arch/i386/kernel/signal.c

   1 /*
   2  *  linux/arch/i386/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   7  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/smp_lock.h>
  14 #include <linux/kernel.h>
  15 #include <linux/signal.h>
  16 #include <linux/errno.h>
  17 #include <linux/wait.h>
  18 #include <linux/unistd.h>
  19 #include <linux/stddef.h>
  20 #include <linux/personality.h>
  21 #include <linux/suspend.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/elf.h>
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/i387.h>
  28 #include "sigframe.h"
  29
  30 #define DEBUG_SIG 0
  31
  32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  33
  34 /*
  35  * Atomically swap in the new signal mask, and wait for a signal.
  36  */
  37 asmlinkage int
  38 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  39 {
  40         struct pt_regs * regs = (struct pt_regs *) &history0;
  41         sigset_t saveset;
  42
  43         mask &= _BLOCKABLE;
  44         spin_lock_irq(&current->sighand->siglock);
  45         saveset = current->blocked;
  46         siginitset(&current->blocked, mask);
  47         recalc_sigpending();
  48         spin_unlock_irq(&current->sighand->siglock);
  49
  50         regs->eax = -EINTR;
  51         while (1) {
  52                 current->state = TASK_INTERRUPTIBLE;
  53                 schedule();
  54                 if (do_signal(regs, &saveset))
  55                         return -EINTR;
  56         }
  57 }
  58
  59 asmlinkage int
  60 sys_rt_sigsuspend(struct pt_regs regs)
  61 {
  62         sigset_t saveset, newset;
  63
  64         /* XXX: Don't preclude handling different sized sigset_t's.  */
  65         if (regs.ecx != sizeof(sigset_t))
  66                 return -EINVAL;
  67
  68         if (copy_from_user(&newset, (sigset_t __user *)regs.ebx, sizeof(newset)))
  69                 return -EFAULT;
  70         sigdelsetmask(&newset, ~_BLOCKABLE);
  71
  72         spin_lock_irq(&current->sighand->siglock);
  73         saveset = current->blocked;
  74         current->blocked = newset;
  75         recalc_sigpending();
  76         spin_unlock_irq(&current->sighand->siglock);
  77
  78         regs.eax = -EINTR;
  79         while (1) {
  80                 current->state = TASK_INTERRUPTIBLE;
  81                 schedule();
  82                 if (do_signal(&regs, &saveset))
  83                         return -EINTR;
  84         }
  85 }
  86
  87 asmlinkage int
  88 sys_sigaction(int sig, const struct old_sigaction __user *act,
  89               struct old_sigaction __user *oact)
  90 {
  91         struct k_sigaction new_ka, old_ka;
  92         int ret;
  93
  94         if (act) {
  95                 old_sigset_t mask;
  96                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  97                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  98                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  99                         return -EFAULT;
 100                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 101                 __get_user(mask, &act->sa_mask);
 102                 siginitset(&new_ka.sa.sa_mask, mask);
 103         }
 104
 105         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 106
 107         if (!ret && oact) {
 108                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 109                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 110                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 111                         return -EFAULT;
 112                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 113                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 114         }
 115
 116         return ret;
 117 }
 118
 119 asmlinkage int
 120 sys_sigaltstack(unsigned long ebx)
 121 {
 122         /* This is needed to make gcc realize it doesn't own the "struct pt_regs" */
 123         struct pt_regs *regs = (struct pt_regs *)&ebx;
 124         const stack_t __user *uss = (const stack_t __user *)ebx;
 125         stack_t __user *uoss = (stack_t __user *)regs->ecx;
 126
 127         return do_sigaltstack(uss, uoss, regs->esp);
 128 }
 129
 130
 131 /*
 132  * Do a signal return; undo the signal stack.
 133  */
 134
 135 static int
 136 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax)
 137 {
 138         unsigned int err = 0;
 139
 140         /* Always make any pending restarted system calls return -EINTR */
 141         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 142
 143 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 144
 145 #define COPY_SEG(seg)                                                   \
 146         { unsigned short tmp;                                           \
 147           err |= __get_user(tmp, &sc->seg);                             \
 148           regs->x##seg = tmp; }
 149
 150 #define COPY_SEG_STRICT(seg)                                            \
 151         { unsigned short tmp;                                           \
 152           err |= __get_user(tmp, &sc->seg);                             \
 153           regs->x##seg = tmp|3; }
 154
 155 #define GET_SEG(seg)                                                    \
 156         { unsigned short tmp;                                           \
 157           err |= __get_user(tmp, &sc->seg);                             \
 158           loadsegment(seg,tmp); }
 159
 160 #define FIX_EFLAGS      (X86_EFLAGS_AC | X86_EFLAGS_OF | X86_EFLAGS_DF | \
 161                          X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \
 162                          X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF)
 163
 164         GET_SEG(gs);
 165         GET_SEG(fs);
 166         COPY_SEG(es);
 167         COPY_SEG(ds);
 168         COPY(edi);
 169         COPY(esi);
 170         COPY(ebp);
 171         COPY(esp);
 172         COPY(ebx);
 173         COPY(edx);
 174         COPY(ecx);
 175         COPY(eip);
 176         COPY_SEG_STRICT(cs);
 177         COPY_SEG_STRICT(ss);
 178
 179         {
 180                 unsigned int tmpflags;
 181                 err |= __get_user(tmpflags, &sc->eflags);
 182                 regs->eflags = (regs->eflags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 183                 regs->orig_eax = -1;            /* disable syscall checks */
 184         }
 185
 186         {
 187                 struct _fpstate __user * buf;
 188                 err |= __get_user(buf, &sc->fpstate);
 189                 if (buf) {
 190                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 191                                 goto badframe;
 192                         err |= restore_i387(buf);
 193                 } else {
 194                         struct task_struct *me = current;
 195                         if (used_math()) {
 196                                 clear_fpu(me);
 197                                 clear_used_math();
 198                         }
 199                 }
 200         }
 201
 202         err |= __get_user(*peax, &sc->eax);
 203         return err;
 204
 205 badframe:
 206         return 1;
 207 }
 208
 209 asmlinkage int sys_sigreturn(unsigned long __unused)
 210 {
 211         struct pt_regs *regs = (struct pt_regs *) &__unused;
 212         struct sigframe __user *frame = (struct sigframe __user *)(regs->esp - 8);
 213         sigset_t set;
 214         int eax;
 215
 216         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 217                 goto badframe;
 218         if (__get_user(set.sig[0], &frame->sc.oldmask)
 219             || (_NSIG_WORDS > 1
 220                 && __copy_from_user(&set.sig[1], &frame->extramask,
 221                                     sizeof(frame->extramask))))
 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->sc, &eax))
 231                 goto badframe;
 232         return eax;
 233
 234 badframe:
 235         force_sig(SIGSEGV, current);
 236         return 0;
 237 }
 238
 239 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 240 {
 241         struct pt_regs *regs = (struct pt_regs *) &__unused;
 242         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->esp - 4);
 243         sigset_t set;
 244         int eax;
 245
 246         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 247                 goto badframe;
 248         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 249                 goto badframe;
 250
 251         sigdelsetmask(&set, ~_BLOCKABLE);
 252         spin_lock_irq(&current->sighand->siglock);
 253         current->blocked = set;
 254         recalc_sigpending();
 255         spin_unlock_irq(&current->sighand->siglock);
 256
 257         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 258                 goto badframe;
 259
 260         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT)
 261                 goto badframe;
 262
 263         return eax;
 264
 265 badframe:
 266         force_sig(SIGSEGV, current);
 267         return 0;
 268 }
 269
 270 /*
 271  * Set up a signal frame.
 272  */
 273
 274 static int
 275 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 276                  struct pt_regs *regs, unsigned long mask)
 277 {
 278         int tmp, err = 0;
 279
 280         tmp = 0;
 281         __asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
 282         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 283         __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
 284         err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
 285
 286         err |= __put_user(regs->xes, (unsigned int __user *)&sc->es);
 287         err |= __put_user(regs->xds, (unsigned int __user *)&sc->ds);
 288         err |= __put_user(regs->edi, &sc->edi);
 289         err |= __put_user(regs->esi, &sc->esi);
 290         err |= __put_user(regs->ebp, &sc->ebp);
 291         err |= __put_user(regs->esp, &sc->esp);
 292         err |= __put_user(regs->ebx, &sc->ebx);
 293         err |= __put_user(regs->edx, &sc->edx);
 294         err |= __put_user(regs->ecx, &sc->ecx);
 295         err |= __put_user(regs->eax, &sc->eax);
 296         err |= __put_user(current->thread.trap_no, &sc->trapno);
 297         err |= __put_user(current->thread.error_code, &sc->err);
 298         err |= __put_user(regs->eip, &sc->eip);
 299         err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs);
 300         err |= __put_user(regs->eflags, &sc->eflags);
 301         err |= __put_user(regs->esp, &sc->esp_at_signal);
 302         err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss);
 303
 304         tmp = save_i387(fpstate);
 305         if (tmp < 0)
 306           err = 1;
 307         else
 308           err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 309
 310         /* non-iBCS2 extensions.. */
 311         err |= __put_user(mask, &sc->oldmask);
 312         err |= __put_user(current->thread.cr2, &sc->cr2);
 313
 314         return err;
 315 }
 316
 317 /*
 318  * Determine which stack to use..
 319  */
 320 static inline void __user *
 321 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 322 {
 323         unsigned long esp;
 324
 325         /* Default to using normal stack */
 326         esp = regs->esp;
 327
 328         /* This is the X/Open sanctioned signal stack switching.  */
 329         if (ka->sa.sa_flags & SA_ONSTACK) {
 330                 if (sas_ss_flags(esp) == 0)
 331                         esp = current->sas_ss_sp + current->sas_ss_size;
 332         }
 333
 334         /* This is the legacy signal stack switching. */
 335         else if ((regs->xss & 0xffff) != __USER_DS &&
 336                  !(ka->sa.sa_flags & SA_RESTORER) &&
 337                  ka->sa.sa_restorer) {
 338                 esp = (unsigned long) ka->sa.sa_restorer;
 339         }
 340
 341         return (void __user *)((esp - frame_size) & -8ul);
 342 }
 343
 344 /* These symbols are defined with the addresses in the vsyscall page.
 345    See vsyscall-sigreturn.S.  */
 346 extern void __user __kernel_sigreturn;
 347 extern void __user __kernel_rt_sigreturn;
 348
 349 static void setup_frame(int sig, struct k_sigaction *ka,
 350                         sigset_t *set, struct pt_regs * regs)
 351 {
 352         void __user *restorer;
 353         struct sigframe __user *frame;
 354         int err = 0;
 355         int usig;
 356
 357         frame = get_sigframe(ka, regs, sizeof(*frame));
 358
 359         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 360                 goto give_sigsegv;
 361
 362         usig = current_thread_info()->exec_domain
 363                 && current_thread_info()->exec_domain->signal_invmap
 364                 && sig < 32
 365                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 366                 : sig;
 367
 368         err = __put_user(usig, &frame->sig);
 369         if (err)
 370                 goto give_sigsegv;
 371
 372         err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
 373         if (err)
 374                 goto give_sigsegv;
 375
 376         if (_NSIG_WORDS > 1) {
 377                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 378                                       sizeof(frame->extramask));
 379                 if (err)
 380                         goto give_sigsegv;
 381         }
 382
 383         restorer = &__kernel_sigreturn;
 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 $,%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->esp = (unsigned long) frame;
 406         regs->eip = (unsigned long) ka->sa.sa_handler;
 407         regs->eax = (unsigned long) sig;
 408         regs->edx = (unsigned long) 0;
 409         regs->ecx = (unsigned long) 0;
 410
 411         set_fs(USER_DS);
 412         regs->xds = __USER_DS;
 413         regs->xes = __USER_DS;
 414         regs->xss = __USER_DS;
 415         regs->xcs = __USER_CS;
 416
 417         /*
 418          * Clear TF when entering the signal handler, but
 419          * notify any tracer that was single-stepping it.
 420          * The tracer may want to single-step inside the
 421          * handler too.
 422          */
 423         regs->eflags &= ~TF_MASK;
 424         if (test_thread_flag(TIF_SINGLESTEP))
 425                 ptrace_notify(SIGTRAP);
 426
 427 #if DEBUG_SIG
 428         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 429                 current->comm, current->pid, frame, regs->eip, frame->pretcode);
 430 #endif
 431
 432         return;
 433
 434 give_sigsegv:
 435         force_sigsegv(sig, current);
 436 }
 437
 438 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 439                            sigset_t *set, struct pt_regs * regs)
 440 {
 441         void __user *restorer;
 442         struct rt_sigframe __user *frame;
 443         int err = 0;
 444         int usig;
 445
 446         frame = get_sigframe(ka, regs, sizeof(*frame));
 447
 448         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 449                 goto give_sigsegv;
 450
 451         usig = current_thread_info()->exec_domain
 452                 && current_thread_info()->exec_domain->signal_invmap
 453                 && sig < 32
 454                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 455                 : sig;
 456
 457         err |= __put_user(usig, &frame->sig);
 458         err |= __put_user(&frame->info, &frame->pinfo);
 459         err |= __put_user(&frame->uc, &frame->puc);
 460         err |= copy_siginfo_to_user(&frame->info, info);
 461         if (err)
 462                 goto give_sigsegv;
 463
 464         /* Create the ucontext.  */
 465         err |= __put_user(0, &frame->uc.uc_flags);
 466         err |= __put_user(0, &frame->uc.uc_link);
 467         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 468         err |= __put_user(sas_ss_flags(regs->esp),
 469                           &frame->uc.uc_stack.ss_flags);
 470         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 471         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 472                                 regs, set->sig[0]);
 473         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 474         if (err)
 475                 goto give_sigsegv;
 476
 477         /* Set up to return from userspace.  */
 478         restorer = &__kernel_rt_sigreturn;
 479         if (ka->sa.sa_flags & SA_RESTORER)
 480                 restorer = ka->sa.sa_restorer;
 481         err |= __put_user(restorer, &frame->pretcode);
 482
 483         /*
 484          * This is movl $,%eax ; int $0x80
 485          *
 486          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 487          * reasons and because gdb uses it as a signature to notice
 488          * signal handler stack frames.
 489          */
 490         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 491         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 492         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 493
 494         if (err)
 495                 goto give_sigsegv;
 496
 497         /* Set up registers for signal handler */
 498         regs->esp = (unsigned long) frame;
 499         regs->eip = (unsigned long) ka->sa.sa_handler;
 500         regs->eax = (unsigned long) usig;
 501         regs->edx = (unsigned long) &frame->info;
 502         regs->ecx = (unsigned long) &frame->uc;
 503
 504         set_fs(USER_DS);
 505         regs->xds = __USER_DS;
 506         regs->xes = __USER_DS;
 507         regs->xss = __USER_DS;
 508         regs->xcs = __USER_CS;
 509
 510         /*
 511          * Clear TF when entering the signal handler, but
 512          * notify any tracer that was single-stepping it.
 513          * The tracer may want to single-step inside the
 514          * handler too.
 515          */
 516         regs->eflags &= ~TF_MASK;
 517         if (test_thread_flag(TIF_SINGLESTEP))
 518                 ptrace_notify(SIGTRAP);
 519
 520 #if DEBUG_SIG
 521         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 522                 current->comm, current->pid, frame, regs->eip, frame->pretcode);
 523 #endif
 524
 525         return;
 526
 527 give_sigsegv:
 528         force_sigsegv(sig, current);
 529 }
 530
 531 /*
 532  * OK, we're invoking a handler
 533  */
 534
 535 static void
 536 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 537               sigset_t *oldset, struct pt_regs * regs)
 538 {
 539         /* Are we from a system call? */
 540         if (regs->orig_eax >= 0) {
 541                 /* If so, check system call restarting.. */
 542                 switch (regs->eax) {
 543                         case -ERESTART_RESTARTBLOCK:
 544                         case -ERESTARTNOHAND:
 545                                 regs->eax = -EINTR;
 546                                 break;
 547
 548                         case -ERESTARTSYS:
 549                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 550                                         regs->eax = -EINTR;
 551                                         break;
 552                                 }
 553                         /* fallthrough */
 554                         case -ERESTARTNOINTR:
 555                                 regs->eax = regs->orig_eax;
 556                                 regs->eip -= 2;
 557                 }
 558         }
 559
 560         /*
 561          * If TF is set due to a debugger (PT_DTRACE), clear the TF flag so
 562          * that register information in the sigcontext is correct.
 563          */
 564         if (unlikely(regs->eflags & TF_MASK)
 565             && likely(current->ptrace & PT_DTRACE)) {
 566                 current->ptrace &= ~PT_DTRACE;
 567                 regs->eflags &= ~TF_MASK;
 568         }
 569
 570         /* Set up the stack frame */
 571         if (ka->sa.sa_flags & SA_SIGINFO)
 572                 setup_rt_frame(sig, ka, info, oldset, regs);
 573         else
 574                 setup_frame(sig, ka, oldset, regs);
 575
 576         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 577                 spin_lock_irq(&current->sighand->siglock);
 578                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 579                 sigaddset(&current->blocked,sig);
 580                 recalc_sigpending();
 581                 spin_unlock_irq(&current->sighand->siglock);
 582         }
 583 }
 584
 585 /*
 586  * Note that 'init' is a special process: it doesn't get signals it doesn't
 587  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 588  * mistake.
 589  */
 590 int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
 591 {
 592         siginfo_t info;
 593         int signr;
 594         struct k_sigaction ka;
 595
 596         /*
 597          * We want the common case to go fast, which
 598          * is why we may in certain cases get here from
 599          * kernel mode. Just return without doing anything
 600          * if so.
 601          */
 602         if ((regs->xcs & 3) != 3)
 603                 return 1;
 604
 605         if (current->flags & PF_FREEZE) {
 606                 refrigerator(0);
 607                 goto no_signal;
 608         }
 609
 610         if (!oldset)
 611                 oldset = &current->blocked;
 612
 613         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 614         if (signr > 0) {
 615                 /* Reenable any watchpoints before delivering the
 616                  * signal to user space. The processor register will
 617                  * have been cleared if the watchpoint triggered
 618                  * inside the kernel.
 619                  */
 620                 if (unlikely(current->thread.debugreg[7])) {
 621                         __asm__("movl %0,%%db7" : : "r" (current->thread.debugreg[7]));
 622                 }
 623
 624                 /* Whee!  Actually deliver the signal.  */
 625                 handle_signal(signr, &info, &ka, oldset, regs);
 626                 return 1;
 627         }
 628
 629  no_signal:
 630         /* Did we come from a system call? */
 631         if (regs->orig_eax >= 0) {
 632                 /* Restart the system call - no handlers present */
 633                 if (regs->eax == -ERESTARTNOHAND ||
 634                     regs->eax == -ERESTARTSYS ||
 635                     regs->eax == -ERESTARTNOINTR) {
 636                         regs->eax = regs->orig_eax;
 637                         regs->eip -= 2;
 638                 }
 639                 if (regs->eax == -ERESTART_RESTARTBLOCK){
 640                         regs->eax = __NR_restart_syscall;
 641                         regs->eip -= 2;
 642                 }
 643         }
 644         return 0;
 645 }
 646
 647 /*
 648  * notification of userspace execution resumption
 649  * - triggered by current->work.notify_resume
 650  */
 651 __attribute__((regparm(3)))
 652 void do_notify_resume(struct pt_regs *regs, sigset_t *oldset,
 653                       __u32 thread_info_flags)
 654 {
 655         /* Pending single-step? */
 656         if (thread_info_flags & _TIF_SINGLESTEP) {
 657                 regs->eflags |= TF_MASK;
 658                 clear_thread_flag(TIF_SINGLESTEP);
 659         }
 660         /* deal with pending signal delivery */
 661         if (thread_info_flags & _TIF_SIGPENDING)
 662                 do_signal(regs,oldset);
 663
 664         clear_thread_flag(TIF_IRET);
 665 }