LXR linux/arch/x86/kernel/signal

   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 */
  51asmlinkage int
  52sys_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
  68asmlinkage int
  69sys_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
 103asmlinkage 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 */
 141static int
 142restore_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
 172asmlinkage 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
 199badframe:
 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
 215static 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
 241badframe:
 242        signal_fault(regs, frame, "rt_sigreturn");
 243        return 0;
 244}
 245
 246asmlinkage 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 */
 256static int
 257setup_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 */
 300static inline void __user *
 301get_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
 343static 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
 408static 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 */
 482static 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
 495static int
 496setup_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
 519static int
 520handle_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 */
 601static 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 */
 679void
 680do_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
 702void 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}
 717