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_thread_flag(TIF_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(KERN_INFO "%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 {
 311         unsigned long sp;
 312
 313         /* Default to using normal stack */
 314         sp = regs->sp;
 315
 316         /*
 317          * If we are on the alternate signal stack and would overflow it, don't.
 318          * Return an always-bogus address instead so we will die with SIGSEGV.
 319          */
 320         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 321                 return (void __user *) -1L;
 322
 323         /* This is the X/Open sanctioned signal stack switching.  */
 324         if (ka->sa.sa_flags & SA_ONSTACK) {
 325                 if (sas_ss_flags(sp) == 0)
 326                         sp = current->sas_ss_sp + current->sas_ss_size;
 327         } else {
 328                 /* This is the legacy signal stack switching. */
 329                 if ((regs->ss & 0xffff) != __USER_DS &&
 330                         !(ka->sa.sa_flags & SA_RESTORER) &&
 331                                 ka->sa.sa_restorer)
 332                         sp = (unsigned long) ka->sa.sa_restorer;
 333         }
 334
 335         sp -= frame_size;
 336         /*
 337          * Align the stack pointer according to the i386 ABI,
 338          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 339          */
 340         sp = ((sp + 4) & -16ul) - 4;
 341
 342         return (void __user *) sp;
 343 }
 344
 345 static int
 346 setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 347             struct pt_regs *regs)
 348 {
 349         struct sigframe __user *frame;
 350         void __user *restorer;
 351         int err = 0;
 352         int usig;
 353
 354         frame = get_sigframe(ka, regs, sizeof(*frame));
 355
 356         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 357                 goto give_sigsegv;
 358
 359         usig = current_thread_info()->exec_domain
 360                 && current_thread_info()->exec_domain->signal_invmap
 361                 && sig < 32
 362                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 363                 : sig;
 364
 365         err = __put_user(usig, &frame->sig);
 366         if (err)
 367                 goto give_sigsegv;
 368
 369         err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
 370         if (err)
 371                 goto give_sigsegv;
 372
 373         if (_NSIG_WORDS > 1) {
 374                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 375                                       sizeof(frame->extramask));
 376                 if (err)
 377                         goto give_sigsegv;
 378         }
 379
 380         if (current->mm->context.vdso)
 381                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 382         else
 383                 restorer = &frame->retcode;
 384         if (ka->sa.sa_flags & SA_RESTORER)
 385                 restorer = ka->sa.sa_restorer;
 386
 387         /* Set up to return from userspace.  */
 388         err |= __put_user(restorer, &frame->pretcode);
 389
 390         /*
 391          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 392          *
 393          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 394          * reasons and because gdb uses it as a signature to notice
 395          * signal handler stack frames.
 396          */
 397         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 398         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 399         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 400
 401         if (err)
 402                 goto give_sigsegv;
 403
 404         /* Set up registers for signal handler */
 405         regs->sp = (unsigned long)frame;
 406         regs->ip = (unsigned long)ka->sa.sa_handler;
 407         regs->ax = (unsigned long)sig;
 408         regs->dx = 0;
 409         regs->cx = 0;
 410
 411         regs->ds = __USER_DS;
 412         regs->es = __USER_DS;
 413         regs->ss = __USER_DS;
 414         regs->cs = __USER_CS;
 415
 416         /*
 417          * Clear TF when entering the signal handler, but
 418          * notify any tracer that was single-stepping it.
 419          * The tracer may want to single-step inside the
 420          * handler too.
 421          */
 422         regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
 423         if (test_thread_flag(TIF_SINGLESTEP))
 424                 ptrace_notify(SIGTRAP);
 425
 426         return 0;
 427
 428 give_sigsegv:
 429         force_sigsegv(sig, current);
 430         return -EFAULT;
 431 }
 432
 433 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 434                           sigset_t *set, struct pt_regs *regs)
 435 {
 436         struct rt_sigframe __user *frame;
 437         void __user *restorer;
 438         int err = 0;
 439         int usig;
 440
 441         frame = get_sigframe(ka, regs, sizeof(*frame));
 442
 443         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 444                 goto give_sigsegv;
 445
 446         usig = current_thread_info()->exec_domain
 447                 && current_thread_info()->exec_domain->signal_invmap
 448                 && sig < 32
 449                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 450                 : sig;
 451
 452         err |= __put_user(usig, &frame->sig);
 453         err |= __put_user(&frame->info, &frame->pinfo);
 454         err |= __put_user(&frame->uc, &frame->puc);
 455         err |= copy_siginfo_to_user(&frame->info, info);
 456         if (err)
 457                 goto give_sigsegv;
 458
 459         /* Create the ucontext.  */
 460         err |= __put_user(0, &frame->uc.uc_flags);
 461         err |= __put_user(0, &frame->uc.uc_link);
 462         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 463         err |= __put_user(sas_ss_flags(regs->sp),
 464                           &frame->uc.uc_stack.ss_flags);
 465         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 466         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 467                                 regs, set->sig[0]);
 468         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 469         if (err)
 470                 goto give_sigsegv;
 471
 472         /* Set up to return from userspace.  */
 473         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 474         if (ka->sa.sa_flags & SA_RESTORER)
 475                 restorer = ka->sa.sa_restorer;
 476         err |= __put_user(restorer, &frame->pretcode);
 477
 478         /*
 479          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 480          *
 481          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 482          * reasons and because gdb uses it as a signature to notice
 483          * signal handler stack frames.
 484          */
 485         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 486         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 487         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 488
 489         if (err)
 490                 goto give_sigsegv;
 491
 492         /* Set up registers for signal handler */
 493         regs->sp = (unsigned long)frame;
 494         regs->ip = (unsigned long)ka->sa.sa_handler;
 495         regs->ax = (unsigned long)usig;
 496         regs->dx = (unsigned long)&frame->info;
 497         regs->cx = (unsigned long)&frame->uc;
 498
 499         regs->ds = __USER_DS;
 500         regs->es = __USER_DS;
 501         regs->ss = __USER_DS;
 502         regs->cs = __USER_CS;
 503
 504         /*
 505          * Clear TF when entering the signal handler, but
 506          * notify any tracer that was single-stepping it.
 507          * The tracer may want to single-step inside the
 508          * handler too.
 509          */
 510         regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
 511         if (test_thread_flag(TIF_SINGLESTEP))
 512                 ptrace_notify(SIGTRAP);
 513
 514         return 0;
 515
 516 give_sigsegv:
 517         force_sigsegv(sig, current);
 518         return -EFAULT;
 519 }
 520
 521 /*
 522  * OK, we're invoking a handler:
 523  */
 524 static int
 525 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 526               sigset_t *oldset, struct pt_regs *regs)
 527 {
 528         int ret;
 529
 530         /* Are we from a system call? */
 531         if ((long)regs->orig_ax >= 0) {
 532                 /* If so, check system call restarting.. */
 533                 switch (regs->ax) {
 534                 case -ERESTART_RESTARTBLOCK:
 535                 case -ERESTARTNOHAND:
 536                         regs->ax = -EINTR;
 537                         break;
 538
 539                 case -ERESTARTSYS:
 540                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 541                                 regs->ax = -EINTR;
 542                                 break;
 543                         }
 544                 /* fallthrough */
 545                 case -ERESTARTNOINTR:
 546                         regs->ax = regs->orig_ax;
 547                         regs->ip -= 2;
 548                         break;
 549                 }
 550         }
 551
 552         /*
 553          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 554          * flag so that register information in the sigcontext is correct.
 555          */
 556         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 557             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 558                 regs->flags &= ~X86_EFLAGS_TF;
 559
 560         /* Set up the stack frame */
 561         if (ka->sa.sa_flags & SA_SIGINFO)
 562                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 563         else
 564                 ret = setup_frame(sig, ka, oldset, regs);
 565
 566         if (ret)
 567                 return ret;
 568
 569         spin_lock_irq(&current->sighand->siglock);
 570         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 571         if (!(ka->sa.sa_flags & SA_NODEFER))
 572                 sigaddset(&current->blocked, sig);
 573         recalc_sigpending();
 574         spin_unlock_irq(&current->sighand->siglock);
 575
 576         return 0;
 577 }
 578
 579 /*
 580  * Note that 'init' is a special process: it doesn't get signals it doesn't
 581  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 582  * mistake.
 583  */
 584 static void do_signal(struct pt_regs *regs)
 585 {
 586         struct k_sigaction ka;
 587         siginfo_t info;
 588         int signr;
 589         sigset_t *oldset;
 590
 591         /*
 592          * We want the common case to go fast, which is why we may in certain
 593          * cases get here from kernel mode. Just return without doing anything
 594          * if so.
 595          * X86_32: vm86 regs switched out by assembly code before reaching
 596          * here, so testing against kernel CS suffices.
 597          */
 598         if (!user_mode(regs))
 599                 return;
 600
 601         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 602                 oldset = &current->saved_sigmask;
 603         else
 604                 oldset = &current->blocked;
 605
 606         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 607         if (signr > 0) {
 608                 /*
 609                  * Re-enable any watchpoints before delivering the
 610                  * signal to user space. The processor register will
 611                  * have been cleared if the watchpoint triggered
 612                  * inside the kernel.
 613                  */
 614                 if (current->thread.debugreg7)
 615                         set_debugreg(current->thread.debugreg7, 7);
 616
 617                 /* Whee! Actually deliver the signal.  */
 618                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 619                         /*
 620                          * a signal was successfully delivered; the saved
 621                          * sigmask will have been stored in the signal frame,
 622                          * and will be restored by sigreturn, so we can simply
 623                          * clear the TIF_RESTORE_SIGMASK flag
 624                          */
 625                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 626                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 627                 }
 628                 return;
 629         }
 630
 631         /* Did we come from a system call? */
 632         if ((long)regs->orig_ax >= 0) {
 633                 /* Restart the system call - no handlers present */
 634                 switch (regs->ax) {
 635                 case -ERESTARTNOHAND:
 636                 case -ERESTARTSYS:
 637                 case -ERESTARTNOINTR:
 638                         regs->ax = regs->orig_ax;
 639                         regs->ip -= 2;
 640                         break;
 641
 642                 case -ERESTART_RESTARTBLOCK:
 643                         regs->ax = __NR_restart_syscall;
 644                         regs->ip -= 2;
 645                         break;
 646                 }
 647         }
 648
 649         /*
 650          * If there's no signal to deliver, we just put the saved sigmask
 651          * back.
 652          */
 653         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 654                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 655                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 656         }
 657 }
 658
 659 /*
 660  * notification of userspace execution resumption
 661  * - triggered by the TIF_WORK_MASK flags
 662  */
 663 void
 664 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 665 {
 666         /* Pending single-step? */
 667         if (thread_info_flags & _TIF_SINGLESTEP) {
 668                 regs->flags |= X86_EFLAGS_TF;
 669                 clear_thread_flag(TIF_SINGLESTEP);
 670         }
 671
 672         /* deal with pending signal delivery */
 673         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 674                 do_signal(regs);
 675
 676         if (thread_info_flags & _TIF_HRTICK_RESCHED)
 677                 hrtick_resched();
 678
 679         clear_thread_flag(TIF_IRET);
 680 }