vm86_32.c revision 975e5f45500dff6d15c0001bb662e9aac0ce0076
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 */ 92static 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 */ 110static 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 126struct 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 166static 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); 191out: 192 flush_tlb(); 193} 194 195 196 197static int do_vm86_irq_handling(int subfunction, int irqnumber); 198static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk); 199 200int sys_vm86old(struct pt_regs *regs) 201{ 202 struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs->bx; 203 struct kernel_vm86_struct info; /* declare this _on top_, 204 * this avoids wasting of stack space. 205 * This remains on the stack until we 206 * return to 32 bit user space. 207 */ 208 struct task_struct *tsk; 209 int tmp, ret = -EPERM; 210 211 tsk = current; 212 if (tsk->thread.saved_sp0) 213 goto out; 214 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 215 offsetof(struct kernel_vm86_struct, vm86plus) - 216 sizeof(info.regs)); 217 ret = -EFAULT; 218 if (tmp) 219 goto out; 220 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus); 221 info.regs32 = regs; 222 tsk->thread.vm86_info = v86; 223 do_sys_vm86(&info, tsk); 224 ret = 0; /* we never return here */ 225out: 226 return ret; 227} 228 229 230int sys_vm86(struct pt_regs *regs) 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, ret; 239 struct vm86plus_struct __user *v86; 240 241 tsk = current; 242 switch (regs->bx) { 243 case VM86_REQUEST_IRQ: 244 case VM86_FREE_IRQ: 245 case VM86_GET_IRQ_BITS: 246 case VM86_GET_AND_RESET_IRQ: 247 ret = do_vm86_irq_handling(regs->bx, (int)regs->cx); 248 goto out; 249 case VM86_PLUS_INSTALL_CHECK: 250 /* 251 * NOTE: on old vm86 stuff this will return the error 252 * from access_ok(), because the subfunction is 253 * interpreted as (invalid) address to vm86_struct. 254 * So the installation check works. 255 */ 256 ret = 0; 257 goto out; 258 } 259 260 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 261 ret = -EPERM; 262 if (tsk->thread.saved_sp0) 263 goto out; 264 v86 = (struct vm86plus_struct __user *)regs->cx; 265 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, 266 offsetof(struct kernel_vm86_struct, regs32) - 267 sizeof(info.regs)); 268 ret = -EFAULT; 269 if (tmp) 270 goto out; 271 info.regs32 = regs; 272 info.vm86plus.is_vm86pus = 1; 273 tsk->thread.vm86_info = (struct vm86_struct __user *)v86; 274 do_sys_vm86(&info, tsk); 275 ret = 0; /* we never return here */ 276out: 277 return ret; 278} 279 280 281static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk) 282{ 283 struct tss_struct *tss; 284/* 285 * make sure the vm86() system call doesn't try to do anything silly 286 */ 287 info->regs.pt.ds = 0; 288 info->regs.pt.es = 0; 289 info->regs.pt.fs = 0; 290 291/* we are clearing gs later just before "jmp resume_userspace", 292 * because it is not saved/restored. 293 */ 294 295/* 296 * The flags register is also special: we cannot trust that the user 297 * has set it up safely, so this makes sure interrupt etc flags are 298 * inherited from protected mode. 299 */ 300 VEFLAGS = info->regs.pt.flags; 301 info->regs.pt.flags &= SAFE_MASK; 302 info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK; 303 info->regs.pt.flags |= X86_VM_MASK; 304 305 switch (info->cpu_type) { 306 case CPU_286: 307 tsk->thread.v86mask = 0; 308 break; 309 case CPU_386: 310 tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 311 break; 312 case CPU_486: 313 tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 314 break; 315 default: 316 tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 317 break; 318 } 319 320/* 321 * Save old state, set default return value (%ax) to 0 (VM86_SIGNAL) 322 */ 323 info->regs32->ax = VM86_SIGNAL; 324 tsk->thread.saved_sp0 = tsk->thread.sp0; 325 tsk->thread.saved_fs = info->regs32->fs; 326 tsk->thread.saved_gs = get_user_gs(info->regs32); 327 328 tss = &per_cpu(init_tss, get_cpu()); 329 tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0; 330 if (cpu_has_sep) 331 tsk->thread.sysenter_cs = 0; 332 load_sp0(tss, &tsk->thread); 333 put_cpu(); 334 335 tsk->thread.screen_bitmap = info->screen_bitmap; 336 if (info->flags & VM86_SCREEN_BITMAP) 337 mark_screen_rdonly(tsk->mm); 338 339 /*call audit_syscall_exit since we do not exit via the normal paths */ 340 if (unlikely(current->audit_context)) 341 audit_syscall_exit(AUDITSC_RESULT(0), 0); 342 343 __asm__ __volatile__( 344 "movl %0,%%esp\n\t" 345 "movl %1,%%ebp\n\t" 346 "mov %2, %%gs\n\t" 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 353static 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 365static 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 372static inline void clear_IF(struct kernel_vm86_regs *regs) 373{ 374 VEFLAGS &= ~X86_EFLAGS_VIF; 375} 376 377static inline void clear_TF(struct kernel_vm86_regs *regs) 378{ 379 regs->pt.flags &= ~X86_EFLAGS_TF; 380} 381 382static 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 399static 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 409static 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 419static 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 429static 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 */ 519static 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 547cannot_handle: 548 return_to_32bit(regs, VM86_INTx + (i << 8)); 549} 550 551int 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 return_to_32bit(regs, VM86_TRAP + (trapno << 8)); 556 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 557 return 0; 558 } 559 if (trapno != 1) 560 return 1; /* we let this handle by the calling routine */ 561 current->thread.trap_no = trapno; 562 current->thread.error_code = error_code; 563 force_sig(SIGTRAP, current); 564 return 0; 565} 566 567void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 568{ 569 unsigned char opcode; 570 unsigned char __user *csp; 571 unsigned char __user *ssp; 572 unsigned short ip, sp, orig_flags; 573 int data32, pref_done; 574 575#define CHECK_IF_IN_TRAP \ 576 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \ 577 newflags |= X86_EFLAGS_TF 578#define VM86_FAULT_RETURN do { \ 579 if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ 580 return_to_32bit(regs, VM86_PICRETURN); \ 581 if (orig_flags & X86_EFLAGS_TF) \ 582 handle_vm86_trap(regs, 0, 1); \ 583 return; } while (0) 584 585 orig_flags = *(unsigned short *)®s->pt.flags; 586 587 csp = (unsigned char __user *) (regs->pt.cs << 4); 588 ssp = (unsigned char __user *) (regs->pt.ss << 4); 589 sp = SP(regs); 590 ip = IP(regs); 591 592 data32 = 0; 593 pref_done = 0; 594 do { 595 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 596 case 0x66: /* 32-bit data */ data32 = 1; break; 597 case 0x67: /* 32-bit address */ break; 598 case 0x2e: /* CS */ break; 599 case 0x3e: /* DS */ break; 600 case 0x26: /* ES */ break; 601 case 0x36: /* SS */ break; 602 case 0x65: /* GS */ break; 603 case 0x64: /* FS */ break; 604 case 0xf2: /* repnz */ break; 605 case 0xf3: /* rep */ break; 606 default: pref_done = 1; 607 } 608 } while (!pref_done); 609 610 switch (opcode) { 611 612 /* pushf */ 613 case 0x9c: 614 if (data32) { 615 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 616 SP(regs) -= 4; 617 } else { 618 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 619 SP(regs) -= 2; 620 } 621 IP(regs) = ip; 622 VM86_FAULT_RETURN; 623 624 /* popf */ 625 case 0x9d: 626 { 627 unsigned long newflags; 628 if (data32) { 629 newflags = popl(ssp, sp, simulate_sigsegv); 630 SP(regs) += 4; 631 } else { 632 newflags = popw(ssp, sp, simulate_sigsegv); 633 SP(regs) += 2; 634 } 635 IP(regs) = ip; 636 CHECK_IF_IN_TRAP; 637 if (data32) 638 set_vflags_long(newflags, regs); 639 else 640 set_vflags_short(newflags, regs); 641 642 VM86_FAULT_RETURN; 643 } 644 645 /* int xx */ 646 case 0xcd: { 647 int intno = popb(csp, ip, simulate_sigsegv); 648 IP(regs) = ip; 649 if (VMPI.vm86dbg_active) { 650 if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3]) 651 return_to_32bit(regs, VM86_INTx + (intno << 8)); 652 } 653 do_int(regs, intno, ssp, sp); 654 return; 655 } 656 657 /* iret */ 658 case 0xcf: 659 { 660 unsigned long newip; 661 unsigned long newcs; 662 unsigned long newflags; 663 if (data32) { 664 newip = popl(ssp, sp, simulate_sigsegv); 665 newcs = popl(ssp, sp, simulate_sigsegv); 666 newflags = popl(ssp, sp, simulate_sigsegv); 667 SP(regs) += 12; 668 } else { 669 newip = popw(ssp, sp, simulate_sigsegv); 670 newcs = popw(ssp, sp, simulate_sigsegv); 671 newflags = popw(ssp, sp, simulate_sigsegv); 672 SP(regs) += 6; 673 } 674 IP(regs) = newip; 675 regs->pt.cs = newcs; 676 CHECK_IF_IN_TRAP; 677 if (data32) { 678 set_vflags_long(newflags, regs); 679 } else { 680 set_vflags_short(newflags, regs); 681 } 682 VM86_FAULT_RETURN; 683 } 684 685 /* cli */ 686 case 0xfa: 687 IP(regs) = ip; 688 clear_IF(regs); 689 VM86_FAULT_RETURN; 690 691 /* sti */ 692 /* 693 * Damn. This is incorrect: the 'sti' instruction should actually 694 * enable interrupts after the /next/ instruction. Not good. 695 * 696 * Probably needs some horsing around with the TF flag. Aiee.. 697 */ 698 case 0xfb: 699 IP(regs) = ip; 700 set_IF(regs); 701 VM86_FAULT_RETURN; 702 703 default: 704 return_to_32bit(regs, VM86_UNKNOWN); 705 } 706 707 return; 708 709simulate_sigsegv: 710 /* FIXME: After a long discussion with Stas we finally 711 * agreed, that this is wrong. Here we should 712 * really send a SIGSEGV to the user program. 713 * But how do we create the correct context? We 714 * are inside a general protection fault handler 715 * and has just returned from a page fault handler. 716 * The correct context for the signal handler 717 * should be a mixture of the two, but how do we 718 * get the information? [KD] 719 */ 720 return_to_32bit(regs, VM86_UNKNOWN); 721} 722 723/* ---------------- vm86 special IRQ passing stuff ----------------- */ 724 725#define VM86_IRQNAME "vm86irq" 726 727static struct vm86_irqs { 728 struct task_struct *tsk; 729 int sig; 730} vm86_irqs[16]; 731 732static DEFINE_SPINLOCK(irqbits_lock); 733static int irqbits; 734 735#define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 736 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 737 | (1 << SIGUNUSED)) 738 739static irqreturn_t irq_handler(int intno, void *dev_id) 740{ 741 int irq_bit; 742 unsigned long flags; 743 744 spin_lock_irqsave(&irqbits_lock, flags); 745 irq_bit = 1 << intno; 746 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 747 goto out; 748 irqbits |= irq_bit; 749 if (vm86_irqs[intno].sig) 750 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 751 /* 752 * IRQ will be re-enabled when user asks for the irq (whether 753 * polling or as a result of the signal) 754 */ 755 disable_irq_nosync(intno); 756 spin_unlock_irqrestore(&irqbits_lock, flags); 757 return IRQ_HANDLED; 758 759out: 760 spin_unlock_irqrestore(&irqbits_lock, flags); 761 return IRQ_NONE; 762} 763 764static inline void free_vm86_irq(int irqnumber) 765{ 766 unsigned long flags; 767 768 free_irq(irqnumber, NULL); 769 vm86_irqs[irqnumber].tsk = NULL; 770 771 spin_lock_irqsave(&irqbits_lock, flags); 772 irqbits &= ~(1 << irqnumber); 773 spin_unlock_irqrestore(&irqbits_lock, flags); 774} 775 776void release_vm86_irqs(struct task_struct *task) 777{ 778 int i; 779 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 780 if (vm86_irqs[i].tsk == task) 781 free_vm86_irq(i); 782} 783 784static inline int get_and_reset_irq(int irqnumber) 785{ 786 int bit; 787 unsigned long flags; 788 int ret = 0; 789 790 if (invalid_vm86_irq(irqnumber)) return 0; 791 if (vm86_irqs[irqnumber].tsk != current) return 0; 792 spin_lock_irqsave(&irqbits_lock, flags); 793 bit = irqbits & (1 << irqnumber); 794 irqbits &= ~bit; 795 if (bit) { 796 enable_irq(irqnumber); 797 ret = 1; 798 } 799 800 spin_unlock_irqrestore(&irqbits_lock, flags); 801 return ret; 802} 803 804 805static int do_vm86_irq_handling(int subfunction, int irqnumber) 806{ 807 int ret; 808 switch (subfunction) { 809 case VM86_GET_AND_RESET_IRQ: { 810 return get_and_reset_irq(irqnumber); 811 } 812 case VM86_GET_IRQ_BITS: { 813 return irqbits; 814 } 815 case VM86_REQUEST_IRQ: { 816 int sig = irqnumber >> 8; 817 int irq = irqnumber & 255; 818 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 819 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 820 if (invalid_vm86_irq(irq)) return -EPERM; 821 if (vm86_irqs[irq].tsk) return -EPERM; 822 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 823 if (ret) return ret; 824 vm86_irqs[irq].sig = sig; 825 vm86_irqs[irq].tsk = current; 826 return irq; 827 } 828 case VM86_FREE_IRQ: { 829 if (invalid_vm86_irq(irqnumber)) return -EPERM; 830 if (!vm86_irqs[irqnumber].tsk) return 0; 831 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 832 free_vm86_irq(irqnumber); 833 return 0; 834 } 835 } 836 return -EINVAL; 837} 838 839