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
  64 int 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
 121 int 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  */
 186 static 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
 200 static inline void __user *
 201 get_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
 252 static 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
 262 static 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
 274 static 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 = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 302         else
 303                 restorer = &frame->retcode;
 304         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 305                 restorer = ksig->ka.sa.sa_restorer;
 306
 307         /* Set up to return from userspace.  */
 308         err |= __put_user(restorer, &frame->pretcode);
 309
 310         /*
 311          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 312          *
 313          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 314          * reasons and because gdb uses it as a signature to notice
 315          * signal handler stack frames.
 316          */
 317         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 318
 319         if (err)
 320                 return -EFAULT;
 321
 322         /* Set up registers for signal handler */
 323         regs->sp = (unsigned long)frame;
 324         regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 325         regs->ax = (unsigned long)sig;
 326         regs->dx = 0;
 327         regs->cx = 0;
 328
 329         regs->ds = __USER_DS;
 330         regs->es = __USER_DS;
 331         regs->ss = __USER_DS;
 332         regs->cs = __USER_CS;
 333
 334         return 0;
 335 }
 336
 337 static int __setup_rt_frame(int sig, struct ksignal *ksig,
 338                             sigset_t *set, struct pt_regs *regs)
 339 {
 340         struct rt_sigframe __user *frame;
 341         void __user *restorer;
 342         int err = 0;
 343         void __user *fpstate = NULL;
 344
 345         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 346
 347         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 348                 return -EFAULT;
 349
 350         put_user_try {
 351                 put_user_ex(sig, &frame->sig);
 352                 put_user_ex(&frame->info, &frame->pinfo);
 353                 put_user_ex(&frame->uc, &frame->puc);
 354
 355                 /* Create the ucontext.  */
 356                 if (cpu_has_xsave)
 357                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 358                 else
 359                         put_user_ex(0, &frame->uc.uc_flags);
 360                 put_user_ex(0, &frame->uc.uc_link);
 361                 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 362
 363                 /* Set up to return from userspace.  */
 364                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 365                 if (ksig->ka.sa.sa_flags & SA_RESTORER)
 366                         restorer = ksig->ka.sa.sa_restorer;
 367                 put_user_ex(restorer, &frame->pretcode);
 368
 369                 /*
 370                  * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 371                  *
 372                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
 373                  * reasons and because gdb uses it as a signature to notice
 374                  * signal handler stack frames.
 375                  */
 376                 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 377         } put_user_catch(err);
 378
 379         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 380         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 381                                 regs, set->sig[0]);
 382         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 383
 384         if (err)
 385                 return -EFAULT;
 386
 387         /* Set up registers for signal handler */
 388         regs->sp = (unsigned long)frame;
 389         regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 390         regs->ax = (unsigned long)sig;
 391         regs->dx = (unsigned long)&frame->info;
 392         regs->cx = (unsigned long)&frame->uc;
 393
 394         regs->ds = __USER_DS;
 395         regs->es = __USER_DS;
 396         regs->ss = __USER_DS;
 397         regs->cs = __USER_CS;
 398
 399         return 0;
 400 }
 401 #else /* !CONFIG_X86_32 */
 402 static int __setup_rt_frame(int sig, struct ksignal *ksig,
 403                             sigset_t *set, struct pt_regs *regs)
 404 {
 405         struct rt_sigframe __user *frame;
 406         void __user *fp = NULL;
 407         int err = 0;
 408
 409         frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 410
 411         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 412                 return -EFAULT;
 413
 414         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 415                 if (copy_siginfo_to_user(&frame->info, &ksig->info))
 416                         return -EFAULT;
 417         }
 418
 419         put_user_try {
 420                 /* Create the ucontext.  */
 421                 if (cpu_has_xsave)
 422                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 423                 else
 424                         put_user_ex(0, &frame->uc.uc_flags);
 425                 put_user_ex(0, &frame->uc.uc_link);
 426                 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 427
 428                 /* Set up to return from userspace.  If provided, use a stub
 429                    already in userspace.  */
 430                 /* x86-64 should always use SA_RESTORER. */
 431                 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 432                         put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
 433                 } else {
 434                         /* could use a vstub here */
 435                         err |= -EFAULT;
 436                 }
 437         } put_user_catch(err);
 438
 439         err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 440         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 441
 442         if (err)
 443                 return -EFAULT;
 444
 445         /* Set up registers for signal handler */
 446         regs->di = sig;
 447         /* In case the signal handler was declared without prototypes */
 448         regs->ax = 0;
 449
 450         /* This also works for non SA_SIGINFO handlers because they expect the
 451            next argument after the signal number on the stack. */
 452         regs->si = (unsigned long)&frame->info;
 453         regs->dx = (unsigned long)&frame->uc;
 454         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 455
 456         regs->sp = (unsigned long)frame;
 457
 458         /* Set up the CS register to run signal handlers in 64-bit mode,
 459            even if the handler happens to be interrupting 32-bit code. */
 460         regs->cs = __USER_CS;
 461
 462         return 0;
 463 }
 464 #endif /* CONFIG_X86_32 */
 465
 466 static int x32_setup_rt_frame(struct ksignal *ksig,
 467                               compat_sigset_t *set,
 468                               struct pt_regs *regs)
 469 {
 470 #ifdef CONFIG_X86_X32_ABI
 471         struct rt_sigframe_x32 __user *frame;
 472         void __user *restorer;
 473         int err = 0;
 474         void __user *fpstate = NULL;
 475
 476         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 477
 478         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 479                 return -EFAULT;
 480
 481         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 482                 if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 483                         return -EFAULT;
 484         }
 485
 486         put_user_try {
 487                 /* Create the ucontext.  */
 488                 if (cpu_has_xsave)
 489                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 490                 else
 491                         put_user_ex(0, &frame->uc.uc_flags);
 492                 put_user_ex(0, &frame->uc.uc_link);
 493                 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 494                 put_user_ex(0, &frame->uc.uc__pad0);
 495
 496                 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 497                         restorer = ksig->ka.sa.sa_restorer;
 498                 } else {
 499                         /* could use a vstub here */
 500                         restorer = NULL;
 501                         err |= -EFAULT;
 502                 }
 503                 put_user_ex(restorer, &frame->pretcode);
 504         } put_user_catch(err);
 505
 506         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 507                                 regs, set->sig[0]);
 508         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 509
 510         if (err)
 511                 return -EFAULT;
 512
 513         /* Set up registers for signal handler */
 514         regs->sp = (unsigned long) frame;
 515         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 516
 517         /* We use the x32 calling convention here... */
 518         regs->di = ksig->sig;
 519         regs->si = (unsigned long) &frame->info;
 520         regs->dx = (unsigned long) &frame->uc;
 521
 522         loadsegment(ds, __USER_DS);
 523         loadsegment(es, __USER_DS);
 524
 525         regs->cs = __USER_CS;
 526         regs->ss = __USER_DS;
 527 #endif  /* CONFIG_X86_X32_ABI */
 528
 529         return 0;
 530 }
 531
 532 /*
 533  * Do a signal return; undo the signal stack.
 534  */
 535 #ifdef CONFIG_X86_32
 536 asmlinkage unsigned long sys_sigreturn(void)
 537 {
 538         struct pt_regs *regs = current_pt_regs();
 539         struct sigframe __user *frame;
 540         unsigned long ax;
 541         sigset_t set;
 542
 543         frame = (struct sigframe __user *)(regs->sp - 8);
 544
 545         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 546                 goto badframe;
 547         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 548                 && __copy_from_user(&set.sig[1], &frame->extramask,
 549                                     sizeof(frame->extramask))))
 550                 goto badframe;
 551
 552         set_current_blocked(&set);
 553
 554         if (restore_sigcontext(regs, &frame->sc, &ax))
 555                 goto badframe;
 556         return ax;
 557
 558 badframe:
 559         signal_fault(regs, frame, "sigreturn");
 560
 561         return 0;
 562 }
 563 #endif /* CONFIG_X86_32 */
 564
 565 asmlinkage long sys_rt_sigreturn(void)
 566 {
 567         struct pt_regs *regs = current_pt_regs();
 568         struct rt_sigframe __user *frame;
 569         unsigned long ax;
 570         sigset_t set;
 571
 572         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 573         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 574                 goto badframe;
 575         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 576                 goto badframe;
 577
 578         set_current_blocked(&set);
 579
 580         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 581                 goto badframe;
 582
 583         if (restore_altstack(&frame->uc.uc_stack))
 584                 goto badframe;
 585
 586         return ax;
 587
 588 badframe:
 589         signal_fault(regs, frame, "rt_sigreturn");
 590         return 0;
 591 }
 592
 593 /*
 594  * OK, we're invoking a handler:
 595  */
 596 static int signr_convert(int sig)
 597 {
 598 #ifdef CONFIG_X86_32
 599         struct thread_info *info = current_thread_info();
 600
 601         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 602                 return info->exec_domain->signal_invmap[sig];
 603 #endif /* CONFIG_X86_32 */
 604         return sig;
 605 }
 606
 607 static int
 608 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 609 {
 610         int usig = signr_convert(ksig->sig);
 611         sigset_t *set = sigmask_to_save();
 612         compat_sigset_t *cset = (compat_sigset_t *) set;
 613
 614         /* Set up the stack frame */
 615         if (is_ia32_frame()) {
 616                 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 617                         return ia32_setup_rt_frame(usig, ksig, cset, regs);
 618                 else
 619                         return ia32_setup_frame(usig, ksig, cset, regs);
 620         } else if (is_x32_frame()) {
 621                 return x32_setup_rt_frame(ksig, cset, regs);
 622         } else {
 623                 return __setup_rt_frame(ksig->sig, ksig, set, regs);
 624         }
 625 }
 626
 627 static void
 628 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 629 {
 630         bool failed;
 631         /* Are we from a system call? */
 632         if (syscall_get_nr(current, regs) >= 0) {
 633                 /* If so, check system call restarting.. */
 634                 switch (syscall_get_error(current, regs)) {
 635                 case -ERESTART_RESTARTBLOCK:
 636                 case -ERESTARTNOHAND:
 637                         regs->ax = -EINTR;
 638                         break;
 639
 640                 case -ERESTARTSYS:
 641                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 642                                 regs->ax = -EINTR;
 643                                 break;
 644                         }
 645                 /* fallthrough */
 646                 case -ERESTARTNOINTR:
 647                         regs->ax = regs->orig_ax;
 648                         regs->ip -= 2;
 649                         break;
 650                 }
 651         }
 652
 653         /*
 654          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 655          * flag so that register information in the sigcontext is correct.
 656          */
 657         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 658             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 659                 regs->flags &= ~X86_EFLAGS_TF;
 660
 661         failed = (setup_rt_frame(ksig, regs) < 0);
 662         if (!failed) {
 663                 /*
 664                  * Clear the direction flag as per the ABI for function entry.
 665                  *
 666                  * Clear RF when entering the signal handler, because
 667                  * it might disable possible debug exception from the
 668                  * signal handler.
 669                  *
 670                  * Clear TF when entering the signal handler, but
 671                  * notify any tracer that was single-stepping it.
 672                  * The tracer may want to single-step inside the
 673                  * handler too.
 674                  */
 675                 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
 676         }
 677         signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 678 }
 679
 680 #ifdef CONFIG_X86_32
 681 #define NR_restart_syscall      __NR_restart_syscall
 682 #else /* !CONFIG_X86_32 */
 683 #define NR_restart_syscall      \
 684         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 685 #endif /* CONFIG_X86_32 */
 686
 687 /*
 688  * Note that 'init' is a special process: it doesn't get signals it doesn't
 689  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 690  * mistake.
 691  */
 692 static void do_signal(struct pt_regs *regs)
 693 {
 694         struct ksignal ksig;
 695
 696         if (get_signal(&ksig)) {
 697                 /* Whee! Actually deliver the signal.  */
 698                 handle_signal(&ksig, regs);
 699                 return;
 700         }
 701
 702         /* Did we come from a system call? */
 703         if (syscall_get_nr(current, regs) >= 0) {
 704                 /* Restart the system call - no handlers present */
 705                 switch (syscall_get_error(current, regs)) {
 706                 case -ERESTARTNOHAND:
 707                 case -ERESTARTSYS:
 708                 case -ERESTARTNOINTR:
 709                         regs->ax = regs->orig_ax;
 710                         regs->ip -= 2;
 711                         break;
 712
 713                 case -ERESTART_RESTARTBLOCK:
 714                         regs->ax = NR_restart_syscall;
 715                         regs->ip -= 2;
 716                         break;
 717                 }
 718         }
 719
 720         /*
 721          * If there's no signal to deliver, we just put the saved sigmask
 722          * back.
 723          */
 724         restore_saved_sigmask();
 725 }
 726
 727 /*
 728  * notification of userspace execution resumption
 729  * - triggered by the TIF_WORK_MASK flags
 730  */
 731 __visible void
 732 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 733 {
 734         user_exit();
 735
 736 #ifdef CONFIG_X86_MCE
 737         /* notify userspace of pending MCEs */
 738         if (thread_info_flags & _TIF_MCE_NOTIFY)
 739                 mce_notify_process();
 740 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 741
 742         if (thread_info_flags & _TIF_UPROBE)
 743                 uprobe_notify_resume(regs);
 744
 745         /* deal with pending signal delivery */
 746         if (thread_info_flags & _TIF_SIGPENDING)
 747                 do_signal(regs);
 748
 749         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 750                 clear_thread_flag(TIF_NOTIFY_RESUME);
 751                 tracehook_notify_resume(regs);
 752         }
 753         if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
 754                 fire_user_return_notifiers();
 755
 756         user_enter();
 757 }
 758
 759 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 760 {
 761         struct task_struct *me = current;
 762
 763         if (show_unhandled_signals && printk_ratelimit()) {
 764                 printk("%s"
 765                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 766                        task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 767                        me->comm, me->pid, where, frame,
 768                        regs->ip, regs->sp, regs->orig_ax);
 769                 print_vma_addr(" in ", regs->ip);
 770                 pr_cont("\n");
 771         }
 772
 773         force_sig(SIGSEGV, me);
 774 }
 775
 776 #ifdef CONFIG_X86_X32_ABI
 777 asmlinkage long sys32_x32_rt_sigreturn(void)
 778 {
 779         struct pt_regs *regs = current_pt_regs();
 780         struct rt_sigframe_x32 __user *frame;
 781         sigset_t set;
 782         unsigned long ax;
 783
 784         frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 785
 786         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 787                 goto badframe;
 788         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 789                 goto badframe;
 790
 791         set_current_blocked(&set);
 792
 793         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 794                 goto badframe;
 795
 796         if (compat_restore_altstack(&frame->uc.uc_stack))
 797                 goto badframe;
 798
 799         return ax;
 800
 801 badframe:
 802         signal_fault(regs, frame, "x32 rt_sigreturn");
 803         return 0;
 804 }
 805 #endif