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
  70 int 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
 127 int 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  */
 192 static 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
 206 static inline void __user *
 207 get_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
 258 static 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
 268 static 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
 280 static 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
 343 static 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                 save_altstack_ex(&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 */
 408 static 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                 save_altstack_ex(&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
 472 static 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                 compat_save_altstack_ex(&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
 542 unsigned 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
 564 badframe:
 565         signal_fault(regs, frame, "sigreturn");
 566
 567         return 0;
 568 }
 569 #endif /* CONFIG_X86_32 */
 570
 571 long 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
 594 badframe:
 595         signal_fault(regs, frame, "rt_sigreturn");
 596         return 0;
 597 }
 598
 599 /*
 600  * OK, we're invoking a handler:
 601  */
 602 static 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
 613 static int
 614 setup_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
 633 static void
 634 handle_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                  * Ensure the signal handler starts with the new fpu state.
 682                  */
 683                 if (used_math())
 684                         drop_init_fpu(current);
 685         }
 686         signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 687 }
 688
 689 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
 690 {
 691 #if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
 692         return __NR_restart_syscall;
 693 #else /* !CONFIG_X86_32 && CONFIG_X86_64 */
 694         return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
 695                 __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
 696 #endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
 697 }
 698
 699 /*
 700  * Note that 'init' is a special process: it doesn't get signals it doesn't
 701  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 702  * mistake.
 703  */
 704 static void do_signal(struct pt_regs *regs)
 705 {
 706         struct ksignal ksig;
 707
 708         if (get_signal(&ksig)) {
 709                 /* Whee! Actually deliver the signal.  */
 710                 handle_signal(&ksig, regs);
 711                 return;
 712         }
 713
 714         /* Did we come from a system call? */
 715         if (syscall_get_nr(current, regs) >= 0) {
 716                 /* Restart the system call - no handlers present */
 717                 switch (syscall_get_error(current, regs)) {
 718                 case -ERESTARTNOHAND:
 719                 case -ERESTARTSYS:
 720                 case -ERESTARTNOINTR:
 721                         regs->ax = regs->orig_ax;
 722                         regs->ip -= 2;
 723                         break;
 724
 725                 case -ERESTART_RESTARTBLOCK:
 726                         regs->ax = get_nr_restart_syscall(regs);
 727                         regs->ip -= 2;
 728                         break;
 729                 }
 730         }
 731
 732         /*
 733          * If there's no signal to deliver, we just put the saved sigmask
 734          * back.
 735          */
 736         restore_saved_sigmask();
 737 }
 738
 739 /*
 740  * notification of userspace execution resumption
 741  * - triggered by the TIF_WORK_MASK flags
 742  */
 743 void
 744 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 745 {
 746         user_exit();
 747
 748 #ifdef CONFIG_X86_MCE
 749         /* notify userspace of pending MCEs */
 750         if (thread_info_flags & _TIF_MCE_NOTIFY)
 751                 mce_notify_process();
 752 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 753
 754         if (thread_info_flags & _TIF_UPROBE)
 755                 uprobe_notify_resume(regs);
 756
 757         /* deal with pending signal delivery */
 758         if (thread_info_flags & _TIF_SIGPENDING)
 759                 do_signal(regs);
 760
 761         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 762                 clear_thread_flag(TIF_NOTIFY_RESUME);
 763                 tracehook_notify_resume(regs);
 764         }
 765         if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
 766                 fire_user_return_notifiers();
 767
 768         user_enter();
 769 }
 770
 771 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 772 {
 773         struct task_struct *me = current;
 774
 775         if (show_unhandled_signals && printk_ratelimit()) {
 776                 printk("%s"
 777                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 778                        task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 779                        me->comm, me->pid, where, frame,
 780                        regs->ip, regs->sp, regs->orig_ax);
 781                 print_vma_addr(" in ", regs->ip);
 782                 pr_cont("\n");
 783         }
 784
 785         force_sig(SIGSEGV, me);
 786 }
 787
 788 #ifdef CONFIG_X86_X32_ABI
 789 asmlinkage long sys32_x32_rt_sigreturn(void)
 790 {
 791         struct pt_regs *regs = current_pt_regs();
 792         struct rt_sigframe_x32 __user *frame;
 793         sigset_t set;
 794         unsigned long ax;
 795
 796         frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 797
 798         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 799                 goto badframe;
 800         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 801                 goto badframe;
 802
 803         set_current_blocked(&set);
 804
 805         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 806                 goto badframe;
 807
 808         if (compat_restore_altstack(&frame->uc.uc_stack))
 809                 goto badframe;
 810
 811         return ax;
 812
 813 badframe:
 814         signal_fault(regs, frame, "x32 rt_sigreturn");
 815         return 0;
 816 }
 817 #endif