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
   8 #include <linux/sched.h>
   9 #include <linux/mm.h>
  10 #include <linux/smp.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/wait.h>
  15 #include <linux/unistd.h>
  16 #include <linux/stddef.h>
  17 #include <linux/personality.h>
  18 #include <linux/suspend.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/elf.h>
  21 #include <linux/binfmts.h>
  22 #include <asm/processor.h>
  23 #include <asm/ucontext.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/i387.h>
  26 #include <asm/vdso.h>
  27 #include "sigframe_32.h"
  28
  29 #define DEBUG_SIG 0
  30
  31 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  32
  33 /*
  34  * Atomically swap in the new signal mask, and wait for a signal.
  35  */
  36 asmlinkage int
  37 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  38 {
  39         mask &= _BLOCKABLE;
  40         spin_lock_irq(&current->sighand->siglock);
  41         current->saved_sigmask = current->blocked;
  42         siginitset(&current->blocked, mask);
  43         recalc_sigpending();
  44         spin_unlock_irq(&current->sighand->siglock);
  45
  46         current->state = TASK_INTERRUPTIBLE;
  47         schedule();
  48         set_thread_flag(TIF_RESTORE_SIGMASK);
  49         return -ERESTARTNOHAND;
  50 }
  51
  52 asmlinkage int
  53 sys_sigaction(int sig, const struct old_sigaction __user *act,
  54               struct old_sigaction __user *oact)
  55 {
  56         struct k_sigaction new_ka, old_ka;
  57         int ret;
  58
  59         if (act) {
  60                 old_sigset_t mask;
  61                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  62                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  63                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  64                         return -EFAULT;
  65                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  66                 __get_user(mask, &act->sa_mask);
  67                 siginitset(&new_ka.sa.sa_mask, mask);
  68         }
  69
  70         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  71
  72         if (!ret && oact) {
  73                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  74                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  75                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  76                         return -EFAULT;
  77                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  78                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  79         }
  80
  81         return ret;
  82 }
  83
  84 asmlinkage int
  85 sys_sigaltstack(unsigned long bx)
  86 {
  87         /* This is needed to make gcc realize it doesn't own the "struct pt_regs" */
  88         struct pt_regs *regs = (struct pt_regs *)&bx;
  89         const stack_t __user *uss = (const stack_t __user *)bx;
  90         stack_t __user *uoss = (stack_t __user *)regs->cx;
  91
  92         return do_sigaltstack(uss, uoss, regs->sp);
  93 }
  94
  95
  96 /*
  97  * Do a signal return; undo the signal stack.
  98  */
  99
 100 static int
 101 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax)
 102 {
 103         unsigned int err = 0;
 104
 105         /* Always make any pending restarted system calls return -EINTR */
 106         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 107
 108 #define COPY(x)         err |= __get_user(regs->x, &sc->e ## x)
 109
 110 #define COPY_SEG(seg)                                                   \
 111         { unsigned short tmp;                                           \
 112           err |= __get_user(tmp, &sc->seg);                             \
 113           regs->seg = tmp; }
 114
 115 #define COPY_SEG_STRICT(seg)                                            \
 116         { unsigned short tmp;                                           \
 117           err |= __get_user(tmp, &sc->seg);                             \
 118           regs->seg = tmp|3; }
 119
 120 #define GET_SEG(seg)                                                    \
 121         { unsigned short tmp;                                           \
 122           err |= __get_user(tmp, &sc->seg);                             \
 123           loadsegment(seg,tmp); }
 124
 125 #define FIX_EFLAGS      (X86_EFLAGS_AC | X86_EFLAGS_RF |                 \
 126                          X86_EFLAGS_OF | X86_EFLAGS_DF |                 \
 127                          X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \
 128                          X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF)
 129
 130         GET_SEG(gs);
 131         COPY_SEG(fs);
 132         COPY_SEG(es);
 133         COPY_SEG(ds);
 134         COPY(di);
 135         COPY(si);
 136         COPY(bp);
 137         COPY(sp);
 138         COPY(bx);
 139         COPY(dx);
 140         COPY(cx);
 141         COPY(ip);
 142         COPY_SEG_STRICT(cs);
 143         COPY_SEG_STRICT(ss);
 144
 145         {
 146                 unsigned int tmpflags;
 147                 err |= __get_user(tmpflags, &sc->eflags);
 148                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 149                 regs->orig_ax = -1;             /* disable syscall checks */
 150         }
 151
 152         {
 153                 struct _fpstate __user * buf;
 154                 err |= __get_user(buf, &sc->fpstate);
 155                 if (buf) {
 156                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 157                                 goto badframe;
 158                         err |= restore_i387(buf);
 159                 } else {
 160                         struct task_struct *me = current;
 161                         if (used_math()) {
 162                                 clear_fpu(me);
 163                                 clear_used_math();
 164                         }
 165                 }
 166         }
 167
 168         err |= __get_user(*peax, &sc->eax);
 169         return err;
 170
 171 badframe:
 172         return 1;
 173 }
 174
 175 asmlinkage int sys_sigreturn(unsigned long __unused)
 176 {
 177         struct pt_regs *regs = (struct pt_regs *) &__unused;
 178         struct sigframe __user *frame = (struct sigframe __user *)(regs->sp - 8);
 179         sigset_t set;
 180         int ax;
 181
 182         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 183                 goto badframe;
 184         if (__get_user(set.sig[0], &frame->sc.oldmask)
 185             || (_NSIG_WORDS > 1
 186                 && __copy_from_user(&set.sig[1], &frame->extramask,
 187                                     sizeof(frame->extramask))))
 188                 goto badframe;
 189
 190         sigdelsetmask(&set, ~_BLOCKABLE);
 191         spin_lock_irq(&current->sighand->siglock);
 192         current->blocked = set;
 193         recalc_sigpending();
 194         spin_unlock_irq(&current->sighand->siglock);
 195
 196         if (restore_sigcontext(regs, &frame->sc, &ax))
 197                 goto badframe;
 198         return ax;
 199
 200 badframe:
 201         if (show_unhandled_signals && printk_ratelimit())
 202                 printk("%s%s[%d] bad frame in sigreturn frame:%p ip:%lx"
 203                        " sp:%lx oeax:%lx\n",
 204                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 205                     current->comm, task_pid_nr(current), frame, regs->ip,
 206                     regs->sp, regs->orig_ax);
 207
 208         force_sig(SIGSEGV, current);
 209         return 0;
 210 }
 211
 212 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 213 {
 214         struct pt_regs *regs = (struct pt_regs *) &__unused;
 215         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->sp - 4);
 216         sigset_t set;
 217         int ax;
 218
 219         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 220                 goto badframe;
 221         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 222                 goto badframe;
 223
 224         sigdelsetmask(&set, ~_BLOCKABLE);
 225         spin_lock_irq(&current->sighand->siglock);
 226         current->blocked = set;
 227         recalc_sigpending();
 228         spin_unlock_irq(&current->sighand->siglock);
 229
 230         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 231                 goto badframe;
 232
 233         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 234                 goto badframe;
 235
 236         return ax;
 237
 238 badframe:
 239         force_sig(SIGSEGV, current);
 240         return 0;
 241 }
 242
 243 /*
 244  * Set up a signal frame.
 245  */
 246
 247 static int
 248 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 249                  struct pt_regs *regs, unsigned long mask)
 250 {
 251         int tmp, err = 0;
 252
 253         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 254         savesegment(gs, tmp);
 255         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 256
 257         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 258         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 259         err |= __put_user(regs->di, &sc->edi);
 260         err |= __put_user(regs->si, &sc->esi);
 261         err |= __put_user(regs->bp, &sc->ebp);
 262         err |= __put_user(regs->sp, &sc->esp);
 263         err |= __put_user(regs->bx, &sc->ebx);
 264         err |= __put_user(regs->dx, &sc->edx);
 265         err |= __put_user(regs->cx, &sc->ecx);
 266         err |= __put_user(regs->ax, &sc->eax);
 267         err |= __put_user(current->thread.trap_no, &sc->trapno);
 268         err |= __put_user(current->thread.error_code, &sc->err);
 269         err |= __put_user(regs->ip, &sc->eip);
 270         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 271         err |= __put_user(regs->flags, &sc->eflags);
 272         err |= __put_user(regs->sp, &sc->esp_at_signal);
 273         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 274
 275         tmp = save_i387(fpstate);
 276         if (tmp < 0)
 277           err = 1;
 278         else
 279           err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 280
 281         /* non-iBCS2 extensions.. */
 282         err |= __put_user(mask, &sc->oldmask);
 283         err |= __put_user(current->thread.cr2, &sc->cr2);
 284
 285         return err;
 286 }
 287
 288 /*
 289  * Determine which stack to use..
 290  */
 291 static inline void __user *
 292 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 293 {
 294         unsigned long sp;
 295
 296         /* Default to using normal stack */
 297         sp = regs->sp;
 298
 299         /*
 300          * If we are on the alternate signal stack and would overflow it, don't.
 301          * Return an always-bogus address instead so we will die with SIGSEGV.
 302          */
 303         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 304                 return (void __user *) -1L;
 305
 306         /* This is the X/Open sanctioned signal stack switching.  */
 307         if (ka->sa.sa_flags & SA_ONSTACK) {
 308                 if (sas_ss_flags(sp) == 0)
 309                         sp = current->sas_ss_sp + current->sas_ss_size;
 310         }
 311
 312         /* This is the legacy signal stack switching. */
 313         else if ((regs->ss & 0xffff) != __USER_DS &&
 314                  !(ka->sa.sa_flags & SA_RESTORER) &&
 315                  ka->sa.sa_restorer) {
 316                 sp = (unsigned long) ka->sa.sa_restorer;
 317         }
 318
 319         sp -= frame_size;
 320         /* Align the stack pointer according to the i386 ABI,
 321          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 322         sp = ((sp + 4) & -16ul) - 4;
 323         return (void __user *) sp;
 324 }
 325
 326 /* These symbols are defined with the addresses in the vsyscall page.
 327    See vsyscall-sigreturn.S.  */
 328 extern void __user __kernel_sigreturn;
 329 extern void __user __kernel_rt_sigreturn;
 330
 331 static int setup_frame(int sig, struct k_sigaction *ka,
 332                        sigset_t *set, struct pt_regs * regs)
 333 {
 334         void __user *restorer;
 335         struct sigframe __user *frame;
 336         int err = 0;
 337         int usig;
 338
 339         frame = get_sigframe(ka, regs, sizeof(*frame));
 340
 341         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 342                 goto give_sigsegv;
 343
 344         usig = current_thread_info()->exec_domain
 345                 && current_thread_info()->exec_domain->signal_invmap
 346                 && sig < 32
 347                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 348                 : sig;
 349
 350         err = __put_user(usig, &frame->sig);
 351         if (err)
 352                 goto give_sigsegv;
 353
 354         err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
 355         if (err)
 356                 goto give_sigsegv;
 357
 358         if (_NSIG_WORDS > 1) {
 359                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 360                                       sizeof(frame->extramask));
 361                 if (err)
 362                         goto give_sigsegv;
 363         }
 364
 365         if (current->binfmt->hasvdso)
 366                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 367         else
 368                 restorer = (void *)&frame->retcode;
 369         if (ka->sa.sa_flags & SA_RESTORER)
 370                 restorer = ka->sa.sa_restorer;
 371
 372         /* Set up to return from userspace.  */
 373         err |= __put_user(restorer, &frame->pretcode);
 374
 375         /*
 376          * This is popl %eax ; movl $,%eax ; int $0x80
 377          *
 378          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 379          * reasons and because gdb uses it as a signature to notice
 380          * signal handler stack frames.
 381          */
 382         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 383         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 384         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 385
 386         if (err)
 387                 goto give_sigsegv;
 388
 389         /* Set up registers for signal handler */
 390         regs->sp = (unsigned long) frame;
 391         regs->ip = (unsigned long) ka->sa.sa_handler;
 392         regs->ax = (unsigned long) sig;
 393         regs->dx = (unsigned long) 0;
 394         regs->cx = (unsigned long) 0;
 395
 396         regs->ds = __USER_DS;
 397         regs->es = __USER_DS;
 398         regs->ss = __USER_DS;
 399         regs->cs = __USER_CS;
 400
 401         /*
 402          * Clear TF when entering the signal handler, but
 403          * notify any tracer that was single-stepping it.
 404          * The tracer may want to single-step inside the
 405          * handler too.
 406          */
 407         regs->flags &= ~TF_MASK;
 408         if (test_thread_flag(TIF_SINGLESTEP))
 409                 ptrace_notify(SIGTRAP);
 410
 411 #if DEBUG_SIG
 412         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 413                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 414 #endif
 415
 416         return 0;
 417
 418 give_sigsegv:
 419         force_sigsegv(sig, current);
 420         return -EFAULT;
 421 }
 422
 423 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 424                            sigset_t *set, struct pt_regs * regs)
 425 {
 426         void __user *restorer;
 427         struct rt_sigframe __user *frame;
 428         int err = 0;
 429         int usig;
 430
 431         frame = get_sigframe(ka, regs, sizeof(*frame));
 432
 433         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 434                 goto give_sigsegv;
 435
 436         usig = current_thread_info()->exec_domain
 437                 && current_thread_info()->exec_domain->signal_invmap
 438                 && sig < 32
 439                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 440                 : sig;
 441
 442         err |= __put_user(usig, &frame->sig);
 443         err |= __put_user(&frame->info, &frame->pinfo);
 444         err |= __put_user(&frame->uc, &frame->puc);
 445         err |= copy_siginfo_to_user(&frame->info, info);
 446         if (err)
 447                 goto give_sigsegv;
 448
 449         /* Create the ucontext.  */
 450         err |= __put_user(0, &frame->uc.uc_flags);
 451         err |= __put_user(0, &frame->uc.uc_link);
 452         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 453         err |= __put_user(sas_ss_flags(regs->sp),
 454                           &frame->uc.uc_stack.ss_flags);
 455         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 456         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 457                                 regs, set->sig[0]);
 458         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 459         if (err)
 460                 goto give_sigsegv;
 461
 462         /* Set up to return from userspace.  */
 463         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 464         if (ka->sa.sa_flags & SA_RESTORER)
 465                 restorer = ka->sa.sa_restorer;
 466         err |= __put_user(restorer, &frame->pretcode);
 467
 468         /*
 469          * This is movl $,%ax ; int $0x80
 470          *
 471          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 472          * reasons and because gdb uses it as a signature to notice
 473          * signal handler stack frames.
 474          */
 475         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 476         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 477         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 478
 479         if (err)
 480                 goto give_sigsegv;
 481
 482         /* Set up registers for signal handler */
 483         regs->sp = (unsigned long) frame;
 484         regs->ip = (unsigned long) ka->sa.sa_handler;
 485         regs->ax = (unsigned long) usig;
 486         regs->dx = (unsigned long) &frame->info;
 487         regs->cx = (unsigned long) &frame->uc;
 488
 489         regs->ds = __USER_DS;
 490         regs->es = __USER_DS;
 491         regs->ss = __USER_DS;
 492         regs->cs = __USER_CS;
 493
 494         /*
 495          * Clear TF when entering the signal handler, but
 496          * notify any tracer that was single-stepping it.
 497          * The tracer may want to single-step inside the
 498          * handler too.
 499          */
 500         regs->flags &= ~TF_MASK;
 501         if (test_thread_flag(TIF_SINGLESTEP))
 502                 ptrace_notify(SIGTRAP);
 503
 504 #if DEBUG_SIG
 505         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 506                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 507 #endif
 508
 509         return 0;
 510
 511 give_sigsegv:
 512         force_sigsegv(sig, current);
 513         return -EFAULT;
 514 }
 515
 516 /*
 517  * OK, we're invoking a handler
 518  */
 519
 520 static int
 521 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 522               sigset_t *oldset, struct pt_regs * regs)
 523 {
 524         int ret;
 525
 526         /* Are we from a system call? */
 527         if (regs->orig_ax >= 0) {
 528                 /* If so, check system call restarting.. */
 529                 switch (regs->ax) {
 530                         case -ERESTART_RESTARTBLOCK:
 531                         case -ERESTARTNOHAND:
 532                                 regs->ax = -EINTR;
 533                                 break;
 534
 535                         case -ERESTARTSYS:
 536                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 537                                         regs->ax = -EINTR;
 538                                         break;
 539                                 }
 540                         /* fallthrough */
 541                         case -ERESTARTNOINTR:
 542                                 regs->ax = regs->orig_ax;
 543                                 regs->ip -= 2;
 544                 }
 545         }
 546
 547         /*
 548          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 549          * flag so that register information in the sigcontext is correct.
 550          */
 551         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 552             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 553                 regs->flags &= ~X86_EFLAGS_TF;
 554
 555         /* Set up the stack frame */
 556         if (ka->sa.sa_flags & SA_SIGINFO)
 557                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 558         else
 559                 ret = setup_frame(sig, ka, oldset, regs);
 560
 561         if (ret == 0) {
 562                 spin_lock_irq(&current->sighand->siglock);
 563                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 564                 if (!(ka->sa.sa_flags & SA_NODEFER))
 565                         sigaddset(&current->blocked,sig);
 566                 recalc_sigpending();
 567                 spin_unlock_irq(&current->sighand->siglock);
 568         }
 569
 570         return ret;
 571 }
 572
 573 /*
 574  * Note that 'init' is a special process: it doesn't get signals it doesn't
 575  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 576  * mistake.
 577  */
 578 static void fastcall do_signal(struct pt_regs *regs)
 579 {
 580         siginfo_t info;
 581         int signr;
 582         struct k_sigaction ka;
 583         sigset_t *oldset;
 584
 585         /*
 586          * We want the common case to go fast, which
 587          * is why we may in certain cases get here from
 588          * kernel mode. Just return without doing anything
 589          * if so.  vm86 regs switched out by assembly code
 590          * before reaching here, so testing against kernel
 591          * CS suffices.
 592          */
 593         if (!user_mode(regs))
 594                 return;
 595
 596         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 597                 oldset = &current->saved_sigmask;
 598         else
 599                 oldset = &current->blocked;
 600
 601         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 602         if (signr > 0) {
 603                 /* Re-enable any watchpoints before delivering the
 604                  * signal to user space. The processor register will
 605                  * have been cleared if the watchpoint triggered
 606                  * inside the kernel.
 607                  */
 608                 if (unlikely(current->thread.debugreg[7]))
 609                         set_debugreg(current->thread.debugreg[7], 7);
 610
 611                 /* Whee!  Actually deliver the signal.  */
 612                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 613                         /* a signal was successfully delivered; the saved
 614                          * sigmask will have been stored in the signal frame,
 615                          * and will be restored by sigreturn, so we can simply
 616                          * clear the TIF_RESTORE_SIGMASK flag */
 617                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 618                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 619                 }
 620
 621                 return;
 622         }
 623
 624         /* Did we come from a system call? */
 625         if (regs->orig_ax >= 0) {
 626                 /* Restart the system call - no handlers present */
 627                 switch (regs->ax) {
 628                 case -ERESTARTNOHAND:
 629                 case -ERESTARTSYS:
 630                 case -ERESTARTNOINTR:
 631                         regs->ax = regs->orig_ax;
 632                         regs->ip -= 2;
 633                         break;
 634
 635                 case -ERESTART_RESTARTBLOCK:
 636                         regs->ax = __NR_restart_syscall;
 637                         regs->ip -= 2;
 638                         break;
 639                 }
 640         }
 641
 642         /* if there's no signal to deliver, we just put the saved sigmask
 643          * back */
 644         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 645                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 646                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 647         }
 648 }
 649
 650 /*
 651  * notification of userspace execution resumption
 652  * - triggered by the TIF_WORK_MASK flags
 653  */
 654 __attribute__((regparm(3)))
 655 void do_notify_resume(struct pt_regs *regs, void *_unused,
 656                       __u32 thread_info_flags)
 657 {
 658         /* Pending single-step? */
 659         if (thread_info_flags & _TIF_SINGLESTEP) {
 660                 regs->flags |= TF_MASK;
 661                 clear_thread_flag(TIF_SINGLESTEP);
 662         }
 663
 664         /* deal with pending signal delivery */
 665         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 666                 do_signal(regs);
 667
 668         if (thread_info_flags & _TIF_HRTICK_RESCHED)
 669                 hrtick_resched();
 670
 671         clear_thread_flag(TIF_IRET);
 672 }