __u16 __val = val; \ 459 ptr--; \ 460 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 461 goto err_label; \ 462 ptr--; \ 463 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 464 goto err_label; \ 465 } while (0) 466 467 #define pushl(base, ptr, val, err_label) \ 468 do { \ 469 __u32 __val = val; \ 470 ptr--; \ 471 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 472 goto err_label; \ 473 ptr--; \ 474 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 475 goto err_label; \ 476 ptr--; \ 477 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 478 goto err_label; \ 479 ptr--; \ 480 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 481 goto err_label; \ 482 } while (0) 483 484 #define popb(base, ptr, err_label) \ 485 ({ \ 486 __u8 __res; \ 487 if (get_user(__res, base + ptr) < 0) \ 488 goto err_label; \ 489 ptr++; \ 490 __res; \ 491 }) 492 493 #define popw(base, ptr, err_label) \ 494 ({ \ 495 __u16 __res; \ 496 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 497 goto err_label; \ 498 ptr++; \ 499 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 500 goto err_label; \ 501 ptr++; \ 502 __res; \ 503 }) 504 505 #define popl(base, ptr, err_label) \ 506 ({ \ 507 __u32 __res; \ 508 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 509 goto err_label; \ 510 ptr++; \ 511 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 512 goto err_label; \ 513 ptr++; \ 514 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 515 goto err_label; \ 516 ptr++; \ 517 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 518 goto err_label; \ 519 ptr++; \ 520 __res; \ 521 }) 522 523 /* There are so many possible reasons for this function to return 524 * VM86_INTx, so adding another doesn't bother me. We can expect 525 * userspace programs to be able to handle it. (Getting a problem 526 * in userspace is always better than an Oops anyway.) [KD] 527 */ 528 static void do_int(struct kernel_vm86_regs *regs, int i, 529 unsigned char __user *ssp, unsigned short sp) 530 { 531 unsigned long __user *intr_ptr; 532 unsigned long segoffs; 533 struct vm86 *vm86 = current->thread.vm86; 534 535 if (regs->pt.cs == BIOSSEG) 536 goto cannot_handle; 537 if (is_revectored(i, &vm86->int_revectored)) 538 goto cannot_handle; 539 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 540 goto cannot_handle; 541 intr_ptr = (unsigned long __user *) (i << 2); 542 if (get_user(segoffs, intr_ptr)) 543 goto cannot_handle; 544 if ((segoffs >> 16) == BIOSSEG) 545 goto cannot_handle; 546 pushw(ssp, sp, get_vflags(regs), cannot_handle); 547 pushw(ssp, sp, regs->pt.cs, cannot_handle); 548 pushw(ssp, sp, IP(regs), cannot_handle); 549 regs->pt.cs = segoffs >> 16; 550 SP(regs) -= 6; 551 IP(regs) = segoffs & 0xffff; 552 clear_TF(regs); 553 clear_IF(regs); 554 clear_AC(regs); 555 return; 556 557 cannot_handle: 558 save_v86_state(regs, VM86_INTx + (i << 8)); 559 } 560 561 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 562 { 563 struct vm86 *vm86 = current->thread.vm86; 564 565 if (vm86->vm86plus.is_vm86pus) { 566 if ((trapno == 3) || (trapno == 1)) { 567 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 568 return 0; 569 } 570 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 571 return 0; 572 } 573 if (trapno != 1) 574 return 1; /* we let this handle by the calling routine */ 575 current->thread.trap_nr = trapno; 576 current->thread.error_code = error_code; 577 force_sig(SIGTRAP, current); 578 return 0; 579 } 580 581 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 582 { 583 unsigned char opcode; 584 unsigned char __user *csp; 585 unsigned char __user *ssp; 586 unsigned short ip, sp, orig_flags; 587 int data32, pref_done; 588 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 589 590 #define CHECK_IF_IN_TRAP \ 591 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 592 newflags |= X86_EFLAGS_TF 593 594 orig_flags = *(unsigned short *)®s->pt.flags; 595 596 csp = (unsigned char __user *) (regs->pt.cs << 4); 597 ssp = (unsigned char __user *) (regs->pt.ss << 4); 598 sp = SP(regs); 599 ip = IP(regs); 600 601 data32 = 0; 602 pref_done = 0; 603 do { 604 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 605 case 0x66: /* 32-bit data */ data32 = 1; break; 606 case 0x67: /* 32-bit address */ break; 607 case 0x2e: /* CS */ break; 608 case 0x3e: /* DS */ break; 609 case 0x26: /* ES */ break; 610 case 0x36: /* SS */ break; 611 case 0x65: /* GS */ break; 612 case 0x64: /* FS */ break; 613 case 0xf2: /* repnz */ break; 614 case 0xf3: /* rep */ break; 615 default: pref_done = 1; 616 } 617 } while (!pref_done); 618 619 switch (opcode) { 620 621 /* pushf */ 622 case 0x9c: 623 if (data32) { 624 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 625 SP(regs) -= 4; 626 } else { 627 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 628 SP(regs) -= 2; 629 } 630 IP(regs) = ip; 631 goto vm86_fault_return; 632 633 /* popf */ 634 case 0x9d: 635 { 636 unsigned long newflags; 637 if (data32) { 638 newflags = popl(ssp, sp, simulate_sigsegv); 639 SP(regs) += 4; 640 } else { 641 newflags = popw(ssp, sp, simulate_sigsegv); 642 SP(regs) += 2; 643 } 644 IP(regs) = ip; 645 CHECK_IF_IN_TRAP; 646 if (data32) 647 set_vflags_long(newflags, regs); 648 else 649 set_vflags_short(newflags, regs); 650 651 goto check_vip; 652 } 653 654 /* int xx */ 655 case 0xcd: { 656 int intno = popb(csp, ip, simulate_sigsegv); 657 IP(regs) = ip; 658 if (vmpi->vm86dbg_active) { 659 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 660 save_v86_state(regs, VM86_INTx + (intno << 8)); 661 return; 662 } 663 } 664 do_int(regs, intno, ssp, sp); 665 return; 666 } 667 668 /* iret */ 669 case 0xcf: 670 { 671 unsigned long newip; 672 unsigned long newcs; 673 unsigned long newflags; 674 if (data32) { 675 newip = popl(ssp, sp, simulate_sigsegv); 676 newcs = popl(ssp, sp, simulate_sigsegv); 677 newflags = popl(ssp, sp, simulate_sigsegv); 678 SP(regs) += 12; 679 } else { 680 newip = popw(ssp, sp, simulate_sigsegv); 681 newcs = popw(ssp, sp, simulate_sigsegv); 682 newflags = popw(ssp, sp, simulate_sigsegv); 683 SP(regs) += 6; 684 } 685 IP(regs) = newip; 686 regs->pt.cs = newcs; 687 CHECK_IF_IN_TRAP; 688 if (data32) { 689 set_vflags_long(newflags, regs); 690 } else { 691 set_vflags_short(newflags, regs); 692 } 693 goto check_vip; 694 } 695 696 /* cli */ 697 case 0xfa: 698 IP(regs) = ip; 699 clear_IF(regs); 700 goto vm86_fault_return; 701 702 /* sti */ 703 /* 704 * Damn. This is incorrect: the 'sti' instruction should actually 705 * enable interrupts after the /next/ instruction. Not good. 706 * 707 * Probably needs some horsing around with the TF flag. Aiee.. 708 */ 709 case 0xfb: 710 IP(regs) = ip; 711 set_IF(regs); 712 goto check_vip; 713 714 default: 715 save_v86_state(regs, VM86_UNKNOWN); 716 } 717 718 return; 719 720 check_vip: 721 if (VEFLAGS & X86_EFLAGS_VIP) { 722 save_v86_state(regs, VM86_STI); 723 return; 724 } 725 726 vm86_fault_return: 727 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 728 save_v86_state(regs, VM86_PICRETURN); 729 return; 730 } 731 if (orig_flags & X86_EFLAGS_TF) 732 handle_vm86_trap(regs, 0, X86_TRAP_DB); 733 return; 734 735 simulate_sigsegv: 736 /* FIXME: After a long discussion with Stas we finally 737 * agreed, that this is wrong. Here we should 738 * really send a SIGSEGV to the user program. 739 * But how do we create the correct context? We 740 * are inside a general protection fault handler 741 * and has just returned from a page fault handler. 742 * The correct context for the signal handler 743 * should be a mixture of the two, but how do we 744 * get the information? [KD] 745 */ 746 save_v86_state(regs, VM86_UNKNOWN); 747 } 748 749 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 750 751 #define VM86_IRQNAME "vm86irq" 752 753 static struct vm86_irqs { 754 struct task_struct *tsk; 755 int sig; 756 } vm86_irqs[16]; 757 758 static DEFINE_SPINLOCK(irqbits_lock); 759 static int irqbits; 760 761 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 762 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 763 | (1 << SIGUNUSED)) 764 765 static irqreturn_t irq_handler(int intno, void *dev_id) 766 { 767 int irq_bit; 768 unsigned long flags; 769 770 spin_lock_irqsave(&irqbits_lock, flags); 771 irq_bit = 1 << intno; 772 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 773 goto out; 774 irqbits |= irq_bit; 775 if (vm86_irqs[intno].sig) 776 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 777 /* 778 * IRQ will be re-enabled when user asks for the irq (whether 779 * polling or as a result of the signal) 780 */ 781 disable_irq_nosync(intno); 782 spin_unlock_irqrestore(&irqbits_lock, flags); 783 return IRQ_HANDLED; 784 785 out: 786 spin_unlock_irqrestore(&irqbits_lock, flags); 787 return IRQ_NONE; 788 } 789 790 static inline void free_vm86_irq(int irqnumber) 791 { 792 unsigned long flags; 793 794 free_irq(irqnumber, NULL); 795 vm86_irqs[irqnumber].tsk = NULL; 796 797 spin_lock_irqsave(&irqbits_lock, flags); 798 irqbits &= ~(1 << irqnumber); 799 spin_unlock_irqrestore(&irqbits_lock, flags); 800 } 801 802 void release_vm86_irqs(struct task_struct *task) 803 { 804 int i; 805 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 806 if (vm86_irqs[i].tsk == task) 807 free_vm86_irq(i); 808 } 809 810 static inline int get_and_reset_irq(int irqnumber) 811 { 812 int bit; 813 unsigned long flags; 814 int ret = 0; 815 816 if (invalid_vm86_irq(irqnumber)) return 0; 817 if (vm86_irqs[irqnumber].tsk != current) return 0; 818 spin_lock_irqsave(&irqbits_lock, flags); 819 bit = irqbits & (1 << irqnumber); 820 irqbits &= ~bit; 821 if (bit) { 822 enable_irq(irqnumber); 823 ret = 1; 824 } 825 826 spin_unlock_irqrestore(&irqbits_lock, flags); 827 return ret; 828 } 829 830 831 static int do_vm86_irq_handling(int subfunction, int irqnumber) 832 { 833 int ret; 834 switch (subfunction) { 835 case VM86_GET_AND_RESET_IRQ: { 836 return get_and_reset_irq(irqnumber); 837 } 838 case VM86_GET_IRQ_BITS: { 839 return irqbits; 840 } 841 case VM86_REQUEST_IRQ: { 842 int sig = irqnumber >> 8; 843 int irq = irqnumber & 255; 844 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 845 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 846 if (invalid_vm86_irq(irq)) return -EPERM; 847 if (vm86_irqs[irq].tsk) return -EPERM; 848 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 849 if (ret) return ret; 850 vm86_irqs[irq].sig = sig; 851 vm86_irqs[irq].tsk = current; 852 return irq; 853 } 854 case VM86_FREE_IRQ: { 855 if (invalid_vm86_irq(irqnumber)) return -EPERM; 856 if (!vm86_irqs[irqnumber].tsk) return 0; 857 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 858 free_vm86_irq(irqnumber); 859 return 0; 860 } 861 } 862 return -EINVAL; 863 } 864 865