arch/i386/kernel/signal.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/smp_lock.h>
  14 #include <linux/kernel.h>
  15 #include <linux/signal.h>
  16 #include <linux/errno.h>
  17 #include <linux/wait.h>
  18 #include <linux/unistd.h>
  19 #include <linux/stddef.h>
  20 #include <linux/personality.h>
  21 #include <linux/suspend.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/elf.h>
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/i387.h>
  28 #include "sigframe.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         GET_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         force_sig(SIGSEGV, current);
 203         return 0;
 204 }
 205
 206 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 207 {
 208         struct pt_regs *regs = (struct pt_regs *) &__unused;
 209         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->esp - 4);
 210         sigset_t set;
 211         int eax;
 212
 213         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 214                 goto badframe;
 215         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 216                 goto badframe;
 217
 218         sigdelsetmask(&set, ~_BLOCKABLE);
 219         spin_lock_irq(&current->sighand->siglock);
 220         current->blocked = set;
 221         recalc_sigpending();
 222         spin_unlock_irq(&current->sighand->siglock);
 223
 224         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 225                 goto badframe;
 226
 227         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT)
 228                 goto badframe;
 229
 230         return eax;
 231
 232 badframe:
 233         force_sig(SIGSEGV, current);
 234         return 0;
 235 }
 236
 237 /*
 238  * Set up a signal frame.
 239  */
 240
 241 static int
 242 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 243                  struct pt_regs *regs, unsigned long mask)
 244 {
 245         int tmp, err = 0;
 246
 247         tmp = 0;
 248         savesegment(gs, tmp);
 249         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 250         savesegment(fs, tmp);
 251         err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
 252
 253         err |= __put_user(regs->xes, (unsigned int __user *)&sc->es);
 254         err |= __put_user(regs->xds, (unsigned int __user *)&sc->ds);
 255         err |= __put_user(regs->edi, &sc->edi);
 256         err |= __put_user(regs->esi, &sc->esi);
 257         err |= __put_user(regs->ebp, &sc->ebp);
 258         err |= __put_user(regs->esp, &sc->esp);
 259         err |= __put_user(regs->ebx, &sc->ebx);
 260         err |= __put_user(regs->edx, &sc->edx);
 261         err |= __put_user(regs->ecx, &sc->ecx);
 262         err |= __put_user(regs->eax, &sc->eax);
 263         err |= __put_user(current->thread.trap_no, &sc->trapno);
 264         err |= __put_user(current->thread.error_code, &sc->err);
 265         err |= __put_user(regs->eip, &sc->eip);
 266         err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs);
 267         err |= __put_user(regs->eflags, &sc->eflags);
 268         err |= __put_user(regs->esp, &sc->esp_at_signal);
 269         err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss);
 270
 271         tmp = save_i387(fpstate);
 272         if (tmp < 0)
 273           err = 1;
 274         else
 275           err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 276
 277         /* non-iBCS2 extensions.. */
 278         err |= __put_user(mask, &sc->oldmask);
 279         err |= __put_user(current->thread.cr2, &sc->cr2);
 280
 281         return err;
 282 }
 283
 284 /*
 285  * Determine which stack to use..
 286  */
 287 static inline void __user *
 288 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 289 {
 290         unsigned long esp;
 291
 292         /* Default to using normal stack */
 293         esp = regs->esp;
 294
 295         /* This is the X/Open sanctioned signal stack switching.  */
 296         if (ka->sa.sa_flags & SA_ONSTACK) {
 297                 if (sas_ss_flags(esp) == 0)
 298                         esp = current->sas_ss_sp + current->sas_ss_size;
 299         }
 300
 301         /* This is the legacy signal stack switching. */
 302         else if ((regs->xss & 0xffff) != __USER_DS &&
 303                  !(ka->sa.sa_flags & SA_RESTORER) &&
 304                  ka->sa.sa_restorer) {
 305                 esp = (unsigned long) ka->sa.sa_restorer;
 306         }
 307
 308         esp -= frame_size;
 309         /* Align the stack pointer according to the i386 ABI,
 310          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 311         esp = ((esp + 4) & -16ul) - 4;
 312         return (void __user *) esp;
 313 }
 314
 315 /* These symbols are defined with the addresses in the vsyscall page.
 316    See vsyscall-sigreturn.S.  */
 317 extern void __user __kernel_sigreturn;
 318 extern void __user __kernel_rt_sigreturn;
 319
 320 static int setup_frame(int sig, struct k_sigaction *ka,
 321                        sigset_t *set, struct pt_regs * regs)
 322 {
 323         void __user *restorer;
 324         struct sigframe __user *frame;
 325         int err = 0;
 326         int usig;
 327
 328         frame = get_sigframe(ka, regs, sizeof(*frame));
 329
 330         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 331                 goto give_sigsegv;
 332
 333         usig = current_thread_info()->exec_domain
 334                 && current_thread_info()->exec_domain->signal_invmap
 335                 && sig < 32
 336                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 337                 : sig;
 338
 339         err = __put_user(usig, &frame->sig);
 340         if (err)
 341                 goto give_sigsegv;
 342
 343         err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
 344         if (err)
 345                 goto give_sigsegv;
 346
 347         if (_NSIG_WORDS > 1) {
 348                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 349                                       sizeof(frame->extramask));
 350                 if (err)
 351                         goto give_sigsegv;
 352         }
 353
 354         restorer = (void *)VDSO_SYM(&__kernel_sigreturn);
 355         if (ka->sa.sa_flags & SA_RESTORER)
 356                 restorer = ka->sa.sa_restorer;
 357
 358         /* Set up to return from userspace.  */
 359         err |= __put_user(restorer, &frame->pretcode);
 360
 361         /*
 362          * This is popl %eax ; movl $,%eax ; int $0x80
 363          *
 364          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 365          * reasons and because gdb uses it as a signature to notice
 366          * signal handler stack frames.
 367          */
 368         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 369         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 370         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 371
 372         if (err)
 373                 goto give_sigsegv;
 374
 375         /* Set up registers for signal handler */
 376         regs->esp = (unsigned long) frame;
 377         regs->eip = (unsigned long) ka->sa.sa_handler;
 378         regs->eax = (unsigned long) sig;
 379         regs->edx = (unsigned long) 0;
 380         regs->ecx = (unsigned long) 0;
 381
 382         set_fs(USER_DS);
 383         regs->xds = __USER_DS;
 384         regs->xes = __USER_DS;
 385         regs->xss = __USER_DS;
 386         regs->xcs = __USER_CS;
 387
 388         /*
 389          * Clear TF when entering the signal handler, but
 390          * notify any tracer that was single-stepping it.
 391          * The tracer may want to single-step inside the
 392          * handler too.
 393          */
 394         regs->eflags &= ~TF_MASK;
 395         if (test_thread_flag(TIF_SINGLESTEP))
 396                 ptrace_notify(SIGTRAP);
 397
 398 #if DEBUG_SIG
 399         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 400                 current->comm, current->pid, frame, regs->eip, frame->pretcode);
 401 #endif
 402
 403         return 0;
 404
 405 give_sigsegv:
 406         force_sigsegv(sig, current);
 407         return -EFAULT;
 408 }
 409
 410 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 411                            sigset_t *set, struct pt_regs * regs)
 412 {
 413         void __user *restorer;
 414         struct rt_sigframe __user *frame;
 415         int err = 0;
 416         int usig;
 417
 418         frame = get_sigframe(ka, regs, sizeof(*frame));
 419
 420         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 421                 goto give_sigsegv;
 422
 423         usig = current_thread_info()->exec_domain
 424                 && current_thread_info()->exec_domain->signal_invmap
 425                 && sig < 32
 426                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 427                 : sig;
 428
 429         err |= __put_user(usig, &frame->sig);
 430         err |= __put_user(&frame->info, &frame->pinfo);
 431         err |= __put_user(&frame->uc, &frame->puc);
 432         err |= copy_siginfo_to_user(&frame->info, info);
 433         if (err)
 434                 goto give_sigsegv;
 435
 436         /* Create the ucontext.  */
 437         err |= __put_user(0, &frame->uc.uc_flags);
 438         err |= __put_user(0, &frame->uc.uc_link);
 439         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 440         err |= __put_user(sas_ss_flags(regs->esp),
 441                           &frame->uc.uc_stack.ss_flags);
 442         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 443         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 444                                 regs, set->sig[0]);
 445         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 446         if (err)
 447                 goto give_sigsegv;
 448
 449         /* Set up to return from userspace.  */
 450         restorer = (void *)VDSO_SYM(&__kernel_rt_sigreturn);
 451         if (ka->sa.sa_flags & SA_RESTORER)
 452                 restorer = ka->sa.sa_restorer;
 453         err |= __put_user(restorer, &frame->pretcode);
 454
 455         /*
 456          * This is movl $,%eax ; int $0x80
 457          *
 458          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 459          * reasons and because gdb uses it as a signature to notice
 460          * signal handler stack frames.
 461          */
 462         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 463         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 464         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 465
 466         if (err)
 467                 goto give_sigsegv;
 468
 469         /* Set up registers for signal handler */
 470         regs->esp = (unsigned long) frame;
 471         regs->eip = (unsigned long) ka->sa.sa_handler;
 472         regs->eax = (unsigned long) usig;
 473         regs->edx = (unsigned long) &frame->info;
 474         regs->ecx = (unsigned long) &frame->uc;
 475
 476         set_fs(USER_DS);
 477         regs->xds = __USER_DS;
 478         regs->xes = __USER_DS;
 479         regs->xss = __USER_DS;
 480         regs->xcs = __USER_CS;
 481
 482         /*
 483          * Clear TF when entering the signal handler, but
 484          * notify any tracer that was single-stepping it.
 485          * The tracer may want to single-step inside the
 486          * handler too.
 487          */
 488         regs->eflags &= ~TF_MASK;
 489         if (test_thread_flag(TIF_SINGLESTEP))
 490                 ptrace_notify(SIGTRAP);
 491
 492 #if DEBUG_SIG
 493         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 494                 current->comm, current->pid, frame, regs->eip, frame->pretcode);
 495 #endif
 496
 497         return 0;
 498
 499 give_sigsegv:
 500         force_sigsegv(sig, current);
 501         return -EFAULT;
 502 }
 503
 504 /*
 505  * OK, we're invoking a handler
 506  */
 507
 508 static int
 509 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 510               sigset_t *oldset, struct pt_regs * regs)
 511 {
 512         int ret;
 513
 514         /* Are we from a system call? */
 515         if (regs->orig_eax >= 0) {
 516                 /* If so, check system call restarting.. */
 517                 switch (regs->eax) {
 518                         case -ERESTART_RESTARTBLOCK:
 519                         case -ERESTARTNOHAND:
 520                                 regs->eax = -EINTR;
 521                                 break;
 522
 523                         case -ERESTARTSYS:
 524                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 525                                         regs->eax = -EINTR;
 526                                         break;
 527                                 }
 528                         /* fallthrough */
 529                         case -ERESTARTNOINTR:
 530                                 regs->eax = regs->orig_eax;
 531                                 regs->eip -= 2;
 532                 }
 533         }
 534
 535         /*
 536          * If TF is set due to a debugger (PT_DTRACE), clear the TF flag so
 537          * that register information in the sigcontext is correct.
 538          */
 539         if (unlikely(regs->eflags & TF_MASK)
 540             && likely(current->ptrace & PT_DTRACE)) {
 541                 current->ptrace &= ~PT_DTRACE;
 542                 regs->eflags &= ~TF_MASK;
 543         }
 544
 545         /* Set up the stack frame */
 546         if (ka->sa.sa_flags & SA_SIGINFO)
 547                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 548         else
 549                 ret = setup_frame(sig, ka, oldset, regs);
 550
 551         if (ret == 0) {
 552                 spin_lock_irq(&current->sighand->siglock);
 553                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 554                 if (!(ka->sa.sa_flags & SA_NODEFER))
 555                         sigaddset(&current->blocked,sig);
 556                 recalc_sigpending();
 557                 spin_unlock_irq(&current->sighand->siglock);
 558         }
 559
 560         return ret;
 561 }
 562
 563 /*
 564  * Note that 'init' is a special process: it doesn't get signals it doesn't
 565  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 566  * mistake.
 567  */
 568 static void fastcall do_signal(struct pt_regs *regs)
 569 {
 570         siginfo_t info;
 571         int signr;
 572         struct k_sigaction ka;
 573         sigset_t *oldset;
 574
 575         /*
 576          * We want the common case to go fast, which
 577          * is why we may in certain cases get here from
 578          * kernel mode. Just return without doing anything
 579          * if so.  vm86 regs switched out by assembly code
 580          * before reaching here, so testing against kernel
 581          * CS suffices.
 582          */
 583         if (!user_mode(regs))
 584                 return;
 585
 586         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 587                 oldset = &current->saved_sigmask;
 588         else
 589                 oldset = &current->blocked;
 590
 591         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 592         if (signr > 0) {
 593                 /* Reenable any watchpoints before delivering the
 594                  * signal to user space. The processor register will
 595                  * have been cleared if the watchpoint triggered
 596                  * inside the kernel.
 597                  */
 598                 if (unlikely(current->thread.debugreg[7]))
 599                         set_debugreg(current->thread.debugreg[7], 7);
 600
 601                 /* Whee!  Actually deliver the signal.  */
 602                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 603                         /* a signal was successfully delivered; the saved
 604                          * sigmask will have been stored in the signal frame,
 605                          * and will be restored by sigreturn, so we can simply
 606                          * clear the TIF_RESTORE_SIGMASK flag */
 607                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 608                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 609                 }
 610
 611                 return;
 612         }
 613
 614         /* Did we come from a system call? */
 615         if (regs->orig_eax >= 0) {
 616                 /* Restart the system call - no handlers present */
 617                 switch (regs->eax) {
 618                 case -ERESTARTNOHAND:
 619                 case -ERESTARTSYS:
 620                 case -ERESTARTNOINTR:
 621                         regs->eax = regs->orig_eax;
 622                         regs->eip -= 2;
 623                         break;
 624
 625                 case -ERESTART_RESTARTBLOCK:
 626                         regs->eax = __NR_restart_syscall;
 627                         regs->eip -= 2;
 628                         break;
 629                 }
 630         }
 631
 632         /* if there's no signal to deliver, we just put the saved sigmask
 633          * back */
 634         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 635                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 636                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 637         }
 638 }
 639
 640 /*
 641  * notification of userspace execution resumption
 642  * - triggered by the TIF_WORK_MASK flags
 643  */
 644 __attribute__((regparm(3)))
 645 void do_notify_resume(struct pt_regs *regs, void *_unused,
 646                       __u32 thread_info_flags)
 647 {
 648         /* Pending single-step? */
 649         if (thread_info_flags & _TIF_SINGLESTEP) {
 650                 regs->eflags |= TF_MASK;
 651                 clear_thread_flag(TIF_SINGLESTEP);
 652         }
 653
 654         /* deal with pending signal delivery */
 655         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 656                 do_signal(regs);
 657
 658         clear_thread_flag(TIF_IRET);
 659 }