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/tracehook.h>
  21 #include <linux/elf.h>
  22 #include <linux/smp.h>
  23 #include <linux/mm.h>
  24
  25 #include <asm/processor.h>
  26 #include <asm/ucontext.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/i387.h>
  29 #include <asm/vdso.h>
  30 #include <asm/syscall.h>
  31 #include <asm/syscalls.h>
  32
  33 #include "sigframe.h"
  34
  35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  36
  37 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  38                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  39                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  40                          X86_EFLAGS_CF)
  41
  42 #ifdef CONFIG_X86_32
  43 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  44 #else
  45 # define FIX_EFLAGS     __FIX_EFLAGS
  46 #endif
  47
  48 /*
  49  * Atomically swap in the new signal mask, and wait for a signal.
  50  */
  51 asmlinkage int
  52 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  53 {
  54         mask &= _BLOCKABLE;
  55         spin_lock_irq(&current->sighand->siglock);
  56         current->saved_sigmask = current->blocked;
  57         siginitset(&current->blocked, mask);
  58         recalc_sigpending();
  59         spin_unlock_irq(&current->sighand->siglock);
  60
  61         current->state = TASK_INTERRUPTIBLE;
  62         schedule();
  63         set_restore_sigmask();
  64
  65         return -ERESTARTNOHAND;
  66 }
  67
  68 asmlinkage int
  69 sys_sigaction(int sig, const struct old_sigaction __user *act,
  70               struct old_sigaction __user *oact)
  71 {
  72         struct k_sigaction new_ka, old_ka;
  73         int ret;
  74
  75         if (act) {
  76                 old_sigset_t mask;
  77
  78                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  79                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  80                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  81                         return -EFAULT;
  82
  83                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  84                 __get_user(mask, &act->sa_mask);
  85                 siginitset(&new_ka.sa.sa_mask, mask);
  86         }
  87
  88         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  89
  90         if (!ret && oact) {
  91                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  92                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  93                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  94                         return -EFAULT;
  95
  96                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  97                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  98         }
  99
 100         return ret;
 101 }
 102
 103 asmlinkage int sys_sigaltstack(unsigned long bx)
 104 {
 105         /*
 106          * This is needed to make gcc realize it doesn't own the
 107          * "struct pt_regs"
 108          */
 109         struct pt_regs *regs = (struct pt_regs *)&bx;
 110         const stack_t __user *uss = (const stack_t __user *)bx;
 111         stack_t __user *uoss = (stack_t __user *)regs->cx;
 112
 113         return do_sigaltstack(uss, uoss, regs->sp);
 114 }
 115
 116 #define COPY(x)                 {               \
 117         err |= __get_user(regs->x, &sc->x);     \
 118 }
 119
 120 #define COPY_SEG(seg)           {                       \
 121                 unsigned short tmp;                     \
 122                 err |= __get_user(tmp, &sc->seg);       \
 123                 regs->seg = tmp;                        \
 124 }
 125
 126 #define COPY_SEG_STRICT(seg)    {                       \
 127                 unsigned short tmp;                     \
 128                 err |= __get_user(tmp, &sc->seg);       \
 129                 regs->seg = tmp | 3;                    \
 130 }
 131
 132 #define GET_SEG(seg)            {                       \
 133                 unsigned short tmp;                     \
 134                 err |= __get_user(tmp, &sc->seg);       \
 135                 loadsegment(seg, tmp);                  \
 136 }
 137
 138 /*
 139  * Do a signal return; undo the signal stack.
 140  */
 141 static int
 142 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 143                    unsigned long *pax)
 144 {
 145         unsigned int err = 0;
 146
 147         /* Always make any pending restarted system calls return -EINTR */
 148         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 149
 150         GET_SEG(gs);
 151         COPY_SEG(fs);
 152         COPY_SEG(es);
 153         COPY_SEG(ds);
 154         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 155         COPY(dx); COPY(cx); COPY(ip);
 156         COPY_SEG_STRICT(cs);
 157         COPY_SEG_STRICT(ss);
 158
 159         {
 160                 unsigned int tmpflags;
 161
 162                 err |= __get_user(tmpflags, &sc->flags);
 163                 regs->flags = (regs->flags & ~FIX_EFLAGS) |
 164                                                 (tmpflags & FIX_EFLAGS);
 165                 regs->orig_ax = -1;             /* disable syscall checks */
 166         }
 167
 168         {
 169                 void __user *buf;
 170
 171                 err |= __get_user(buf, &sc->fpstate);
 172                 err |= restore_i387_xstate(buf);
 173         }
 174
 175         err |= __get_user(*pax, &sc->ax);
 176         return err;
 177 }
 178
 179 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 180 {
 181         struct sigframe __user *frame;
 182         struct pt_regs *regs;
 183         unsigned long ax;
 184         sigset_t set;
 185
 186         regs = (struct pt_regs *) &__unused;
 187         frame = (struct sigframe __user *)(regs->sp - 8);
 188
 189         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 190                 goto badframe;
 191         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 192                 && __copy_from_user(&set.sig[1], &frame->extramask,
 193                                     sizeof(frame->extramask))))
 194                 goto badframe;
 195
 196         sigdelsetmask(&set, ~_BLOCKABLE);
 197         spin_lock_irq(&current->sighand->siglock);
 198         current->blocked = set;
 199         recalc_sigpending();
 200         spin_unlock_irq(&current->sighand->siglock);
 201
 202         if (restore_sigcontext(regs, &frame->sc, &ax))
 203                 goto badframe;
 204         return ax;
 205
 206 badframe:
 207         if (show_unhandled_signals && printk_ratelimit()) {
 208                 printk("%s%s[%d] bad frame in sigreturn frame:"
 209                         "%p ip:%lx sp:%lx oeax:%lx",
 210                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 211                     current->comm, task_pid_nr(current), frame, regs->ip,
 212                     regs->sp, regs->orig_ax);
 213                 print_vma_addr(" in ", regs->ip);
 214                 printk(KERN_CONT "\n");
 215         }
 216
 217         force_sig(SIGSEGV, current);
 218
 219         return 0;
 220 }
 221
 222 static long do_rt_sigreturn(struct pt_regs *regs)
 223 {
 224         struct rt_sigframe __user *frame;
 225         unsigned long ax;
 226         sigset_t set;
 227
 228         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 229         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 230                 goto badframe;
 231         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 232                 goto badframe;
 233
 234         sigdelsetmask(&set, ~_BLOCKABLE);
 235         spin_lock_irq(&current->sighand->siglock);
 236         current->blocked = set;
 237         recalc_sigpending();
 238         spin_unlock_irq(&current->sighand->siglock);
 239
 240         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 241                 goto badframe;
 242
 243         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 244                 goto badframe;
 245
 246         return ax;
 247
 248 badframe:
 249         signal_fault(regs, frame, "rt_sigreturn");
 250         return 0;
 251 }
 252
 253 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 254 {
 255         struct pt_regs *regs = (struct pt_regs *)&__unused;
 256
 257         return do_rt_sigreturn(regs);
 258 }
 259
 260 /*
 261  * Set up a signal frame.
 262  */
 263 static int
 264 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 265                  struct pt_regs *regs, unsigned long mask)
 266 {
 267         int tmp, err = 0;
 268
 269         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 270         savesegment(gs, tmp);
 271         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 272
 273         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 274         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 275         err |= __put_user(regs->di, &sc->di);
 276         err |= __put_user(regs->si, &sc->si);
 277         err |= __put_user(regs->bp, &sc->bp);
 278         err |= __put_user(regs->sp, &sc->sp);
 279         err |= __put_user(regs->bx, &sc->bx);
 280         err |= __put_user(regs->dx, &sc->dx);
 281         err |= __put_user(regs->cx, &sc->cx);
 282         err |= __put_user(regs->ax, &sc->ax);
 283         err |= __put_user(current->thread.trap_no, &sc->trapno);
 284         err |= __put_user(current->thread.error_code, &sc->err);
 285         err |= __put_user(regs->ip, &sc->ip);
 286         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 287         err |= __put_user(regs->flags, &sc->flags);
 288         err |= __put_user(regs->sp, &sc->sp_at_signal);
 289         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 290
 291         tmp = save_i387_xstate(fpstate);
 292         if (tmp < 0)
 293                 err = 1;
 294         else
 295                 err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 296
 297         /* non-iBCS2 extensions.. */
 298         err |= __put_user(mask, &sc->oldmask);
 299         err |= __put_user(current->thread.cr2, &sc->cr2);
 300
 301         return err;
 302 }
 303
 304 /*
 305  * Determine which stack to use..
 306  */
 307 static inline void __user *
 308 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 309              void **fpstate)
 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         if (used_math()) {
 336                 sp = sp - sig_xstate_size;
 337                 *fpstate = (struct _fpstate *) sp;
 338         }
 339
 340         sp -= frame_size;
 341         /*
 342          * Align the stack pointer according to the i386 ABI,
 343          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 344          */
 345         sp = ((sp + 4) & -16ul) - 4;
 346
 347         return (void __user *) sp;
 348 }
 349
 350 static int
 351 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 352               struct pt_regs *regs)
 353 {
 354         struct sigframe __user *frame;
 355         void __user *restorer;
 356         int err = 0;
 357         void __user *fpstate = NULL;
 358
 359         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 360
 361         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 362                 return -EFAULT;
 363
 364         if (__put_user(sig, &frame->sig))
 365                 return -EFAULT;
 366
 367         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 368                 return -EFAULT;
 369
 370         if (_NSIG_WORDS > 1) {
 371                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 372                                    sizeof(frame->extramask)))
 373                         return -EFAULT;
 374         }
 375
 376         if (current->mm->context.vdso)
 377                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 378         else
 379                 restorer = &frame->retcode;
 380         if (ka->sa.sa_flags & SA_RESTORER)
 381                 restorer = ka->sa.sa_restorer;
 382
 383         /* Set up to return from userspace.  */
 384         err |= __put_user(restorer, &frame->pretcode);
 385
 386         /*
 387          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 388          *
 389          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 390          * reasons and because gdb uses it as a signature to notice
 391          * signal handler stack frames.
 392          */
 393         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 394         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 395         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 396
 397         if (err)
 398                 return -EFAULT;
 399
 400         /* Set up registers for signal handler */
 401         regs->sp = (unsigned long)frame;
 402         regs->ip = (unsigned long)ka->sa.sa_handler;
 403         regs->ax = (unsigned long)sig;
 404         regs->dx = 0;
 405         regs->cx = 0;
 406
 407         regs->ds = __USER_DS;
 408         regs->es = __USER_DS;
 409         regs->ss = __USER_DS;
 410         regs->cs = __USER_CS;
 411
 412         return 0;
 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         struct rt_sigframe __user *frame;
 419         void __user *restorer;
 420         int err = 0;
 421         void __user *fpstate = NULL;
 422
 423         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 424
 425         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 426                 return -EFAULT;
 427
 428         err |= __put_user(sig, &frame->sig);
 429         err |= __put_user(&frame->info, &frame->pinfo);
 430         err |= __put_user(&frame->uc, &frame->puc);
 431         err |= copy_siginfo_to_user(&frame->info, info);
 432         if (err)
 433                 return -EFAULT;
 434
 435         /* Create the ucontext.  */
 436         if (cpu_has_xsave)
 437                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 438         else
 439                 err |= __put_user(0, &frame->uc.uc_flags);
 440         err |= __put_user(0, &frame->uc.uc_link);
 441         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 442         err |= __put_user(sas_ss_flags(regs->sp),
 443                           &frame->uc.uc_stack.ss_flags);
 444         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 445         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 446                                 regs, set->sig[0]);
 447         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 448         if (err)
 449                 return -EFAULT;
 450
 451         /* Set up to return from userspace.  */
 452         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 453         if (ka->sa.sa_flags & SA_RESTORER)
 454                 restorer = ka->sa.sa_restorer;
 455         err |= __put_user(restorer, &frame->pretcode);
 456
 457         /*
 458          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 459          *
 460          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 461          * reasons and because gdb uses it as a signature to notice
 462          * signal handler stack frames.
 463          */
 464         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 465         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 466         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 467
 468         if (err)
 469                 return -EFAULT;
 470
 471         /* Set up registers for signal handler */
 472         regs->sp = (unsigned long)frame;
 473         regs->ip = (unsigned long)ka->sa.sa_handler;
 474         regs->ax = (unsigned long)sig;
 475         regs->dx = (unsigned long)&frame->info;
 476         regs->cx = (unsigned long)&frame->uc;
 477
 478         regs->ds = __USER_DS;
 479         regs->es = __USER_DS;
 480         regs->ss = __USER_DS;
 481         regs->cs = __USER_CS;
 482
 483         return 0;
 484 }
 485
 486 /*
 487  * OK, we're invoking a handler:
 488  */
 489 static int signr_convert(int sig)
 490 {
 491         struct thread_info *info = current_thread_info();
 492
 493         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 494                 return info->exec_domain->signal_invmap[sig];
 495         return sig;
 496 }
 497
 498 #define is_ia32 1
 499 #define ia32_setup_frame        __setup_frame
 500 #define ia32_setup_rt_frame     __setup_rt_frame
 501
 502 static int
 503 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 504                sigset_t *set, struct pt_regs *regs)
 505 {
 506         int usig = signr_convert(sig);
 507         int ret;
 508
 509         /* Set up the stack frame */
 510         if (is_ia32) {
 511                 if (ka->sa.sa_flags & SA_SIGINFO)
 512                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 513                 else
 514                         ret = ia32_setup_frame(usig, ka, set, regs);
 515         } else
 516                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 517
 518         if (ret) {
 519                 force_sigsegv(sig, current);
 520                 return -EFAULT;
 521         }
 522
 523         return ret;
 524 }
 525
 526 static int
 527 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 528               sigset_t *oldset, struct pt_regs *regs)
 529 {
 530         int ret;
 531
 532         /* Are we from a system call? */
 533         if (syscall_get_nr(current, regs) >= 0) {
 534                 /* If so, check system call restarting.. */
 535                 switch (syscall_get_error(current, regs)) {
 536                 case -ERESTART_RESTARTBLOCK:
 537                 case -ERESTARTNOHAND:
 538                         regs->ax = -EINTR;
 539                         break;
 540
 541                 case -ERESTARTSYS:
 542                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 543                                 regs->ax = -EINTR;
 544                                 break;
 545                         }
 546                 /* fallthrough */
 547                 case -ERESTARTNOINTR:
 548                         regs->ax = regs->orig_ax;
 549                         regs->ip -= 2;
 550                         break;
 551                 }
 552         }
 553
 554         /*
 555          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 556          * flag so that register information in the sigcontext is correct.
 557          */
 558         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 559             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 560                 regs->flags &= ~X86_EFLAGS_TF;
 561
 562         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 563
 564         if (ret)
 565                 return ret;
 566
 567 #ifdef CONFIG_X86_64
 568         /*
 569          * This has nothing to do with segment registers,
 570          * despite the name.  This magic affects uaccess.h
 571          * macros' behavior.  Reset it to the normal setting.
 572          */
 573         set_fs(USER_DS);
 574 #endif
 575
 576         /*
 577          * Clear the direction flag as per the ABI for function entry.
 578          */
 579         regs->flags &= ~X86_EFLAGS_DF;
 580
 581         /*
 582          * Clear TF when entering the signal handler, but
 583          * notify any tracer that was single-stepping it.
 584          * The tracer may want to single-step inside the
 585          * handler too.
 586          */
 587         regs->flags &= ~X86_EFLAGS_TF;
 588
 589         spin_lock_irq(&current->sighand->siglock);
 590         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 591         if (!(ka->sa.sa_flags & SA_NODEFER))
 592                 sigaddset(&current->blocked, sig);
 593         recalc_sigpending();
 594         spin_unlock_irq(&current->sighand->siglock);
 595
 596         tracehook_signal_handler(sig, info, ka, regs,
 597                                  test_thread_flag(TIF_SINGLESTEP));
 598
 599         return 0;
 600 }
 601
 602 #define NR_restart_syscall      __NR_restart_syscall
 603 /*
 604  * Note that 'init' is a special process: it doesn't get signals it doesn't
 605  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 606  * mistake.
 607  */
 608 static void do_signal(struct pt_regs *regs)
 609 {
 610         struct k_sigaction ka;
 611         siginfo_t info;
 612         int signr;
 613         sigset_t *oldset;
 614
 615         /*
 616          * We want the common case to go fast, which is why we may in certain
 617          * cases get here from kernel mode. Just return without doing anything
 618          * if so.
 619          * X86_32: vm86 regs switched out by assembly code before reaching
 620          * here, so testing against kernel CS suffices.
 621          */
 622         if (!user_mode(regs))
 623                 return;
 624
 625         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 626                 oldset = &current->saved_sigmask;
 627         else
 628                 oldset = &current->blocked;
 629
 630         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 631         if (signr > 0) {
 632                 /*
 633                  * Re-enable any watchpoints before delivering the
 634                  * signal to user space. The processor register will
 635                  * have been cleared if the watchpoint triggered
 636                  * inside the kernel.
 637                  */
 638                 if (current->thread.debugreg7)
 639                         set_debugreg(current->thread.debugreg7, 7);
 640
 641                 /* Whee! Actually deliver the signal.  */
 642                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 643                         /*
 644                          * A signal was successfully delivered; the saved
 645                          * sigmask will have been stored in the signal frame,
 646                          * and will be restored by sigreturn, so we can simply
 647                          * clear the TS_RESTORE_SIGMASK flag.
 648                          */
 649                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 650                 }
 651                 return;
 652         }
 653
 654         /* Did we come from a system call? */
 655         if (syscall_get_nr(current, regs) >= 0) {
 656                 /* Restart the system call - no handlers present */
 657                 switch (syscall_get_error(current, regs)) {
 658                 case -ERESTARTNOHAND:
 659                 case -ERESTARTSYS:
 660                 case -ERESTARTNOINTR:
 661                         regs->ax = regs->orig_ax;
 662                         regs->ip -= 2;
 663                         break;
 664
 665                 case -ERESTART_RESTARTBLOCK:
 666                         regs->ax = NR_restart_syscall;
 667                         regs->ip -= 2;
 668                         break;
 669                 }
 670         }
 671
 672         /*
 673          * If there's no signal to deliver, we just put the saved sigmask
 674          * back.
 675          */
 676         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 677                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 678                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 679         }
 680 }
 681
 682 /*
 683  * notification of userspace execution resumption
 684  * - triggered by the TIF_WORK_MASK flags
 685  */
 686 void
 687 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 688 {
 689 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 690         /* notify userspace of pending MCEs */
 691         if (thread_info_flags & _TIF_MCE_NOTIFY)
 692                 mce_notify_user();
 693 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 694
 695         /* deal with pending signal delivery */
 696         if (thread_info_flags & _TIF_SIGPENDING)
 697                 do_signal(regs);
 698
 699         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 700                 clear_thread_flag(TIF_NOTIFY_RESUME);
 701                 tracehook_notify_resume(regs);
 702         }
 703
 704 #ifdef CONFIG_X86_32
 705         clear_thread_flag(TIF_IRET);
 706 #endif /* CONFIG_X86_32 */
 707 }
 708
 709 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 710 {
 711         struct task_struct *me = current;
 712
 713         if (show_unhandled_signals && printk_ratelimit()) {
 714                 printk(KERN_INFO
 715                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 716                        me->comm, me->pid, where, frame,
 717                        regs->ip, regs->sp, regs->orig_ax);
 718                 print_vma_addr(" in ", regs->ip);
 719                 printk(KERN_CONT "\n");
 720         }
 721
 722         force_sig(SIGSEGV, me);
 723 }