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 #include <linux/capability.h> 32 #include <linux/errno.h> 33 #include <linux/interrupt.h> 34 #include <linux/sched.h> 35 #include <linux/kernel.h> 36 #include <linux/signal.h> 37 #include <linux/string.h> 38 #include <linux/mm.h> 39 #include <linux/smp.h> 40 #include <linux/highmem.h> 41 #include <linux/ptrace.h> 42 #include <linux/audit.h> 43 #include <linux/stddef.h> 44 45 #include <asm/uaccess.h> 46 #include <asm/io.h> 47 #include <asm/tlbflush.h> 48 #include <asm/irq.h> 49 #include <asm/syscalls.h> 50 51 /* 52 * Known problems: 53 * 54 * Interrupt handling is not guaranteed: 55 * - a real x86 will disable all interrupts for one instruction 56 * after a "mov ss,xx" to make stack handling atomic even without 57 * the 'lss' instruction. We can't guarantee this in v86 mode, 58 * as the next instruction might result in a page fault or similar. 59 * - a real x86 will have interrupts disabled for one instruction 60 * past the 'sti' that enables them. We don't bother with all the 61 * details yet. 62 * 63 * Let's hope these problems do not actually matter for anything. 64 */ 65 66 67 #define KVM86 ((struct kernel_vm86_struct *)regs) 68 #define VMPI KVM86->vm86plus 69 70 71 /* 72 * 8- and 16-bit register defines.. 73 */ 74 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 75 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 76 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 77 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 78 79 /* 80 * virtual flags (16 and 32-bit versions) 81 */ 82 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags)) 83 #define VEFLAGS (current->thread.v86flags) 84 85 #define set_flags(X, new, mask) \ 86 ((X) = ((X) & ~(mask)) | ((new) & (mask))) 87 88 #define SAFE_MASK (0xDD5) 89 #define RETURN_MASK (0xDFF) 90 91 /* convert kernel_vm86_regs to vm86_regs */ 92 static int copy_vm86_regs_to_user(struct vm86_regs __user *user, 93 const struct kernel_vm86_regs *regs) 94 { 95 int ret = 0; 96 97 /* 98 * kernel_vm86_regs is missing gs, so copy everything up to 99 * (but not including) orig_eax, and then rest including orig_eax. 100 */ 101 ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax)); 102 ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax, 103 sizeof(struct kernel_vm86_regs) - 104 offsetof(struct kernel_vm86_regs, pt.orig_ax)); 105 106 return ret; 107 } 108 109 /* convert vm86_regs to kernel_vm86_regs */ 110 static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs, 111 const struct vm86_regs __user *user, 112 unsigned extra) 113 { 114 int ret = 0; 115 116 /* copy ax-fs inclusive */ 117 ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax)); 118 /* copy orig_ax-__gsh+extra */ 119 ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax, 120 sizeof(struct kernel_vm86_regs) - 121 offsetof(struct kernel_vm86_regs, pt.orig_ax) + 122 extra); 123 return ret; 124 } 125 126 struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) 127 { 128 struct tss_struct *tss; 129 struct pt_regs *ret; 130 unsigned long tmp; 131 132 /* 133 * This gets called from entry.S with interrupts disabled, but 134 * from process context. Enable interrupts here, before trying 135 * to access user space. 136 */ 137 local_irq_enable(); 138 139 if (!current->thread.vm86_info) { 140 printk("no vm86_info: BAD\n"); 141 do_exit(SIGSEGV); 142 } 143 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask); 144 tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs); 145 tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap); 146 if (tmp) { 147 printk("vm86: could not access userspace vm86_info\n"); 148 do_exit(SIGSEGV); 149 } 150 151 tss = &per_cpu(init_tss, get_cpu()); 152 current->thread.sp0 = current->thread.saved_sp0; 153 current->thread.sysenter_cs = __KERNEL_CS; 154 load_sp0(tss, ¤t->thread); 155 current->thread.saved_sp0 = 0; 156 put_cpu(); 157 158 ret = KVM86->regs32; 159 160 ret->fs = current->thread.saved_fs; 161 set_user_gs(ret, current->thread.saved_gs); 162 163 return ret; 164 } 165 166 static void mark_screen_rdonly(struct mm_struct *mm) 167 { 168 pgd_t *pgd; 169 pud_t *pud; 170 pmd_t *pmd; 171 pte_t *pte; 172 spinlock_t *ptl; 173 int i; 174 175 pgd = pgd_offset(mm, 0xA0000); 176 if (pgd_none_or_clear_bad(pgd)) 177 goto out; 178 pud = pud_offset(pgd, 0xA0000); 179 if (pud_none_or_clear_bad(pud)) 180 goto out; 181 pmd = pmd_offset(pud, 0xA0000); 182 if (pmd_none_or_clear_bad(pmd)) 183 goto out; 184 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 185 for (i = 0; i < 32; i++) { 186 if (pte_present(*pte)) 187 set_pte(pte, pte_wrprotect(*pte)); 188 pte++; 189 } 190 pte_unmap_unlock(pte, ptl); 191 out: 192 flush_tlb(); 193 } 194 195 196 197 static int do_vm86_irq_handling(int subfunction, int irqnumber); 198 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk); 199 200 int sys_vm86old(struct vm86_struct __user *v86, struct pt_regs *regs) 201 { 202 struct kernel_vm86_struct info; /* declare this _on top_, 203 * this avoids wasting of stack space. 204 * This remains on the stack until we 205 * return to 32 bit user space. 206 */ 207 struct task_struct *tsk; 208 int tmp, ret = -EPERM; 209 210 tsk = current; 211 if (tsk->thread.saved_sp0) 212 goto out; 213 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 214 offsetof(struct kernel_vm86_struct, vm86plus) - 215 sizeof(info.regs)); 216 ret = -EFAULT; 217 if (tmp) 218 goto out; 219 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus); 220 info.regs32 = regs; 221 tsk->thread.vm86_info = v86; 222 do_sys_vm86(&info, tsk); 223 ret = 0; /* we never return here */ 224 out: 225 return ret; 226 } 227 228 229 int sys_vm86(unsigned long cmd, unsigned long arg, struct pt_regs *regs) 230 { 231 struct kernel_vm86_struct info; /* declare this _on top_, 232 * this avoids wasting of stack space. 233 * This remains on the stack until we 234 * return to 32 bit user space. 235 */ 236 struct task_struct *tsk; 237 int tmp, ret; 238 struct vm86plus_struct __user *v86; 239 240 tsk = current; 241 switch (cmd) { 242 case VM86_REQUEST_IRQ: 243 case VM86_FREE_IRQ: 244 case VM86_GET_IRQ_BITS: 245 case VM86_GET_AND_RESET_IRQ: 246 ret = do_vm86_irq_handling(cmd, (int)arg); 247 goto out; 248 case VM86_PLUS_INSTALL_CHECK: 249 /* 250 * NOTE: on old vm86 stuff this will return the error 251 * from access_ok(), because the subfunction is 252 * interpreted as (invalid) address to vm86_struct. 253 * So the installation check works. 254 */ 255 ret = 0; 256 goto out; 257 } 258 259 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 260 ret = -EPERM; 261 if (tsk->thread.saved_sp0) 262 goto out; 263 v86 = (struct vm86plus_struct __user *)arg; 264 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 265 offsetof(struct kernel_vm86_struct, regs32) - 266 sizeof(info.regs)); 267 ret = -EFAULT; 268 if (tmp) 269 goto out; 270 info.regs32 = regs; 271 info.vm86plus.is_vm86pus = 1; 272 tsk->thread.vm86_info = (struct vm86_struct __user *)v86; 273 do_sys_vm86(&info, tsk); 274 ret = 0; /* we never return here */ 275 out: 276 return ret; 277 } 278 279 280 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk) 281 { 282 struct tss_struct *tss; 283 /* 284 * make sure the vm86() system call doesn't try to do anything silly 285 */ 286 info->regs.pt.ds = 0; 287 info->regs.pt.es = 0; 288 info->regs.pt.fs = 0; 289 #ifndef CONFIG_X86_32_LAZY_GS 290 info->regs.pt.gs = 0; 291 #endif 292 293 /* 294 * The flags register is also special: we cannot trust that the user 295 * has set it up safely, so this makes sure interrupt etc flags are 296 * inherited from protected mode. 297 */ 298 VEFLAGS = info->regs.pt.flags; 299 info->regs.pt.flags &= SAFE_MASK; 300 info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK; 301 info->regs.pt.flags |= X86_VM_MASK; 302 303 switch (info->cpu_type) { 304 case CPU_286: 305 tsk->thread.v86mask = 0; 306 break; 307 case CPU_386: 308 tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 309 break; 310 case CPU_486: 311 tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 312 break; 313 default: 314 tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 315 break; 316 } 317 318 /* 319 * Save old state, set default return value (%ax) to 0 (VM86_SIGNAL) 320 */ 321 info->regs32->ax = VM86_SIGNAL; 322 tsk->thread.saved_sp0 = tsk->thread.sp0; 323 tsk->thread.saved_fs = info->regs32->fs; 324 tsk->thread.saved_gs = get_user_gs(info->regs32); 325 326 tss = &per_cpu(init_tss, get_cpu()); 327 tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0; 328 if (cpu_has_sep) 329 tsk->thread.sysenter_cs = 0; 330 load_sp0(tss, &tsk->thread); 331 put_cpu(); 332 333 tsk->thread.screen_bitmap = info->screen_bitmap; 334 if (info->flags & VM86_SCREEN_BITMAP) 335 mark_screen_rdonly(tsk->mm); 336 337 /*call audit_syscall_exit since we do not exit via the normal paths */ 338 if (unlikely(current->audit_context)) 339 audit_syscall_exit(AUDITSC_RESULT(0), 0); 340 341 __asm__ __volatile__( 342 "movl %0,%%esp\n\t" 343 "movl %1,%%ebp\n\t" 344 #ifdef CONFIG_X86_32_LAZY_GS 345 "mov %2, %%gs\n\t" 346 #endif 347 "jmp resume_userspace" 348 : /* no outputs */ 349 :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0)); 350 /* we never return here */ 351 } 352 353 static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval) 354 { 355 struct pt_regs *regs32; 356 357 regs32 = save_v86_state(regs16); 358 regs32->ax = retval; 359 __asm__ __volatile__("movl %0,%%esp\n\t" 360 "movl %1,%%ebp\n\t" 361 "jmp resume_userspace" 362 : : "r" (regs32), "r" (current_thread_info())); 363 } 364 365 static inline void set_IF(struct kernel_vm86_regs *regs) 366 { 367 VEFLAGS |= X86_EFLAGS_VIF; 368 if (VEFLAGS & X86_EFLAGS_VIP) 369 return_to_32bit(regs, VM86_STI); 370 } 371 372 static inline void clear_IF(struct kernel_vm86_regs *regs) 373 { 374 VEFLAGS &= ~X86_EFLAGS_VIF; 375 } 376 377 static inline void clear_TF(struct kernel_vm86_regs *regs) 378 { 379 regs->pt.flags &= ~X86_EFLAGS_TF; 380 } 381 382 static inline void clear_AC(struct kernel_vm86_regs *regs) 383 { 384 regs->pt.flags &= ~X86_EFLAGS_AC; 385 } 386 387 /* 388 * It is correct to call set_IF(regs) from the set_vflags_* 389 * functions. However someone forgot to call clear_IF(regs) 390 * in the opposite case. 391 * After the command sequence CLI PUSHF STI POPF you should 392 * end up with interrupts disabled, but you ended up with 393 * interrupts enabled. 394 * ( I was testing my own changes, but the only bug I 395 * could find was in a function I had not changed. ) 396 * [KD] 397 */ 398 399 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 400 { 401 set_flags(VEFLAGS, flags, current->thread.v86mask); 402 set_flags(regs->pt.flags, flags, SAFE_MASK); 403 if (flags & X86_EFLAGS_IF) 404 set_IF(regs); 405 else 406 clear_IF(regs); 407 } 408 409 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 410 { 411 set_flags(VFLAGS, flags, current->thread.v86mask); 412 set_flags(regs->pt.flags, flags, SAFE_MASK); 413 if (flags & X86_EFLAGS_IF) 414 set_IF(regs); 415 else 416 clear_IF(regs); 417 } 418 419 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 420 { 421 unsigned long flags = regs->pt.flags & RETURN_MASK; 422 423 if (VEFLAGS & X86_EFLAGS_VIF) 424 flags |= X86_EFLAGS_IF; 425 flags |= X86_EFLAGS_IOPL; 426 return flags | (VEFLAGS & current->thread.v86mask); 427 } 428 429 static inline int is_revectored(int nr, struct revectored_struct *bitmap) 430 { 431 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0" 432 :"=r" (nr) 433 :"m" (*bitmap), "r" (nr)); 434 return nr; 435 } 436 437 #define val_byte(val, n) (((__u8 *)&val)[n]) 438 439 #define pushb(base, ptr, val, err_label) \ 440 do { \ 441 __u8 __val = val; \ 442 ptr--; \ 443 if (put_user(__val, base + ptr) < 0) \ 444 goto err_label; \ 445 } while (0) 446 447 #define pushw(base, ptr, val, err_label) \ 448 do { \ 449 __u16 __val = val; \ 450 ptr--; \ 451 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 452 goto err_label; \ 453 ptr--; \ 454 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 455 goto err_label; \ 456 } while (0) 457 458 #define pushl(base, ptr, val, err_label) \ 459 do { \ 460 __u32 __val = val; \ 461 ptr--; \ 462 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 463 goto err_label; \ 464 ptr--; \ 465 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 466 goto err_label; \ 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 popb(base, ptr, err_label) \ 476 ({ \ 477 __u8 __res; \ 478 if (get_user(__res, base + ptr) < 0) \ 479 goto err_label; \ 480 ptr++; \ 481 __res; \ 482 }) 483 484 #define popw(base, ptr, err_label) \ 485 ({ \ 486 __u16 __res; \ 487 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 488 goto err_label; \ 489 ptr++; \ 490 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 491 goto err_label; \ 492 ptr++; \ 493 __res; \ 494 }) 495 496 #define popl(base, ptr, err_label) \ 497 ({ \ 498 __u32 __res; \ 499 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 500 goto err_label; \ 501 ptr++; \ 502 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 503 goto err_label; \ 504 ptr++; \ 505 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 506 goto err_label; \ 507 ptr++; \ 508 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 509 goto err_label; \ 510 ptr++; \ 511 __res; \ 512 }) 513 514 /* There are so many possible reasons for this function to return 515 * VM86_INTx, so adding another doesn't bother me. We can expect 516 * userspace programs to be able to handle it. (Getting a problem 517 * in userspace is always better than an Oops anyway.) [KD] 518 */ 519 static void do_int(struct kernel_vm86_regs *regs, int i, 520 unsigned char __user *ssp, unsigned short sp) 521 { 522 unsigned long __user *intr_ptr; 523 unsigned long segoffs; 524 525 if (regs->pt.cs == BIOSSEG) 526 goto cannot_handle; 527 if (is_revectored(i, &KVM86->int_revectored)) 528 goto cannot_handle; 529 if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored)) 530 goto cannot_handle; 531 intr_ptr = (unsigned long __user *) (i << 2); 532 if (get_user(segoffs, intr_ptr)) 533 goto cannot_handle; 534 if ((segoffs >> 16) == BIOSSEG) 535 goto cannot_handle; 536 pushw(ssp, sp, get_vflags(regs), cannot_handle); 537 pushw(ssp, sp, regs->pt.cs, cannot_handle); 538 pushw(ssp, sp, IP(regs), cannot_handle); 539 regs->pt.cs = segoffs >> 16; 540 SP(regs) -= 6; 541 IP(regs) = segoffs & 0xffff; 542 clear_TF(regs); 543 clear_IF(regs); 544 clear_AC(regs); 545 return; 546 547 cannot_handle: 548 return_to_32bit(regs, VM86_INTx + (i << 8)); 549 } 550 551 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 552 { 553 if (VMPI.is_vm86pus) { 554 if ((trapno == 3) || (trapno == 1)) { 555 KVM86->regs32->ax = VM86_TRAP + (trapno << 8); 556 /* setting this flag forces the code in entry_32.S to 557 call save_v86_state() and change the stack pointer 558 to KVM86->regs32 */ 559 set_thread_flag(TIF_IRET); 560 return 0; 561 } 562 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 563 return 0; 564 } 565 if (trapno != 1) 566 return 1; /* we let this handle by the calling routine */ 567 current->thread.trap_no = trapno; 568 current->thread.error_code = error_code; 569 force_sig(SIGTRAP, current); 570 return 0; 571 } 572 573 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 574 { 575 unsigned char opcode; 576 unsigned char __user *csp; 577 unsigned char __user *ssp; 578 unsigned short ip, sp, orig_flags; 579 int data32, pref_done; 580 581 #define CHECK_IF_IN_TRAP \ 582 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \ 583 newflags |= X86_EFLAGS_TF 584 #define VM86_FAULT_RETURN do { \ 585 if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ 586 return_to_32bit(regs, VM86_PICRETURN); \ 587 if (orig_flags & X86_EFLAGS_TF) \ 588 handle_vm86_trap(regs, 0, 1); \ 589 return; } while (0) 590 591 orig_flags = *(unsigned short *)®s->pt.flags; 592 593 csp = (unsigned char __user *) (regs->pt.cs << 4); 594 ssp = (unsigned char __user *) (regs->pt.ss << 4); 595 sp = SP(regs); 596 ip = IP(regs); 597 598 data32 = 0; 599 pref_done = 0; 600 do { 601 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 602 case 0x66: /* 32-bit data */ data32 = 1; break; 603 case 0x67: /* 32-bit address */ break; 604 case 0x2e: /* CS */ break; 605 case 0x3e: /* DS */ break; 606 case 0x26: /* ES */ break; 607 case 0x36: /* SS */ break; 608 case 0x65: /* GS */ break; 609 case 0x64: /* FS */ break; 610 case 0xf2: /* repnz */ break; 611 case 0xf3: /* rep */ break; 612 default: pref_done = 1; 613 } 614 } while (!pref_done); 615 616 switch (opcode) { 617 618 /* pushf */ 619 case 0x9c: 620 if (data32) { 621 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 622 SP(regs) -= 4; 623 } else { 624 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 625 SP(regs) -= 2; 626 } 627 IP(regs) = ip; 628 VM86_FAULT_RETURN; 629 630 /* popf */ 631 case 0x9d: 632 { 633 unsigned long newflags; 634 if (data32) { 635 newflags = popl(ssp, sp, simulate_sigsegv); 636 SP(regs) += 4; 637 } else { 638 newflags = popw(ssp, sp, simulate_sigsegv); 639 SP(regs) += 2; 640 } 641 IP(regs) = ip; 642 CHECK_IF_IN_TRAP; 643 if (data32) 644 set_vflags_long(newflags, regs); 645 else 646 set_vflags_short(newflags, regs); 647 648 VM86_FAULT_RETURN; 649 } 650 651 /* int xx */ 652 case 0xcd: { 653 int intno = popb(csp, ip, simulate_sigsegv); 654 IP(regs) = ip; 655 if (VMPI.vm86dbg_active) { 656 if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3]) 657 return_to_32bit(regs, VM86_INTx + (intno << 8)); 658 } 659 do_int(regs, intno, ssp, sp); 660 return; 661 } 662 663 /* iret */ 664 case 0xcf: 665 { 666 unsigned long newip; 667 unsigned long newcs; 668 unsigned long newflags; 669 if (data32) { 670 newip = popl(ssp, sp, simulate_sigsegv); 671 newcs = popl(ssp, sp, simulate_sigsegv); 672 newflags = popl(ssp, sp, simulate_sigsegv); 673 SP(regs) += 12; 674 } else { 675 newip = popw(ssp, sp, simulate_sigsegv); 676 newcs = popw(ssp, sp, simulate_sigsegv); 677 newflags = popw(ssp, sp, simulate_sigsegv); 678 SP(regs) += 6; 679 } 680 IP(regs) = newip; 681 regs->pt.cs = newcs; 682 CHECK_IF_IN_TRAP; 683 if (data32) { 684 set_vflags_long(newflags, regs); 685 } else { 686 set_vflags_short(newflags, regs); 687 } 688 VM86_FAULT_RETURN; 689 } 690 691 /* cli */ 692 case 0xfa: 693 IP(regs) = ip; 694 clear_IF(regs); 695 VM86_FAULT_RETURN; 696 697 /* sti */ 698 /* 699 * Damn. This is incorrect: the 'sti' instruction should actually 700 * enable interrupts after the /next/ instruction. Not good. 701 * 702 * Probably needs some horsing around with the TF flag. Aiee.. 703 */ 704 case 0xfb: 705 IP(regs) = ip; 706 set_IF(regs); 707 VM86_FAULT_RETURN; 708 709 default: 710 return_to_32bit(regs, VM86_UNKNOWN); 711 } 712 713 return; 714 715 simulate_sigsegv: 716 /* FIXME: After a long discussion with Stas we finally 717 * agreed, that this is wrong. Here we should 718 * really send a SIGSEGV to the user program. 719 * But how do we create the correct context? We 720 * are inside a general protection fault handler 721 * and has just returned from a page fault handler. 722 * The correct context for the signal handler 723 * should be a mixture of the two, but how do we 724 * get the information? [KD] 725 */ 726 return_to_32bit(regs, VM86_UNKNOWN); 727 } 728 729 /* ---------------- vm86 special IRQ passing stuff ----------------- */ 730 731 #define VM86_IRQNAME "vm86irq" 732 733 static struct vm86_irqs { 734 struct task_struct *tsk; 735 int sig; 736 } vm86_irqs[16]; 737 738 static DEFINE_SPINLOCK(irqbits_lock); 739 static int irqbits; 740 741 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 742 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 743 | (1 << SIGUNUSED)) 744 745 static irqreturn_t irq_handler(int intno, void *dev_id) 746 { 747 int irq_bit; 748 unsigned long flags; 749 750 spin_lock_irqsave(&irqbits_lock, flags); 751 irq_bit = 1 << intno; 752 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 753 goto out; 754 irqbits |= irq_bit; 755 if (vm86_irqs[intno].sig) 756 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 757 /* 758 * IRQ will be re-enabled when user asks for the irq (whether 759 * polling or as a result of the signal) 760 */ 761 disable_irq_nosync(intno); 762 spin_unlock_irqrestore(&irqbits_lock, flags); 763 return IRQ_HANDLED; 764 765 out: 766 spin_unlock_irqrestore(&irqbits_lock, flags); 767 return IRQ_NONE; 768 } 769 770 static inline void free_vm86_irq(int irqnumber) 771 { 772 unsigned long flags; 773 774 free_irq(irqnumber, NULL); 775 vm86_irqs[irqnumber].tsk = NULL; 776 777 spin_lock_irqsave(&irqbits_lock, flags); 778 irqbits &= ~(1 << irqnumber); 779 spin_unlock_irqrestore(&irqbits_lock, flags); 780 } 781 782 void release_vm86_irqs(struct task_struct *task) 783 { 784 int i; 785 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 786 if (vm86_irqs[i].tsk == task) 787 free_vm86_irq(i); 788 } 789 790 static inline int get_and_reset_irq(int irqnumber) 791 { 792 int bit; 793 unsigned long flags; 794 int ret = 0; 795 796 if (invalid_vm86_irq(irqnumber)) return 0; 797 if (vm86_irqs[irqnumber].tsk != current) return 0; 798 spin_lock_irqsave(&irqbits_lock, flags); 799 bit = irqbits & (1 << irqnumber); 800 irqbits &= ~bit; 801 if (bit) { 802 enable_irq(irqnumber); 803 ret = 1; 804 } 805 806 spin_unlock_irqrestore(&irqbits_lock, flags); 807 return ret; 808 } 809 810 811 static int do_vm86_irq_handling(int subfunction, int irqnumber) 812 { 813 int ret; 814 switch (subfunction) { 815 case VM86_GET_AND_RESET_IRQ: { 816 return get_and_reset_irq(irqnumber); 817 } 818 case VM86_GET_IRQ_BITS: { 819 return irqbits; 820 } 821 case VM86_REQUEST_IRQ: { 822 int sig = irqnumber >> 8; 823 int irq = irqnumber & 255; 824 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 825 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 826 if (invalid_vm86_irq(irq)) return -EPERM; 827 if (vm86_irqs[irq].tsk) return -EPERM; 828 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 829 if (ret) return ret; 830 vm86_irqs[irq].sig = sig; 831 vm86_irqs[irq].tsk = current; 832 return irq; 833 } 834 case VM86_FREE_IRQ: { 835 if (invalid_vm86_irq(irqnumber)) return -EPERM; 836 if (!vm86_irqs[irqnumber].tsk) return 0; 837 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 838 free_vm86_irq(irqnumber); 839 return 0; 840 } 841 } 842 return -EINVAL; 843 } 844 845