arch/x86/kernel/signal_32.c

   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(&current->sighand->siglock);
  42         current->saved_sigmask = current->blocked;
  43         siginitset(&current->blocked, mask);
  44         recalc_sigpending();
  45         spin_unlock_irq(&current->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(&current->sighand->siglock);
 193         current->blocked = set;
 194         recalc_sigpending();
 195         spin_unlock_irq(&current->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(&current->sighand->siglock);
 227         current->blocked = set;
 228         recalc_sigpending();
 229         spin_unlock_irq(&current->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(&current->sighand->siglock);
 561                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 562                 if (!(ka->sa.sa_flags & SA_NODEFER))
 563                         sigaddset(&current->blocked,sig);
 564                 recalc_sigpending();
 565                 spin_unlock_irq(&current->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 = &current->saved_sigmask;
 596         else
 597                 oldset = &current->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, &current->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 }