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         void __user *buf;
 146         unsigned int tmpflags;
 147         unsigned int err = 0;
 148
 149         /* Always make any pending restarted system calls return -EINTR */
 150         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 151
 152         GET_SEG(gs);
 153         COPY_SEG(fs);
 154         COPY_SEG(es);
 155         COPY_SEG(ds);
 156         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 157         COPY(dx); COPY(cx); COPY(ip);
 158         COPY_SEG_STRICT(cs);
 159         COPY_SEG_STRICT(ss);
 160
 161         err |= __get_user(tmpflags, &sc->flags);
 162         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 163         regs->orig_ax = -1;             /* disable syscall checks */
 164
 165         err |= __get_user(buf, &sc->fpstate);
 166         err |= restore_i387_xstate(buf);
 167
 168         err |= __get_user(*pax, &sc->ax);
 169         return err;
 170 }
 171
 172 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 173 {
 174         struct sigframe __user *frame;
 175         struct pt_regs *regs;
 176         unsigned long ax;
 177         sigset_t set;
 178
 179         regs = (struct pt_regs *) &__unused;
 180         frame = (struct sigframe __user *)(regs->sp - 8);
 181
 182         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 183                 goto badframe;
 184         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_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, &ax))
 196                 goto badframe;
 197         return ax;
 198
 199 badframe:
 200         if (show_unhandled_signals && printk_ratelimit()) {
 201                 printk("%s%s[%d] bad frame in sigreturn frame:"
 202                         "%p ip:%lx sp:%lx oeax:%lx",
 203                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 204                     current->comm, task_pid_nr(current), frame, regs->ip,
 205                     regs->sp, regs->orig_ax);
 206                 print_vma_addr(" in ", regs->ip);
 207                 printk(KERN_CONT "\n");
 208         }
 209
 210         force_sig(SIGSEGV, current);
 211
 212         return 0;
 213 }
 214
 215 static long do_rt_sigreturn(struct pt_regs *regs)
 216 {
 217         struct rt_sigframe __user *frame;
 218         unsigned long ax;
 219         sigset_t set;
 220
 221         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 222         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 223                 goto badframe;
 224         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 225                 goto badframe;
 226
 227         sigdelsetmask(&set, ~_BLOCKABLE);
 228         spin_lock_irq(&current->sighand->siglock);
 229         current->blocked = set;
 230         recalc_sigpending();
 231         spin_unlock_irq(&current->sighand->siglock);
 232
 233         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 234                 goto badframe;
 235
 236         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 237                 goto badframe;
 238
 239         return ax;
 240
 241 badframe:
 242         signal_fault(regs, frame, "rt_sigreturn");
 243         return 0;
 244 }
 245
 246 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 247 {
 248         struct pt_regs *regs = (struct pt_regs *)&__unused;
 249
 250         return do_rt_sigreturn(regs);
 251 }
 252
 253 /*
 254  * Set up a signal frame.
 255  */
 256 static int
 257 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 258                  struct pt_regs *regs, unsigned long mask)
 259 {
 260         int tmp, err = 0;
 261
 262         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 263         savesegment(gs, tmp);
 264         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 265
 266         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 267         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 268         err |= __put_user(regs->di, &sc->di);
 269         err |= __put_user(regs->si, &sc->si);
 270         err |= __put_user(regs->bp, &sc->bp);
 271         err |= __put_user(regs->sp, &sc->sp);
 272         err |= __put_user(regs->bx, &sc->bx);
 273         err |= __put_user(regs->dx, &sc->dx);
 274         err |= __put_user(regs->cx, &sc->cx);
 275         err |= __put_user(regs->ax, &sc->ax);
 276         err |= __put_user(current->thread.trap_no, &sc->trapno);
 277         err |= __put_user(current->thread.error_code, &sc->err);
 278         err |= __put_user(regs->ip, &sc->ip);
 279         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 280         err |= __put_user(regs->flags, &sc->flags);
 281         err |= __put_user(regs->sp, &sc->sp_at_signal);
 282         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 283
 284         tmp = save_i387_xstate(fpstate);
 285         if (tmp < 0)
 286                 err = 1;
 287         else
 288                 err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 289
 290         /* non-iBCS2 extensions.. */
 291         err |= __put_user(mask, &sc->oldmask);
 292         err |= __put_user(current->thread.cr2, &sc->cr2);
 293
 294         return err;
 295 }
 296
 297 /*
 298  * Determine which stack to use..
 299  */
 300 static inline void __user *
 301 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 302              void **fpstate)
 303 {
 304         unsigned long sp;
 305
 306         /* Default to using normal stack */
 307         sp = regs->sp;
 308
 309         /*
 310          * If we are on the alternate signal stack and would overflow it, don't.
 311          * Return an always-bogus address instead so we will die with SIGSEGV.
 312          */
 313         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 314                 return (void __user *) -1L;
 315
 316         /* This is the X/Open sanctioned signal stack switching.  */
 317         if (ka->sa.sa_flags & SA_ONSTACK) {
 318                 if (sas_ss_flags(sp) == 0)
 319                         sp = current->sas_ss_sp + current->sas_ss_size;
 320         } else {
 321                 /* This is the legacy signal stack switching. */
 322                 if ((regs->ss & 0xffff) != __USER_DS &&
 323                         !(ka->sa.sa_flags & SA_RESTORER) &&
 324                                 ka->sa.sa_restorer)
 325                         sp = (unsigned long) ka->sa.sa_restorer;
 326         }
 327
 328         if (used_math()) {
 329                 sp = sp - sig_xstate_size;
 330                 *fpstate = (struct _fpstate *) sp;
 331         }
 332
 333         sp -= frame_size;
 334         /*
 335          * Align the stack pointer according to the i386 ABI,
 336          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 337          */
 338         sp = ((sp + 4) & -16ul) - 4;
 339
 340         return (void __user *) sp;
 341 }
 342
 343 static int
 344 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 345               struct pt_regs *regs)
 346 {
 347         struct sigframe __user *frame;
 348         void __user *restorer;
 349         int err = 0;
 350         void __user *fpstate = NULL;
 351
 352         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 353
 354         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 355                 return -EFAULT;
 356
 357         if (__put_user(sig, &frame->sig))
 358                 return -EFAULT;
 359
 360         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 361                 return -EFAULT;
 362
 363         if (_NSIG_WORDS > 1) {
 364                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 365                                    sizeof(frame->extramask)))
 366                         return -EFAULT;
 367         }
 368
 369         if (current->mm->context.vdso)
 370                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 371         else
 372                 restorer = &frame->retcode;
 373         if (ka->sa.sa_flags & SA_RESTORER)
 374                 restorer = ka->sa.sa_restorer;
 375
 376         /* Set up to return from userspace.  */
 377         err |= __put_user(restorer, &frame->pretcode);
 378
 379         /*
 380          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 381          *
 382          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 383          * reasons and because gdb uses it as a signature to notice
 384          * signal handler stack frames.
 385          */
 386         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 387         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 388         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 389
 390         if (err)
 391                 return -EFAULT;
 392
 393         /* Set up registers for signal handler */
 394         regs->sp = (unsigned long)frame;
 395         regs->ip = (unsigned long)ka->sa.sa_handler;
 396         regs->ax = (unsigned long)sig;
 397         regs->dx = 0;
 398         regs->cx = 0;
 399
 400         regs->ds = __USER_DS;
 401         regs->es = __USER_DS;
 402         regs->ss = __USER_DS;
 403         regs->cs = __USER_CS;
 404
 405         return 0;
 406 }
 407
 408 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 409                             sigset_t *set, struct pt_regs *regs)
 410 {
 411         struct rt_sigframe __user *frame;
 412         void __user *restorer;
 413         int err = 0;
 414         void __user *fpstate = NULL;
 415
 416         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 417
 418         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 419                 return -EFAULT;
 420
 421         err |= __put_user(sig, &frame->sig);
 422         err |= __put_user(&frame->info, &frame->pinfo);
 423         err |= __put_user(&frame->uc, &frame->puc);
 424         err |= copy_siginfo_to_user(&frame->info, info);
 425         if (err)
 426                 return -EFAULT;
 427
 428         /* Create the ucontext.  */
 429         if (cpu_has_xsave)
 430                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 431         else
 432                 err |= __put_user(0, &frame->uc.uc_flags);
 433         err |= __put_user(0, &frame->uc.uc_link);
 434         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 435         err |= __put_user(sas_ss_flags(regs->sp),
 436                           &frame->uc.uc_stack.ss_flags);
 437         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 438         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 439                                 regs, set->sig[0]);
 440         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 441         if (err)
 442                 return -EFAULT;
 443
 444         /* Set up to return from userspace.  */
 445         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 446         if (ka->sa.sa_flags & SA_RESTORER)
 447                 restorer = ka->sa.sa_restorer;
 448         err |= __put_user(restorer, &frame->pretcode);
 449
 450         /*
 451          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 452          *
 453          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 454          * reasons and because gdb uses it as a signature to notice
 455          * signal handler stack frames.
 456          */
 457         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 458         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 459         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 460
 461         if (err)
 462                 return -EFAULT;
 463
 464         /* Set up registers for signal handler */
 465         regs->sp = (unsigned long)frame;
 466         regs->ip = (unsigned long)ka->sa.sa_handler;
 467         regs->ax = (unsigned long)sig;
 468         regs->dx = (unsigned long)&frame->info;
 469         regs->cx = (unsigned long)&frame->uc;
 470
 471         regs->ds = __USER_DS;
 472         regs->es = __USER_DS;
 473         regs->ss = __USER_DS;
 474         regs->cs = __USER_CS;
 475
 476         return 0;
 477 }
 478
 479 /*
 480  * OK, we're invoking a handler:
 481  */
 482 static int signr_convert(int sig)
 483 {
 484         struct thread_info *info = current_thread_info();
 485
 486         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 487                 return info->exec_domain->signal_invmap[sig];
 488         return sig;
 489 }
 490
 491 #define is_ia32 1
 492 #define ia32_setup_frame        __setup_frame
 493 #define ia32_setup_rt_frame     __setup_rt_frame
 494
 495 static int
 496 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 497                sigset_t *set, struct pt_regs *regs)
 498 {
 499         int usig = signr_convert(sig);
 500         int ret;
 501
 502         /* Set up the stack frame */
 503         if (is_ia32) {
 504                 if (ka->sa.sa_flags & SA_SIGINFO)
 505                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 506                 else
 507                         ret = ia32_setup_frame(usig, ka, set, regs);
 508         } else
 509                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 510
 511         if (ret) {
 512                 force_sigsegv(sig, current);
 513                 return -EFAULT;
 514         }
 515
 516         return ret;
 517 }
 518
 519 static int
 520 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 521               sigset_t *oldset, struct pt_regs *regs)
 522 {
 523         int ret;
 524
 525         /* Are we from a system call? */
 526         if (syscall_get_nr(current, regs) >= 0) {
 527                 /* If so, check system call restarting.. */
 528                 switch (syscall_get_error(current, regs)) {
 529                 case -ERESTART_RESTARTBLOCK:
 530                 case -ERESTARTNOHAND:
 531                         regs->ax = -EINTR;
 532                         break;
 533
 534                 case -ERESTARTSYS:
 535                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 536                                 regs->ax = -EINTR;
 537                                 break;
 538                         }
 539                 /* fallthrough */
 540                 case -ERESTARTNOINTR:
 541                         regs->ax = regs->orig_ax;
 542                         regs->ip -= 2;
 543                         break;
 544                 }
 545         }
 546
 547         /*
 548          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 549          * flag so that register information in the sigcontext is correct.
 550          */
 551         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 552             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 553                 regs->flags &= ~X86_EFLAGS_TF;
 554
 555         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 556
 557         if (ret)
 558                 return ret;
 559
 560 #ifdef CONFIG_X86_64
 561         /*
 562          * This has nothing to do with segment registers,
 563          * despite the name.  This magic affects uaccess.h
 564          * macros' behavior.  Reset it to the normal setting.
 565          */
 566         set_fs(USER_DS);
 567 #endif
 568
 569         /*
 570          * Clear the direction flag as per the ABI for function entry.
 571          */
 572         regs->flags &= ~X86_EFLAGS_DF;
 573
 574         /*
 575          * Clear TF when entering the signal handler, but
 576          * notify any tracer that was single-stepping it.
 577          * The tracer may want to single-step inside the
 578          * handler too.
 579          */
 580         regs->flags &= ~X86_EFLAGS_TF;
 581
 582         spin_lock_irq(&current->sighand->siglock);
 583         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 584         if (!(ka->sa.sa_flags & SA_NODEFER))
 585                 sigaddset(&current->blocked, sig);
 586         recalc_sigpending();
 587         spin_unlock_irq(&current->sighand->siglock);
 588
 589         tracehook_signal_handler(sig, info, ka, regs,
 590                                  test_thread_flag(TIF_SINGLESTEP));
 591
 592         return 0;
 593 }
 594
 595 #define NR_restart_syscall      __NR_restart_syscall
 596 /*
 597  * Note that 'init' is a special process: it doesn't get signals it doesn't
 598  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 599  * mistake.
 600  */
 601 static void do_signal(struct pt_regs *regs)
 602 {
 603         struct k_sigaction ka;
 604         siginfo_t info;
 605         int signr;
 606         sigset_t *oldset;
 607
 608         /*
 609          * We want the common case to go fast, which is why we may in certain
 610          * cases get here from kernel mode. Just return without doing anything
 611          * if so.
 612          * X86_32: vm86 regs switched out by assembly code before reaching
 613          * here, so testing against kernel CS suffices.
 614          */
 615         if (!user_mode(regs))
 616                 return;
 617
 618         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 619                 oldset = &current->saved_sigmask;
 620         else
 621                 oldset = &current->blocked;
 622
 623         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 624         if (signr > 0) {
 625                 /*
 626                  * Re-enable any watchpoints before delivering the
 627                  * signal to user space. The processor register will
 628                  * have been cleared if the watchpoint triggered
 629                  * inside the kernel.
 630                  */
 631                 if (current->thread.debugreg7)
 632                         set_debugreg(current->thread.debugreg7, 7);
 633
 634                 /* Whee! Actually deliver the signal.  */
 635                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 636                         /*
 637                          * A signal was successfully delivered; the saved
 638                          * sigmask will have been stored in the signal frame,
 639                          * and will be restored by sigreturn, so we can simply
 640                          * clear the TS_RESTORE_SIGMASK flag.
 641                          */
 642                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 643                 }
 644                 return;
 645         }
 646
 647         /* Did we come from a system call? */
 648         if (syscall_get_nr(current, regs) >= 0) {
 649                 /* Restart the system call - no handlers present */
 650                 switch (syscall_get_error(current, regs)) {
 651                 case -ERESTARTNOHAND:
 652                 case -ERESTARTSYS:
 653                 case -ERESTARTNOINTR:
 654                         regs->ax = regs->orig_ax;
 655                         regs->ip -= 2;
 656                         break;
 657
 658                 case -ERESTART_RESTARTBLOCK:
 659                         regs->ax = NR_restart_syscall;
 660                         regs->ip -= 2;
 661                         break;
 662                 }
 663         }
 664
 665         /*
 666          * If there's no signal to deliver, we just put the saved sigmask
 667          * back.
 668          */
 669         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 670                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 671                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 672         }
 673 }
 674
 675 /*
 676  * notification of userspace execution resumption
 677  * - triggered by the TIF_WORK_MASK flags
 678  */
 679 void
 680 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 681 {
 682 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 683         /* notify userspace of pending MCEs */
 684         if (thread_info_flags & _TIF_MCE_NOTIFY)
 685                 mce_notify_user();
 686 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 687
 688         /* deal with pending signal delivery */
 689         if (thread_info_flags & _TIF_SIGPENDING)
 690                 do_signal(regs);
 691
 692         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 693                 clear_thread_flag(TIF_NOTIFY_RESUME);
 694                 tracehook_notify_resume(regs);
 695         }
 696
 697 #ifdef CONFIG_X86_32
 698         clear_thread_flag(TIF_IRET);
 699 #endif /* CONFIG_X86_32 */
 700 }
 701
 702 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 703 {
 704         struct task_struct *me = current;
 705
 706         if (show_unhandled_signals && printk_ratelimit()) {
 707                 printk(KERN_INFO
 708                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 709                        me->comm, me->pid, where, frame,
 710                        regs->ip, regs->sp, regs->orig_ax);
 711                 print_vma_addr(" in ", regs->ip);
 712                 printk(KERN_CONT "\n");
 713         }
 714
 715         force_sig(SIGSEGV, me);
 716 }