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