vm86_32.c revision 5522ddb3fc0dfd4a503c8278eafd88c9f2d3fada
1/* 2 * Copyright (C) 1994 Linus Torvalds 3 * 4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86 5 * stack - Manfred Spraul <manfred@colorfullife.com> 6 * 7 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle 8 * them correctly. Now the emulation will be in a 9 * consistent state after stackfaults - Kasper Dupont 10 * <kasperd@daimi.au.dk> 11 * 12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont 13 * <kasperd@daimi.au.dk> 14 * 15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault 16 * caused by Kasper Dupont's changes - Stas Sergeev 17 * 18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes. 19 * Kasper Dupont <kasperd@daimi.au.dk> 20 * 21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault. 22 * Kasper Dupont <kasperd@daimi.au.dk> 23 * 24 * 9 apr 2002 - Changed stack access macros to jump to a label 25 * instead of returning to userspace. This simplifies 26 * do_int, and is needed by handle_vm6_fault. Kasper 27 * Dupont <kasperd@daimi.au.dk> 28 * 29 */ 30 31#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 32 33#include <linux/capability.h> 34#include <linux/errno.h> 35#include <linux/interrupt.h> 36#include <linux/syscalls.h> 37#include <linux/sched.h> 38#include <linux/kernel.h> 39#include <linux/signal.h> 40#include <linux/string.h> 41#include <linux/mm.h> 42#include <linux/smp.h> 43#include <linux/highmem.h> 44#include <linux/ptrace.h> 45#include <linux/audit.h> 46#include <linux/stddef.h> 47 48#include <asm/uaccess.h> 49#include <asm/io.h> 50#include <asm/tlbflush.h> 51#include <asm/irq.h> 52 53/* 54 * Known problems: 55 * 56 * Interrupt handling is not guaranteed: 57 * - a real x86 will disable all interrupts for one instruction 58 * after a "mov ss,xx" to make stack handling atomic even without 59 * the 'lss' instruction. We can't guarantee this in v86 mode, 60 * as the next instruction might result in a page fault or similar. 61 * - a real x86 will have interrupts disabled for one instruction 62 * past the 'sti' that enables them. We don't bother with all the 63 * details yet. 64 * 65 * Let's hope these problems do not actually matter for anything. 66 */ 67 68 69#define KVM86 ((struct kernel_vm86_struct *)regs) 70#define VMPI KVM86->vm86plus 71 72 73/* 74 * 8- and 16-bit register defines.. 75 */ 76#define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 77#define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 78#define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 79#define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 80 81/* 82 * virtual flags (16 and 32-bit versions) 83 */ 84#define VFLAGS (*(unsigned short *)&(current->thread.v86flags)) 85#define VEFLAGS (current->thread.v86flags) 86 87#define set_flags(X, new, mask) \ 88((X) = ((X) & ~(mask)) | ((new) & (mask))) 89 90#define SAFE_MASK (0xDD5) 91#define RETURN_MASK (0xDFF) 92 93/* convert kernel_vm86_regs to vm86_regs */ 94static int copy_vm86_regs_to_user(struct vm86_regs __user *user, 95 const struct kernel_vm86_regs *regs) 96{ 97 int ret = 0; 98 99 /* 100 * kernel_vm86_regs is missing gs, so copy everything up to 101 * (but not including) orig_eax, and then rest including orig_eax. 102 */ 103 ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax)); 104 ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax, 105 sizeof(struct kernel_vm86_regs) - 106 offsetof(struct kernel_vm86_regs, pt.orig_ax)); 107 108 return ret; 109} 110 111/* convert vm86_regs to kernel_vm86_regs */ 112static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs, 113 const struct vm86_regs __user *user, 114 unsigned extra) 115{ 116 int ret = 0; 117 118 /* copy ax-fs inclusive */ 119 ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax)); 120 /* copy orig_ax-__gsh+extra */ 121 ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax, 122 sizeof(struct kernel_vm86_regs) - 123 offsetof(struct kernel_vm86_regs, pt.orig_ax) + 124 extra); 125 return ret; 126} 127 128struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) 129{ 130 struct tss_struct *tss; 131 struct pt_regs *ret; 132 unsigned long tmp; 133 134 /* 135 * This gets called from entry.S with interrupts disabled, but 136 * from process context. Enable interrupts here, before trying 137 * to access user space. 138 */ 139 local_irq_enable(); 140 141 if (!current->thread.vm86_info) { 142 pr_alert("no vm86_info: BAD\n"); 143 do_exit(SIGSEGV); 144 } 145 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask); 146 tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs); 147 tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap); 148 if (tmp) { 149 pr_alert("could not access userspace vm86_info\n"); 150 do_exit(SIGSEGV); 151 } 152 153 tss = &per_cpu(init_tss, get_cpu()); 154 current->thread.sp0 = current->thread.saved_sp0; 155 current->thread.sysenter_cs = __KERNEL_CS; 156 load_sp0(tss, ¤t->thread); 157 current->thread.saved_sp0 = 0; 158 put_cpu(); 159 160 ret = KVM86->regs32; 161 162 ret->fs = current->thread.saved_fs; 163 set_user_gs(ret, current->thread.saved_gs); 164 165 return ret; 166} 167 168static void mark_screen_rdonly(struct mm_struct *mm) 169{ 170 pgd_t *pgd; 171 pud_t *pud; 172 pmd_t *pmd; 173 pte_t *pte; 174 spinlock_t *ptl; 175 int i; 176 177 down_write(&mm->mmap_sem); 178 pgd = pgd_offset(mm, 0xA0000); 179 if (pgd_none_or_clear_bad(pgd)) 180 goto out; 181 pud = pud_offset(pgd, 0xA0000); 182 if (pud_none_or_clear_bad(pud)) 183 goto out; 184 pmd = pmd_offset(pud, 0xA0000); 185 split_huge_page_pmd_mm(mm, 0xA0000, pmd); 186 if (pmd_none_or_clear_bad(pmd)) 187 goto out; 188 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 189 for (i = 0; i < 32; i++) { 190 if (pte_present(*pte)) 191 set_pte(pte, pte_wrprotect(*pte)); 192 pte++; 193 } 194 pte_unmap_unlock(pte, ptl); 195out: 196 up_write(&mm->mmap_sem); 197 flush_tlb(); 198} 199 200 201 202static int do_vm86_irq_handling(int subfunction, int irqnumber); 203static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk); 204 205SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86) 206{ 207 struct kernel_vm86_struct info; /* declare this _on top_, 208 * this avoids wasting of stack space. 209 * This remains on the stack until we 210 * return to 32 bit user space. 211 */ 212 struct task_struct *tsk = current; 213 int tmp; 214 215 if (tsk->thread.saved_sp0) 216 return -EPERM; 217 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 218 offsetof(struct kernel_vm86_struct, vm86plus) - 219 sizeof(info.regs)); 220 if (tmp) 221 return -EFAULT; 222 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus); 223 info.regs32 = current_pt_regs(); 224 tsk->thread.vm86_info = v86; 225 do_sys_vm86(&info, tsk); 226 return 0; /* we never return here */ 227} 228 229 230SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 231{ 232 struct kernel_vm86_struct info; /* declare this _on top_, 233 * this avoids wasting of stack space. 234 * This remains on the stack until we 235 * return to 32 bit user space. 236 */ 237 struct task_struct *tsk; 238 int tmp; 239 struct vm86plus_struct __user *v86; 240 241 tsk = current; 242 switch (cmd) { 243 case VM86_REQUEST_IRQ: 244 case VM86_FREE_IRQ: 245 case VM86_GET_IRQ_BITS: 246 case VM86_GET_AND_RESET_IRQ: 247 return do_vm86_irq_handling(cmd, (int)arg); 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 return 0; 256 } 257 258 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 259 if (tsk->thread.saved_sp0) 260 return -EPERM; 261 v86 = (struct vm86plus_struct __user *)arg; 262 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 263 offsetof(struct kernel_vm86_struct, regs32) - 264 sizeof(info.regs)); 265 if (tmp) 266 return -EFAULT; 267 info.regs32 = current_pt_regs(); 268 info.vm86plus.is_vm86pus = 1; 269 tsk->thread.vm86_info = (struct vm86_struct __user *)v86; 270 do_sys_vm86(&info, tsk); 271 return 0; /* we never return here */ 272} 273 274 275static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk) 276{ 277 struct tss_struct *tss; 278/* 279 * make sure the vm86() system call doesn't try to do anything silly 280 */ 281 info->regs.pt.ds = 0; 282 info->regs.pt.es = 0; 283 info->regs.pt.fs = 0; 284#ifndef CONFIG_X86_32_LAZY_GS 285 info->regs.pt.gs = 0; 286#endif 287 288/* 289 * The flags register is also special: we cannot trust that the user 290 * has set it up safely, so this makes sure interrupt etc flags are 291 * inherited from protected mode. 292 */ 293 VEFLAGS = info->regs.pt.flags; 294 info->regs.pt.flags &= SAFE_MASK; 295 info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK; 296 info->regs.pt.flags |= X86_VM_MASK; 297 298 switch (info->cpu_type) { 299 case CPU_286: 300 tsk->thread.v86mask = 0; 301 break; 302 case CPU_386: 303 tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 304 break; 305 case CPU_486: 306 tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 307 break; 308 default: 309 tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 310 break; 311 } 312 313/* 314 * Save old state, set default return value (%ax) to 0 (VM86_SIGNAL) 315 */ 316 info->regs32->ax = VM86_SIGNAL; 317 tsk->thread.saved_sp0 = tsk->thread.sp0; 318 tsk->thread.saved_fs = info->regs32->fs; 319 tsk->thread.saved_gs = get_user_gs(info->regs32); 320 321 tss = &per_cpu(init_tss, get_cpu()); 322 tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0; 323 if (cpu_has_sep) 324 tsk->thread.sysenter_cs = 0; 325 load_sp0(tss, &tsk->thread); 326 put_cpu(); 327 328 tsk->thread.screen_bitmap = info->screen_bitmap; 329 if (info->flags & VM86_SCREEN_BITMAP) 330 mark_screen_rdonly(tsk->mm); 331 332 /*call __audit_syscall_exit since we do not exit via the normal paths */ 333#ifdef CONFIG_AUDITSYSCALL 334 if (unlikely(current->audit_context)) 335 __audit_syscall_exit(1, 0); 336#endif 337 338 __asm__ __volatile__( 339 "movl %0,%%esp\n\t" 340 "movl %1,%%ebp\n\t" 341#ifdef CONFIG_X86_32_LAZY_GS 342 "mov %2, %%gs\n\t" 343#endif 344 "jmp resume_userspace" 345 : /* no outputs */ 346 :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0)); 347 /* we never return here */ 348} 349 350static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval) 351{ 352 struct pt_regs *regs32; 353 354 regs32 = save_v86_state(regs16); 355 regs32->ax = retval; 356 __asm__ __volatile__("movl %0,%%esp\n\t" 357 "movl %1,%%ebp\n\t" 358 "jmp resume_userspace" 359 : : "r" (regs32), "r" (current_thread_info())); 360} 361 362static inline void set_IF(struct kernel_vm86_regs *regs) 363{ 364 VEFLAGS |= X86_EFLAGS_VIF; 365 if (VEFLAGS & X86_EFLAGS_VIP) 366 return_to_32bit(regs, VM86_STI); 367} 368 369static inline void clear_IF(struct kernel_vm86_regs *regs) 370{ 371 VEFLAGS &= ~X86_EFLAGS_VIF; 372} 373 374static inline void clear_TF(struct kernel_vm86_regs *regs) 375{ 376 regs->pt.flags &= ~X86_EFLAGS_TF; 377} 378 379static inline void clear_AC(struct kernel_vm86_regs *regs) 380{ 381 regs->pt.flags &= ~X86_EFLAGS_AC; 382} 383 384/* 385 * It is correct to call set_IF(regs) from the set_vflags_* 386 * functions. However someone forgot to call clear_IF(regs) 387 * in the opposite case. 388 * After the command sequence CLI PUSHF STI POPF you should 389 * end up with interrupts disabled, but you ended up with 390 * interrupts enabled. 391 * ( I was testing my own changes, but the only bug I 392 * could find was in a function I had not changed. ) 393 * [KD] 394 */ 395 396static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 397{ 398 set_flags(VEFLAGS, flags, current->thread.v86mask); 399 set_flags(regs->pt.flags, flags, SAFE_MASK); 400 if (flags & X86_EFLAGS_IF) 401 set_IF(regs); 402 else 403 clear_IF(regs); 404} 405 406static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 407{ 408 set_flags(VFLAGS, flags, current->thread.v86mask); 409 set_flags(regs->pt.flags, flags, SAFE_MASK); 410 if (flags & X86_EFLAGS_IF) 411 set_IF(regs); 412 else 413 clear_IF(regs); 414} 415 416static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 417{ 418 unsigned long flags = regs->pt.flags & RETURN_MASK; 419 420 if (VEFLAGS & X86_EFLAGS_VIF) 421 flags |= X86_EFLAGS_IF; 422 flags |= X86_EFLAGS_IOPL; 423 return flags | (VEFLAGS & current->thread.v86mask); 424} 425 426static inline int is_revectored(int nr, struct revectored_struct *bitmap) 427{ 428 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0" 429 :"=r" (nr) 430 :"m" (*bitmap), "r" (nr)); 431 return nr; 432} 433 434#define val_byte(val, n) (((__u8 *)&val)[n]) 435 436#define pushb(base, ptr, val, err_label) \ 437 do { \ 438 __u8 __val = val; \ 439 ptr--; \ 440 if (put_user(__val, base + ptr) < 0) \ 441 goto err_label; \ 442 } while (0) 443 444#define pushw(base, ptr, val, err_label) \ 445 do { \ 446 __u16 __val = val; \ 447 ptr--; \ 448 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 449 goto err_label; \ 450 ptr--; \ 451 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 452 goto err_label; \ 453 } while (0) 454 455#define pushl(base, ptr, val, err_label) \ 456 do { \ 457 __u32 __val = val; \ 458 ptr--; \ 459 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 460 goto err_label; \ 461 ptr--; \ 462 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 463 goto err_label; \ 464 ptr--; \ 465 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 466 goto err_label; \ 467 ptr--; \ 468 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 469 goto err_label; \ 470 } while (0) 471 472#define popb(base, ptr, err_label) \ 473 ({ \ 474 __u8 __res; \ 475 if (get_user(__res, base + ptr) < 0) \ 476 goto err_label; \ 477 ptr++; \ 478 __res; \ 479 }) 480 481#define popw(base, ptr, err_label) \ 482 ({ \ 483 __u16 __res; \ 484 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 485 goto err_label; \ 486 ptr++; \ 487 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 488 goto err_label; \ 489 ptr++; \ 490 __res; \ 491 }) 492 493#define popl(base, ptr, err_label) \ 494 ({ \ 495 __u32 __res; \ 496 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 497 goto err_label; \ 498 ptr++; \ 499 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 500 goto err_label; \ 501 ptr++; \ 502 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 503 goto err_label; \ 504 ptr++; \ 505 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 506 goto err_label; \ 507 ptr++; \ 508 __res; \ 509 }) 510 511/* There are so many possible reasons for this function to return 512 * VM86_INTx, so adding another doesn't bother me. We can expect 513 * userspace programs to be able to handle it. (Getting a problem 514 * in userspace is always better than an Oops anyway.) [KD] 515 */ 516static void do_int(struct kernel_vm86_regs *regs, int i, 517 unsigned char __user *ssp, unsigned short sp) 518{ 519 unsigned long __user *intr_ptr; 520 unsigned long segoffs; 521 522 if (regs->pt.cs == BIOSSEG) 523 goto cannot_handle; 524 if (is_revectored(i, &KVM86->int_revectored)) 525 goto cannot_handle; 526 if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored)) 527 goto cannot_handle; 528 intr_ptr = (unsigned long __user *) (i << 2); 529 if (get_user(segoffs, intr_ptr)) 530 goto cannot_handle; 531 if ((segoffs >> 16) == BIOSSEG) 532 goto cannot_handle; 533 pushw(ssp, sp, get_vflags(regs), cannot_handle); 534 pushw(ssp, sp, regs->pt.cs, cannot_handle); 535 pushw(ssp, sp, IP(regs), cannot_handle); 536 regs->pt.cs = segoffs >> 16; 537 SP(regs) -= 6; 538 IP(regs) = segoffs & 0xffff; 539 clear_TF(regs); 540 clear_IF(regs); 541 clear_AC(regs); 542 return; 543 544cannot_handle: 545 return_to_32bit(regs, VM86_INTx + (i << 8)); 546} 547 548int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 549{ 550 if (VMPI.is_vm86pus) { 551 if ((trapno == 3) || (trapno == 1)) { 552 KVM86->regs32->ax = VM86_TRAP + (trapno << 8); 553 /* setting this flag forces the code in entry_32.S to 554 the path where we call save_v86_state() and change 555 the stack pointer to KVM86->regs32 */ 556 set_thread_flag(TIF_NOTIFY_RESUME); 557 return 0; 558 } 559 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 560 return 0; 561 } 562 if (trapno != 1) 563 return 1; /* we let this handle by the calling routine */ 564 current->thread.trap_nr = trapno; 565 current->thread.error_code = error_code; 566 force_sig(SIGTRAP, current); 567 return 0; 568} 569 570void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 571{ 572 unsigned char opcode; 573 unsigned char __user *csp; 574 unsigned char __user *ssp; 575 unsigned short ip, sp, orig_flags; 576 int data32, pref_done; 577 578#define CHECK_IF_IN_TRAP \ 579 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \ 580 newflags |= X86_EFLAGS_TF 581#define VM86_FAULT_RETURN do { \ 582 if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ 583 return_to_32bit(regs, VM86_PICRETURN); \ 584 if (orig_flags & X86_EFLAGS_TF) \ 585 handle_vm86_trap(regs, 0, 1); \ 586 return; } while (0) 587 588 orig_flags = *(unsigned short *)®s->pt.flags; 589 590 csp = (unsigned char __user *) (regs->pt.cs << 4); 591 ssp = (unsigned char __user *) (regs->pt.ss << 4); 592 sp = SP(regs); 593 ip = IP(regs); 594 595 data32 = 0; 596 pref_done = 0; 597 do { 598 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 599 case 0x66: /* 32-bit data */ data32 = 1; break; 600 case 0x67: /* 32-bit address */ break; 601 case 0x2e: /* CS */ break; 602 case 0x3e: /* DS */ break; 603 case 0x26: /* ES */ break; 604 case 0x36: /* SS */ break; 605 case 0x65: /* GS */ break; 606 case 0x64: /* FS */ break; 607 case 0xf2: /* repnz */ break; 608 case 0xf3: /* rep */ break; 609 default: pref_done = 1; 610 } 611 } while (!pref_done); 612 613 switch (opcode) { 614 615 /* pushf */ 616 case 0x9c: 617 if (data32) { 618 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 619 SP(regs) -= 4; 620 } else { 621 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 622 SP(regs) -= 2; 623 } 624 IP(regs) = ip; 625 VM86_FAULT_RETURN; 626 627 /* popf */ 628 case 0x9d: 629 { 630 unsigned long newflags; 631 if (data32) { 632 newflags = popl(ssp, sp, simulate_sigsegv); 633 SP(regs) += 4; 634 } else { 635 newflags = popw(ssp, sp, simulate_sigsegv); 636 SP(regs) += 2; 637 } 638 IP(regs) = ip; 639 CHECK_IF_IN_TRAP; 640 if (data32) 641 set_vflags_long(newflags, regs); 642 else 643 set_vflags_short(newflags, regs); 644 645 VM86_FAULT_RETURN; 646 } 647 648 /* int xx */ 649 case 0xcd: { 650 int intno = popb(csp, ip, simulate_sigsegv); 651 IP(regs) = ip; 652 if (VMPI.vm86dbg_active) { 653 if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3]) 654 return_to_32bit(regs, VM86_INTx + (intno << 8)); 655 } 656 do_int(regs, intno, ssp, sp); 657 return; 658 } 659 660 /* iret */ 661 case 0xcf: 662 { 663 unsigned long newip; 664 unsigned long newcs; 665 unsigned long newflags; 666 if (data32) { 667 newip = popl(ssp, sp, simulate_sigsegv); 668 newcs = popl(ssp, sp, simulate_sigsegv); 669 newflags = popl(ssp, sp, simulate_sigsegv); 670 SP(regs) += 12; 671 } else { 672 newip = popw(ssp, sp, simulate_sigsegv); 673 newcs = popw(ssp, sp, simulate_sigsegv); 674 newflags = popw(ssp, sp, simulate_sigsegv); 675 SP(regs) += 6; 676 } 677 IP(regs) = newip; 678 regs->pt.cs = newcs; 679 CHECK_IF_IN_TRAP; 680 if (data32) { 681 set_vflags_long(newflags, regs); 682 } else { 683 set_vflags_short(newflags, regs); 684 } 685 VM86_FAULT_RETURN; 686 } 687 688 /* cli */ 689 case 0xfa: 690 IP(regs) = ip; 691 clear_IF(regs); 692 VM86_FAULT_RETURN; 693 694 /* sti */ 695 /* 696 * Damn. This is incorrect: the 'sti' instruction should actually 697 * enable interrupts after the /next/ instruction. Not good. 698 * 699 * Probably needs some horsing around with the TF flag. Aiee.. 700 */ 701 case 0xfb: 702 IP(regs) = ip; 703 set_IF(regs); 704 VM86_FAULT_RETURN; 705 706 default: 707 return_to_32bit(regs, VM86_UNKNOWN); 708 } 709 710 return; 711 712simulate_sigsegv: 713 /* FIXME: After a long discussion with Stas we finally 714 * agreed, that this is wrong. Here we should 715 * really send a SIGSEGV to the user program. 716 * But how do we create the correct context? We 717 * are inside a general protection fault handler 718 * and has just returned from a page fault handler. 719 * The correct context for the signal handler 720 * should be a mixture of the two, but how do we 721 * get the information? [KD] 722 */ 723 return_to_32bit(regs, VM86_UNKNOWN); 724} 725 726/* ---------------- vm86 special IRQ passing stuff ----------------- */ 727 728#define VM86_IRQNAME "vm86irq" 729 730static struct vm86_irqs { 731 struct task_struct *tsk; 732 int sig; 733} vm86_irqs[16]; 734 735static DEFINE_SPINLOCK(irqbits_lock); 736static int irqbits; 737 738#define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 739 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 740 | (1 << SIGUNUSED)) 741 742static irqreturn_t irq_handler(int intno, void *dev_id) 743{ 744 int irq_bit; 745 unsigned long flags; 746 747 spin_lock_irqsave(&irqbits_lock, flags); 748 irq_bit = 1 << intno; 749 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 750 goto out; 751 irqbits |= irq_bit; 752 if (vm86_irqs[intno].sig) 753 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 754 /* 755 * IRQ will be re-enabled when user asks for the irq (whether 756 * polling or as a result of the signal) 757 */ 758 disable_irq_nosync(intno); 759 spin_unlock_irqrestore(&irqbits_lock, flags); 760 return IRQ_HANDLED; 761 762out: 763 spin_unlock_irqrestore(&irqbits_lock, flags); 764 return IRQ_NONE; 765} 766 767static inline void free_vm86_irq(int irqnumber) 768{ 769 unsigned long flags; 770 771 free_irq(irqnumber, NULL); 772 vm86_irqs[irqnumber].tsk = NULL; 773 774 spin_lock_irqsave(&irqbits_lock, flags); 775 irqbits &= ~(1 << irqnumber); 776 spin_unlock_irqrestore(&irqbits_lock, flags); 777} 778 779void release_vm86_irqs(struct task_struct *task) 780{ 781 int i; 782 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 783 if (vm86_irqs[i].tsk == task) 784 free_vm86_irq(i); 785} 786 787static inline int get_and_reset_irq(int irqnumber) 788{ 789 int bit; 790 unsigned long flags; 791 int ret = 0; 792 793 if (invalid_vm86_irq(irqnumber)) return 0; 794 if (vm86_irqs[irqnumber].tsk != current) return 0; 795 spin_lock_irqsave(&irqbits_lock, flags); 796 bit = irqbits & (1 << irqnumber); 797 irqbits &= ~bit; 798 if (bit) { 799 enable_irq(irqnumber); 800 ret = 1; 801 } 802 803 spin_unlock_irqrestore(&irqbits_lock, flags); 804 return ret; 805} 806 807 808static int do_vm86_irq_handling(int subfunction, int irqnumber) 809{ 810 int ret; 811 switch (subfunction) { 812 case VM86_GET_AND_RESET_IRQ: { 813 return get_and_reset_irq(irqnumber); 814 } 815 case VM86_GET_IRQ_BITS: { 816 return irqbits; 817 } 818 case VM86_REQUEST_IRQ: { 819 int sig = irqnumber >> 8; 820 int irq = irqnumber & 255; 821 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 822 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 823 if (invalid_vm86_irq(irq)) return -EPERM; 824 if (vm86_irqs[irq].tsk) return -EPERM; 825 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 826 if (ret) return ret; 827 vm86_irqs[irq].sig = sig; 828 vm86_irqs[irq].tsk = current; 829 return irq; 830 } 831 case VM86_FREE_IRQ: { 832 if (invalid_vm86_irq(irqnumber)) return -EPERM; 833 if (!vm86_irqs[irqnumber].tsk) return 0; 834 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 835 free_vm86_irq(irqnumber); 836 return 0; 837 } 838 } 839 return -EINVAL; 840} 841 842