arch/x86/kernel/signal_32.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   5  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   6  */
   7 #include <linux/list.h>
   8
   9 #include <linux/personality.h>
  10 #include <linux/binfmts.h>
  11 #include <linux/suspend.h>
  12 #include <linux/kernel.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/signal.h>
  15 #include <linux/stddef.h>
  16 #include <linux/unistd.h>
  17 #include <linux/errno.h>
  18 #include <linux/sched.h>
  19 #include <linux/wait.h>
  20 #include <linux/elf.h>
  21 #include <linux/smp.h>
  22 #include <linux/mm.h>
  23
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/i387.h>
  28 #include <asm/vdso.h>
  29
  30 #include "sigframe.h"
  31
  32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  33
  34 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  35                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  36                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  37                          X86_EFLAGS_CF)
  38
  39 #ifdef CONFIG_X86_32
  40 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  41 #else
  42 # define FIX_EFLAGS     __FIX_EFLAGS
  43 #endif
  44
  45 /*
  46  * Atomically swap in the new signal mask, and wait for a signal.
  47  */
  48 asmlinkage int
  49 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  50 {
  51         mask &= _BLOCKABLE;
  52         spin_lock_irq(&current->sighand->siglock);
  53         current->saved_sigmask = current->blocked;
  54         siginitset(&current->blocked, mask);
  55         recalc_sigpending();
  56         spin_unlock_irq(&current->sighand->siglock);
  57
  58         current->state = TASK_INTERRUPTIBLE;
  59         schedule();
  60         set_restore_sigmask();
  61
  62         return -ERESTARTNOHAND;
  63 }
  64
  65 asmlinkage int
  66 sys_sigaction(int sig, const struct old_sigaction __user *act,
  67               struct old_sigaction __user *oact)
  68 {
  69         struct k_sigaction new_ka, old_ka;
  70         int ret;
  71
  72         if (act) {
  73                 old_sigset_t mask;
  74
  75                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  76                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  77                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  78                         return -EFAULT;
  79
  80                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  81                 __get_user(mask, &act->sa_mask);
  82                 siginitset(&new_ka.sa.sa_mask, mask);
  83         }
  84
  85         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  86
  87         if (!ret && oact) {
  88                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  89                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  90                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  91                         return -EFAULT;
  92
  93                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  94                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  95         }
  96
  97         return ret;
  98 }
  99
 100 asmlinkage int sys_sigaltstack(unsigned long bx)
 101 {
 102         /*
 103          * This is needed to make gcc realize it doesn't own the
 104          * "struct pt_regs"
 105          */
 106         struct pt_regs *regs = (struct pt_regs *)&bx;
 107         const stack_t __user *uss = (const stack_t __user *)bx;
 108         stack_t __user *uoss = (stack_t __user *)regs->cx;
 109
 110         return do_sigaltstack(uss, uoss, regs->sp);
 111 }
 112
 113
 114 /*
 115  * Do a signal return; undo the signal stack.
 116  */
 117 static int
 118 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 119                    unsigned long *pax)
 120 {
 121         unsigned int err = 0;
 122
 123         /* Always make any pending restarted system calls return -EINTR */
 124         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 125
 126 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 127
 128 #define COPY_SEG(seg)                                                   \
 129         { unsigned short tmp;                                           \
 130           err |= __get_user(tmp, &sc->seg);                             \
 131           regs->seg = tmp; }
 132
 133 #define COPY_SEG_STRICT(seg)                                            \
 134         { unsigned short tmp;                                           \
 135           err |= __get_user(tmp, &sc->seg);                             \
 136           regs->seg = tmp|3; }
 137
 138 #define GET_SEG(seg)                                                    \
 139         { unsigned short tmp;                                           \
 140           err |= __get_user(tmp, &sc->seg);                             \
 141           loadsegment(seg, tmp); }
 142
 143         GET_SEG(gs);
 144         COPY_SEG(fs);
 145         COPY_SEG(es);
 146         COPY_SEG(ds);
 147         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 148         COPY(dx); COPY(cx); COPY(ip);
 149         COPY_SEG_STRICT(cs);
 150         COPY_SEG_STRICT(ss);
 151
 152         {
 153                 unsigned int tmpflags;
 154
 155                 err |= __get_user(tmpflags, &sc->flags);
 156                 regs->flags = (regs->flags & ~FIX_EFLAGS) |
 157                                                 (tmpflags & FIX_EFLAGS);
 158                 regs->orig_ax = -1;             /* disable syscall checks */
 159         }
 160
 161         {
 162                 struct _fpstate __user *buf;
 163
 164                 err |= __get_user(buf, &sc->fpstate);
 165                 if (buf) {
 166                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 167                                 goto badframe;
 168                         err |= restore_i387(buf);
 169                 } else {
 170                         struct task_struct *me = current;
 171
 172                         if (used_math()) {
 173                                 clear_fpu(me);
 174                                 clear_used_math();
 175                         }
 176                 }
 177         }
 178
 179         err |= __get_user(*pax, &sc->ax);
 180         return err;
 181
 182 badframe:
 183         return 1;
 184 }
 185
 186 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 187 {
 188         struct sigframe __user *frame;
 189         struct pt_regs *regs;
 190         unsigned long ax;
 191         sigset_t set;
 192
 193         regs = (struct pt_regs *) &__unused;
 194         frame = (struct sigframe __user *)(regs->sp - 8);
 195
 196         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 197                 goto badframe;
 198         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 199                 && __copy_from_user(&set.sig[1], &frame->extramask,
 200                                     sizeof(frame->extramask))))
 201                 goto badframe;
 202
 203         sigdelsetmask(&set, ~_BLOCKABLE);
 204         spin_lock_irq(&current->sighand->siglock);
 205         current->blocked = set;
 206         recalc_sigpending();
 207         spin_unlock_irq(&current->sighand->siglock);
 208
 209         if (restore_sigcontext(regs, &frame->sc, &ax))
 210                 goto badframe;
 211         return ax;
 212
 213 badframe:
 214         if (show_unhandled_signals && printk_ratelimit()) {
 215                 printk("%s%s[%d] bad frame in sigreturn frame:"
 216                         "%p ip:%lx sp:%lx oeax:%lx",
 217                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 218                     current->comm, task_pid_nr(current), frame, regs->ip,
 219                     regs->sp, regs->orig_ax);
 220                 print_vma_addr(" in ", regs->ip);
 221                 printk(KERN_CONT "\n");
 222         }
 223
 224         force_sig(SIGSEGV, current);
 225
 226         return 0;
 227 }
 228
 229 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 230 {
 231         struct pt_regs *regs = (struct pt_regs *)&__unused;
 232         struct rt_sigframe __user *frame;
 233         unsigned long ax;
 234         sigset_t set;
 235
 236         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 237         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 238                 goto badframe;
 239         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 240                 goto badframe;
 241
 242         sigdelsetmask(&set, ~_BLOCKABLE);
 243         spin_lock_irq(&current->sighand->siglock);
 244         current->blocked = set;
 245         recalc_sigpending();
 246         spin_unlock_irq(&current->sighand->siglock);
 247
 248         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 249                 goto badframe;
 250
 251         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 252                 goto badframe;
 253
 254         return ax;
 255
 256 badframe:
 257         force_sig(SIGSEGV, current);
 258         return 0;
 259 }
 260
 261 /*
 262  * Set up a signal frame.
 263  */
 264 static int
 265 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 266                  struct pt_regs *regs, unsigned long mask)
 267 {
 268         int tmp, err = 0;
 269
 270         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 271         savesegment(gs, tmp);
 272         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 273
 274         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 275         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 276         err |= __put_user(regs->di, &sc->di);
 277         err |= __put_user(regs->si, &sc->si);
 278         err |= __put_user(regs->bp, &sc->bp);
 279         err |= __put_user(regs->sp, &sc->sp);
 280         err |= __put_user(regs->bx, &sc->bx);
 281         err |= __put_user(regs->dx, &sc->dx);
 282         err |= __put_user(regs->cx, &sc->cx);
 283         err |= __put_user(regs->ax, &sc->ax);
 284         err |= __put_user(current->thread.trap_no, &sc->trapno);
 285         err |= __put_user(current->thread.error_code, &sc->err);
 286         err |= __put_user(regs->ip, &sc->ip);
 287         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 288         err |= __put_user(regs->flags, &sc->flags);
 289         err |= __put_user(regs->sp, &sc->sp_at_signal);
 290         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 291
 292         tmp = save_i387(fpstate);
 293         if (tmp < 0)
 294                 err = 1;
 295         else
 296                 err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 297
 298         /* non-iBCS2 extensions.. */
 299         err |= __put_user(mask, &sc->oldmask);
 300         err |= __put_user(current->thread.cr2, &sc->cr2);
 301
 302         return err;
 303 }
 304
 305 /*
 306  * Determine which stack to use..
 307  */
 308 static inline void __user *
 309 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 310              struct _fpstate **fpstate)
 311 {
 312         unsigned long sp;
 313
 314         /* Default to using normal stack */
 315         sp = regs->sp;
 316
 317         /*
 318          * If we are on the alternate signal stack and would overflow it, don't.
 319          * Return an always-bogus address instead so we will die with SIGSEGV.
 320          */
 321         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 322                 return (void __user *) -1L;
 323
 324         /* This is the X/Open sanctioned signal stack switching.  */
 325         if (ka->sa.sa_flags & SA_ONSTACK) {
 326                 if (sas_ss_flags(sp) == 0)
 327                         sp = current->sas_ss_sp + current->sas_ss_size;
 328         } else {
 329                 /* This is the legacy signal stack switching. */
 330                 if ((regs->ss & 0xffff) != __USER_DS &&
 331                         !(ka->sa.sa_flags & SA_RESTORER) &&
 332                                 ka->sa.sa_restorer)
 333                         sp = (unsigned long) ka->sa.sa_restorer;
 334         }
 335
 336         if (used_math()) {
 337                 sp = sp - sig_xstate_size;
 338                 *fpstate = (struct _fpstate *) sp;
 339         }
 340
 341         sp -= frame_size;
 342         /*
 343          * Align the stack pointer according to the i386 ABI,
 344          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 345          */
 346         sp = ((sp + 4) & -16ul) - 4;
 347
 348         return (void __user *) sp;
 349 }
 350
 351 static int
 352 setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 353             struct pt_regs *regs)
 354 {
 355         struct sigframe __user *frame;
 356         void __user *restorer;
 357         int err = 0;
 358         int usig;
 359         struct _fpstate __user *fpstate = NULL;
 360
 361         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 362
 363         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 364                 goto give_sigsegv;
 365
 366         usig = current_thread_info()->exec_domain
 367                 && current_thread_info()->exec_domain->signal_invmap
 368                 && sig < 32
 369                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 370                 : sig;
 371
 372         err = __put_user(usig, &frame->sig);
 373         if (err)
 374                 goto give_sigsegv;
 375
 376         err = setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]);
 377         if (err)
 378                 goto give_sigsegv;
 379
 380         if (_NSIG_WORDS > 1) {
 381                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 382                                       sizeof(frame->extramask));
 383                 if (err)
 384                         goto give_sigsegv;
 385         }
 386
 387         if (current->mm->context.vdso)
 388                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 389         else
 390                 restorer = &frame->retcode;
 391         if (ka->sa.sa_flags & SA_RESTORER)
 392                 restorer = ka->sa.sa_restorer;
 393
 394         /* Set up to return from userspace.  */
 395         err |= __put_user(restorer, &frame->pretcode);
 396
 397         /*
 398          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 399          *
 400          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 401          * reasons and because gdb uses it as a signature to notice
 402          * signal handler stack frames.
 403          */
 404         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 405         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 406         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 407
 408         if (err)
 409                 goto give_sigsegv;
 410
 411         /* Set up registers for signal handler */
 412         regs->sp = (unsigned long)frame;
 413         regs->ip = (unsigned long)ka->sa.sa_handler;
 414         regs->ax = (unsigned long)sig;
 415         regs->dx = 0;
 416         regs->cx = 0;
 417
 418         regs->ds = __USER_DS;
 419         regs->es = __USER_DS;
 420         regs->ss = __USER_DS;
 421         regs->cs = __USER_CS;
 422
 423         return 0;
 424
 425 give_sigsegv:
 426         force_sigsegv(sig, current);
 427         return -EFAULT;
 428 }
 429
 430 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 431                           sigset_t *set, struct pt_regs *regs)
 432 {
 433         struct rt_sigframe __user *frame;
 434         void __user *restorer;
 435         int err = 0;
 436         int usig;
 437         struct _fpstate __user *fpstate = NULL;
 438
 439         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 440
 441         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 442                 goto give_sigsegv;
 443
 444         usig = current_thread_info()->exec_domain
 445                 && current_thread_info()->exec_domain->signal_invmap
 446                 && sig < 32
 447                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 448                 : sig;
 449
 450         err |= __put_user(usig, &frame->sig);
 451         err |= __put_user(&frame->info, &frame->pinfo);
 452         err |= __put_user(&frame->uc, &frame->puc);
 453         err |= copy_siginfo_to_user(&frame->info, info);
 454         if (err)
 455                 goto give_sigsegv;
 456
 457         /* Create the ucontext.  */
 458         err |= __put_user(0, &frame->uc.uc_flags);
 459         err |= __put_user(0, &frame->uc.uc_link);
 460         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 461         err |= __put_user(sas_ss_flags(regs->sp),
 462                           &frame->uc.uc_stack.ss_flags);
 463         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 464         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 465                                 regs, set->sig[0]);
 466         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 467         if (err)
 468                 goto give_sigsegv;
 469
 470         /* Set up to return from userspace.  */
 471         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 472         if (ka->sa.sa_flags & SA_RESTORER)
 473                 restorer = ka->sa.sa_restorer;
 474         err |= __put_user(restorer, &frame->pretcode);
 475
 476         /*
 477          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 478          *
 479          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 480          * reasons and because gdb uses it as a signature to notice
 481          * signal handler stack frames.
 482          */
 483         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 484         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 485         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 486
 487         if (err)
 488                 goto give_sigsegv;
 489
 490         /* Set up registers for signal handler */
 491         regs->sp = (unsigned long)frame;
 492         regs->ip = (unsigned long)ka->sa.sa_handler;
 493         regs->ax = (unsigned long)usig;
 494         regs->dx = (unsigned long)&frame->info;
 495         regs->cx = (unsigned long)&frame->uc;
 496
 497         regs->ds = __USER_DS;
 498         regs->es = __USER_DS;
 499         regs->ss = __USER_DS;
 500         regs->cs = __USER_CS;
 501
 502         return 0;
 503
 504 give_sigsegv:
 505         force_sigsegv(sig, current);
 506         return -EFAULT;
 507 }
 508
 509 /*
 510  * OK, we're invoking a handler:
 511  */
 512 static int
 513 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 514               sigset_t *oldset, struct pt_regs *regs)
 515 {
 516         int ret;
 517
 518         /* Are we from a system call? */
 519         if ((long)regs->orig_ax >= 0) {
 520                 /* If so, check system call restarting.. */
 521                 switch (regs->ax) {
 522                 case -ERESTART_RESTARTBLOCK:
 523                 case -ERESTARTNOHAND:
 524                         regs->ax = -EINTR;
 525                         break;
 526
 527                 case -ERESTARTSYS:
 528                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 529                                 regs->ax = -EINTR;
 530                                 break;
 531                         }
 532                 /* fallthrough */
 533                 case -ERESTARTNOINTR:
 534                         regs->ax = regs->orig_ax;
 535                         regs->ip -= 2;
 536                         break;
 537                 }
 538         }
 539
 540         /*
 541          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 542          * flag so that register information in the sigcontext is correct.
 543          */
 544         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 545             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 546                 regs->flags &= ~X86_EFLAGS_TF;
 547
 548         /* Set up the stack frame */
 549         if (ka->sa.sa_flags & SA_SIGINFO)
 550                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 551         else
 552                 ret = setup_frame(sig, ka, oldset, regs);
 553
 554         if (ret)
 555                 return ret;
 556
 557         /*
 558          * Clear the direction flag as per the ABI for function entry.
 559          */
 560         regs->flags &= ~X86_EFLAGS_DF;
 561
 562         /*
 563          * Clear TF when entering the signal handler, but
 564          * notify any tracer that was single-stepping it.
 565          * The tracer may want to single-step inside the
 566          * handler too.
 567          */
 568         regs->flags &= ~X86_EFLAGS_TF;
 569         if (test_thread_flag(TIF_SINGLESTEP))
 570                 ptrace_notify(SIGTRAP);
 571
 572         spin_lock_irq(&current->sighand->siglock);
 573         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 574         if (!(ka->sa.sa_flags & SA_NODEFER))
 575                 sigaddset(&current->blocked, sig);
 576         recalc_sigpending();
 577         spin_unlock_irq(&current->sighand->siglock);
 578
 579         return 0;
 580 }
 581
 582 /*
 583  * Note that 'init' is a special process: it doesn't get signals it doesn't
 584  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 585  * mistake.
 586  */
 587 static void do_signal(struct pt_regs *regs)
 588 {
 589         struct k_sigaction ka;
 590         siginfo_t info;
 591         int signr;
 592         sigset_t *oldset;
 593
 594         /*
 595          * We want the common case to go fast, which is why we may in certain
 596          * cases get here from kernel mode. Just return without doing anything
 597          * if so.
 598          * X86_32: vm86 regs switched out by assembly code before reaching
 599          * here, so testing against kernel CS suffices.
 600          */
 601         if (!user_mode(regs))
 602                 return;
 603
 604         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 605                 oldset = &current->saved_sigmask;
 606         else
 607                 oldset = &current->blocked;
 608
 609         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 610         if (signr > 0) {
 611                 /*
 612                  * Re-enable any watchpoints before delivering the
 613                  * signal to user space. The processor register will
 614                  * have been cleared if the watchpoint triggered
 615                  * inside the kernel.
 616                  */
 617                 if (current->thread.debugreg7)
 618                         set_debugreg(current->thread.debugreg7, 7);
 619
 620                 /* Whee! Actually deliver the signal.  */
 621                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 622                         /*
 623                          * A signal was successfully delivered; the saved
 624                          * sigmask will have been stored in the signal frame,
 625                          * and will be restored by sigreturn, so we can simply
 626                          * clear the TS_RESTORE_SIGMASK flag.
 627                          */
 628                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 629                 }
 630                 return;
 631         }
 632
 633         /* Did we come from a system call? */
 634         if ((long)regs->orig_ax >= 0) {
 635                 /* Restart the system call - no handlers present */
 636                 switch (regs->ax) {
 637                 case -ERESTARTNOHAND:
 638                 case -ERESTARTSYS:
 639                 case -ERESTARTNOINTR:
 640                         regs->ax = regs->orig_ax;
 641                         regs->ip -= 2;
 642                         break;
 643
 644                 case -ERESTART_RESTARTBLOCK:
 645                         regs->ax = __NR_restart_syscall;
 646                         regs->ip -= 2;
 647                         break;
 648                 }
 649         }
 650
 651         /*
 652          * If there's no signal to deliver, we just put the saved sigmask
 653          * back.
 654          */
 655         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 656                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 657                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 658         }
 659 }
 660
 661 /*
 662  * notification of userspace execution resumption
 663  * - triggered by the TIF_WORK_MASK flags
 664  */
 665 void
 666 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 667 {
 668         /* deal with pending signal delivery */
 669         if (thread_info_flags & _TIF_SIGPENDING)
 670                 do_signal(regs);
 671
 672         clear_thread_flag(TIF_IRET);
 673 }