1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1994 Linus Torvalds 4 * 5 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86 6 * stack - Manfred Spraul <manfred@colorfullife.com> 7 * 8 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle 9 * them correctly. Now the emulation will be in a 10 * consistent state after stackfaults - Kasper Dupont 11 * <kasperd@daimi.au.dk> 12 * 13 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont 14 * <kasperd@daimi.au.dk> 15 * 16 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault 17 * caused by Kasper Dupont's changes - Stas Sergeev 18 * 19 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes. 20 * Kasper Dupont <kasperd@daimi.au.dk> 21 * 22 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault. 23 * Kasper Dupont <kasperd@daimi.au.dk> 24 * 25 * 9 apr 2002 - Changed stack access macros to jump to a label 26 * instead of returning to userspace. This simplifies 27 * do_int, and is needed by handle_vm6_fault. Kasper 28 * Dupont <kasperd@daimi.au.dk> 29 * 30 */ 31 32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 33 34 #include <linux/capability.h> 35 #include <linux/errno.h> 36 #include <linux/interrupt.h> 37 #include <linux/syscalls.h> 38 #include <linux/sched.h> 39 #include <linux/sched/task_stack.h> 40 #include <linux/kernel.h> 41 #include <linux/signal.h> 42 #include <linux/string.h> 43 #include <linux/mm.h> 44 #include <linux/smp.h> 45 #include <linux/highmem.h> 46 #include <linux/ptrace.h> 47 #include <linux/audit.h> 48 #include <linux/stddef.h> 49 #include <linux/slab.h> 50 #include <linux/security.h> 51 52 #include <linux/uaccess.h> 53 #include <asm/io.h> 54 #include <asm/tlbflush.h> 55 #include <asm/irq.h> 56 #include <asm/traps.h> 57 #include <asm/vm86.h> 58 59 /* 60 * Known problems: 61 * 62 * Interrupt handling is not guaranteed: 63 * - a real x86 will disable all interrupts for one instruction 64 * after a "mov ss,xx" to make stack handling atomic even without 65 * the 'lss' instruction. We can't guarantee this in v86 mode, 66 * as the next instruction might result in a page fault or similar. 67 * - a real x86 will have interrupts disabled for one instruction 68 * past the 'sti' that enables them. We don't bother with all the 69 * details yet. 70 * 71 * Let's hope these problems do not actually matter for anything. 72 */ 73 74 75 /* 76 * 8- and 16-bit register defines.. 77 */ 78 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 79 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 80 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 81 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 82 83 /* 84 * virtual flags (16 and 32-bit versions) 85 */ 86 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) 87 #define VEFLAGS (current->thread.vm86->veflags) 88 89 #define set_flags(X, new, mask) \ 90 ((X) = ((X) & ~(mask)) | ((new) & (mask))) 91 92 #define SAFE_MASK (0xDD5) 93 #define RETURN_MASK (0xDFF) 94 95 void save_v86_state(struct kernel_vm86_regs *regs, int retval) 96 { 97 struct tss_struct *tss; 98 struct task_struct *tsk = current; 99 struct vm86plus_struct __user *user; 100 struct vm86 *vm86 = current->thread.vm86; 101 long err = 0; 102 103 /* 104 * This gets called from entry.S with interrupts disabled, but 105 * from process context. Enable interrupts here, before trying 106 * to access user space. 107 */ 108 local_irq_enable(); 109 110 if (!vm86 || !vm86->user_vm86) { 111 pr_alert("no user_vm86: BAD\n"); 112 do_exit(SIGSEGV); 113 } 114 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask); 115 user = vm86->user_vm86; 116 117 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ? 118 sizeof(struct vm86plus_struct) : 119 sizeof(struct vm86_struct))) { 120 pr_alert("could not access userspace vm86 info\n"); 121 do_exit(SIGSEGV); 122 } 123 124 put_user_try { 125 put_user_ex(regs->pt.bx, &user->regs.ebx); 126 put_user_ex(regs->pt.cx, &user->regs.ecx); 127 put_user_ex(regs->pt.dx, &user->regs.edx); 128 put_user_ex(regs->pt.si, &user->regs.esi); 129 put_user_ex(regs->pt.di, &user->regs.edi); 130 put_user_ex(regs->pt.bp, &user->regs.ebp); 131 put_user_ex(regs->pt.ax, &user->regs.eax); 132 put_user_ex(regs->pt.ip, &user->regs.eip); 133 put_user_ex(regs->pt.cs, &user->regs.cs); 134 put_user_ex(regs->pt.flags, &user->regs.eflags); 135 put_user_ex(regs->pt.sp, &user->regs.esp); 136 put_user_ex(regs->pt.ss, &user->regs.ss); 137 put_user_ex(regs->es, &user->regs.es); 138 put_user_ex(regs->ds, &user->regs.ds); 139 put_user_ex(regs->fs, &user->regs.fs); 140 put_user_ex(regs->gs, &user->regs.gs); 141 142 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap); 143 } put_user_catch(err); 144 if (err) { 145 pr_alert("could not access userspace vm86 info\n"); 146 do_exit(SIGSEGV); 147 } 148 149 tss = &per_cpu(cpu_tss, get_cpu()); 150 tsk->thread.sp0 = vm86->saved_sp0; 151 tsk->thread.sysenter_cs = __KERNEL_CS; 152 load_sp0(tss, &tsk->thread); 153 vm86->saved_sp0 = 0; 154 put_cpu(); 155 156 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); 157 158 lazy_load_gs(vm86->regs32.gs); 159 160 regs->pt.ax = retval; 161 } 162 163 static void mark_screen_rdonly(struct mm_struct *mm) 164 { 165 struct vm_area_struct *vma; 166 spinlock_t *ptl; 167 pgd_t *pgd; 168 p4d_t *p4d; 169 pud_t *pud; 170 pmd_t *pmd; 171 pte_t *pte; 172 int i; 173 174 down_write(&mm->mmap_sem); 175 pgd = pgd_offset(mm, 0xA0000); 176 if (pgd_none_or_clear_bad(pgd)) 177 goto out; 178 p4d = p4d_offset(pgd, 0xA0000); 179 if (p4d_none_or_clear_bad(p4d)) 180 goto out; 181 pud = pud_offset(p4d, 0xA0000); 182 if (pud_none_or_clear_bad(pud)) 183 goto out; 184 pmd = pmd_offset(pud, 0xA0000); 185 186 if (pmd_trans_huge(*pmd)) { 187 vma = find_vma(mm, 0xA0000); 188 split_huge_pmd(vma, pmd, 0xA0000); 189 } 190 if (pmd_none_or_clear_bad(pmd)) 191 goto out; 192 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 193 for (i = 0; i < 32; i++) { 194 if (pte_present(*pte)) 195 set_pte(pte, pte_wrprotect(*pte)); 196 pte++; 197 } 198 pte_unmap_unlock(pte, ptl); 199 out: 200 up_write(&mm->mmap_sem); 201 flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL); 202 } 203 204 205 206 static int do_vm86_irq_handling(int subfunction, int irqnumber); 207 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); 208 209 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) 210 { 211 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false); 212 } 213 214 215 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 216 { 217 switch (cmd) { 218 case VM86_REQUEST_IRQ: 219 case VM86_FREE_IRQ: 220 case VM86_GET_IRQ_BITS: 221 case VM86_GET_AND_RESET_IRQ: 222 return do_vm86_irq_handling(cmd, (int)arg); 223 case VM86_PLUS_INSTALL_CHECK: 224 /* 225 * NOTE: on old vm86 stuff this will return the error 226 * from access_ok(), because the subfunction is 227 * interpreted as (invalid) address to vm86_struct. 228 * So the installation check works. 229 */ 230 return 0; 231 } 232 233 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 234 return do_sys_vm86((struct vm86plus_struct __user *) arg, true); 235 } 236 237 238 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) 239 { 240 struct tss_struct *tss; 241 struct task_struct *tsk = current; 242 struct vm86 *vm86 = tsk->thread.vm86; 243 struct kernel_vm86_regs vm86regs; 244 struct pt_regs *regs = current_pt_regs(); 245 unsigned long err = 0; 246 247 err = security_mmap_addr(0); 248 if (err) { 249 /* 250 * vm86 cannot virtualize the address space, so vm86 users 251 * need to manage the low 1MB themselves using mmap. Given 252 * that BIOS places important data in the first page, vm86 253 * is essentially useless if mmap_min_addr != 0. DOSEMU, 254 * for example, won't even bother trying to use vm86 if it 255 * can't map a page at virtual address 0. 256 * 257 * To reduce the available kernel attack surface, simply 258 * disallow vm86(old) for users who cannot mmap at va 0. 259 * 260 * The implementation of security_mmap_addr will allow 261 * suitably privileged users to map va 0 even if 262 * vm.mmap_min_addr is set above 0, and we want this 263 * behavior for vm86 as well, as it ensures that legacy 264 * tools like vbetool will not fail just because of 265 * vm.mmap_min_addr. 266 */ 267 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", 268 current->comm, task_pid_nr(current), 269 from_kuid_munged(&init_user_ns, current_uid())); 270 return -EPERM; 271 } 272 273 if (!vm86) { 274 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL))) 275 return -ENOMEM; 276 tsk->thread.vm86 = vm86; 277 } 278 if (vm86->saved_sp0) 279 return -EPERM; 280 281 if (!access_ok(VERIFY_READ, user_vm86, plus ? 282 sizeof(struct vm86_struct) : 283 sizeof(struct vm86plus_struct))) 284 return -EFAULT; 285 286 memset(&vm86regs, 0, sizeof(vm86regs)); 287 get_user_try { 288 unsigned short seg; 289 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx); 290 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx); 291 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx); 292 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi); 293 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi); 294 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp); 295 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax); 296 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip); 297 get_user_ex(seg, &user_vm86->regs.cs); 298 vm86regs.pt.cs = seg; 299 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags); 300 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp); 301 get_user_ex(seg, &user_vm86->regs.ss); 302 vm86regs.pt.ss = seg; 303 get_user_ex(vm86regs.es, &user_vm86->regs.es); 304 get_user_ex(vm86regs.ds, &user_vm86->regs.ds); 305 get_user_ex(vm86regs.fs, &user_vm86->regs.fs); 306 get_user_ex(vm86regs.gs, &user_vm86->regs.gs); 307 308 get_user_ex(vm86->flags, &user_vm86->flags); 309 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap); 310 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type); 311 } get_user_catch(err); 312 if (err) 313 return err; 314 315 if (copy_from_user(&vm86->int_revectored, 316 &user_vm86->int_revectored, 317 sizeof(struct revectored_struct))) 318 return -EFAULT; 319 if (copy_from_user(&vm86->int21_revectored, 320 &user_vm86->int21_revectored, 321 sizeof(struct revectored_struct))) 322 return -EFAULT; 323 if (plus) { 324 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus, 325 sizeof(struct vm86plus_info_struct))) 326 return -EFAULT; 327 vm86->vm86plus.is_vm86pus = 1; 328 } else 329 memset(&vm86->vm86plus, 0, 330 sizeof(struct vm86plus_info_struct)); 331 332 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs)); 333 vm86->user_vm86 = user_vm86; 334 335 /* 336 * The flags register is also special: we cannot trust that the user 337 * has set it up safely, so this makes sure interrupt etc flags are 338 * inherited from protected mode. 339 */ 340 VEFLAGS = vm86regs.pt.flags; 341 vm86regs.pt.flags &= SAFE_MASK; 342 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK; 343 vm86regs.pt.flags |= X86_VM_MASK; 344 345 vm86regs.pt.orig_ax = regs->orig_ax; 346 347 switch (vm86->cpu_type) { 348 case CPU_286: 349 vm86->veflags_mask = 0; 350 break; 351 case CPU_386: 352 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 353 break; 354 case CPU_486: 355 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 356 break; 357 default: 358 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 359 break; 360 } 361 362 /* 363 * Save old state 364 */ 365 vm86->saved_sp0 = tsk->thread.sp0; 366 lazy_save_gs(vm86->regs32.gs); 367 368 tss = &per_cpu(cpu_tss, get_cpu()); 369 /* make room for real-mode segments */ 370 tsk->thread.sp0 += 16; 371 372 if (static_cpu_has(X86_FEATURE_SEP)) 373 tsk->thread.sysenter_cs = 0; 374 375 load_sp0(tss, &tsk->thread); 376 put_cpu(); 377 378 if (vm86->flags & VM86_SCREEN_BITMAP) 379 mark_screen_rdonly(tsk->mm); 380 381 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); 382 force_iret(); 383 return regs->ax; 384 } 385 386 static inline void set_IF(struct kernel_vm86_regs *regs) 387 { 388 VEFLAGS |= X86_EFLAGS_VIF; 389 } 390 391 static inline void clear_IF(struct kernel_vm86_regs *regs) 392 { 393 VEFLAGS &= ~X86_EFLAGS_VIF; 394 } 395 396 static inline void clear_TF(struct kernel_vm86_regs *regs) 397 { 398 regs->pt.flags &= ~X86_EFLAGS_TF; 399 } 400 401 static inline void clear_AC(struct kernel_vm86_regs *regs) 402 { 403 regs->pt.flags &= ~X86_EFLAGS_AC; 404 } 405 406 /* 407 * It is correct to call set_IF(regs) from the set_vflags_* 408 * functions. However someone forgot to call clear_IF(regs) 409 * in the opposite case. 410 * After the command sequence CLI PUSHF STI POPF you should 411 * end up with interrupts disabled, but you ended up with 412 * interrupts enabled. 413 * ( I was testing my own changes, but the only bug I 414 * could find was in a function I had not changed. ) 415 * [KD] 416 */ 417 418 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 419 { 420 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 421 set_flags(regs->pt.flags, flags, SAFE_MASK); 422 if (flags & X86_EFLAGS_IF) 423 set_IF(regs); 424 else 425 clear_IF(regs); 426 } 427 428 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 429 { 430 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 431 set_flags(regs->pt.flags, flags, SAFE_MASK); 432 if (flags & X86_EFLAGS_IF) 433 set_IF(regs); 434 else 435 clear_IF(regs); 436 } 437 438 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 439 { 440 unsigned long flags = regs->pt.flags & RETURN_MASK; 441 442 if (VEFLAGS & X86_EFLAGS_VIF) 443 flags |= X86_EFLAGS_IF; 444 flags |= X86_EFLAGS_IOPL; 445 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 446 } 447 448 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 449 { 450 return test_bit(nr, bitmap->__map); 451 } 452 453 #define val_byte(val, n) (((__u8 *)&val)[n]) 454 455 #define pushb(base, ptr, val, err_label) \ 456 do { \ 457 __u8 __val = val; \ 458 ptr--; \ 459 if (put_user(__val, base + ptr) < 0) \ 460 goto err_label; \ 461 } while (0) 462 463 #define pushw(base, ptr, val, err_label) \ 464 do { \ 465 __u16 __val = val; \ 466 ptr--; \ 467 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 468 goto err_label; \ 469 ptr--; \ 470 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 471 goto err_label; \ 472 } while (0) 473 474 #define pushl(base, ptr, val, err_label) \ 475 do { \ 476 __u32 __val = val; \ 477 ptr--; \ 478 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 479 goto err_label; \ 480 ptr--; \ 481 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 482 goto err_label; \ 483 ptr--; \ 484 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 485 goto err_label; \ 486 ptr--; \ 487 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 488 goto err_label; \ 489 } while (0) 490 491 #define popb(base, ptr, err_label) \ 492 ({ \ 493 __u8 __res; \ 494 if (get_user(__res, base + ptr) < 0) \ 495 goto err_label; \ 496 ptr++; \ 497 __res; \ 498 }) 499 500 #define popw(base, ptr, err_label) \ 501 ({ \ 502 __u16 __res; \ 503 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 504 goto err_label; \ 505 ptr++; \ 506 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 507 goto err_label; \ 508 ptr++; \ 509 __res; \ 510 }) 511 512 #define popl(base, ptr, err_label) \ 513 ({ \ 514 __u32 __res; \ 515 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 516 goto err_label; \ 517 ptr++; \ 518 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 519 goto err_label; \ 520 ptr++; \ 521 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 522 goto err_label; \ 523 ptr++; \ 524 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 525 goto err_label; \ 526 ptr++; \ 527 __res; \ 528 }) 529 530 /* There are so many possible reasons for this function to return 531 * VM86_INTx, so adding another doesn't bother me. We can expect 532 * userspace programs to be able to handle it. (Getting a problem 533 * in userspace is always better than an Oops anyway.) [KD] 534 */ 535 static void do_int(struct kernel_vm86_regs *regs, int i, 536 unsigned char __user *ssp, unsigned short sp) 537 { 538 unsigned long __user *intr_ptr; 539 unsigned long segoffs; 540 struct vm86 *vm86 = current->thread.vm86; 541 542 if (regs->pt.cs == BIOSSEG) 543 goto cannot_handle; 544 if (is_revectored(i, &vm86->int_revectored)) 545 goto cannot_handle; 546 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 547 goto cannot_handle; 548 intr_ptr = (unsigned long __user *) (i << 2); 549 if (get_user(segoffs, intr_ptr)) 550 goto cannot_handle; 551 if ((segoffs >> 16) == BIOSSEG) 552 goto cannot_handle; 553 pushw(ssp, sp, get_vflags(regs), cannot_handle); 554 pushw(ssp, sp, regs->pt.cs, cannot_handle); 555 pushw(ssp, sp, IP(regs), cannot_handle); 556 regs->pt.cs = segoffs >> 16; 557 SP(regs) -= 6; 558 IP(regs) = segoffs & 0xffff; 559 clear_TF(regs); 560 clear_IF(regs); 561 clear_AC(regs); 562 return; 563 564 cannot_handle: 565 save_v86_state(regs, VM86_INTx + (i << 8)); 566 } 567 568 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 569 { 570 struct vm86 *vm86 = current->thread.vm86; 571 572 if (vm86->vm86plus.is_vm86pus) { 573 if ((trapno == 3) || (trapno == 1)) { 574 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 575 return 0; 576 } 577 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 578 return 0; 579 } 580 if (trapno != 1) 581 return 1; /* we let this handle by the calling routine */ 582 current->thread.trap_nr = trapno; 583 current->thread.error_code = error_code; 584 force_sig(SIGTRAP, current); 585 return 0; 586 } 587 588 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 589 { 590 unsigned char opcode; 591 unsigned char __user *csp; 592 unsigned char __user *ssp; 593 unsigned short ip, sp, orig_flags; 594 int data32, pref_done; 595 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 596 597 #define CHECK_IF_IN_TRAP \ 598 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 599 newflags |= X86_EFLAGS_TF 600 601 orig_flags = *(unsigned short *)®s->pt.flags; 602 603 csp = (unsigned char __user *) (regs->pt.cs << 4); 604 ssp = (unsigned char __user *) (regs->pt.ss << 4); 605 sp = SP(regs); 606 ip = IP(regs); 607 608 data32 = 0; 609 pref_done = 0; 610 do { 611 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 612 case 0x66: /* 32-bit data */ data32 = 1; break; 613 case 0x67: /* 32-bit address */ break; 614 case 0x2e: /* CS */ break; 615 case 0x3e: /* DS */ break; 616 case 0x26: /* ES */ break; 617 case 0x36: /* SS */ break; 618 case 0x65: /* GS */ break; 619 case 0x64: /* FS */ break; 620 case 0xf2: /* repnz */ break; 621 case 0xf3: /* rep */ break; 622 default: pref_done = 1; 623 } 624 } while (!pref_done); 625 626 switch (opcode) { 627 628 /* pushf */ 629 case 0x9c: 630 if (data32) { 631 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 632 SP(regs) -= 4; 633 } else { 634 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 635 SP(regs) -= 2; 636 } 637 IP(regs) = ip; 638 goto vm86_fault_return; 639 640 /* popf */ 641 case 0x9d: 642 { 643 unsigned long newflags; 644 if (data32) { 645 newflags = popl(ssp, sp, simulate_sigsegv); 646 SP(regs) += 4; 647 } else { 648 newflags = popw(ssp, sp, simulate_sigsegv); 649 SP(regs) += 2; 650 } 651 IP(regs) = ip; 652 CHECK_IF_IN_TRAP; 653 if (data32) 654 set_vflags_long(newflags, regs); 655 else 656 set_vflags_short(newflags, regs); 657 658 goto check_vip; 659 } 660 661 /* int xx */ 662 case 0xcd: { 663 int intno = popb(csp, ip, simulate_sigsegv); 664 IP(regs) = ip; 665 if (vmpi->vm86dbg_active) { 666 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 667 save_v86_state(regs, VM86_INTx + (intno << 8)); 668 return; 669 } 670 } 671 do_int(regs, intno, ssp, sp); 672 return; 673 } 674 675 /* iret */ 676 case 0xcf: 677 { 678 unsigned long newip; 679 unsigned long newcs; 680 unsigned long newflags; 681 if (data32) { 682 newip = popl(ssp, sp, simulate_sigsegv); 683 newcs = popl(ssp, sp, simulate_sigsegv); 684 newflags = popl(ssp, sp, simulate_sigsegv); 685 SP(regs) += 12; 686 } else { 687 newip = popw(ssp, sp, simulate_sigsegv); 688 newcs = popw(ssp, sp, simulate_sigsegv); 689 newflags = popw(ssp, sp, simulate_sigsegv); 690 SP(regs) += 6; 691 } 692 IP(regs) = newip; 693 regs->pt.cs = newcs; 694 CHECK_IF_IN_TRAP; 695 if (data32) { 696 set_vflags_long(newflags, regs); 697 } else { 698 set_vflags_short(newflags, regs); 699 } 700 goto check_vip; 701 } 702 703 /* cli */ 704 case 0xfa: 705 IP(regs) = ip; 706 clear_IF(regs); 707 goto vm86_fault_return; 708 709 /* sti */ 710 /* 711 * Damn. This is incorrect: the 'sti' instruction should actually 712 * enable interrupts after the /next/ instruction. Not good. 713 * 714 * Probably needs some horsing around with the TF flag. Aiee.. 715 */ 716 case 0xfb: 717 IP(regs) = ip; 718 set_IF(regs); 719 goto check_vip; 720 721 default: 722 save_v86_state(regs, VM86_UNKNOWN); 723 } 724 725 return; 726 727 check_vip: 728 if (VEFLAGS & X86_EFLAGS_VIP) { 729 save_v86_state(regs, VM86_STI); 730 return; 731 } 732 733 vm86_fault_return: 734 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 735 save_v86_state(regs, VM86_PICRETURN); 736 return; 737 } 738 if (orig_flags & X86_EFLAGS_TF) 739 handle_vm86_trap(regs, 0, X86_TRAP_DB); 740 return; 741 742 simulate_sigsegv: 743 /* FIXME: After a long discussion with Stas we finally 744 * agreed, that this is wrong. Here we should 745 * really send a SIGSEGV to the user program. 746 * But how do we create the correct context? We 747 * are inside a general protection fault handler 748 * and has just returned from a page fault handler. 749 * The correct context for the signal handler 750 * should be a mixture of the two, but how do we 751 * get the information? [KD] 752 */ 753 save_v86_state(regs, VM86_UNKNOWN); 754 } 755 756 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 757 758 #define VM86_IRQNAME "vm86irq" 759 760 static struct vm86_irqs { 761 struct task_struct *tsk; 762 int sig; 763 } vm86_irqs[16]; 764 765 static DEFINE_SPINLOCK(irqbits_lock); 766 static int irqbits; 767 768 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 769 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 770 | (1 << SIGUNUSED)) 771 772 static irqreturn_t irq_handler(int intno, void *dev_id) 773 { 774 int irq_bit; 775 unsigned long flags; 776 777 spin_lock_irqsave(&irqbits_lock, flags); 778 irq_bit = 1 << intno; 779 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 780 goto out; 781 irqbits |= irq_bit; 782 if (vm86_irqs[intno].sig) 783 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 784 /* 785 * IRQ will be re-enabled when user asks for the irq (whether 786 * polling or as a result of the signal) 787 */ 788 disable_irq_nosync(intno); 789 spin_unlock_irqrestore(&irqbits_lock, flags); 790 return IRQ_HANDLED; 791 792 out: 793 spin_unlock_irqrestore(&irqbits_lock, flags); 794 return IRQ_NONE; 795 } 796 797 static inline void free_vm86_irq(int irqnumber) 798 { 799 unsigned long flags; 800 801 free_irq(irqnumber, NULL); 802 vm86_irqs[irqnumber].tsk = NULL; 803 804 spin_lock_irqsave(&irqbits_lock, flags); 805 irqbits &= ~(1 << irqnumber); 806 spin_unlock_irqrestore(&irqbits_lock, flags); 807 } 808 809 void release_vm86_irqs(struct task_struct *task) 810 { 811 int i; 812 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 813 if (vm86_irqs[i].tsk == task) 814 free_vm86_irq(i); 815 } 816 817 static inline int get_and_reset_irq(int irqnumber) 818 { 819 int bit; 820 unsigned long flags; 821 int ret = 0; 822 823 if (invalid_vm86_irq(irqnumber)) return 0; 824 if (vm86_irqs[irqnumber].tsk != current) return 0; 825 spin_lock_irqsave(&irqbits_lock, flags); 826 bit = irqbits & (1 << irqnumber); 827 irqbits &= ~bit; 828 if (bit) { 829 enable_irq(irqnumber); 830 ret = 1; 831 } 832 833 spin_unlock_irqrestore(&irqbits_lock, flags); 834 return ret; 835 } 836 837 838 static int do_vm86_irq_handling(int subfunction, int irqnumber) 839 { 840 int ret; 841 switch (subfunction) { 842 case VM86_GET_AND_RESET_IRQ: { 843 return get_and_reset_irq(irqnumber); 844 } 845 case VM86_GET_IRQ_BITS: { 846 return irqbits; 847 } 848 case VM86_REQUEST_IRQ: { 849 int sig = irqnumber >> 8; 850 int irq = irqnumber & 255; 851 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 852 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 853 if (invalid_vm86_irq(irq)) return -EPERM; 854 if (vm86_irqs[irq].tsk) return -EPERM; 855 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 856 if (ret) return ret; 857 vm86_irqs[irq].sig = sig; 858 vm86_irqs[irq].tsk = current; 859 return irq; 860 } 861 case VM86_FREE_IRQ: { 862 if (invalid_vm86_irq(irqnumber)) return -EPERM; 863 if (!vm86_irqs[irqnumber].tsk) return 0; 864 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 865 free_vm86_irq(irqnumber); 866 return 0; 867 } 868 } 869 return -EINVAL; 870 } 871 872