LXR linux/arch/x86/kernel/signal.c

   1/*
   2 *  Copyright (C) 1991, 1992  Linus Torvalds
   3 *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
   4 *
   5 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   6 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   7 *  2000-2002   x86-64 support by Andi Kleen
   8 */
   9
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12#include <linux/sched.h>
  13#include <linux/mm.h>
  14#include <linux/smp.h>
  15#include <linux/kernel.h>
  16#include <linux/errno.h>
  17#include <linux/wait.h>
  18#include <linux/tracehook.h>
  19#include <linux/unistd.h>
  20#include <linux/stddef.h>
  21#include <linux/personality.h>
  22#include <linux/uaccess.h>
  23#include <linux/user-return-notifier.h>
  24#include <linux/uprobes.h>
  25#include <linux/context_tracking.h>
  26
  27#include <asm/processor.h>
  28#include <asm/ucontext.h>
  29#include <asm/i387.h>
  30#include <asm/fpu-internal.h>
  31#include <asm/vdso.h>
  32#include <asm/mce.h>
  33#include <asm/sighandling.h>
  34
  35#ifdef CONFIG_X86_64
  36#include <asm/proto.h>
  37#include <asm/ia32_unistd.h>
  38#include <asm/sys_ia32.h>
  39#endif /* CONFIG_X86_64 */
  40
  41#include <asm/syscall.h>
  42#include <asm/syscalls.h>
  43
  44#include <asm/sigframe.h>
  45
  46#ifdef CONFIG_X86_32
  47# define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  48#else
  49# define FIX_EFLAGS     __FIX_EFLAGS
  50#endif
  51
  52#define COPY(x)                 do {                    \
  53        get_user_ex(regs->x, &sc->x);                   \
  54} while (0)
  55
  56#define GET_SEG(seg)            ({                      \
  57        unsigned short tmp;                             \
  58        get_user_ex(tmp, &sc->seg);                     \
  59        tmp;                                            \
  60})
  61
  62#define COPY_SEG(seg)           do {                    \
  63        regs->seg = GET_SEG(seg);                       \
  64} while (0)
  65
  66#define COPY_SEG_CPL3(seg)      do {                    \
  67        regs->seg = GET_SEG(seg) | 3;                   \
  68} while (0)
  69
  70int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  71                       unsigned long *pax)
  72{
  73        void __user *buf;
  74        unsigned int tmpflags;
  75        unsigned int err = 0;
  76
  77        /* Always make any pending restarted system calls return -EINTR */
  78        current_thread_info()->restart_block.fn = do_no_restart_syscall;
  79
  80        get_user_try {
  81
  82#ifdef CONFIG_X86_32
  83                set_user_gs(regs, GET_SEG(gs));
  84                COPY_SEG(fs);
  85                COPY_SEG(es);
  86                COPY_SEG(ds);
  87#endif /* CONFIG_X86_32 */
  88
  89                COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  90                COPY(dx); COPY(cx); COPY(ip);
  91
  92#ifdef CONFIG_X86_64
  93                COPY(r8);
  94                COPY(r9);
  95                COPY(r10);
  96                COPY(r11);
  97                COPY(r12);
  98                COPY(r13);
  99                COPY(r14);
 100                COPY(r15);
 101#endif /* CONFIG_X86_64 */
 102
 103#ifdef CONFIG_X86_32
 104                COPY_SEG_CPL3(cs);
 105                COPY_SEG_CPL3(ss);
 106#else /* !CONFIG_X86_32 */
 107                /* Kernel saves and restores only the CS segment register on signals,
 108                 * which is the bare minimum needed to allow mixed 32/64-bit code.
 109                 * App's signal handler can save/restore other segments if needed. */
 110                COPY_SEG_CPL3(cs);
 111#endif /* CONFIG_X86_32 */
 112
 113                get_user_ex(tmpflags, &sc->flags);
 114                regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 115                regs->orig_ax = -1;             /* disable syscall checks */
 116
 117                get_user_ex(buf, &sc->fpstate);
 118
 119                get_user_ex(*pax, &sc->ax);
 120        } get_user_catch(err);
 121
 122        err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
 123
 124        return err;
 125}
 126
 127int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 128                     struct pt_regs *regs, unsigned long mask)
 129{
 130        int err = 0;
 131
 132        put_user_try {
 133
 134#ifdef CONFIG_X86_32
 135                put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
 136                put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
 137                put_user_ex(regs->es, (unsigned int __user *)&sc->es);
 138                put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
 139#endif /* CONFIG_X86_32 */
 140
 141                put_user_ex(regs->di, &sc->di);
 142                put_user_ex(regs->si, &sc->si);
 143                put_user_ex(regs->bp, &sc->bp);
 144                put_user_ex(regs->sp, &sc->sp);
 145                put_user_ex(regs->bx, &sc->bx);
 146                put_user_ex(regs->dx, &sc->dx);
 147                put_user_ex(regs->cx, &sc->cx);
 148                put_user_ex(regs->ax, &sc->ax);
 149#ifdef CONFIG_X86_64
 150                put_user_ex(regs->r8, &sc->r8);
 151                put_user_ex(regs->r9, &sc->r9);
 152                put_user_ex(regs->r10, &sc->r10);
 153                put_user_ex(regs->r11, &sc->r11);
 154                put_user_ex(regs->r12, &sc->r12);
 155                put_user_ex(regs->r13, &sc->r13);
 156                put_user_ex(regs->r14, &sc->r14);
 157                put_user_ex(regs->r15, &sc->r15);
 158#endif /* CONFIG_X86_64 */
 159
 160                put_user_ex(current->thread.trap_nr, &sc->trapno);
 161                put_user_ex(current->thread.error_code, &sc->err);
 162                put_user_ex(regs->ip, &sc->ip);
 163#ifdef CONFIG_X86_32
 164                put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 165                put_user_ex(regs->flags, &sc->flags);
 166                put_user_ex(regs->sp, &sc->sp_at_signal);
 167                put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 168#else /* !CONFIG_X86_32 */
 169                put_user_ex(regs->flags, &sc->flags);
 170                put_user_ex(regs->cs, &sc->cs);
 171                put_user_ex(0, &sc->gs);
 172                put_user_ex(0, &sc->fs);
 173#endif /* CONFIG_X86_32 */
 174
 175                put_user_ex(fpstate, &sc->fpstate);
 176
 177                /* non-iBCS2 extensions.. */
 178                put_user_ex(mask, &sc->oldmask);
 179                put_user_ex(current->thread.cr2, &sc->cr2);
 180        } put_user_catch(err);
 181
 182        return err;
 183}
 184
 185/*
 186 * Set up a signal frame.
 187 */
 188
 189/*
 190 * Determine which stack to use..
 191 */
 192static unsigned long align_sigframe(unsigned long sp)
 193{
 194#ifdef CONFIG_X86_32
 195        /*
 196         * Align the stack pointer according to the i386 ABI,
 197         * i.e. so that on function entry ((sp + 4) & 15) == 0.
 198         */
 199        sp = ((sp + 4) & -16ul) - 4;
 200#else /* !CONFIG_X86_32 */
 201        sp = round_down(sp, 16) - 8;
 202#endif
 203        return sp;
 204}
 205
 206static inline void __user *
 207get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 208             void __user **fpstate)
 209{
 210        /* Default to using normal stack */
 211        unsigned long math_size = 0;
 212        unsigned long sp = regs->sp;
 213        unsigned long buf_fx = 0;
 214        int onsigstack = on_sig_stack(sp);
 215
 216        /* redzone */
 217        if (config_enabled(CONFIG_X86_64))
 218                sp -= 128;
 219
 220        if (!onsigstack) {
 221                /* This is the X/Open sanctioned signal stack switching.  */
 222                if (ka->sa.sa_flags & SA_ONSTACK) {
 223                        if (current->sas_ss_size)
 224                                sp = current->sas_ss_sp + current->sas_ss_size;
 225                } else if (config_enabled(CONFIG_X86_32) &&
 226                           (regs->ss & 0xffff) != __USER_DS &&
 227                           !(ka->sa.sa_flags & SA_RESTORER) &&
 228                           ka->sa.sa_restorer) {
 229                                /* This is the legacy signal stack switching. */
 230                                sp = (unsigned long) ka->sa.sa_restorer;
 231                }
 232        }
 233
 234        if (used_math()) {
 235                sp = alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
 236                                     &buf_fx, &math_size);
 237                *fpstate = (void __user *)sp;
 238        }
 239
 240        sp = align_sigframe(sp - frame_size);
 241
 242        /*
 243         * If we are on the alternate signal stack and would overflow it, don't.
 244         * Return an always-bogus address instead so we will die with SIGSEGV.
 245         */
 246        if (onsigstack && !likely(on_sig_stack(sp)))
 247                return (void __user *)-1L;
 248
 249        /* save i387 and extended state */
 250        if (used_math() &&
 251            save_xstate_sig(*fpstate, (void __user *)buf_fx, math_size) < 0)
 252                return (void __user *)-1L;
 253
 254        return (void __user *)sp;
 255}
 256
 257#ifdef CONFIG_X86_32
 258static const struct {
 259        u16 poplmovl;
 260        u32 val;
 261        u16 int80;
 262} __attribute__((packed)) retcode = {
 263        0xb858,         /* popl %eax; movl $..., %eax */
 264        __NR_sigreturn,
 265        0x80cd,         /* int $0x80 */
 266};
 267
 268static const struct {
 269        u8  movl;
 270        u32 val;
 271        u16 int80;
 272        u8  pad;
 273} __attribute__((packed)) rt_retcode = {
 274        0xb8,           /* movl $..., %eax */
 275        __NR_rt_sigreturn,
 276        0x80cd,         /* int $0x80 */
 277        0
 278};
 279
 280static int
 281__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
 282              struct pt_regs *regs)
 283{
 284        struct sigframe __user *frame;
 285        void __user *restorer;
 286        int err = 0;
 287        void __user *fpstate = NULL;
 288
 289        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 290
 291        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 292                return -EFAULT;
 293
 294        if (__put_user(sig, &frame->sig))
 295                return -EFAULT;
 296
 297        if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 298                return -EFAULT;
 299
 300        if (_NSIG_WORDS > 1) {
 301                if (__copy_to_user(&frame->extramask, &set->sig[1],
 302                                   sizeof(frame->extramask)))
 303                        return -EFAULT;
 304        }
 305
 306        if (current->mm->context.vdso)
 307                restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 308        else
 309                restorer = &frame->retcode;
 310        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 311                restorer = ksig->ka.sa.sa_restorer;
 312
 313        /* Set up to return from userspace.  */
 314        err |= __put_user(restorer, &frame->pretcode);
 315
 316        /*
 317         * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 318         *
 319         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 320         * reasons and because gdb uses it as a signature to notice
 321         * signal handler stack frames.
 322         */
 323        err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 324
 325        if (err)
 326                return -EFAULT;
 327
 328        /* Set up registers for signal handler */
 329        regs->sp = (unsigned long)frame;
 330        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 331        regs->ax = (unsigned long)sig;
 332        regs->dx = 0;
 333        regs->cx = 0;
 334
 335        regs->ds = __USER_DS;
 336        regs->es = __USER_DS;
 337        regs->ss = __USER_DS;
 338        regs->cs = __USER_CS;
 339
 340        return 0;
 341}
 342
 343static int __setup_rt_frame(int sig, struct ksignal *ksig,
 344                            sigset_t *set, struct pt_regs *regs)
 345{
 346        struct rt_sigframe __user *frame;
 347        void __user *restorer;
 348        int err = 0;
 349        void __user *fpstate = NULL;
 350
 351        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 352
 353        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 354                return -EFAULT;
 355
 356        put_user_try {
 357                put_user_ex(sig, &frame->sig);
 358                put_user_ex(&frame->info, &frame->pinfo);
 359                put_user_ex(&frame->uc, &frame->puc);
 360
 361                /* Create the ucontext.  */
 362                if (cpu_has_xsave)
 363                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 364                else
 365                        put_user_ex(0, &frame->uc.uc_flags);
 366                put_user_ex(0, &frame->uc.uc_link);
 367                err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 368
 369                /* Set up to return from userspace.  */
 370                restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 371                if (ksig->ka.sa.sa_flags & SA_RESTORER)
 372                        restorer = ksig->ka.sa.sa_restorer;
 373                put_user_ex(restorer, &frame->pretcode);
 374
 375                /*
 376                 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 377                 *
 378                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 379                 * reasons and because gdb uses it as a signature to notice
 380                 * signal handler stack frames.
 381                 */
 382                put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 383        } put_user_catch(err);
 384        
 385        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 386        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 387                                regs, set->sig[0]);
 388        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 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)ksig->ka.sa.sa_handler;
 396        regs->ax = (unsigned long)sig;
 397        regs->dx = (unsigned long)&frame->info;
 398        regs->cx = (unsigned long)&frame->uc;
 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#else /* !CONFIG_X86_32 */
 408static int __setup_rt_frame(int sig, struct ksignal *ksig,
 409                            sigset_t *set, struct pt_regs *regs)
 410{
 411        struct rt_sigframe __user *frame;
 412        void __user *fp = NULL;
 413        int err = 0;
 414
 415        frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 416
 417        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 418                return -EFAULT;
 419
 420        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 421                if (copy_siginfo_to_user(&frame->info, &ksig->info))
 422                        return -EFAULT;
 423        }
 424
 425        put_user_try {
 426                /* Create the ucontext.  */
 427                if (cpu_has_xsave)
 428                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 429                else
 430                        put_user_ex(0, &frame->uc.uc_flags);
 431                put_user_ex(0, &frame->uc.uc_link);
 432                err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 433
 434                /* Set up to return from userspace.  If provided, use a stub
 435                   already in userspace.  */
 436                /* x86-64 should always use SA_RESTORER. */
 437                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 438                        put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
 439                } else {
 440                        /* could use a vstub here */
 441                        err |= -EFAULT;
 442                }
 443        } put_user_catch(err);
 444
 445        err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 446        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 447
 448        if (err)
 449                return -EFAULT;
 450
 451        /* Set up registers for signal handler */
 452        regs->di = sig;
 453        /* In case the signal handler was declared without prototypes */
 454        regs->ax = 0;
 455
 456        /* This also works for non SA_SIGINFO handlers because they expect the
 457           next argument after the signal number on the stack. */
 458        regs->si = (unsigned long)&frame->info;
 459        regs->dx = (unsigned long)&frame->uc;
 460        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 461
 462        regs->sp = (unsigned long)frame;
 463
 464        /* Set up the CS register to run signal handlers in 64-bit mode,
 465           even if the handler happens to be interrupting 32-bit code. */
 466        regs->cs = __USER_CS;
 467
 468        return 0;
 469}
 470#endif /* CONFIG_X86_32 */
 471
 472static int x32_setup_rt_frame(struct ksignal *ksig,
 473                              compat_sigset_t *set,
 474                              struct pt_regs *regs)
 475{
 476#ifdef CONFIG_X86_X32_ABI
 477        struct rt_sigframe_x32 __user *frame;
 478        void __user *restorer;
 479        int err = 0;
 480        void __user *fpstate = NULL;
 481
 482        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 483
 484        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 485                return -EFAULT;
 486
 487        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 488                if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 489                        return -EFAULT;
 490        }
 491
 492        put_user_try {
 493                /* Create the ucontext.  */
 494                if (cpu_has_xsave)
 495                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 496                else
 497                        put_user_ex(0, &frame->uc.uc_flags);
 498                put_user_ex(0, &frame->uc.uc_link);
 499                err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
 500                put_user_ex(0, &frame->uc.uc__pad0);
 501
 502                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 503                        restorer = ksig->ka.sa.sa_restorer;
 504                } else {
 505                        /* could use a vstub here */
 506                        restorer = NULL;
 507                        err |= -EFAULT;
 508                }
 509                put_user_ex(restorer, &frame->pretcode);
 510        } put_user_catch(err);
 511
 512        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 513                                regs, set->sig[0]);
 514        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 515
 516        if (err)
 517                return -EFAULT;
 518
 519        /* Set up registers for signal handler */
 520        regs->sp = (unsigned long) frame;
 521        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 522
 523        /* We use the x32 calling convention here... */
 524        regs->di = ksig->sig;
 525        regs->si = (unsigned long) &frame->info;
 526        regs->dx = (unsigned long) &frame->uc;
 527
 528        loadsegment(ds, __USER_DS);
 529        loadsegment(es, __USER_DS);
 530
 531        regs->cs = __USER_CS;
 532        regs->ss = __USER_DS;
 533#endif  /* CONFIG_X86_X32_ABI */
 534
 535        return 0;
 536}
 537
 538/*
 539 * Do a signal return; undo the signal stack.
 540 */
 541#ifdef CONFIG_X86_32
 542unsigned long sys_sigreturn(void)
 543{
 544        struct pt_regs *regs = current_pt_regs();
 545        struct sigframe __user *frame;
 546        unsigned long ax;
 547        sigset_t set;
 548
 549        frame = (struct sigframe __user *)(regs->sp - 8);
 550
 551        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 552                goto badframe;
 553        if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 554                && __copy_from_user(&set.sig[1], &frame->extramask,
 555                                    sizeof(frame->extramask))))
 556                goto badframe;
 557
 558        set_current_blocked(&set);
 559
 560        if (restore_sigcontext(regs, &frame->sc, &ax))
 561                goto badframe;
 562        return ax;
 563
 564badframe:
 565        signal_fault(regs, frame, "sigreturn");
 566
 567        return 0;
 568}
 569#endif /* CONFIG_X86_32 */
 570
 571long sys_rt_sigreturn(void)
 572{
 573        struct pt_regs *regs = current_pt_regs();
 574        struct rt_sigframe __user *frame;
 575        unsigned long ax;
 576        sigset_t set;
 577
 578        frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 579        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 580                goto badframe;
 581        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 582                goto badframe;
 583
 584        set_current_blocked(&set);
 585
 586        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 587                goto badframe;
 588
 589        if (restore_altstack(&frame->uc.uc_stack))
 590                goto badframe;
 591
 592        return ax;
 593
 594badframe:
 595        signal_fault(regs, frame, "rt_sigreturn");
 596        return 0;
 597}
 598
 599/*
 600 * OK, we're invoking a handler:
 601 */
 602static int signr_convert(int sig)
 603{
 604#ifdef CONFIG_X86_32
 605        struct thread_info *info = current_thread_info();
 606
 607        if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 608                return info->exec_domain->signal_invmap[sig];
 609#endif /* CONFIG_X86_32 */
 610        return sig;
 611}
 612
 613static int
 614setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 615{
 616        int usig = signr_convert(ksig->sig);
 617        sigset_t *set = sigmask_to_save();
 618        compat_sigset_t *cset = (compat_sigset_t *) set;
 619
 620        /* Set up the stack frame */
 621        if (is_ia32_frame()) {
 622                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 623                        return ia32_setup_rt_frame(usig, ksig, cset, regs);
 624                else
 625                        return ia32_setup_frame(usig, ksig, cset, regs);
 626        } else if (is_x32_frame()) {
 627                return x32_setup_rt_frame(ksig, cset, regs);
 628        } else {
 629                return __setup_rt_frame(ksig->sig, ksig, set, regs);
 630        }
 631}
 632
 633static void
 634handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 635{
 636        bool failed;
 637        /* Are we from a system call? */
 638        if (syscall_get_nr(current, regs) >= 0) {
 639                /* If so, check system call restarting.. */
 640                switch (syscall_get_error(current, regs)) {
 641                case -ERESTART_RESTARTBLOCK:
 642                case -ERESTARTNOHAND:
 643                        regs->ax = -EINTR;
 644                        break;
 645
 646                case -ERESTARTSYS:
 647                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 648                                regs->ax = -EINTR;
 649                                break;
 650                        }
 651                /* fallthrough */
 652                case -ERESTARTNOINTR:
 653                        regs->ax = regs->orig_ax;
 654                        regs->ip -= 2;
 655                        break;
 656                }
 657        }
 658
 659        /*
 660         * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 661         * flag so that register information in the sigcontext is correct.
 662         */
 663        if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 664            likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 665                regs->flags &= ~X86_EFLAGS_TF;
 666
 667        failed = (setup_rt_frame(ksig, regs) < 0);
 668        if (!failed) {
 669                /*
 670                 * Clear the direction flag as per the ABI for function entry.
 671                 */
 672                regs->flags &= ~X86_EFLAGS_DF;
 673                /*
 674                 * Clear TF when entering the signal handler, but
 675                 * notify any tracer that was single-stepping it.
 676                 * The tracer may want to single-step inside the
 677                 * handler too.
 678                 */
 679                regs->flags &= ~X86_EFLAGS_TF;
 680        }
 681        signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 682}
 683
 684#ifdef CONFIG_X86_32
 685#define NR_restart_syscall      __NR_restart_syscall
 686#else /* !CONFIG_X86_32 */
 687#define NR_restart_syscall      \
 688        test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 689#endif /* CONFIG_X86_32 */
 690
 691/*
 692 * Note that 'init' is a special process: it doesn't get signals it doesn't
 693 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 694 * mistake.
 695 */
 696static void do_signal(struct pt_regs *regs)
 697{
 698        struct ksignal ksig;
 699
 700        if (get_signal(&ksig)) {
 701                /* Whee! Actually deliver the signal.  */
 702                handle_signal(&ksig, regs);
 703                return;
 704        }
 705
 706        /* Did we come from a system call? */
 707        if (syscall_get_nr(current, regs) >= 0) {
 708                /* Restart the system call - no handlers present */
 709                switch (syscall_get_error(current, regs)) {
 710                case -ERESTARTNOHAND:
 711                case -ERESTARTSYS:
 712                case -ERESTARTNOINTR:
 713                        regs->ax = regs->orig_ax;
 714                        regs->ip -= 2;
 715                        break;
 716
 717                case -ERESTART_RESTARTBLOCK:
 718                        regs->ax = NR_restart_syscall;
 719                        regs->ip -= 2;
 720                        break;
 721                }
 722        }
 723
 724        /*
 725         * If there's no signal to deliver, we just put the saved sigmask
 726         * back.
 727         */
 728        restore_saved_sigmask();
 729}
 730
 731/*
 732 * notification of userspace execution resumption
 733 * - triggered by the TIF_WORK_MASK flags
 734 */
 735void
 736do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 737{
 738        user_exit();
 739
 740#ifdef CONFIG_X86_MCE
 741        /* notify userspace of pending MCEs */
 742        if (thread_info_flags & _TIF_MCE_NOTIFY)
 743                mce_notify_process();
 744#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 745
 746        if (thread_info_flags & _TIF_UPROBE)
 747                uprobe_notify_resume(regs);
 748
 749        /* deal with pending signal delivery */
 750        if (thread_info_flags & _TIF_SIGPENDING)
 751                do_signal(regs);
 752
 753        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 754                clear_thread_flag(TIF_NOTIFY_RESUME);
 755                tracehook_notify_resume(regs);
 756        }
 757        if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
 758                fire_user_return_notifiers();
 759
 760        user_enter();
 761}
 762
 763void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 764{
 765        struct task_struct *me = current;
 766
 767        if (show_unhandled_signals && printk_ratelimit()) {
 768                printk("%s"
 769                       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 770                       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 771                       me->comm, me->pid, where, frame,
 772                       regs->ip, regs->sp, regs->orig_ax);
 773                print_vma_addr(" in ", regs->ip);
 774                pr_cont("\n");
 775        }
 776
 777        force_sig(SIGSEGV, me);
 778}
 779
 780#ifdef CONFIG_X86_X32_ABI
 781asmlinkage long sys32_x32_rt_sigreturn(void)
 782{
 783        struct pt_regs *regs = current_pt_regs();
 784        struct rt_sigframe_x32 __user *frame;
 785        sigset_t set;
 786        unsigned long ax;
 787
 788        frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 789
 790        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 791                goto badframe;
 792        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 793                goto badframe;
 794
 795        set_current_blocked(&set);
 796
 797        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 798                goto badframe;
 799
 800        if (compat_restore_altstack(&frame->uc.uc_stack))
 801                goto badframe;
 802
 803        return ax;
 804
 805badframe:
 806        signal_fault(regs, frame, "x32 rt_sigreturn");
 807        return 0;
 808}
 809#endif
 810