1 /* 2 * linux/arch/i386/kernel/signal.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 6 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 7 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes 8 */ 9 10 #include <linux/sched.h> 11 #include <linux/mm.h> 12 #include <linux/smp.h> 13 #include <linux/kernel.h> 14 #include <linux/signal.h> 15 #include <linux/errno.h> 16 #include <linux/wait.h> 17 #include <linux/unistd.h> 18 #include <linux/stddef.h> 19 #include <linux/personality.h> 20 #include <linux/suspend.h> 21 #include <linux/ptrace.h> 22 #include <linux/elf.h> 23 #include <linux/binfmts.h> 24 #include <asm/processor.h> 25 #include <asm/ucontext.h> 26 #include <asm/uaccess.h> 27 #include <asm/i387.h> 28 #include "sigframe_32.h" 29 30 #define DEBUG_SIG 0 31 32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 33 34 /* 35 * Atomically swap in the new signal mask, and wait for a signal. 36 */ 37 asmlinkage int 38 sys_sigsuspend(int history0, int history1, old_sigset_t mask) 39 { 40 mask &= _BLOCKABLE; 41 spin_lock_irq(¤t->sighand->siglock); 42 current->saved_sigmask = current->blocked; 43 siginitset(¤t->blocked, mask); 44 recalc_sigpending(); 45 spin_unlock_irq(¤t->sighand->siglock); 46 47 current->state = TASK_INTERRUPTIBLE; 48 schedule(); 49 set_thread_flag(TIF_RESTORE_SIGMASK); 50 return -ERESTARTNOHAND; 51 } 52 53 asmlinkage int 54 sys_sigaction(int sig, const struct old_sigaction __user *act, 55 struct old_sigaction __user *oact) 56 { 57 struct k_sigaction new_ka, old_ka; 58 int ret; 59 60 if (act) { 61 old_sigset_t mask; 62 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 63 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 64 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer)) 65 return -EFAULT; 66 __get_user(new_ka.sa.sa_flags, &act->sa_flags); 67 __get_user(mask, &act->sa_mask); 68 siginitset(&new_ka.sa.sa_mask, mask); 69 } 70 71 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 72 73 if (!ret && oact) { 74 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 75 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 76 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer)) 77 return -EFAULT; 78 __put_user(old_ka.sa.sa_flags, &oact->sa_flags); 79 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask); 80 } 81 82 return ret; 83 } 84 85 asmlinkage int 86 sys_sigaltstack(unsigned long ebx) 87 { 88 /* This is needed to make gcc realize it doesn't own the "struct pt_regs" */ 89 struct pt_regs *regs = (struct pt_regs *)&ebx; 90 const stack_t __user *uss = (const stack_t __user *)ebx; 91 stack_t __user *uoss = (stack_t __user *)regs->ecx; 92 93 return do_sigaltstack(uss, uoss, regs->esp); 94 } 95 96 97 /* 98 * Do a signal return; undo the signal stack. 99 */ 100 101 static int 102 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax) 103 { 104 unsigned int err = 0; 105 106 /* Always make any pending restarted system calls return -EINTR */ 107 current_thread_info()->restart_block.fn = do_no_restart_syscall; 108 109 #define COPY(x) err |= __get_user(regs->x, &sc->x) 110 111 #define COPY_SEG(seg) \ 112 { unsigned short tmp; \ 113 err |= __get_user(tmp, &sc->seg); \ 114 regs->x##seg = tmp; } 115 116 #define COPY_SEG_STRICT(seg) \ 117 { unsigned short tmp; \ 118 err |= __get_user(tmp, &sc->seg); \ 119 regs->x##seg = tmp|3; } 120 121 #define GET_SEG(seg) \ 122 { unsigned short tmp; \ 123 err |= __get_user(tmp, &sc->seg); \ 124 loadsegment(seg,tmp); } 125 126 #define FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_RF | \ 127 X86_EFLAGS_OF | X86_EFLAGS_DF | \ 128 X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \ 129 X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF) 130 131 GET_SEG(gs); 132 COPY_SEG(fs); 133 COPY_SEG(es); 134 COPY_SEG(ds); 135 COPY(edi); 136 COPY(esi); 137 COPY(ebp); 138 COPY(esp); 139 COPY(ebx); 140 COPY(edx); 141 COPY(ecx); 142 COPY(eip); 143 COPY_SEG_STRICT(cs); 144 COPY_SEG_STRICT(ss); 145 146 { 147 unsigned int tmpflags; 148 err |= __get_user(tmpflags, &sc->eflags); 149 regs->eflags = (regs->eflags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 150 regs->orig_eax = -1; /* disable syscall checks */ 151 } 152 153 { 154 struct _fpstate __user * buf; 155 err |= __get_user(buf, &sc->fpstate); 156 if (buf) { 157 if (!access_ok(VERIFY_READ, buf, sizeof(*buf))) 158 goto badframe; 159 err |= restore_i387(buf); 160 } else { 161 struct task_struct *me = current; 162 if (used_math()) { 163 clear_fpu(me); 164 clear_used_math(); 165 } 166 } 167 } 168 169 err |= __get_user(*peax, &sc->eax); 170 return err; 171 172 badframe: 173 return 1; 174 } 175 176 asmlinkage int sys_sigreturn(unsigned long __unused) 177 { 178 struct pt_regs *regs = (struct pt_regs *) &__unused; 179 struct sigframe __user *frame = (struct sigframe __user *)(regs->esp - 8); 180 sigset_t set; 181 int eax; 182 183 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 184 goto badframe; 185 if (__get_user(set.sig[0], &frame->sc.oldmask) 186 || (_NSIG_WORDS > 1 187 && __copy_from_user(&set.sig[1], &frame->extramask, 188 sizeof(frame->extramask)))) 189 goto badframe; 190 191 sigdelsetmask(&set, ~_BLOCKABLE); 192 spin_lock_irq(¤t->sighand->siglock); 193 current->blocked = set; 194 recalc_sigpending(); 195 spin_unlock_irq(¤t->sighand->siglock); 196 197 if (restore_sigcontext(regs, &frame->sc, &eax)) 198 goto badframe; 199 return eax; 200 201 badframe: 202 if (show_unhandled_signals && printk_ratelimit()) 203 printk("%s%s[%d] bad frame in sigreturn frame:%p eip:%lx" 204 " esp:%lx oeax:%lx\n", 205 current->pid > 1 ? KERN_INFO : KERN_EMERG, 206 current->comm, current->pid, frame, regs->eip, 207 regs->esp, regs->orig_eax); 208 209 force_sig(SIGSEGV, current); 210 return 0; 211 } 212 213 asmlinkage int sys_rt_sigreturn(unsigned long __unused) 214 { 215 struct pt_regs *regs = (struct pt_regs *) &__unused; 216 struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->esp - 4); 217 sigset_t set; 218 int eax; 219 220 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 221 goto badframe; 222 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 223 goto badframe; 224 225 sigdelsetmask(&set, ~_BLOCKABLE); 226 spin_lock_irq(¤t->sighand->siglock); 227 current->blocked = set; 228 recalc_sigpending(); 229 spin_unlock_irq(¤t->sighand->siglock); 230 231 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax)) 232 goto badframe; 233 234 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT) 235 goto badframe; 236 237 return eax; 238 239 badframe: 240 force_sig(SIGSEGV, current); 241 return 0; 242 } 243 244 /* 245 * Set up a signal frame. 246 */ 247 248 static int 249 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate, 250 struct pt_regs *regs, unsigned long mask) 251 { 252 int tmp, err = 0; 253 254 err |= __put_user(regs->xfs, (unsigned int __user *)&sc->fs); 255 savesegment(gs, tmp); 256 err |= __put_user(tmp, (unsigned int __user *)&sc->gs); 257 258 err |= __put_user(regs->xes, (unsigned int __user *)&sc->es); 259 err |= __put_user(regs->xds, (unsigned int __user *)&sc->ds); 260 err |= __put_user(regs->edi, &sc->edi); 261 err |= __put_user(regs->esi, &sc->esi); 262 err |= __put_user(regs->ebp, &sc->ebp); 263 err |= __put_user(regs->esp, &sc->esp); 264 err |= __put_user(regs->ebx, &sc->ebx); 265 err |= __put_user(regs->edx, &sc->edx); 266 err |= __put_user(regs->ecx, &sc->ecx); 267 err |= __put_user(regs->eax, &sc->eax); 268 err |= __put_user(current->thread.trap_no, &sc->trapno); 269 err |= __put_user(current->thread.error_code, &sc->err); 270 err |= __put_user(regs->eip, &sc->eip); 271 err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs); 272 err |= __put_user(regs->eflags, &sc->eflags); 273 err |= __put_user(regs->esp, &sc->esp_at_signal); 274 err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss); 275 276 tmp = save_i387(fpstate); 277 if (tmp < 0) 278 err = 1; 279 else 280 err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate); 281 282 /* non-iBCS2 extensions.. */ 283 err |= __put_user(mask, &sc->oldmask); 284 err |= __put_user(current->thread.cr2, &sc->cr2); 285 286 return err; 287 } 288 289 /* 290 * Determine which stack to use.. 291 */ 292 static inline void __user * 293 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 294 { 295 unsigned long esp; 296 297 /* Default to using normal stack */ 298 esp = regs->esp; 299 300 /* This is the X/Open sanctioned signal stack switching. */ 301 if (ka->sa.sa_flags & SA_ONSTACK) { 302 if (sas_ss_flags(esp) == 0) 303 esp = current->sas_ss_sp + current->sas_ss_size; 304 } 305 306 /* This is the legacy signal stack switching. */ 307 else if ((regs->xss & 0xffff) != __USER_DS && 308 !(ka->sa.sa_flags & SA_RESTORER) && 309 ka->sa.sa_restorer) { 310 esp = (unsigned long) ka->sa.sa_restorer; 311 } 312 313 esp -= frame_size; 314 /* Align the stack pointer according to the i386 ABI, 315 * i.e. so that on function entry ((sp + 4) & 15) == 0. */ 316 esp = ((esp + 4) & -16ul) - 4; 317 return (void __user *) esp; 318 } 319 320 /* These symbols are defined with the addresses in the vsyscall page. 321 See vsyscall-sigreturn.S. */ 322 extern void __user __kernel_sigreturn; 323 extern void __user __kernel_rt_sigreturn; 324 325 static int setup_frame(int sig, struct k_sigaction *ka, 326 sigset_t *set, struct pt_regs * regs) 327 { 328 void __user *restorer; 329 struct sigframe __user *frame; 330 int err = 0; 331 int usig; 332 333 frame = get_sigframe(ka, regs, sizeof(*frame)); 334 335 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 336 goto give_sigsegv; 337 338 usig = current_thread_info()->exec_domain 339 && current_thread_info()->exec_domain->signal_invmap 340 && sig < 32 341 ? current_thread_info()->exec_domain->signal_invmap[sig] 342 : sig; 343 344 err = __put_user(usig, &frame->sig); 345 if (err) 346 goto give_sigsegv; 347 348 err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]); 349 if (err) 350 goto give_sigsegv; 351 352 if (_NSIG_WORDS > 1) { 353 err = __copy_to_user(&frame->extramask, &set->sig[1], 354 sizeof(frame->extramask)); 355 if (err) 356 goto give_sigsegv; 357 } 358 359 if (current->binfmt->hasvdso) 360 restorer = (void *)VDSO_SYM(&__kernel_sigreturn); 361 else 362 restorer = (void *)&frame->retcode; 363 if (ka->sa.sa_flags & SA_RESTORER) 364 restorer = ka->sa.sa_restorer; 365 366 /* Set up to return from userspace. */ 367 err |= __put_user(restorer, &frame->pretcode); 368 369 /* 370 * This is popl %eax ; movl $,%eax ; int $0x80 371 * 372 * WE DO NOT USE IT ANY MORE! It's only left here for historical 373 * reasons and because gdb uses it as a signature to notice 374 * signal handler stack frames. 375 */ 376 err |= __put_user(0xb858, (short __user *)(frame->retcode+0)); 377 err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2)); 378 err |= __put_user(0x80cd, (short __user *)(frame->retcode+6)); 379 380 if (err) 381 goto give_sigsegv; 382 383 /* Set up registers for signal handler */ 384 regs->esp = (unsigned long) frame; 385 regs->eip = (unsigned long) ka->sa.sa_handler; 386 regs->eax = (unsigned long) sig; 387 regs->edx = (unsigned long) 0; 388 regs->ecx = (unsigned long) 0; 389 390 set_fs(USER_DS); 391 regs->xds = __USER_DS; 392 regs->xes = __USER_DS; 393 regs->xss = __USER_DS; 394 regs->xcs = __USER_CS; 395 396 /* 397 * Clear TF when entering the signal handler, but 398 * notify any tracer that was single-stepping it. 399 * The tracer may want to single-step inside the 400 * handler too. 401 */ 402 regs->eflags &= ~TF_MASK; 403 if (test_thread_flag(TIF_SINGLESTEP)) 404 ptrace_notify(SIGTRAP); 405 406 #if DEBUG_SIG 407 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 408 current->comm, current->pid, frame, regs->eip, frame->pretcode); 409 #endif 410 411 return 0; 412 413 give_sigsegv: 414 force_sigsegv(sig, current); 415 return -EFAULT; 416 } 417 418 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 419 sigset_t *set, struct pt_regs * regs) 420 { 421 void __user *restorer; 422 struct rt_sigframe __user *frame; 423 int err = 0; 424 int usig; 425 426 frame = get_sigframe(ka, regs, sizeof(*frame)); 427 428 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 429 goto give_sigsegv; 430 431 usig = current_thread_info()->exec_domain 432 && current_thread_info()->exec_domain->signal_invmap 433 && sig < 32 434 ? current_thread_info()->exec_domain->signal_invmap[sig] 435 : sig; 436 437 err |= __put_user(usig, &frame->sig); 438 err |= __put_user(&frame->info, &frame->pinfo); 439 err |= __put_user(&frame->uc, &frame->puc); 440 err |= copy_siginfo_to_user(&frame->info, info); 441 if (err) 442 goto give_sigsegv; 443 444 /* Create the ucontext. */ 445 err |= __put_user(0, &frame->uc.uc_flags); 446 err |= __put_user(0, &frame->uc.uc_link); 447 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 448 err |= __put_user(sas_ss_flags(regs->esp), 449 &frame->uc.uc_stack.ss_flags); 450 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 451 err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate, 452 regs, set->sig[0]); 453 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 454 if (err) 455 goto give_sigsegv; 456 457 /* Set up to return from userspace. */ 458 restorer = (void *)VDSO_SYM(&__kernel_rt_sigreturn); 459 if (ka->sa.sa_flags & SA_RESTORER) 460 restorer = ka->sa.sa_restorer; 461 err |= __put_user(restorer, &frame->pretcode); 462 463 /* 464 * This is movl $,%eax ; int $0x80 465 * 466 * WE DO NOT USE IT ANY MORE! It's only left here for historical 467 * reasons and because gdb uses it as a signature to notice 468 * signal handler stack frames. 469 */ 470 err |= __put_user(0xb8, (char __user *)(frame->retcode+0)); 471 err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1)); 472 err |= __put_user(0x80cd, (short __user *)(frame->retcode+5)); 473 474 if (err) 475 goto give_sigsegv; 476 477 /* Set up registers for signal handler */ 478 regs->esp = (unsigned long) frame; 479 regs->eip = (unsigned long) ka->sa.sa_handler; 480 regs->eax = (unsigned long) usig; 481 regs->edx = (unsigned long) &frame->info; 482 regs->ecx = (unsigned long) &frame->uc; 483 484 set_fs(USER_DS); 485 regs->xds = __USER_DS; 486 regs->xes = __USER_DS; 487 regs->xss = __USER_DS; 488 regs->xcs = __USER_CS; 489 490 /* 491 * Clear TF when entering the signal handler, but 492 * notify any tracer that was single-stepping it. 493 * The tracer may want to single-step inside the 494 * handler too. 495 */ 496 regs->eflags &= ~TF_MASK; 497 if (test_thread_flag(TIF_SINGLESTEP)) 498 ptrace_notify(SIGTRAP); 499 500 #if DEBUG_SIG 501 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 502 current->comm, current->pid, frame, regs->eip, frame->pretcode); 503 #endif 504 505 return 0; 506 507 give_sigsegv: 508 force_sigsegv(sig, current); 509 return -EFAULT; 510 } 511 512 /* 513 * OK, we're invoking a handler 514 */ 515 516 static int 517 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 518 sigset_t *oldset, struct pt_regs * regs) 519 { 520 int ret; 521 522 /* Are we from a system call? */ 523 if (regs->orig_eax >= 0) { 524 /* If so, check system call restarting.. */ 525 switch (regs->eax) { 526 case -ERESTART_RESTARTBLOCK: 527 case -ERESTARTNOHAND: 528 regs->eax = -EINTR; 529 break; 530 531 case -ERESTARTSYS: 532 if (!(ka->sa.sa_flags & SA_RESTART)) { 533 regs->eax = -EINTR; 534 break; 535 } 536 /* fallthrough */ 537 case -ERESTARTNOINTR: 538 regs->eax = regs->orig_eax; 539 regs->eip -= 2; 540 } 541 } 542 543 /* 544 * If TF is set due to a debugger (PT_DTRACE), clear the TF flag so 545 * that register information in the sigcontext is correct. 546 */ 547 if (unlikely(regs->eflags & TF_MASK) 548 && likely(current->ptrace & PT_DTRACE)) { 549 current->ptrace &= ~PT_DTRACE; 550 regs->eflags &= ~TF_MASK; 551 } 552 553 /* Set up the stack frame */ 554 if (ka->sa.sa_flags & SA_SIGINFO) 555 ret = setup_rt_frame(sig, ka, info, oldset, regs); 556 else 557 ret = setup_frame(sig, ka, oldset, regs); 558 559 if (ret == 0) { 560 spin_lock_irq(¤t->sighand->siglock); 561 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 562 if (!(ka->sa.sa_flags & SA_NODEFER)) 563 sigaddset(¤t->blocked,sig); 564 recalc_sigpending(); 565 spin_unlock_irq(¤t->sighand->siglock); 566 } 567 568 return ret; 569 } 570 571 /* 572 * Note that 'init' is a special process: it doesn't get signals it doesn't 573 * want to handle. Thus you cannot kill init even with a SIGKILL even by 574 * mistake. 575 */ 576 static void fastcall do_signal(struct pt_regs *regs) 577 { 578 siginfo_t info; 579 int signr; 580 struct k_sigaction ka; 581 sigset_t *oldset; 582 583 /* 584 * We want the common case to go fast, which 585 * is why we may in certain cases get here from 586 * kernel mode. Just return without doing anything 587 * if so. vm86 regs switched out by assembly code 588 * before reaching here, so testing against kernel 589 * CS suffices. 590 */ 591 if (!user_mode(regs)) 592 return; 593 594 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 595 oldset = ¤t->saved_sigmask; 596 else 597 oldset = ¤t->blocked; 598 599 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 600 if (signr > 0) { 601 /* Reenable any watchpoints before delivering the 602 * signal to user space. The processor register will 603 * have been cleared if the watchpoint triggered 604 * inside the kernel. 605 */ 606 if (unlikely(current->thread.debugreg[7])) 607 set_debugreg(current->thread.debugreg[7], 7); 608 609 /* Whee! Actually deliver the signal. */ 610 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 611 /* a signal was successfully delivered; the saved 612 * sigmask will have been stored in the signal frame, 613 * and will be restored by sigreturn, so we can simply 614 * clear the TIF_RESTORE_SIGMASK flag */ 615 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 616 clear_thread_flag(TIF_RESTORE_SIGMASK); 617 } 618 619 return; 620 } 621 622 /* Did we come from a system call? */ 623 if (regs->orig_eax >= 0) { 624 /* Restart the system call - no handlers present */ 625 switch (regs->eax) { 626 case -ERESTARTNOHAND: 627 case -ERESTARTSYS: 628 case -ERESTARTNOINTR: 629 regs->eax = regs->orig_eax; 630 regs->eip -= 2; 631 break; 632 633 case -ERESTART_RESTARTBLOCK: 634 regs->eax = __NR_restart_syscall; 635 regs->eip -= 2; 636 break; 637 } 638 } 639 640 /* if there's no signal to deliver, we just put the saved sigmask 641 * back */ 642 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 643 clear_thread_flag(TIF_RESTORE_SIGMASK); 644 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 645 } 646 } 647 648 /* 649 * notification of userspace execution resumption 650 * - triggered by the TIF_WORK_MASK flags 651 */ 652 __attribute__((regparm(3))) 653 void do_notify_resume(struct pt_regs *regs, void *_unused, 654 __u32 thread_info_flags) 655 { 656 /* Pending single-step? */ 657 if (thread_info_flags & _TIF_SINGLESTEP) { 658 regs->eflags |= TF_MASK; 659 clear_thread_flag(TIF_SINGLESTEP); 660 } 661 662 /* deal with pending signal delivery */ 663 if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK)) 664 do_signal(regs); 665 666 clear_thread_flag(TIF_IRET); 667 } 668