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(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, PAGE_SHIFT, false); 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(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 (boot_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 return regs->ax; 385 } 386 387 static inline void set_IF(struct kernel_vm86_regs *regs) 388 { 389 VEFLAGS |= X86_EFLAGS_VIF; 390 } 391 392 static inline void clear_IF(struct kernel_vm86_regs *regs) 393 { 394 VEFLAGS &= ~X86_EFLAGS_VIF; 395 } 396 397 static inline void clear_TF(struct kernel_vm86_regs *regs) 398 { 399 regs->pt.flags &= ~X86_EFLAGS_TF; 400 } 401 402 static inline void clear_AC(struct kernel_vm86_regs *regs) 403 { 404 regs->pt.flags &= ~X86_EFLAGS_AC; 405 } 406 407 /* 408 * It is correct to call set_IF(regs) from the set_vflags_* 409 * functions. However someone forgot to call clear_IF(regs) 410 * in the opposite case. 411 * After the command sequence CLI PUSHF STI POPF you should 412 * end up with interrupts disabled, but you ended up with 413 * interrupts enabled. 414 * ( I was testing my own changes, but the only bug I 415 * could find was in a function I had not changed. ) 416 * [KD] 417 */ 418 419 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 420 { 421 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 422 set_flags(regs->pt.flags, flags, SAFE_MASK); 423 if (flags & X86_EFLAGS_IF) 424 set_IF(regs); 425 else 426 clear_IF(regs); 427 } 428 429 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 430 { 431 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 432 set_flags(regs->pt.flags, flags, SAFE_MASK); 433 if (flags & X86_EFLAGS_IF) 434 set_IF(regs); 435 else 436 clear_IF(regs); 437 } 438 439 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 440 { 441 unsigned long flags = regs->pt.flags & RETURN_MASK; 442 443 if (VEFLAGS & X86_EFLAGS_VIF) 444 flags |= X86_EFLAGS_IF; 445 flags |= X86_EFLAGS_IOPL; 446 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 447 } 448 449 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 450 { 451 return test_bit(nr, bitmap->__map); 452 } 453 454 #define val_byte(val, n) (((__u8 *)&val)[n]) 455 456 #define pushb(base, ptr, val, err_label) \ 457 do { \ 458 __u8 __val = val; \ 459 ptr--; \ 460 if (put_user(__val, base + ptr) < 0) \ 461 goto err_label; \ 462 } while (0) 463 464 #define pushw(base, ptr, val, err_label) \ 465 do { \ 466 __u16 __val = val; \ 467 ptr--; \ 468 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 469 goto err_label; \ 470 ptr--; \ 471 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 472 goto err_label; \ 473 } while (0) 474 475 #define pushl(base, ptr, val, err_label) \ 476 do { \ 477 __u32 __val = val; \ 478 ptr--; \ 479 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 480 goto err_label; \ 481 ptr--; \ 482 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 483 goto err_label; \ 484 ptr--; \ 485 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 486 goto err_label; \ 487 ptr--; \ 488 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 489 goto err_label; \ 490 } while (0) 491 492 #define popb(base, ptr, err_label) \ 493 ({ \ 494 __u8 __res; \ 495 if (get_user(__res, base + ptr) < 0) \ 496 goto err_label; \ 497 ptr++; \ 498 __res; \ 499 }) 500 501 #define popw(base, ptr, err_label) \ 502 ({ \ 503 __u16 __res; \ 504 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 505 goto err_label; \ 506 ptr++; \ 507 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 508 goto err_label; \ 509 ptr++; \ 510 __res; \ 511 }) 512 513 #define popl(base, ptr, err_label) \ 514 ({ \ 515 __u32 __res; \ 516 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 517 goto err_label; \ 518 ptr++; \ 519 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 520 goto err_label; \ 521 ptr++; \ 522 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 523 goto err_label; \ 524 ptr++; \ 525 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 526 goto err_label; \ 527 ptr++; \ 528 __res; \ 529 }) 530 531 /* There are so many possible reasons for this function to return 532 * VM86_INTx, so adding another doesn't bother me. We can expect 533 * userspace programs to be able to handle it. (Getting a problem 534 * in userspace is always better than an Oops anyway.) [KD] 535 */ 536 static void do_int(struct kernel_vm86_regs *regs, int i, 537 unsigned char __user *ssp, unsigned short sp) 538 { 539 unsigned long __user *intr_ptr; 540 unsigned long segoffs; 541 struct vm86 *vm86 = current->thread.vm86; 542 543 if (regs->pt.cs == BIOSSEG) 544 goto cannot_handle; 545 if (is_revectored(i, &vm86->int_revectored)) 546 goto cannot_handle; 547 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 548 goto cannot_handle; 549 intr_ptr = (unsigned long __user *) (i << 2); 550 if (get_user(segoffs, intr_ptr)) 551 goto cannot_handle; 552 if ((segoffs >> 16) == BIOSSEG) 553 goto cannot_handle; 554 pushw(ssp, sp, get_vflags(regs), cannot_handle); 555 pushw(ssp, sp, regs->pt.cs, cannot_handle); 556 pushw(ssp, sp, IP(regs), cannot_handle); 557 regs->pt.cs = segoffs >> 16; 558 SP(regs) -= 6; 559 IP(regs) = segoffs & 0xffff; 560 clear_TF(regs); 561 clear_IF(regs); 562 clear_AC(regs); 563 return; 564 565 cannot_handle: 566 save_v86_state(regs, VM86_INTx + (i << 8)); 567 } 568 569 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 570 { 571 struct vm86 *vm86 = current->thread.vm86; 572 573 if (vm86->vm86plus.is_vm86pus) { 574 if ((trapno == 3) || (trapno == 1)) { 575 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 576 return 0; 577 } 578 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 579 return 0; 580 } 581 if (trapno != 1) 582 return 1; /* we let this handle by the calling routine */ 583 current->thread.trap_nr = trapno; 584 current->thread.error_code = error_code; 585 force_sig(SIGTRAP); 586 return 0; 587 } 588 589 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 590 { 591 unsigned char opcode; 592 unsigned char __user *csp; 593 unsigned char __user *ssp; 594 unsigned short ip, sp, orig_flags; 595 int data32, pref_done; 596 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 597 598 #define CHECK_IF_IN_TRAP \ 599 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 600 newflags |= X86_EFLAGS_TF 601 602 orig_flags = *(unsigned short *)®s->pt.flags; 603 604 csp = (unsigned char __user *) (regs->pt.cs << 4); 605 ssp = (unsigned char __user *) (regs->pt.ss << 4); 606 sp = SP(regs); 607 ip = IP(regs); 608 609 data32 = 0; 610 pref_done = 0; 611 do { 612 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 613 case 0x66: /* 32-bit data */ data32 = 1; break; 614 case 0x67: /* 32-bit address */ break; 615 case 0x2e: /* CS */ break; 616 case 0x3e: /* DS */ break; 617 case 0x26: /* ES */ break; 618 case 0x36: /* SS */ break; 619 case 0x65: /* GS */ break; 620 case 0x64: /* FS */ break; 621 case 0xf2: /* repnz */ break; 622 case 0xf3: /* rep */ break; 623 default: pref_done = 1; 624 } 625 } while (!pref_done); 626 627 switch (opcode) { 628 629 /* pushf */ 630 case 0x9c: 631 if (data32) { 632 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 633 SP(regs) -= 4; 634 } else { 635 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 636 SP(regs) -= 2; 637 } 638 IP(regs) = ip; 639 goto vm86_fault_return; 640 641 /* popf */ 642 case 0x9d: 643 { 644 unsigned long newflags; 645 if (data32) { 646 newflags = popl(ssp, sp, simulate_sigsegv); 647 SP(regs) += 4; 648 } else { 649 newflags = popw(ssp, sp, simulate_sigsegv); 650 SP(regs) += 2; 651 } 652 IP(regs) = ip; 653 CHECK_IF_IN_TRAP; 654 if (data32) 655 set_vflags_long(newflags, regs); 656 else 657 set_vflags_short(newflags, regs); 658 659 goto check_vip; 660 } 661 662 /* int xx */ 663 case 0xcd: { 664 int intno = popb(csp, ip, simulate_sigsegv); 665 IP(regs) = ip; 666 if (vmpi->vm86dbg_active) { 667 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 668 save_v86_state(regs, VM86_INTx + (intno << 8)); 669 return; 670 } 671 } 672 do_int(regs, intno, ssp, sp); 673 return; 674 } 675 676 /* iret */ 677 case 0xcf: 678 { 679 unsigned long newip; 680 unsigned long newcs; 681 unsigned long newflags; 682 if (data32) { 683 newip = popl(ssp, sp, simulate_sigsegv); 684 newcs = popl(ssp, sp, simulate_sigsegv); 685 newflags = popl(ssp, sp, simulate_sigsegv); 686 SP(regs) += 12; 687 } else { 688 newip = popw(ssp, sp, simulate_sigsegv); 689 newcs = popw(ssp, sp, simulate_sigsegv); 690 newflags = popw(ssp, sp, simulate_sigsegv); 691 SP(regs) += 6; 692 } 693 IP(regs) = newip; 694 regs->pt.cs = newcs; 695 CHECK_IF_IN_TRAP; 696 if (data32) { 697 set_vflags_long(newflags, regs); 698 } else { 699 set_vflags_short(newflags, regs); 700 } 701 goto check_vip; 702 } 703 704 /* cli */ 705 case 0xfa: 706 IP(regs) = ip; 707 clear_IF(regs); 708 goto vm86_fault_return; 709 710 /* sti */ 711 /* 712 * Damn. This is incorrect: the 'sti' instruction should actually 713 * enable interrupts after the /next/ instruction. Not good. 714 * 715 * Probably needs some horsing around with the TF flag. Aiee.. 716 */ 717 case 0xfb: 718 IP(regs) = ip; 719 set_IF(regs); 720 goto check_vip; 721 722 default: 723 save_v86_state(regs, VM86_UNKNOWN); 724 } 725 726 return; 727 728 check_vip: 729 if ((VEFLAGS & (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) == 730 (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) { 731 save_v86_state(regs, VM86_STI); 732 return; 733 } 734 735 vm86_fault_return: 736 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 737 save_v86_state(regs, VM86_PICRETURN); 738 return; 739 } 740 if (orig_flags & X86_EFLAGS_TF) 741 handle_vm86_trap(regs, 0, X86_TRAP_DB); 742 return; 743 744 simulate_sigsegv: 745 /* FIXME: After a long discussion with Stas we finally 746 * agreed, that this is wrong. Here we should 747 * really send a SIGSEGV to the user program. 748 * But how do we create the correct context? We 749 * are inside a general protection fault handler 750 * and has just returned from a page fault handler. 751 * The correct context for the signal handler 752 * should be a mixture of the two, but how do we 753 * get the information? [KD] 754 */ 755 save_v86_state(regs, VM86_UNKNOWN); 756 } 757 758 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 759 760 #define VM86_IRQNAME "vm86irq" 761 762 static struct vm86_irqs { 763 struct task_struct *tsk; 764 int sig; 765 } vm86_irqs[16]; 766 767 static DEFINE_SPINLOCK(irqbits_lock); 768 static int irqbits; 769 770 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 771 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 772 | (1 << SIGUNUSED)) 773 774 static irqreturn_t irq_handler(int intno, void *dev_id) 775 { 776 int irq_bit; 777 unsigned long flags; 778 779 spin_lock_irqsave(&irqbits_lock, flags); 780 irq_bit = 1 << intno; 781 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 782 goto out; 783 irqbits |= irq_bit; 784 if (vm86_irqs[intno].sig) 785 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 786 /* 787 * IRQ will be re-enabled when user asks for the irq (whether 788 * polling or as a result of the signal) 789 */ 790 disable_irq_nosync(intno); 791 spin_unlock_irqrestore(&irqbits_lock, flags); 792 return IRQ_HANDLED; 793 794 out: 795 spin_unlock_irqrestore(&irqbits_lock, flags); 796 return IRQ_NONE; 797 } 798 799 static inline void free_vm86_irq(int irqnumber) 800 { 801 unsigned long flags; 802 803 free_irq(irqnumber, NULL); 804 vm86_irqs[irqnumber].tsk = NULL; 805 806 spin_lock_irqsave(&irqbits_lock, flags); 807 irqbits &= ~(1 << irqnumber); 808 spin_unlock_irqrestore(&irqbits_lock, flags); 809 } 810 811 void release_vm86_irqs(struct task_struct *task) 812 { 813 int i; 814 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 815 if (vm86_irqs[i].tsk == task) 816 free_vm86_irq(i); 817 } 818 819 static inline int get_and_reset_irq(int irqnumber) 820 { 821 int bit; 822 unsigned long flags; 823 int ret = 0; 824 825 if (invalid_vm86_irq(irqnumber)) return 0; 826 if (vm86_irqs[irqnumber].tsk != current) return 0; 827 spin_lock_irqsave(&irqbits_lock, flags); 828 bit = irqbits & (1 << irqnumber); 829 irqbits &= ~bit; 830 if (bit) { 831 enable_irq(irqnumber); 832 ret = 1; 833 } 834 835 spin_unlock_irqrestore(&irqbits_lock, flags); 836 return ret; 837 } 838 839 840 static int do_vm86_irq_handling(int subfunction, int irqnumber) 841 { 842 int ret; 843 switch (subfunction) { 844 case VM86_GET_AND_RESET_IRQ: { 845 return get_and_reset_irq(irqnumber); 846 } 847 case VM86_GET_IRQ_BITS: { 848 return irqbits; 849 } 850 case VM86_REQUEST_IRQ: { 851 int sig = irqnumber >> 8; 852 int irq = irqnumber & 255; 853 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 854 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 855 if (invalid_vm86_irq(irq)) return -EPERM; 856 if (vm86_irqs[irq].tsk) return -EPERM; 857 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 858 if (ret) return ret; 859 vm86_irqs[irq].sig = sig; 860 vm86_irqs[irq].tsk = current; 861 return irq; 862 } 863 case VM86_FREE_IRQ: { 864 if (invalid_vm86_irq(irqnumber)) return -EPERM; 865 if (!vm86_irqs[irqnumber].tsk) return 0; 866 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 867 free_vm86_irq(irqnumber); 868 return 0; 869 } 870 } 871 return -EINVAL; 872 } 873 874