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 #include <asm/switch_to.h> 59 60 /* 61 * Known problems: 62 * 63 * Interrupt handling is not guaranteed: 64 * - a real x86 will disable all interrupts for one instruction 65 * after a "mov ss,xx" to make stack handling atomic even without 66 * the 'lss' instruction. We can't guarantee this in v86 mode, 67 * as the next instruction might result in a page fault or similar. 68 * - a real x86 will have interrupts disabled for one instruction 69 * past the 'sti' that enables them. We don't bother with all the 70 * details yet. 71 * 72 * Let's hope these problems do not actually matter for anything. 73 */ 74 75 76 /* 77 * 8- and 16-bit register defines.. 78 */ 79 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 80 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 81 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 82 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 83 84 /* 85 * virtual flags (16 and 32-bit versions) 86 */ 87 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) 88 #define VEFLAGS (current->thread.vm86->veflags) 89 90 #define set_flags(X, new, mask) \ 91 ((X) = ((X) & ~(mask)) | ((new) & (mask))) 92 93 #define SAFE_MASK (0xDD5) 94 #define RETURN_MASK (0xDFF) 95 96 void save_v86_state(struct kernel_vm86_regs *regs, int retval) 97 { 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 preempt_disable(); 150 tsk->thread.sp0 = vm86->saved_sp0; 151 tsk->thread.sysenter_cs = __KERNEL_CS; 152 update_task_stack(tsk); 153 refresh_sysenter_cs(&tsk->thread); 154 vm86->saved_sp0 = 0; 155 preempt_enable(); 156 157 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); 158 159 lazy_load_gs(vm86->regs32.gs); 160 161 regs->pt.ax = retval; 162 } 163 164 static void mark_screen_rdonly(struct mm_struct *mm) 165 { 166 struct vm_area_struct *vma; 167 spinlock_t *ptl; 168 pgd_t *pgd; 169 p4d_t *p4d; 170 pud_t *pud; 171 pmd_t *pmd; 172 pte_t *pte; 173 int i; 174 175 down_write(&mm->mmap_sem); 176 pgd = pgd_offset(mm, 0xA0000); 177 if (pgd_none_or_clear_bad(pgd)) 178 goto out; 179 p4d = p4d_offset(pgd, 0xA0000); 180 if (p4d_none_or_clear_bad(p4d)) 181 goto out; 182 pud = pud_offset(p4d, 0xA0000); 183 if (pud_none_or_clear_bad(pud)) 184 goto out; 185 pmd = pmd_offset(pud, 0xA0000); 186 187 if (pmd_trans_huge(*pmd)) { 188 vma = find_vma(mm, 0xA0000); 189 split_huge_pmd(vma, pmd, 0xA0000); 190 } 191 if (pmd_none_or_clear_bad(pmd)) 192 goto out; 193 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 194 for (i = 0; i < 32; i++) { 195 if (pte_present(*pte)) 196 set_pte(pte, pte_wrprotect(*pte)); 197 pte++; 198 } 199 pte_unmap_unlock(pte, ptl); 200 out: 201 up_write(&mm->mmap_sem); 202 flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL); 203 } 204 205 206 207 static int do_vm86_irq_handling(int subfunction, int irqnumber); 208 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); 209 210 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) 211 { 212 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false); 213 } 214 215 216 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 217 { 218 switch (cmd) { 219 case VM86_REQUEST_IRQ: 220 case VM86_FREE_IRQ: 221 case VM86_GET_IRQ_BITS: 222 case VM86_GET_AND_RESET_IRQ: 223 return do_vm86_irq_handling(cmd, (int)arg); 224 case VM86_PLUS_INSTALL_CHECK: 225 /* 226 * NOTE: on old vm86 stuff this will return the error 227 * from access_ok(), because the subfunction is 228 * interpreted as (invalid) address to vm86_struct. 229 * So the installation check works. 230 */ 231 return 0; 232 } 233 234 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 235 return do_sys_vm86((struct vm86plus_struct __user *) arg, true); 236 } 237 238 239 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) 240 { 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 /* make room for real-mode segments */ 369 preempt_disable(); 370 tsk->thread.sp0 += 16; 371 372 if (static_cpu_has(X86_FEATURE_SEP)) { 373 tsk->thread.sysenter_cs = 0; 374 refresh_sysenter_cs(&tsk->thread); 375 } 376 377 update_task_stack(tsk); 378 preempt_enable(); 379 380 if (vm86->flags & VM86_SCREEN_BITMAP) 381 mark_screen_rdonly(tsk->mm); 382 383 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); 384 force_iret(); 385 return regs->ax; 386 } 387 388 static inline void set_IF(struct kernel_vm86_regs *regs) 389 { 390 VEFLAGS |= X86_EFLAGS_VIF; 391 } 392 393 static inline void clear_IF(struct kernel_vm86_regs *regs) 394 { 395 VEFLAGS &= ~X86_EFLAGS_VIF; 396 } 397 398 static inline void clear_TF(struct kernel_vm86_regs *regs) 399 { 400 regs->pt.flags &= ~X86_EFLAGS_TF; 401 } 402 403 static inline void clear_AC(struct kernel_vm86_regs *regs) 404 { 405 regs->pt.flags &= ~X86_EFLAGS_AC; 406 } 407 408 /* 409 * It is correct to call set_IF(regs) from the set_vflags_* 410 * functions. However someone forgot to call clear_IF(regs) 411 * in the opposite case. 412 * After the command sequence CLI PUSHF STI POPF you should 413 * end up with interrupts disabled, but you ended up with 414 * interrupts enabled. 415 * ( I was testing my own changes, but the only bug I 416 * could find was in a function I had not changed. ) 417 * [KD] 418 */ 419 420 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 421 { 422 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 423 set_flags(regs->pt.flags, flags, SAFE_MASK); 424 if (flags & X86_EFLAGS_IF) 425 set_IF(regs); 426 else 427 clear_IF(regs); 428 } 429 430 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 431 { 432 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 433 set_flags(regs->pt.flags, flags, SAFE_MASK); 434 if (flags & X86_EFLAGS_IF) 435 set_IF(regs); 436 else 437 clear_IF(regs); 438 } 439 440 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 441 { 442 unsigned long flags = regs->pt.flags & RETURN_MASK; 443 444 if (VEFLAGS & X86_EFLAGS_VIF) 445 flags |= X86_EFLAGS_IF; 446 flags |= X86_EFLAGS_IOPL; 447 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 448 } 449 450 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 451 { 452 return test_bit(nr, bitmap->__map); 453 } 454 455 #define val_byte(val, n) (((__u8 *)&val)[n]) 456 457 #define pushb(base, ptr, val, err_label) \ 458 do { \ 459 __u8 __val = val; \ 460 ptr--; \ 461 if (put_user(__val, base + ptr) < 0) \ 462 goto err_label; \ 463 } while (0) 464 465 #define pushw(base, ptr, val, err_label) \ 466 do { \ 467 __u16 __val = val; \ 468 ptr--; \ 469 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 470 goto err_label; \ 471 ptr--; \ 472 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 473 goto err_label; \ 474 } while (0) 475 476 #define pushl(base, ptr, val, err_label) \ 477 do { \ 478 __u32 __val = val; \ 479 ptr--; \ 480 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 481 goto err_label; \ 482 ptr--; \ 483 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 484 goto err_label; \ 485 ptr--; \ 486 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 487 goto err_label; \ 488 ptr--; \ 489 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 490 goto err_label; \ 491 } while (0) 492 493 #define popb(base, ptr, err_label) \ 494 ({ \ 495 __u8 __res; \ 496 if (get_user(__res, base + ptr) < 0) \ 497 goto err_label; \ 498 ptr++; \ 499 __res; \ 500 }) 501 502 #define popw(base, ptr, err_label) \ 503 ({ \ 504 __u16 __res; \ 505 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 506 goto err_label; \ 507 ptr++; \ 508 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 509 goto err_label; \ 510 ptr++; \ 511 __res; \ 512 }) 513 514 #define popl(base, ptr, err_label) \ 515 ({ \ 516 __u32 __res; \ 517 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 518 goto err_label; \ 519 ptr++; \ 520 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 521 goto err_label; \ 522 ptr++; \ 523 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 524 goto err_label; \ 525 ptr++; \ 526 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 527 goto err_label; \ 528 ptr++; \ 529 __res; \ 530 }) 531 532 /* There are so many possible reasons for this function to return 533 * VM86_INTx, so adding another doesn't bother me. We can expect 534 * userspace programs to be able to handle it. (Getting a problem 535 * in userspace is always better than an Oops anyway.) [KD] 536 */ 537 static void do_int(struct kernel_vm86_regs *regs, int i, 538 unsigned char __user *ssp, unsigned short sp) 539 { 540 unsigned long __user *intr_ptr; 541 unsigned long segoffs; 542 struct vm86 *vm86 = current->thread.vm86; 543 544 if (regs->pt.cs == BIOSSEG) 545 goto cannot_handle; 546 if (is_revectored(i, &vm86->int_revectored)) 547 goto cannot_handle; 548 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 549 goto cannot_handle; 550 intr_ptr = (unsigned long __user *) (i << 2); 551 if (get_user(segoffs, intr_ptr)) 552 goto cannot_handle; 553 if ((segoffs >> 16) == BIOSSEG) 554 goto cannot_handle; 555 pushw(ssp, sp, get_vflags(regs), cannot_handle); 556 pushw(ssp, sp, regs->pt.cs, cannot_handle); 557 pushw(ssp, sp, IP(regs), cannot_handle); 558 regs->pt.cs = segoffs >> 16; 559 SP(regs) -= 6; 560 IP(regs) = segoffs & 0xffff; 561 clear_TF(regs); 562 clear_IF(regs); 563 clear_AC(regs); 564 return; 565 566 cannot_handle: 567 save_v86_state(regs, VM86_INTx + (i << 8)); 568 } 569 570 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 571 { 572 struct vm86 *vm86 = current->thread.vm86; 573 574 if (vm86->vm86plus.is_vm86pus) { 575 if ((trapno == 3) || (trapno == 1)) { 576 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 577 return 0; 578 } 579 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 580 return 0; 581 } 582 if (trapno != 1) 583 return 1; /* we let this handle by the calling routine */ 584 current->thread.trap_nr = trapno; 585 current->thread.error_code = error_code; 586 force_sig(SIGTRAP, current); 587 return 0; 588 } 589 590 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 591 { 592 unsigned char opcode; 593 unsigned char __user *csp; 594 unsigned char __user *ssp; 595 unsigned short ip, sp, orig_flags; 596 int data32, pref_done; 597 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 598 599 #define CHECK_IF_IN_TRAP \ 600 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 601 newflags |= X86_EFLAGS_TF 602 603 orig_flags = *(unsigned short *)®s->pt.flags; 604 605 csp = (unsigned char __user *) (regs->pt.cs << 4); 606 ssp = (unsigned char __user *) (regs->pt.ss << 4); 607 sp = SP(regs); 608 ip = IP(regs); 609 610 data32 = 0; 611 pref_done = 0; 612 do { 613 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 614 case 0x66: /* 32-bit data */ data32 = 1; break; 615 case 0x67: /* 32-bit address */ break; 616 case 0x2e: /* CS */ break; 617 case 0x3e: /* DS */ break; 618 case 0x26: /* ES */ break; 619 case 0x36: /* SS */ break; 620 case 0x65: /* GS */ break; 621 case 0x64: /* FS */ break; 622 case 0xf2: /* repnz */ break; 623 case 0xf3: /* rep */ break; 624 default: pref_done = 1; 625 } 626 } while (!pref_done); 627 628 switch (opcode) { 629 630 /* pushf */ 631 case 0x9c: 632 if (data32) { 633 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 634 SP(regs) -= 4; 635 } else { 636 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 637 SP(regs) -= 2; 638 } 639 IP(regs) = ip; 640 goto vm86_fault_return; 641 642 /* popf */ 643 case 0x9d: 644 { 645 unsigned long newflags; 646 if (data32) { 647 newflags = popl(ssp, sp, simulate_sigsegv); 648 SP(regs) += 4; 649 } else { 650 newflags = popw(ssp, sp, simulate_sigsegv); 651 SP(regs) += 2; 652 } 653 IP(regs) = ip; 654 CHECK_IF_IN_TRAP; 655 if (data32) 656 set_vflags_long(newflags, regs); 657 else 658 set_vflags_short(newflags, regs); 659 660 goto check_vip; 661 } 662 663 /* int xx */ 664 case 0xcd: { 665 int intno = popb(csp, ip, simulate_sigsegv); 666 IP(regs) = ip; 667 if (vmpi->vm86dbg_active) { 668 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 669 save_v86_state(regs, VM86_INTx + (intno << 8)); 670 return; 671 } 672 } 673 do_int(regs, intno, ssp, sp); 674 return; 675 } 676 677 /* iret */ 678 case 0xcf: 679 { 680 unsigned long newip; 681 unsigned long newcs; 682 unsigned long newflags; 683 if (data32) { 684 newip = popl(ssp, sp, simulate_sigsegv); 685 newcs = popl(ssp, sp, simulate_sigsegv); 686 newflags = popl(ssp, sp, simulate_sigsegv); 687 SP(regs) += 12; 688 } else { 689 newip = popw(ssp, sp, simulate_sigsegv); 690 newcs = popw(ssp, sp, simulate_sigsegv); 691 newflags = popw(ssp, sp, simulate_sigsegv); 692 SP(regs) += 6; 693 } 694 IP(regs) = newip; 695 regs->pt.cs = newcs; 696 CHECK_IF_IN_TRAP; 697 if (data32) { 698 set_vflags_long(newflags, regs); 699 } else { 700 set_vflags_short(newflags, regs); 701 } 702 goto check_vip; 703 } 704 705 /* cli */ 706 case 0xfa: 707 IP(regs) = ip; 708 clear_IF(regs); 709 goto vm86_fault_return; 710 711 /* sti */ 712 /* 713 * Damn. This is incorrect: the 'sti' instruction should actually 714 * enable interrupts after the /next/ instruction. Not good. 715 * 716 * Probably needs some horsing around with the TF flag. Aiee.. 717 */ 718 case 0xfb: 719 IP(regs) = ip; 720 set_IF(regs); 721 goto check_vip; 722 723 default: 724 save_v86_state(regs, VM86_UNKNOWN); 725 } 726 727 return; 728 729 check_vip: 730 if ((VEFLAGS & (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) == 731 (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) { 732 save_v86_state(regs, VM86_STI); 733 return; 734 } 735 736 vm86_fault_return: 737 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 738 save_v86_state(regs, VM86_PICRETURN); 739 return; 740 } 741 if (orig_flags & X86_EFLAGS_TF) 742 handle_vm86_trap(regs, 0, X86_TRAP_DB); 743 return; 744 745 simulate_sigsegv: 746 /* FIXME: After a long discussion with Stas we finally 747 * agreed, that this is wrong. Here we should 748 * really send a SIGSEGV to the user program. 749 * But how do we create the correct context? We 750 * are inside a general protection fault handler 751 * and has just returned from a page fault handler. 752 * The correct context for the signal handler 753 * should be a mixture of the two, but how do we 754 * get the information? [KD] 755 */ 756 save_v86_state(regs, VM86_UNKNOWN); 757 } 758 759 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 760 761 #define VM86_IRQNAME "vm86irq" 762 763 static struct vm86_irqs { 764 struct task_struct *tsk; 765 int sig; 766 } vm86_irqs[16]; 767 768 static DEFINE_SPINLOCK(irqbits_lock); 769 static int irqbits; 770 771 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 772 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 773 | (1 << SIGUNUSED)) 774 775 static irqreturn_t irq_handler(int intno, void *dev_id) 776 { 777 int irq_bit; 778 unsigned long flags; 779 780 spin_lock_irqsave(&irqbits_lock, flags); 781 irq_bit = 1 << intno; 782 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 783 goto out; 784 irqbits |= irq_bit; 785 if (vm86_irqs[intno].sig) 786 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 787 /* 788 * IRQ will be re-enabled when user asks for the irq (whether 789 * polling or as a result of the signal) 790 */ 791 disable_irq_nosync(intno); 792 spin_unlock_irqrestore(&irqbits_lock, flags); 793 return IRQ_HANDLED; 794 795 out: 796 spin_unlock_irqrestore(&irqbits_lock, flags); 797 return IRQ_NONE; 798 } 799 800 static inline void free_vm86_irq(int irqnumber) 801 { 802 unsigned long flags; 803 804 free_irq(irqnumber, NULL); 805 vm86_irqs[irqnumber].tsk = NULL; 806 807 spin_lock_irqsave(&irqbits_lock, flags); 808 irqbits &= ~(1 << irqnumber); 809 spin_unlock_irqrestore(&irqbits_lock, flags); 810 } 811 812 void release_vm86_irqs(struct task_struct *task) 813 { 814 int i; 815 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 816 if (vm86_irqs[i].tsk == task) 817 free_vm86_irq(i); 818 } 819 820 static inline int get_and_reset_irq(int irqnumber) 821 { 822 int bit; 823 unsigned long flags; 824 int ret = 0; 825 826 if (invalid_vm86_irq(irqnumber)) return 0; 827 if (vm86_irqs[irqnumber].tsk != current) return 0; 828 spin_lock_irqsave(&irqbits_lock, flags); 829 bit = irqbits & (1 << irqnumber); 830 irqbits &= ~bit; 831 if (bit) { 832 enable_irq(irqnumber); 833 ret = 1; 834 } 835 836 spin_unlock_irqrestore(&irqbits_lock, flags); 837 return ret; 838 } 839 840 841 static int do_vm86_irq_handling(int subfunction, int irqnumber) 842 { 843 int ret; 844 switch (subfunction) { 845 case VM86_GET_AND_RESET_IRQ: { 846 return get_and_reset_irq(irqnumber); 847 } 848 case VM86_GET_IRQ_BITS: { 849 return irqbits; 850 } 851 case VM86_REQUEST_IRQ: { 852 int sig = irqnumber >> 8; 853 int irq = irqnumber & 255; 854 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 855 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 856 if (invalid_vm86_irq(irq)) return -EPERM; 857 if (vm86_irqs[irq].tsk) return -EPERM; 858 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 859 if (ret) return ret; 860 vm86_irqs[irq].sig = sig; 861 vm86_irqs[irq].tsk = current; 862 return irq; 863 } 864 case VM86_FREE_IRQ: { 865 if (invalid_vm86_irq(irqnumber)) return -EPERM; 866 if (!vm86_irqs[irqnumber].tsk) return 0; 867 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 868 free_vm86_irq(irqnumber); 869 return 0; 870 } 871 } 872 return -EINVAL; 873 } 874 875