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#define COPY(x)                 do {                    \
  47        get_user_ex(regs->x, &sc->x);                   \
  48} while (0)
  49
  50#define GET_SEG(seg)            ({                      \
  51        unsigned short tmp;                             \
  52        get_user_ex(tmp, &sc->seg);                     \
  53        tmp;                                            \
  54})
  55
  56#define COPY_SEG(seg)           do {                    \
  57        regs->seg = GET_SEG(seg);                       \
  58} while (0)
  59
  60#define COPY_SEG_CPL3(seg)      do {                    \
  61        regs->seg = GET_SEG(seg) | 3;                   \
  62} while (0)
  63
  64int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  65                       unsigned long *pax)
  66{
  67        void __user *buf;
  68        unsigned int tmpflags;
  69        unsigned int err = 0;
  70
  71        /* Always make any pending restarted system calls return -EINTR */
  72        current_thread_info()->restart_block.fn = do_no_restart_syscall;
  73
  74        get_user_try {
  75
  76#ifdef CONFIG_X86_32
  77                set_user_gs(regs, GET_SEG(gs));
  78                COPY_SEG(fs);
  79                COPY_SEG(es);
  80                COPY_SEG(ds);
  81#endif /* CONFIG_X86_32 */
  82
  83                COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  84                COPY(dx); COPY(cx); COPY(ip);
  85
  86#ifdef CONFIG_X86_64
  87                COPY(r8);
  88                COPY(r9);
  89                COPY(r10);
  90                COPY(r11);
  91                COPY(r12);
  92                COPY(r13);
  93                COPY(r14);
  94                COPY(r15);
  95#endif /* CONFIG_X86_64 */
  96
  97#ifdef CONFIG_X86_32
  98                COPY_SEG_CPL3(cs);
  99                COPY_SEG_CPL3(ss);
 100#else /* !CONFIG_X86_32 */
 101                /* Kernel saves and restores only the CS segment register on signals,
 102                 * which is the bare minimum needed to allow mixed 32/64-bit code.
 103                 * App's signal handler can save/restore other segments if needed. */
 104                COPY_SEG_CPL3(cs);
 105#endif /* CONFIG_X86_32 */
 106
 107                get_user_ex(tmpflags, &sc->flags);
 108                regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 109                regs->orig_ax = -1;             /* disable syscall checks */
 110
 111                get_user_ex(buf, &sc->fpstate);
 112
 113                get_user_ex(*pax, &sc->ax);
 114        } get_user_catch(err);
 115
 116        err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
 117
 118        return err;
 119}
 120
 121int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 122                     struct pt_regs *regs, unsigned long mask)
 123{
 124        int err = 0;
 125
 126        put_user_try {
 127
 128#ifdef CONFIG_X86_32
 129                put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
 130                put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
 131                put_user_ex(regs->es, (unsigned int __user *)&sc->es);
 132                put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
 133#endif /* CONFIG_X86_32 */
 134
 135                put_user_ex(regs->di, &sc->di);
 136                put_user_ex(regs->si, &sc->si);
 137                put_user_ex(regs->bp, &sc->bp);
 138                put_user_ex(regs->sp, &sc->sp);
 139                put_user_ex(regs->bx, &sc->bx);
 140                put_user_ex(regs->dx, &sc->dx);
 141                put_user_ex(regs->cx, &sc->cx);
 142                put_user_ex(regs->ax, &sc->ax);
 143#ifdef CONFIG_X86_64
 144                put_user_ex(regs->r8, &sc->r8);
 145                put_user_ex(regs->r9, &sc->r9);
 146                put_user_ex(regs->r10, &sc->r10);
 147                put_user_ex(regs->r11, &sc->r11);
 148                put_user_ex(regs->r12, &sc->r12);
 149                put_user_ex(regs->r13, &sc->r13);
 150                put_user_ex(regs->r14, &sc->r14);
 151                put_user_ex(regs->r15, &sc->r15);
 152#endif /* CONFIG_X86_64 */
 153
 154                put_user_ex(current->thread.trap_nr, &sc->trapno);
 155                put_user_ex(current->thread.error_code, &sc->err);
 156                put_user_ex(regs->ip, &sc->ip);
 157#ifdef CONFIG_X86_32
 158                put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 159                put_user_ex(regs->flags, &sc->flags);
 160                put_user_ex(regs->sp, &sc->sp_at_signal);
 161                put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 162#else /* !CONFIG_X86_32 */
 163                put_user_ex(regs->flags, &sc->flags);
 164                put_user_ex(regs->cs, &sc->cs);
 165                put_user_ex(0, &sc->gs);
 166                put_user_ex(0, &sc->fs);
 167#endif /* CONFIG_X86_32 */
 168
 169                put_user_ex(fpstate, &sc->fpstate);
 170
 171                /* non-iBCS2 extensions.. */
 172                put_user_ex(mask, &sc->oldmask);
 173                put_user_ex(current->thread.cr2, &sc->cr2);
 174        } put_user_catch(err);
 175
 176        return err;
 177}
 178
 179/*
 180 * Set up a signal frame.
 181 */
 182
 183/*
 184 * Determine which stack to use..
 185 */
 186static unsigned long align_sigframe(unsigned long sp)
 187{
 188#ifdef CONFIG_X86_32
 189        /*
 190         * Align the stack pointer according to the i386 ABI,
 191         * i.e. so that on function entry ((sp + 4) & 15) == 0.
 192         */
 193        sp = ((sp + 4) & -16ul) - 4;
 194#else /* !CONFIG_X86_32 */
 195        sp = round_down(sp, 16) - 8;
 196#endif
 197        return sp;
 198}
 199
 200static inline void __user *
 201get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 202             void __user **fpstate)
 203{
 204        /* Default to using normal stack */
 205        unsigned long math_size = 0;
 206        unsigned long sp = regs->sp;
 207        unsigned long buf_fx = 0;
 208        int onsigstack = on_sig_stack(sp);
 209
 210        /* redzone */
 211        if (config_enabled(CONFIG_X86_64))
 212                sp -= 128;
 213
 214        if (!onsigstack) {
 215                /* This is the X/Open sanctioned signal stack switching.  */
 216                if (ka->sa.sa_flags & SA_ONSTACK) {
 217                        if (current->sas_ss_size)
 218                                sp = current->sas_ss_sp + current->sas_ss_size;
 219                } else if (config_enabled(CONFIG_X86_32) &&
 220                           (regs->ss & 0xffff) != __USER_DS &&
 221                           !(ka->sa.sa_flags & SA_RESTORER) &&
 222                           ka->sa.sa_restorer) {
 223                                /* This is the legacy signal stack switching. */
 224                                sp = (unsigned long) ka->sa.sa_restorer;
 225                }
 226        }
 227
 228        if (used_math()) {
 229                sp = alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
 230                                     &buf_fx, &math_size);
 231                *fpstate = (void __user *)sp;
 232        }
 233
 234        sp = align_sigframe(sp - frame_size);
 235
 236        /*
 237         * If we are on the alternate signal stack and would overflow it, don't.
 238         * Return an always-bogus address instead so we will die with SIGSEGV.
 239         */
 240        if (onsigstack && !likely(on_sig_stack(sp)))
 241                return (void __user *)-1L;
 242
 243        /* save i387 and extended state */
 244        if (used_math() &&
 245            save_xstate_sig(*fpstate, (void __user *)buf_fx, math_size) < 0)
 246                return (void __user *)-1L;
 247
 248        return (void __user *)sp;
 249}
 250
 251#ifdef CONFIG_X86_32
 252static const struct {
 253        u16 poplmovl;
 254        u32 val;
 255        u16 int80;
 256} __attribute__((packed)) retcode = {
 257        0xb858,         /* popl %eax; movl $..., %eax */
 258        __NR_sigreturn,
 259        0x80cd,         /* int $0x80 */
 260};
 261
 262static const struct {
 263        u8  movl;
 264        u32 val;
 265        u16 int80;
 266        u8  pad;
 267} __attribute__((packed)) rt_retcode = {
 268        0xb8,           /* movl $..., %eax */
 269        __NR_rt_sigreturn,
 270        0x80cd,         /* int $0x80 */
 271        0
 272};
 273
 274static int
 275__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
 276              struct pt_regs *regs)
 277{
 278        struct sigframe __user *frame;
 279        void __user *restorer;
 280        int err = 0;
 281        void __user *fpstate = NULL;
 282
 283        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 284
 285        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 286                return -EFAULT;
 287
 288        if (__put_user(sig, &frame->sig))
 289                return -EFAULT;
 290
 291        if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 292                return -EFAULT;
 293
 294        if (_NSIG_WORDS > 1) {
 295                if (__copy_to_user(&frame->extramask, &set->sig[1],
 296                                   sizeof(frame->extramask)))
 297                        return -EFAULT;
 298        }
 299
 300        if (current->mm->context.vdso)
 301                restorer = current->mm->context.vdso +
 302                        selected_vdso32->sym___kernel_sigreturn;
 303        else
 304                restorer = &frame->retcode;
 305        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 306                restorer = ksig->ka.sa.sa_restorer;
 307
 308        /* Set up to return from userspace.  */
 309        err |= __put_user(restorer, &frame->pretcode);
 310
 311        /*
 312         * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 313         *
 314         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 315         * reasons and because gdb uses it as a signature to notice
 316         * signal handler stack frames.
 317         */
 318        err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 319
 320        if (err)
 321                return -EFAULT;
 322
 323        /* Set up registers for signal handler */
 324        regs->sp = (unsigned long)frame;
 325        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 326        regs->ax = (unsigned long)sig;
 327        regs->dx = 0;
 328        regs->cx = 0;
 329
 330        regs->ds = __USER_DS;
 331        regs->es = __USER_DS;
 332        regs->ss = __USER_DS;
 333        regs->cs = __USER_CS;
 334
 335        return 0;
 336}
 337
 338static int __setup_rt_frame(int sig, struct ksignal *ksig,
 339                            sigset_t *set, struct pt_regs *regs)
 340{
 341        struct rt_sigframe __user *frame;
 342        void __user *restorer;
 343        int err = 0;
 344        void __user *fpstate = NULL;
 345
 346        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 347
 348        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 349                return -EFAULT;
 350
 351        put_user_try {
 352                put_user_ex(sig, &frame->sig);
 353                put_user_ex(&frame->info, &frame->pinfo);
 354                put_user_ex(&frame->uc, &frame->puc);
 355
 356                /* Create the ucontext.  */
 357                if (cpu_has_xsave)
 358                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 359                else
 360                        put_user_ex(0, &frame->uc.uc_flags);
 361                put_user_ex(0, &frame->uc.uc_link);
 362                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 363
 364                /* Set up to return from userspace.  */
 365                restorer = current->mm->context.vdso +
 366                        selected_vdso32->sym___kernel_rt_sigreturn;
 367                if (ksig->ka.sa.sa_flags & SA_RESTORER)
 368                        restorer = ksig->ka.sa.sa_restorer;
 369                put_user_ex(restorer, &frame->pretcode);
 370
 371                /*
 372                 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 373                 *
 374                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 375                 * reasons and because gdb uses it as a signature to notice
 376                 * signal handler stack frames.
 377                 */
 378                put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 379        } put_user_catch(err);
 380        
 381        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 382        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 383                                regs, set->sig[0]);
 384        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 385
 386        if (err)
 387                return -EFAULT;
 388
 389        /* Set up registers for signal handler */
 390        regs->sp = (unsigned long)frame;
 391        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 392        regs->ax = (unsigned long)sig;
 393        regs->dx = (unsigned long)&frame->info;
 394        regs->cx = (unsigned long)&frame->uc;
 395
 396        regs->ds = __USER_DS;
 397        regs->es = __USER_DS;
 398        regs->ss = __USER_DS;
 399        regs->cs = __USER_CS;
 400
 401        return 0;
 402}
 403#else /* !CONFIG_X86_32 */
 404static int __setup_rt_frame(int sig, struct ksignal *ksig,
 405                            sigset_t *set, struct pt_regs *regs)
 406{
 407        struct rt_sigframe __user *frame;
 408        void __user *fp = NULL;
 409        int err = 0;
 410
 411        frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 412
 413        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 414                return -EFAULT;
 415
 416        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 417                if (copy_siginfo_to_user(&frame->info, &ksig->info))
 418                        return -EFAULT;
 419        }
 420
 421        put_user_try {
 422                /* Create the ucontext.  */
 423                if (cpu_has_xsave)
 424                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 425                else
 426                        put_user_ex(0, &frame->uc.uc_flags);
 427                put_user_ex(0, &frame->uc.uc_link);
 428                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 429
 430                /* Set up to return from userspace.  If provided, use a stub
 431                   already in userspace.  */
 432                /* x86-64 should always use SA_RESTORER. */
 433                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 434                        put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
 435                } else {
 436                        /* could use a vstub here */
 437                        err |= -EFAULT;
 438                }
 439        } put_user_catch(err);
 440
 441        err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 442        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 443
 444        if (err)
 445                return -EFAULT;
 446
 447        /* Set up registers for signal handler */
 448        regs->di = sig;
 449        /* In case the signal handler was declared without prototypes */
 450        regs->ax = 0;
 451
 452        /* This also works for non SA_SIGINFO handlers because they expect the
 453           next argument after the signal number on the stack. */
 454        regs->si = (unsigned long)&frame->info;
 455        regs->dx = (unsigned long)&frame->uc;
 456        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 457
 458        regs->sp = (unsigned long)frame;
 459
 460        /* Set up the CS register to run signal handlers in 64-bit mode,
 461           even if the handler happens to be interrupting 32-bit code. */
 462        regs->cs = __USER_CS;
 463
 464        return 0;
 465}
 466#endif /* CONFIG_X86_32 */
 467
 468static int x32_setup_rt_frame(struct ksignal *ksig,
 469                              compat_sigset_t *set,
 470                              struct pt_regs *regs)
 471{
 472#ifdef CONFIG_X86_X32_ABI
 473        struct rt_sigframe_x32 __user *frame;
 474        void __user *restorer;
 475        int err = 0;
 476        void __user *fpstate = NULL;
 477
 478        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 479
 480        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 481                return -EFAULT;
 482
 483        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 484                if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 485                        return -EFAULT;
 486        }
 487
 488        put_user_try {
 489                /* Create the ucontext.  */
 490                if (cpu_has_xsave)
 491                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 492                else
 493                        put_user_ex(0, &frame->uc.uc_flags);
 494                put_user_ex(0, &frame->uc.uc_link);
 495                compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 496                put_user_ex(0, &frame->uc.uc__pad0);
 497
 498                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 499                        restorer = ksig->ka.sa.sa_restorer;
 500                } else {
 501                        /* could use a vstub here */
 502                        restorer = NULL;
 503                        err |= -EFAULT;
 504                }
 505                put_user_ex(restorer, &frame->pretcode);
 506        } put_user_catch(err);
 507
 508        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 509                                regs, set->sig[0]);
 510        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 511
 512        if (err)
 513                return -EFAULT;
 514
 515        /* Set up registers for signal handler */
 516        regs->sp = (unsigned long) frame;
 517        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 518
 519        /* We use the x32 calling convention here... */
 520        regs->di = ksig->sig;
 521        regs->si = (unsigned long) &frame->info;
 522        regs->dx = (unsigned long) &frame->uc;
 523
 524        loadsegment(ds, __USER_DS);
 525        loadsegment(es, __USER_DS);
 526
 527        regs->cs = __USER_CS;
 528        regs->ss = __USER_DS;
 529#endif  /* CONFIG_X86_X32_ABI */
 530
 531        return 0;
 532}
 533
 534/*
 535 * Do a signal return; undo the signal stack.
 536 */
 537#ifdef CONFIG_X86_32
 538asmlinkage unsigned long sys_sigreturn(void)
 539{
 540        struct pt_regs *regs = current_pt_regs();
 541        struct sigframe __user *frame;
 542        unsigned long ax;
 543        sigset_t set;
 544
 545        frame = (struct sigframe __user *)(regs->sp - 8);
 546
 547        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 548                goto badframe;
 549        if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 550                && __copy_from_user(&set.sig[1], &frame->extramask,
 551                                    sizeof(frame->extramask))))
 552                goto badframe;
 553
 554        set_current_blocked(&set);
 555
 556        if (restore_sigcontext(regs, &frame->sc, &ax))
 557                goto badframe;
 558        return ax;
 559
 560badframe:
 561        signal_fault(regs, frame, "sigreturn");
 562
 563        return 0;
 564}
 565#endif /* CONFIG_X86_32 */
 566
 567asmlinkage long sys_rt_sigreturn(void)
 568{
 569        struct pt_regs *regs = current_pt_regs();
 570        struct rt_sigframe __user *frame;
 571        unsigned long ax;
 572        sigset_t set;
 573
 574        frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 575        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 576                goto badframe;
 577        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 578                goto badframe;
 579
 580        set_current_blocked(&set);
 581
 582        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 583                goto badframe;
 584
 585        if (restore_altstack(&frame->uc.uc_stack))
 586                goto badframe;
 587
 588        return ax;
 589
 590badframe:
 591        signal_fault(regs, frame, "rt_sigreturn");
 592        return 0;
 593}
 594
 595/*
 596 * OK, we're invoking a handler:
 597 */
 598static int signr_convert(int sig)
 599{
 600#ifdef CONFIG_X86_32
 601        struct thread_info *info = current_thread_info();
 602
 603        if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 604                return info->exec_domain->signal_invmap[sig];
 605#endif /* CONFIG_X86_32 */
 606        return sig;
 607}
 608
 609static int
 610setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 611{
 612        int usig = signr_convert(ksig->sig);
 613        sigset_t *set = sigmask_to_save();
 614        compat_sigset_t *cset = (compat_sigset_t *) set;
 615
 616        /* Set up the stack frame */
 617        if (is_ia32_frame()) {
 618                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 619                        return ia32_setup_rt_frame(usig, ksig, cset, regs);
 620                else
 621                        return ia32_setup_frame(usig, ksig, cset, regs);
 622        } else if (is_x32_frame()) {
 623                return x32_setup_rt_frame(ksig, cset, regs);
 624        } else {
 625                return __setup_rt_frame(ksig->sig, ksig, set, regs);
 626        }
 627}
 628
 629static void
 630handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 631{
 632        bool failed;
 633        /* Are we from a system call? */
 634        if (syscall_get_nr(current, regs) >= 0) {
 635                /* If so, check system call restarting.. */
 636                switch (syscall_get_error(current, regs)) {
 637                case -ERESTART_RESTARTBLOCK:
 638                case -ERESTARTNOHAND:
 639                        regs->ax = -EINTR;
 640                        break;
 641
 642                case -ERESTARTSYS:
 643                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 644                                regs->ax = -EINTR;
 645                                break;
 646                        }
 647                /* fallthrough */
 648                case -ERESTARTNOINTR:
 649                        regs->ax = regs->orig_ax;
 650                        regs->ip -= 2;
 651                        break;
 652                }
 653        }
 654
 655        /*
 656         * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 657         * flag so that register information in the sigcontext is correct.
 658         */
 659        if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 660            likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 661                regs->flags &= ~X86_EFLAGS_TF;
 662
 663        failed = (setup_rt_frame(ksig, regs) < 0);
 664        if (!failed) {
 665                /*
 666                 * Clear the direction flag as per the ABI for function entry.
 667                 *
 668                 * Clear RF when entering the signal handler, because
 669                 * it might disable possible debug exception from the
 670                 * signal handler.
 671                 *
 672                 * Clear TF when entering the signal handler, but
 673                 * notify any tracer that was single-stepping it.
 674                 * The tracer may want to single-step inside the
 675                 * handler too.
 676                 */
 677                regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
 678        }
 679        signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 680}
 681
 682#ifdef CONFIG_X86_32
 683#define NR_restart_syscall      __NR_restart_syscall
 684#else /* !CONFIG_X86_32 */
 685#define NR_restart_syscall      \
 686        test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 687#endif /* CONFIG_X86_32 */
 688
 689/*
 690 * Note that 'init' is a special process: it doesn't get signals it doesn't
 691 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 692 * mistake.
 693 */
 694static void do_signal(struct pt_regs *regs)
 695{
 696        struct ksignal ksig;
 697
 698        if (get_signal(&ksig)) {
 699                /* Whee! Actually deliver the signal.  */
 700                handle_signal(&ksig, regs);
 701                return;
 702        }
 703
 704        /* Did we come from a system call? */
 705        if (syscall_get_nr(current, regs) >= 0) {
 706                /* Restart the system call - no handlers present */
 707                switch (syscall_get_error(current, regs)) {
 708                case -ERESTARTNOHAND:
 709                case -ERESTARTSYS:
 710                case -ERESTARTNOINTR:
 711                        regs->ax = regs->orig_ax;
 712                        regs->ip -= 2;
 713                        break;
 714
 715                case -ERESTART_RESTARTBLOCK:
 716                        regs->ax = NR_restart_syscall;
 717                        regs->ip -= 2;
 718                        break;
 719                }
 720        }
 721
 722        /*
 723         * If there's no signal to deliver, we just put the saved sigmask
 724         * back.
 725         */
 726        restore_saved_sigmask();
 727}
 728
 729/*
 730 * notification of userspace execution resumption
 731 * - triggered by the TIF_WORK_MASK flags
 732 */
 733__visible void
 734do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 735{
 736        user_exit();
 737
 738#ifdef CONFIG_X86_MCE
 739        /* notify userspace of pending MCEs */
 740        if (thread_info_flags & _TIF_MCE_NOTIFY)
 741                mce_notify_process();
 742#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 743
 744        if (thread_info_flags & _TIF_UPROBE)
 745                uprobe_notify_resume(regs);
 746
 747        /* deal with pending signal delivery */
 748        if (thread_info_flags & _TIF_SIGPENDING)
 749                do_signal(regs);
 750
 751        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 752                clear_thread_flag(TIF_NOTIFY_RESUME);
 753                tracehook_notify_resume(regs);
 754        }
 755        if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
 756                fire_user_return_notifiers();
 757
 758        user_enter();
 759}
 760
 761void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 762{
 763        struct task_struct *me = current;
 764
 765        if (show_unhandled_signals && printk_ratelimit()) {
 766                printk("%s"
 767                       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 768                       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 769                       me->comm, me->pid, where, frame,
 770                       regs->ip, regs->sp, regs->orig_ax);
 771                print_vma_addr(" in ", regs->ip);
 772                pr_cont("\n");
 773        }
 774
 775        force_sig(SIGSEGV, me);
 776}
 777
 778#ifdef CONFIG_X86_X32_ABI
 779asmlinkage long sys32_x32_rt_sigreturn(void)
 780{
 781        struct pt_regs *regs = current_pt_regs();
 782        struct rt_sigframe_x32 __user *frame;
 783        sigset_t set;
 784        unsigned long ax;
 785
 786        frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 787
 788        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 789                goto badframe;
 790        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 791                goto badframe;
 792
 793        set_current_blocked(&set);
 794
 795        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 796                goto badframe;
 797
 798        if (compat_restore_altstack(&frame->uc.uc_stack))
 799                goto badframe;
 800
 801        return ax;
 802
 803badframe:
 804        signal_fault(regs, frame, "x32 rt_sigreturn");
 805        return 0;
 806}
 807#endif
 808