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 static const struct {
  49         u16 poplmovl;
  50         u32 val;
  51         u16 int80;
  52 } __attribute__((packed)) retcode = {
  53         0xb858,         /* popl %eax; movl $..., %eax */
  54         __NR_sigreturn,
  55         0x80cd,         /* int $0x80 */
  56 };
  57
  58 static const struct {
  59         u8  movl;
  60         u32 val;
  61         u16 int80;
  62         u8  pad;
  63 } __attribute__((packed)) rt_retcode = {
  64         0xb8,           /* movl $..., %eax */
  65         __NR_rt_sigreturn,
  66         0x80cd,         /* int $0x80 */
  67         0
  68 };
  69
  70 /*
  71  * Atomically swap in the new signal mask, and wait for a signal.
  72  */
  73 asmlinkage int
  74 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  75 {
  76         mask &= _BLOCKABLE;
  77         spin_lock_irq(&current->sighand->siglock);
  78         current->saved_sigmask = current->blocked;
  79         siginitset(&current->blocked, mask);
  80         recalc_sigpending();
  81         spin_unlock_irq(&current->sighand->siglock);
  82
  83         current->state = TASK_INTERRUPTIBLE;
  84         schedule();
  85         set_restore_sigmask();
  86
  87         return -ERESTARTNOHAND;
  88 }
  89
  90 asmlinkage int
  91 sys_sigaction(int sig, const struct old_sigaction __user *act,
  92               struct old_sigaction __user *oact)
  93 {
  94         struct k_sigaction new_ka, old_ka;
  95         int ret;
  96
  97         if (act) {
  98                 old_sigset_t mask;
  99
 100                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 101                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 102                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 103                         return -EFAULT;
 104
 105                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 106                 __get_user(mask, &act->sa_mask);
 107                 siginitset(&new_ka.sa.sa_mask, mask);
 108         }
 109
 110         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 111
 112         if (!ret && oact) {
 113                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 114                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 115                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 116                         return -EFAULT;
 117
 118                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 119                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 120         }
 121
 122         return ret;
 123 }
 124
 125 asmlinkage int sys_sigaltstack(unsigned long bx)
 126 {
 127         /*
 128          * This is needed to make gcc realize it doesn't own the
 129          * "struct pt_regs"
 130          */
 131         struct pt_regs *regs = (struct pt_regs *)&bx;
 132         const stack_t __user *uss = (const stack_t __user *)bx;
 133         stack_t __user *uoss = (stack_t __user *)regs->cx;
 134
 135         return do_sigaltstack(uss, uoss, regs->sp);
 136 }
 137
 138 #define COPY(x)                 {               \
 139         err |= __get_user(regs->x, &sc->x);     \
 140 }
 141
 142 #define COPY_SEG(seg)           {                       \
 143                 unsigned short tmp;                     \
 144                 err |= __get_user(tmp, &sc->seg);       \
 145                 regs->seg = tmp;                        \
 146 }
 147
 148 #define COPY_SEG_CPL3(seg)      {                       \
 149                 unsigned short tmp;                     \
 150                 err |= __get_user(tmp, &sc->seg);       \
 151                 regs->seg = tmp | 3;                    \
 152 }
 153
 154 #define GET_SEG(seg)            {                       \
 155                 unsigned short tmp;                     \
 156                 err |= __get_user(tmp, &sc->seg);       \
 157                 loadsegment(seg, tmp);                  \
 158 }
 159
 160 /*
 161  * Do a signal return; undo the signal stack.
 162  */
 163 static int
 164 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 165                    unsigned long *pax)
 166 {
 167         void __user *buf;
 168         unsigned int tmpflags;
 169         unsigned int err = 0;
 170
 171         /* Always make any pending restarted system calls return -EINTR */
 172         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 173
 174 #ifdef CONFIG_X86_32
 175         GET_SEG(gs);
 176         COPY_SEG(fs);
 177         COPY_SEG(es);
 178         COPY_SEG(ds);
 179 #endif /* CONFIG_X86_32 */
 180
 181         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 182         COPY(dx); COPY(cx); COPY(ip);
 183
 184 #ifdef CONFIG_X86_64
 185         COPY(r8);
 186         COPY(r9);
 187         COPY(r10);
 188         COPY(r11);
 189         COPY(r12);
 190         COPY(r13);
 191         COPY(r14);
 192         COPY(r15);
 193 #endif /* CONFIG_X86_64 */
 194
 195 #ifdef CONFIG_X86_32
 196         COPY_SEG_CPL3(cs);
 197         COPY_SEG_CPL3(ss);
 198 #else /* !CONFIG_X86_32 */
 199         /* Kernel saves and restores only the CS segment register on signals,
 200          * which is the bare minimum needed to allow mixed 32/64-bit code.
 201          * App's signal handler can save/restore other segments if needed. */
 202         COPY_SEG_CPL3(cs);
 203 #endif /* CONFIG_X86_32 */
 204
 205         err |= __get_user(tmpflags, &sc->flags);
 206         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 207         regs->orig_ax = -1;             /* disable syscall checks */
 208
 209         err |= __get_user(buf, &sc->fpstate);
 210         err |= restore_i387_xstate(buf);
 211
 212         err |= __get_user(*pax, &sc->ax);
 213         return err;
 214 }
 215
 216 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 217 {
 218         struct sigframe __user *frame;
 219         struct pt_regs *regs;
 220         unsigned long ax;
 221         sigset_t set;
 222
 223         regs = (struct pt_regs *) &__unused;
 224         frame = (struct sigframe __user *)(regs->sp - 8);
 225
 226         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 227                 goto badframe;
 228         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 229                 && __copy_from_user(&set.sig[1], &frame->extramask,
 230                                     sizeof(frame->extramask))))
 231                 goto badframe;
 232
 233         sigdelsetmask(&set, ~_BLOCKABLE);
 234         spin_lock_irq(&current->sighand->siglock);
 235         current->blocked = set;
 236         recalc_sigpending();
 237         spin_unlock_irq(&current->sighand->siglock);
 238
 239         if (restore_sigcontext(regs, &frame->sc, &ax))
 240                 goto badframe;
 241         return ax;
 242
 243 badframe:
 244         if (show_unhandled_signals && printk_ratelimit()) {
 245                 printk("%s%s[%d] bad frame in sigreturn frame:"
 246                         "%p ip:%lx sp:%lx oeax:%lx",
 247                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 248                     current->comm, task_pid_nr(current), frame, regs->ip,
 249                     regs->sp, regs->orig_ax);
 250                 print_vma_addr(" in ", regs->ip);
 251                 printk(KERN_CONT "\n");
 252         }
 253
 254         force_sig(SIGSEGV, current);
 255
 256         return 0;
 257 }
 258
 259 static long do_rt_sigreturn(struct pt_regs *regs)
 260 {
 261         struct rt_sigframe __user *frame;
 262         unsigned long ax;
 263         sigset_t set;
 264
 265         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 266         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 267                 goto badframe;
 268         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 269                 goto badframe;
 270
 271         sigdelsetmask(&set, ~_BLOCKABLE);
 272         spin_lock_irq(&current->sighand->siglock);
 273         current->blocked = set;
 274         recalc_sigpending();
 275         spin_unlock_irq(&current->sighand->siglock);
 276
 277         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 278                 goto badframe;
 279
 280         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 281                 goto badframe;
 282
 283         return ax;
 284
 285 badframe:
 286         signal_fault(regs, frame, "rt_sigreturn");
 287         return 0;
 288 }
 289
 290 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 291 {
 292         struct pt_regs *regs = (struct pt_regs *)&__unused;
 293
 294         return do_rt_sigreturn(regs);
 295 }
 296
 297 /*
 298  * Set up a signal frame.
 299  */
 300 static int
 301 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 302                  struct pt_regs *regs, unsigned long mask)
 303 {
 304         int err = 0;
 305
 306 #ifdef CONFIG_X86_32
 307         {
 308                 unsigned int tmp;
 309
 310                 savesegment(gs, tmp);
 311                 err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 312         }
 313         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 314         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 315         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 316 #endif /* CONFIG_X86_32 */
 317
 318         err |= __put_user(regs->di, &sc->di);
 319         err |= __put_user(regs->si, &sc->si);
 320         err |= __put_user(regs->bp, &sc->bp);
 321         err |= __put_user(regs->sp, &sc->sp);
 322         err |= __put_user(regs->bx, &sc->bx);
 323         err |= __put_user(regs->dx, &sc->dx);
 324         err |= __put_user(regs->cx, &sc->cx);
 325         err |= __put_user(regs->ax, &sc->ax);
 326 #ifdef CONFIG_X86_64
 327         err |= __put_user(regs->r8, &sc->r8);
 328         err |= __put_user(regs->r9, &sc->r9);
 329         err |= __put_user(regs->r10, &sc->r10);
 330         err |= __put_user(regs->r11, &sc->r11);
 331         err |= __put_user(regs->r12, &sc->r12);
 332         err |= __put_user(regs->r13, &sc->r13);
 333         err |= __put_user(regs->r14, &sc->r14);
 334         err |= __put_user(regs->r15, &sc->r15);
 335 #endif /* CONFIG_X86_64 */
 336
 337         err |= __put_user(current->thread.trap_no, &sc->trapno);
 338         err |= __put_user(current->thread.error_code, &sc->err);
 339         err |= __put_user(regs->ip, &sc->ip);
 340 #ifdef CONFIG_X86_32
 341         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 342         err |= __put_user(regs->flags, &sc->flags);
 343         err |= __put_user(regs->sp, &sc->sp_at_signal);
 344         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 345 #else /* !CONFIG_X86_32 */
 346         err |= __put_user(regs->flags, &sc->flags);
 347         err |= __put_user(regs->cs, &sc->cs);
 348         err |= __put_user(0, &sc->gs);
 349         err |= __put_user(0, &sc->fs);
 350 #endif /* CONFIG_X86_32 */
 351
 352         err |= __put_user(fpstate, &sc->fpstate);
 353
 354         /* non-iBCS2 extensions.. */
 355         err |= __put_user(mask, &sc->oldmask);
 356         err |= __put_user(current->thread.cr2, &sc->cr2);
 357
 358         return err;
 359 }
 360
 361 /*
 362  * Determine which stack to use..
 363  */
 364 static inline void __user *
 365 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 366              void **fpstate)
 367 {
 368         unsigned long sp;
 369
 370         /* Default to using normal stack */
 371         sp = regs->sp;
 372
 373         /*
 374          * If we are on the alternate signal stack and would overflow it, don't.
 375          * Return an always-bogus address instead so we will die with SIGSEGV.
 376          */
 377         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 378                 return (void __user *) -1L;
 379
 380         /* This is the X/Open sanctioned signal stack switching.  */
 381         if (ka->sa.sa_flags & SA_ONSTACK) {
 382                 if (sas_ss_flags(sp) == 0)
 383                         sp = current->sas_ss_sp + current->sas_ss_size;
 384         } else {
 385                 /* This is the legacy signal stack switching. */
 386                 if ((regs->ss & 0xffff) != __USER_DS &&
 387                         !(ka->sa.sa_flags & SA_RESTORER) &&
 388                                 ka->sa.sa_restorer)
 389                         sp = (unsigned long) ka->sa.sa_restorer;
 390         }
 391
 392         if (used_math()) {
 393                 sp = sp - sig_xstate_size;
 394                 *fpstate = (struct _fpstate *) sp;
 395                 if (save_i387_xstate(*fpstate) < 0)
 396                         return (void __user *)-1L;
 397         }
 398
 399         sp -= frame_size;
 400         /*
 401          * Align the stack pointer according to the i386 ABI,
 402          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 403          */
 404         sp = ((sp + 4) & -16ul) - 4;
 405
 406         return (void __user *) sp;
 407 }
 408
 409 static int
 410 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 411               struct pt_regs *regs)
 412 {
 413         struct sigframe __user *frame;
 414         void __user *restorer;
 415         int err = 0;
 416         void __user *fpstate = NULL;
 417
 418         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 419
 420         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 421                 return -EFAULT;
 422
 423         if (__put_user(sig, &frame->sig))
 424                 return -EFAULT;
 425
 426         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 427                 return -EFAULT;
 428
 429         if (_NSIG_WORDS > 1) {
 430                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 431                                    sizeof(frame->extramask)))
 432                         return -EFAULT;
 433         }
 434
 435         if (current->mm->context.vdso)
 436                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 437         else
 438                 restorer = &frame->retcode;
 439         if (ka->sa.sa_flags & SA_RESTORER)
 440                 restorer = ka->sa.sa_restorer;
 441
 442         /* Set up to return from userspace.  */
 443         err |= __put_user(restorer, &frame->pretcode);
 444
 445         /*
 446          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 447          *
 448          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 449          * reasons and because gdb uses it as a signature to notice
 450          * signal handler stack frames.
 451          */
 452         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 453
 454         if (err)
 455                 return -EFAULT;
 456
 457         /* Set up registers for signal handler */
 458         regs->sp = (unsigned long)frame;
 459         regs->ip = (unsigned long)ka->sa.sa_handler;
 460         regs->ax = (unsigned long)sig;
 461         regs->dx = 0;
 462         regs->cx = 0;
 463
 464         regs->ds = __USER_DS;
 465         regs->es = __USER_DS;
 466         regs->ss = __USER_DS;
 467         regs->cs = __USER_CS;
 468
 469         return 0;
 470 }
 471
 472 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 473                             sigset_t *set, struct pt_regs *regs)
 474 {
 475         struct rt_sigframe __user *frame;
 476         void __user *restorer;
 477         int err = 0;
 478         void __user *fpstate = NULL;
 479
 480         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 481
 482         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 483                 return -EFAULT;
 484
 485         err |= __put_user(sig, &frame->sig);
 486         err |= __put_user(&frame->info, &frame->pinfo);
 487         err |= __put_user(&frame->uc, &frame->puc);
 488         err |= copy_siginfo_to_user(&frame->info, info);
 489         if (err)
 490                 return -EFAULT;
 491
 492         /* Create the ucontext.  */
 493         if (cpu_has_xsave)
 494                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 495         else
 496                 err |= __put_user(0, &frame->uc.uc_flags);
 497         err |= __put_user(0, &frame->uc.uc_link);
 498         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 499         err |= __put_user(sas_ss_flags(regs->sp),
 500                           &frame->uc.uc_stack.ss_flags);
 501         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 502         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 503                                 regs, set->sig[0]);
 504         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 505         if (err)
 506                 return -EFAULT;
 507
 508         /* Set up to return from userspace.  */
 509         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 510         if (ka->sa.sa_flags & SA_RESTORER)
 511                 restorer = ka->sa.sa_restorer;
 512         err |= __put_user(restorer, &frame->pretcode);
 513
 514         /*
 515          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 516          *
 517          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 518          * reasons and because gdb uses it as a signature to notice
 519          * signal handler stack frames.
 520          */
 521         err |= __put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 522
 523         if (err)
 524                 return -EFAULT;
 525
 526         /* Set up registers for signal handler */
 527         regs->sp = (unsigned long)frame;
 528         regs->ip = (unsigned long)ka->sa.sa_handler;
 529         regs->ax = (unsigned long)sig;
 530         regs->dx = (unsigned long)&frame->info;
 531         regs->cx = (unsigned long)&frame->uc;
 532
 533         regs->ds = __USER_DS;
 534         regs->es = __USER_DS;
 535         regs->ss = __USER_DS;
 536         regs->cs = __USER_CS;
 537
 538         return 0;
 539 }
 540
 541 /*
 542  * OK, we're invoking a handler:
 543  */
 544 static int signr_convert(int sig)
 545 {
 546 #ifdef CONFIG_X86_32
 547         struct thread_info *info = current_thread_info();
 548
 549         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 550                 return info->exec_domain->signal_invmap[sig];
 551 #endif /* CONFIG_X86_32 */
 552         return sig;
 553 }
 554
 555 #ifdef CONFIG_X86_32
 556
 557 #define is_ia32 1
 558 #define ia32_setup_frame        __setup_frame
 559 #define ia32_setup_rt_frame     __setup_rt_frame
 560
 561 #else /* !CONFIG_X86_32 */
 562
 563 #ifdef CONFIG_IA32_EMULATION
 564 #define is_ia32 test_thread_flag(TIF_IA32)
 565 #else /* !CONFIG_IA32_EMULATION */
 566 #define is_ia32 0
 567 #endif /* CONFIG_IA32_EMULATION */
 568
 569 #endif /* CONFIG_X86_32 */
 570
 571 static int
 572 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 573                sigset_t *set, struct pt_regs *regs)
 574 {
 575         int usig = signr_convert(sig);
 576         int ret;
 577
 578         /* Set up the stack frame */
 579         if (is_ia32) {
 580                 if (ka->sa.sa_flags & SA_SIGINFO)
 581                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 582                 else
 583                         ret = ia32_setup_frame(usig, ka, set, regs);
 584         } else
 585                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 586
 587         if (ret) {
 588                 force_sigsegv(sig, current);
 589                 return -EFAULT;
 590         }
 591
 592         return ret;
 593 }
 594
 595 static int
 596 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 597               sigset_t *oldset, struct pt_regs *regs)
 598 {
 599         int ret;
 600
 601         /* Are we from a system call? */
 602         if (syscall_get_nr(current, regs) >= 0) {
 603                 /* If so, check system call restarting.. */
 604                 switch (syscall_get_error(current, regs)) {
 605                 case -ERESTART_RESTARTBLOCK:
 606                 case -ERESTARTNOHAND:
 607                         regs->ax = -EINTR;
 608                         break;
 609
 610                 case -ERESTARTSYS:
 611                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 612                                 regs->ax = -EINTR;
 613                                 break;
 614                         }
 615                 /* fallthrough */
 616                 case -ERESTARTNOINTR:
 617                         regs->ax = regs->orig_ax;
 618                         regs->ip -= 2;
 619                         break;
 620                 }
 621         }
 622
 623         /*
 624          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 625          * flag so that register information in the sigcontext is correct.
 626          */
 627         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 628             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 629                 regs->flags &= ~X86_EFLAGS_TF;
 630
 631         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 632
 633         if (ret)
 634                 return ret;
 635
 636 #ifdef CONFIG_X86_64
 637         /*
 638          * This has nothing to do with segment registers,
 639          * despite the name.  This magic affects uaccess.h
 640          * macros' behavior.  Reset it to the normal setting.
 641          */
 642         set_fs(USER_DS);
 643 #endif
 644
 645         /*
 646          * Clear the direction flag as per the ABI for function entry.
 647          */
 648         regs->flags &= ~X86_EFLAGS_DF;
 649
 650         /*
 651          * Clear TF when entering the signal handler, but
 652          * notify any tracer that was single-stepping it.
 653          * The tracer may want to single-step inside the
 654          * handler too.
 655          */
 656         regs->flags &= ~X86_EFLAGS_TF;
 657
 658         spin_lock_irq(&current->sighand->siglock);
 659         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 660         if (!(ka->sa.sa_flags & SA_NODEFER))
 661                 sigaddset(&current->blocked, sig);
 662         recalc_sigpending();
 663         spin_unlock_irq(&current->sighand->siglock);
 664
 665         tracehook_signal_handler(sig, info, ka, regs,
 666                                  test_thread_flag(TIF_SINGLESTEP));
 667
 668         return 0;
 669 }
 670
 671 #ifdef CONFIG_X86_32
 672 #define NR_restart_syscall      __NR_restart_syscall
 673 #else /* !CONFIG_X86_32 */
 674 #define NR_restart_syscall      \
 675         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 676 #endif /* CONFIG_X86_32 */
 677
 678 /*
 679  * Note that 'init' is a special process: it doesn't get signals it doesn't
 680  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 681  * mistake.
 682  */
 683 static void do_signal(struct pt_regs *regs)
 684 {
 685         struct k_sigaction ka;
 686         siginfo_t info;
 687         int signr;
 688         sigset_t *oldset;
 689
 690         /*
 691          * We want the common case to go fast, which is why we may in certain
 692          * cases get here from kernel mode. Just return without doing anything
 693          * if so.
 694          * X86_32: vm86 regs switched out by assembly code before reaching
 695          * here, so testing against kernel CS suffices.
 696          */
 697         if (!user_mode(regs))
 698                 return;
 699
 700         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 701                 oldset = &current->saved_sigmask;
 702         else
 703                 oldset = &current->blocked;
 704
 705         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 706         if (signr > 0) {
 707                 /*
 708                  * Re-enable any watchpoints before delivering the
 709                  * signal to user space. The processor register will
 710                  * have been cleared if the watchpoint triggered
 711                  * inside the kernel.
 712                  */
 713                 if (current->thread.debugreg7)
 714                         set_debugreg(current->thread.debugreg7, 7);
 715
 716                 /* Whee! Actually deliver the signal.  */
 717                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 718                         /*
 719                          * A signal was successfully delivered; the saved
 720                          * sigmask will have been stored in the signal frame,
 721                          * and will be restored by sigreturn, so we can simply
 722                          * clear the TS_RESTORE_SIGMASK flag.
 723                          */
 724                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 725                 }
 726                 return;
 727         }
 728
 729         /* Did we come from a system call? */
 730         if (syscall_get_nr(current, regs) >= 0) {
 731                 /* Restart the system call - no handlers present */
 732                 switch (syscall_get_error(current, regs)) {
 733                 case -ERESTARTNOHAND:
 734                 case -ERESTARTSYS:
 735                 case -ERESTARTNOINTR:
 736                         regs->ax = regs->orig_ax;
 737                         regs->ip -= 2;
 738                         break;
 739
 740                 case -ERESTART_RESTARTBLOCK:
 741                         regs->ax = NR_restart_syscall;
 742                         regs->ip -= 2;
 743                         break;
 744                 }
 745         }
 746
 747         /*
 748          * If there's no signal to deliver, we just put the saved sigmask
 749          * back.
 750          */
 751         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 752                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 753                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 754         }
 755 }
 756
 757 /*
 758  * notification of userspace execution resumption
 759  * - triggered by the TIF_WORK_MASK flags
 760  */
 761 void
 762 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 763 {
 764 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 765         /* notify userspace of pending MCEs */
 766         if (thread_info_flags & _TIF_MCE_NOTIFY)
 767                 mce_notify_user();
 768 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 769
 770         /* deal with pending signal delivery */
 771         if (thread_info_flags & _TIF_SIGPENDING)
 772                 do_signal(regs);
 773
 774         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 775                 clear_thread_flag(TIF_NOTIFY_RESUME);
 776                 tracehook_notify_resume(regs);
 777         }
 778
 779 #ifdef CONFIG_X86_32
 780         clear_thread_flag(TIF_IRET);
 781 #endif /* CONFIG_X86_32 */
 782 }
 783
 784 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 785 {
 786         struct task_struct *me = current;
 787
 788         if (show_unhandled_signals && printk_ratelimit()) {
 789                 printk(KERN_INFO
 790                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 791                        me->comm, me->pid, where, frame,
 792                        regs->ip, regs->sp, regs->orig_ax);
 793                 print_vma_addr(" in ", regs->ip);
 794                 printk(KERN_CONT "\n");
 795         }
 796
 797         force_sig(SIGSEGV, me);
 798 }