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 #ifdef CONFIG_X86_32
 153         GET_SEG(gs);
 154         COPY_SEG(fs);
 155         COPY_SEG(es);
 156         COPY_SEG(ds);
 157 #endif /* CONFIG_X86_32 */
 158
 159         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 160         COPY(dx); COPY(cx); COPY(ip);
 161
 162 #ifdef CONFIG_X86_64
 163         COPY(r8);
 164         COPY(r9);
 165         COPY(r10);
 166         COPY(r11);
 167         COPY(r12);
 168         COPY(r13);
 169         COPY(r14);
 170         COPY(r15);
 171 #endif /* CONFIG_X86_64 */
 172
 173 #ifdef CONFIG_X86_32
 174         COPY_SEG_STRICT(cs);
 175         COPY_SEG_STRICT(ss);
 176 #else /* !CONFIG_X86_32 */
 177         /* Kernel saves and restores only the CS segment register on signals,
 178          * which is the bare minimum needed to allow mixed 32/64-bit code.
 179          * App's signal handler can save/restore other segments if needed. */
 180         COPY_SEG_STRICT(cs);
 181 #endif /* CONFIG_X86_32 */
 182
 183         err |= __get_user(tmpflags, &sc->flags);
 184         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 185         regs->orig_ax = -1;             /* disable syscall checks */
 186
 187         err |= __get_user(buf, &sc->fpstate);
 188         err |= restore_i387_xstate(buf);
 189
 190         err |= __get_user(*pax, &sc->ax);
 191         return err;
 192 }
 193
 194 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 195 {
 196         struct sigframe __user *frame;
 197         struct pt_regs *regs;
 198         unsigned long ax;
 199         sigset_t set;
 200
 201         regs = (struct pt_regs *) &__unused;
 202         frame = (struct sigframe __user *)(regs->sp - 8);
 203
 204         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 205                 goto badframe;
 206         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 207                 && __copy_from_user(&set.sig[1], &frame->extramask,
 208                                     sizeof(frame->extramask))))
 209                 goto badframe;
 210
 211         sigdelsetmask(&set, ~_BLOCKABLE);
 212         spin_lock_irq(&current->sighand->siglock);
 213         current->blocked = set;
 214         recalc_sigpending();
 215         spin_unlock_irq(&current->sighand->siglock);
 216
 217         if (restore_sigcontext(regs, &frame->sc, &ax))
 218                 goto badframe;
 219         return ax;
 220
 221 badframe:
 222         if (show_unhandled_signals && printk_ratelimit()) {
 223                 printk("%s%s[%d] bad frame in sigreturn frame:"
 224                         "%p ip:%lx sp:%lx oeax:%lx",
 225                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 226                     current->comm, task_pid_nr(current), frame, regs->ip,
 227                     regs->sp, regs->orig_ax);
 228                 print_vma_addr(" in ", regs->ip);
 229                 printk(KERN_CONT "\n");
 230         }
 231
 232         force_sig(SIGSEGV, current);
 233
 234         return 0;
 235 }
 236
 237 static long do_rt_sigreturn(struct pt_regs *regs)
 238 {
 239         struct rt_sigframe __user *frame;
 240         unsigned long ax;
 241         sigset_t set;
 242
 243         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 244         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 245                 goto badframe;
 246         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 247                 goto badframe;
 248
 249         sigdelsetmask(&set, ~_BLOCKABLE);
 250         spin_lock_irq(&current->sighand->siglock);
 251         current->blocked = set;
 252         recalc_sigpending();
 253         spin_unlock_irq(&current->sighand->siglock);
 254
 255         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 256                 goto badframe;
 257
 258         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 259                 goto badframe;
 260
 261         return ax;
 262
 263 badframe:
 264         signal_fault(regs, frame, "rt_sigreturn");
 265         return 0;
 266 }
 267
 268 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 269 {
 270         struct pt_regs *regs = (struct pt_regs *)&__unused;
 271
 272         return do_rt_sigreturn(regs);
 273 }
 274
 275 /*
 276  * Set up a signal frame.
 277  */
 278 static int
 279 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 280                  struct pt_regs *regs, unsigned long mask)
 281 {
 282         int tmp, err = 0;
 283
 284         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 285         savesegment(gs, tmp);
 286         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 287
 288         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 289         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 290         err |= __put_user(regs->di, &sc->di);
 291         err |= __put_user(regs->si, &sc->si);
 292         err |= __put_user(regs->bp, &sc->bp);
 293         err |= __put_user(regs->sp, &sc->sp);
 294         err |= __put_user(regs->bx, &sc->bx);
 295         err |= __put_user(regs->dx, &sc->dx);
 296         err |= __put_user(regs->cx, &sc->cx);
 297         err |= __put_user(regs->ax, &sc->ax);
 298         err |= __put_user(current->thread.trap_no, &sc->trapno);
 299         err |= __put_user(current->thread.error_code, &sc->err);
 300         err |= __put_user(regs->ip, &sc->ip);
 301         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 302         err |= __put_user(regs->flags, &sc->flags);
 303         err |= __put_user(regs->sp, &sc->sp_at_signal);
 304         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 305
 306         err |= __put_user(fpstate, &sc->fpstate);
 307
 308         /* non-iBCS2 extensions.. */
 309         err |= __put_user(mask, &sc->oldmask);
 310         err |= __put_user(current->thread.cr2, &sc->cr2);
 311
 312         return err;
 313 }
 314
 315 /*
 316  * Determine which stack to use..
 317  */
 318 static inline void __user *
 319 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 320              void **fpstate)
 321 {
 322         unsigned long sp;
 323
 324         /* Default to using normal stack */
 325         sp = regs->sp;
 326
 327         /*
 328          * If we are on the alternate signal stack and would overflow it, don't.
 329          * Return an always-bogus address instead so we will die with SIGSEGV.
 330          */
 331         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 332                 return (void __user *) -1L;
 333
 334         /* This is the X/Open sanctioned signal stack switching.  */
 335         if (ka->sa.sa_flags & SA_ONSTACK) {
 336                 if (sas_ss_flags(sp) == 0)
 337                         sp = current->sas_ss_sp + current->sas_ss_size;
 338         } else {
 339                 /* This is the legacy signal stack switching. */
 340                 if ((regs->ss & 0xffff) != __USER_DS &&
 341                         !(ka->sa.sa_flags & SA_RESTORER) &&
 342                                 ka->sa.sa_restorer)
 343                         sp = (unsigned long) ka->sa.sa_restorer;
 344         }
 345
 346         if (used_math()) {
 347                 sp = sp - sig_xstate_size;
 348                 *fpstate = (struct _fpstate *) sp;
 349                 if (save_i387_xstate(*fpstate) < 0)
 350                         return (void __user *)-1L;
 351         }
 352
 353         sp -= frame_size;
 354         /*
 355          * Align the stack pointer according to the i386 ABI,
 356          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 357          */
 358         sp = ((sp + 4) & -16ul) - 4;
 359
 360         return (void __user *) sp;
 361 }
 362
 363 static int
 364 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 365               struct pt_regs *regs)
 366 {
 367         struct sigframe __user *frame;
 368         void __user *restorer;
 369         int err = 0;
 370         void __user *fpstate = NULL;
 371
 372         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 373
 374         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 375                 return -EFAULT;
 376
 377         if (__put_user(sig, &frame->sig))
 378                 return -EFAULT;
 379
 380         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 381                 return -EFAULT;
 382
 383         if (_NSIG_WORDS > 1) {
 384                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 385                                    sizeof(frame->extramask)))
 386                         return -EFAULT;
 387         }
 388
 389         if (current->mm->context.vdso)
 390                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 391         else
 392                 restorer = &frame->retcode;
 393         if (ka->sa.sa_flags & SA_RESTORER)
 394                 restorer = ka->sa.sa_restorer;
 395
 396         /* Set up to return from userspace.  */
 397         err |= __put_user(restorer, &frame->pretcode);
 398
 399         /*
 400          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 401          *
 402          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 403          * reasons and because gdb uses it as a signature to notice
 404          * signal handler stack frames.
 405          */
 406         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 407         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 408         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 409
 410         if (err)
 411                 return -EFAULT;
 412
 413         /* Set up registers for signal handler */
 414         regs->sp = (unsigned long)frame;
 415         regs->ip = (unsigned long)ka->sa.sa_handler;
 416         regs->ax = (unsigned long)sig;
 417         regs->dx = 0;
 418         regs->cx = 0;
 419
 420         regs->ds = __USER_DS;
 421         regs->es = __USER_DS;
 422         regs->ss = __USER_DS;
 423         regs->cs = __USER_CS;
 424
 425         return 0;
 426 }
 427
 428 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 429                             sigset_t *set, struct pt_regs *regs)
 430 {
 431         struct rt_sigframe __user *frame;
 432         void __user *restorer;
 433         int err = 0;
 434         void __user *fpstate = NULL;
 435
 436         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 437
 438         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 439                 return -EFAULT;
 440
 441         err |= __put_user(sig, &frame->sig);
 442         err |= __put_user(&frame->info, &frame->pinfo);
 443         err |= __put_user(&frame->uc, &frame->puc);
 444         err |= copy_siginfo_to_user(&frame->info, info);
 445         if (err)
 446                 return -EFAULT;
 447
 448         /* Create the ucontext.  */
 449         if (cpu_has_xsave)
 450                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 451         else
 452                 err |= __put_user(0, &frame->uc.uc_flags);
 453         err |= __put_user(0, &frame->uc.uc_link);
 454         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 455         err |= __put_user(sas_ss_flags(regs->sp),
 456                           &frame->uc.uc_stack.ss_flags);
 457         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 458         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 459                                 regs, set->sig[0]);
 460         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 461         if (err)
 462                 return -EFAULT;
 463
 464         /* Set up to return from userspace.  */
 465         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 466         if (ka->sa.sa_flags & SA_RESTORER)
 467                 restorer = ka->sa.sa_restorer;
 468         err |= __put_user(restorer, &frame->pretcode);
 469
 470         /*
 471          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 472          *
 473          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 474          * reasons and because gdb uses it as a signature to notice
 475          * signal handler stack frames.
 476          */
 477         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 478         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 479         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 480
 481         if (err)
 482                 return -EFAULT;
 483
 484         /* Set up registers for signal handler */
 485         regs->sp = (unsigned long)frame;
 486         regs->ip = (unsigned long)ka->sa.sa_handler;
 487         regs->ax = (unsigned long)sig;
 488         regs->dx = (unsigned long)&frame->info;
 489         regs->cx = (unsigned long)&frame->uc;
 490
 491         regs->ds = __USER_DS;
 492         regs->es = __USER_DS;
 493         regs->ss = __USER_DS;
 494         regs->cs = __USER_CS;
 495
 496         return 0;
 497 }
 498
 499 /*
 500  * OK, we're invoking a handler:
 501  */
 502 static int signr_convert(int sig)
 503 {
 504 #ifdef CONFIG_X86_32
 505         struct thread_info *info = current_thread_info();
 506
 507         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 508                 return info->exec_domain->signal_invmap[sig];
 509 #endif /* CONFIG_X86_32 */
 510         return sig;
 511 }
 512
 513 #ifdef CONFIG_X86_32
 514
 515 #define is_ia32 1
 516 #define ia32_setup_frame        __setup_frame
 517 #define ia32_setup_rt_frame     __setup_rt_frame
 518
 519 #else /* !CONFIG_X86_32 */
 520
 521 #ifdef CONFIG_IA32_EMULATION
 522 #define is_ia32 test_thread_flag(TIF_IA32)
 523 #else /* !CONFIG_IA32_EMULATION */
 524 #define is_ia32 0
 525 #endif /* CONFIG_IA32_EMULATION */
 526
 527 #endif /* CONFIG_X86_32 */
 528
 529 static int
 530 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 531                sigset_t *set, struct pt_regs *regs)
 532 {
 533         int usig = signr_convert(sig);
 534         int ret;
 535
 536         /* Set up the stack frame */
 537         if (is_ia32) {
 538                 if (ka->sa.sa_flags & SA_SIGINFO)
 539                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 540                 else
 541                         ret = ia32_setup_frame(usig, ka, set, regs);
 542         } else
 543                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 544
 545         if (ret) {
 546                 force_sigsegv(sig, current);
 547                 return -EFAULT;
 548         }
 549
 550         return ret;
 551 }
 552
 553 static int
 554 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 555               sigset_t *oldset, struct pt_regs *regs)
 556 {
 557         int ret;
 558
 559         /* Are we from a system call? */
 560         if (syscall_get_nr(current, regs) >= 0) {
 561                 /* If so, check system call restarting.. */
 562                 switch (syscall_get_error(current, regs)) {
 563                 case -ERESTART_RESTARTBLOCK:
 564                 case -ERESTARTNOHAND:
 565                         regs->ax = -EINTR;
 566                         break;
 567
 568                 case -ERESTARTSYS:
 569                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 570                                 regs->ax = -EINTR;
 571                                 break;
 572                         }
 573                 /* fallthrough */
 574                 case -ERESTARTNOINTR:
 575                         regs->ax = regs->orig_ax;
 576                         regs->ip -= 2;
 577                         break;
 578                 }
 579         }
 580
 581         /*
 582          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 583          * flag so that register information in the sigcontext is correct.
 584          */
 585         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 586             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 587                 regs->flags &= ~X86_EFLAGS_TF;
 588
 589         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 590
 591         if (ret)
 592                 return ret;
 593
 594 #ifdef CONFIG_X86_64
 595         /*
 596          * This has nothing to do with segment registers,
 597          * despite the name.  This magic affects uaccess.h
 598          * macros' behavior.  Reset it to the normal setting.
 599          */
 600         set_fs(USER_DS);
 601 #endif
 602
 603         /*
 604          * Clear the direction flag as per the ABI for function entry.
 605          */
 606         regs->flags &= ~X86_EFLAGS_DF;
 607
 608         /*
 609          * Clear TF when entering the signal handler, but
 610          * notify any tracer that was single-stepping it.
 611          * The tracer may want to single-step inside the
 612          * handler too.
 613          */
 614         regs->flags &= ~X86_EFLAGS_TF;
 615
 616         spin_lock_irq(&current->sighand->siglock);
 617         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 618         if (!(ka->sa.sa_flags & SA_NODEFER))
 619                 sigaddset(&current->blocked, sig);
 620         recalc_sigpending();
 621         spin_unlock_irq(&current->sighand->siglock);
 622
 623         tracehook_signal_handler(sig, info, ka, regs,
 624                                  test_thread_flag(TIF_SINGLESTEP));
 625
 626         return 0;
 627 }
 628
 629 #ifdef CONFIG_X86_32
 630 #define NR_restart_syscall      __NR_restart_syscall
 631 #else /* !CONFIG_X86_32 */
 632 #define NR_restart_syscall      \
 633         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 634 #endif /* CONFIG_X86_32 */
 635
 636 /*
 637  * Note that 'init' is a special process: it doesn't get signals it doesn't
 638  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 639  * mistake.
 640  */
 641 static void do_signal(struct pt_regs *regs)
 642 {
 643         struct k_sigaction ka;
 644         siginfo_t info;
 645         int signr;
 646         sigset_t *oldset;
 647
 648         /*
 649          * We want the common case to go fast, which is why we may in certain
 650          * cases get here from kernel mode. Just return without doing anything
 651          * if so.
 652          * X86_32: vm86 regs switched out by assembly code before reaching
 653          * here, so testing against kernel CS suffices.
 654          */
 655         if (!user_mode(regs))
 656                 return;
 657
 658         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 659                 oldset = &current->saved_sigmask;
 660         else
 661                 oldset = &current->blocked;
 662
 663         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 664         if (signr > 0) {
 665                 /*
 666                  * Re-enable any watchpoints before delivering the
 667                  * signal to user space. The processor register will
 668                  * have been cleared if the watchpoint triggered
 669                  * inside the kernel.
 670                  */
 671                 if (current->thread.debugreg7)
 672                         set_debugreg(current->thread.debugreg7, 7);
 673
 674                 /* Whee! Actually deliver the signal.  */
 675                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 676                         /*
 677                          * A signal was successfully delivered; the saved
 678                          * sigmask will have been stored in the signal frame,
 679                          * and will be restored by sigreturn, so we can simply
 680                          * clear the TS_RESTORE_SIGMASK flag.
 681                          */
 682                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 683                 }
 684                 return;
 685         }
 686
 687         /* Did we come from a system call? */
 688         if (syscall_get_nr(current, regs) >= 0) {
 689                 /* Restart the system call - no handlers present */
 690                 switch (syscall_get_error(current, regs)) {
 691                 case -ERESTARTNOHAND:
 692                 case -ERESTARTSYS:
 693                 case -ERESTARTNOINTR:
 694                         regs->ax = regs->orig_ax;
 695                         regs->ip -= 2;
 696                         break;
 697
 698                 case -ERESTART_RESTARTBLOCK:
 699                         regs->ax = NR_restart_syscall;
 700                         regs->ip -= 2;
 701                         break;
 702                 }
 703         }
 704
 705         /*
 706          * If there's no signal to deliver, we just put the saved sigmask
 707          * back.
 708          */
 709         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 710                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 711                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 712         }
 713 }
 714
 715 /*
 716  * notification of userspace execution resumption
 717  * - triggered by the TIF_WORK_MASK flags
 718  */
 719 void
 720 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 721 {
 722 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 723         /* notify userspace of pending MCEs */
 724         if (thread_info_flags & _TIF_MCE_NOTIFY)
 725                 mce_notify_user();
 726 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 727
 728         /* deal with pending signal delivery */
 729         if (thread_info_flags & _TIF_SIGPENDING)
 730                 do_signal(regs);
 731
 732         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 733                 clear_thread_flag(TIF_NOTIFY_RESUME);
 734                 tracehook_notify_resume(regs);
 735         }
 736
 737 #ifdef CONFIG_X86_32
 738         clear_thread_flag(TIF_IRET);
 739 #endif /* CONFIG_X86_32 */
 740 }
 741
 742 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 743 {
 744         struct task_struct *me = current;
 745
 746         if (show_unhandled_signals && printk_ratelimit()) {
 747                 printk(KERN_INFO
 748                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 749                        me->comm, me->pid, where, frame,
 750                        regs->ip, regs->sp, regs->orig_ax);
 751                 print_vma_addr(" in ", regs->ip);
 752                 printk(KERN_CONT "\n");
 753         }
 754
 755         force_sig(SIGSEGV, me);
 756 }