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