arch/x86/kernel/signal_64.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 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/kernel.h>
  14 #include <linux/signal.h>
  15 #include <linux/errno.h>
  16 #include <linux/wait.h>
  17 #include <linux/ptrace.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
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/i387.h>
  27 #include <asm/vdso.h>
  28
  29 #ifdef CONFIG_X86_64
  30 #include <asm/proto.h>
  31 #include <asm/ia32_unistd.h>
  32 #include <asm/mce.h>
  33 #endif /* CONFIG_X86_64 */
  34
  35 #include <asm/syscall.h>
  36 #include <asm/syscalls.h>
  37
  38 #include "sigframe.h"
  39
  40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  41
  42 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  43                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  44                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  45                          X86_EFLAGS_CF)
  46
  47 #ifdef CONFIG_X86_32
  48 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  49 #else
  50 # define FIX_EFLAGS     __FIX_EFLAGS
  51 #endif
  52
  53 #define COPY(x)                 {               \
  54         err |= __get_user(regs->x, &sc->x);     \
  55 }
  56
  57 #define COPY_SEG_CPL3(seg)      {                       \
  58                 unsigned short tmp;                     \
  59                 err |= __get_user(tmp, &sc->seg);       \
  60                 regs->seg = tmp | 3;                    \
  61 }
  62
  63 static int
  64 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 #ifdef CONFIG_X86_32
  75         GET_SEG(gs);
  76         COPY_SEG(fs);
  77         COPY_SEG(es);
  78         COPY_SEG(ds);
  79 #endif /* CONFIG_X86_32 */
  80
  81         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  82         COPY(dx); COPY(cx); COPY(ip);
  83
  84 #ifdef CONFIG_X86_64
  85         COPY(r8);
  86         COPY(r9);
  87         COPY(r10);
  88         COPY(r11);
  89         COPY(r12);
  90         COPY(r13);
  91         COPY(r14);
  92         COPY(r15);
  93 #endif /* CONFIG_X86_64 */
  94
  95 #ifdef CONFIG_X86_32
  96         COPY_SEG_CPL3(cs);
  97         COPY_SEG_CPL3(ss);
  98 #else /* !CONFIG_X86_32 */
  99         /* Kernel saves and restores only the CS segment register on signals,
 100          * which is the bare minimum needed to allow mixed 32/64-bit code.
 101          * App's signal handler can save/restore other segments if needed. */
 102         COPY_SEG_CPL3(cs);
 103 #endif /* CONFIG_X86_32 */
 104
 105         err |= __get_user(tmpflags, &sc->flags);
 106         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 107         regs->orig_ax = -1;             /* disable syscall checks */
 108
 109         err |= __get_user(buf, &sc->fpstate);
 110         err |= restore_i387_xstate(buf);
 111
 112         err |= __get_user(*pax, &sc->ax);
 113         return err;
 114 }
 115
 116 static int
 117 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 118                  struct pt_regs *regs, unsigned long mask)
 119 {
 120         int err = 0;
 121
 122 #ifdef CONFIG_X86_32
 123         {
 124                 unsigned int tmp;
 125
 126                 savesegment(gs, tmp);
 127                 err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 128         }
 129         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 130         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 131         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 132 #endif /* CONFIG_X86_32 */
 133
 134         err |= __put_user(regs->di, &sc->di);
 135         err |= __put_user(regs->si, &sc->si);
 136         err |= __put_user(regs->bp, &sc->bp);
 137         err |= __put_user(regs->sp, &sc->sp);
 138         err |= __put_user(regs->bx, &sc->bx);
 139         err |= __put_user(regs->dx, &sc->dx);
 140         err |= __put_user(regs->cx, &sc->cx);
 141         err |= __put_user(regs->ax, &sc->ax);
 142 #ifdef CONFIG_X86_64
 143         err |= __put_user(regs->r8, &sc->r8);
 144         err |= __put_user(regs->r9, &sc->r9);
 145         err |= __put_user(regs->r10, &sc->r10);
 146         err |= __put_user(regs->r11, &sc->r11);
 147         err |= __put_user(regs->r12, &sc->r12);
 148         err |= __put_user(regs->r13, &sc->r13);
 149         err |= __put_user(regs->r14, &sc->r14);
 150         err |= __put_user(regs->r15, &sc->r15);
 151 #endif /* CONFIG_X86_64 */
 152
 153         err |= __put_user(current->thread.trap_no, &sc->trapno);
 154         err |= __put_user(current->thread.error_code, &sc->err);
 155         err |= __put_user(regs->ip, &sc->ip);
 156 #ifdef CONFIG_X86_32
 157         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 158         err |= __put_user(regs->flags, &sc->flags);
 159         err |= __put_user(regs->sp, &sc->sp_at_signal);
 160         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 161 #else /* !CONFIG_X86_32 */
 162         err |= __put_user(regs->flags, &sc->flags);
 163         err |= __put_user(regs->cs, &sc->cs);
 164         err |= __put_user(0, &sc->gs);
 165         err |= __put_user(0, &sc->fs);
 166 #endif /* CONFIG_X86_32 */
 167
 168         err |= __put_user(fpstate, &sc->fpstate);
 169
 170         /* non-iBCS2 extensions.. */
 171         err |= __put_user(mask, &sc->oldmask);
 172         err |= __put_user(current->thread.cr2, &sc->cr2);
 173
 174         return err;
 175 }
 176
 177 /*
 178  * Set up a signal frame.
 179  */
 180 #ifdef CONFIG_X86_32
 181 static const struct {
 182         u16 poplmovl;
 183         u32 val;
 184         u16 int80;
 185 } __attribute__((packed)) retcode = {
 186         0xb858,         /* popl %eax; movl $..., %eax */
 187         __NR_sigreturn,
 188         0x80cd,         /* int $0x80 */
 189 };
 190
 191 static const struct {
 192         u8  movl;
 193         u32 val;
 194         u16 int80;
 195         u8  pad;
 196 } __attribute__((packed)) rt_retcode = {
 197         0xb8,           /* movl $..., %eax */
 198         __NR_rt_sigreturn,
 199         0x80cd,         /* int $0x80 */
 200         0
 201 };
 202
 203 /*
 204  * Determine which stack to use..
 205  */
 206 static inline void __user *
 207 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 208              void **fpstate)
 209 {
 210         unsigned long sp;
 211
 212         /* Default to using normal stack */
 213         sp = regs->sp;
 214
 215         /*
 216          * If we are on the alternate signal stack and would overflow it, don't.
 217          * Return an always-bogus address instead so we will die with SIGSEGV.
 218          */
 219         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 220                 return (void __user *) -1L;
 221
 222         /* This is the X/Open sanctioned signal stack switching.  */
 223         if (ka->sa.sa_flags & SA_ONSTACK) {
 224                 if (sas_ss_flags(sp) == 0)
 225                         sp = current->sas_ss_sp + current->sas_ss_size;
 226         } else {
 227                 /* This is the legacy signal stack switching. */
 228                 if ((regs->ss & 0xffff) != __USER_DS &&
 229                         !(ka->sa.sa_flags & SA_RESTORER) &&
 230                                 ka->sa.sa_restorer)
 231                         sp = (unsigned long) ka->sa.sa_restorer;
 232         }
 233
 234         if (used_math()) {
 235                 sp = sp - sig_xstate_size;
 236                 *fpstate = (struct _fpstate *) sp;
 237                 if (save_i387_xstate(*fpstate) < 0)
 238                         return (void __user *)-1L;
 239         }
 240
 241         sp -= frame_size;
 242         /*
 243          * Align the stack pointer according to the i386 ABI,
 244          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 245          */
 246         sp = ((sp + 4) & -16ul) - 4;
 247
 248         return (void __user *) sp;
 249 }
 250
 251 static int
 252 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 253               struct pt_regs *regs)
 254 {
 255         struct sigframe __user *frame;
 256         void __user *restorer;
 257         int err = 0;
 258         void __user *fpstate = NULL;
 259
 260         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 261
 262         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 263                 return -EFAULT;
 264
 265         if (__put_user(sig, &frame->sig))
 266                 return -EFAULT;
 267
 268         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 269                 return -EFAULT;
 270
 271         if (_NSIG_WORDS > 1) {
 272                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 273                                    sizeof(frame->extramask)))
 274                         return -EFAULT;
 275         }
 276
 277         if (current->mm->context.vdso)
 278                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 279         else
 280                 restorer = &frame->retcode;
 281         if (ka->sa.sa_flags & SA_RESTORER)
 282                 restorer = ka->sa.sa_restorer;
 283
 284         /* Set up to return from userspace.  */
 285         err |= __put_user(restorer, &frame->pretcode);
 286
 287         /*
 288          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 289          *
 290          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 291          * reasons and because gdb uses it as a signature to notice
 292          * signal handler stack frames.
 293          */
 294         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 295
 296         if (err)
 297                 return -EFAULT;
 298
 299         /* Set up registers for signal handler */
 300         regs->sp = (unsigned long)frame;
 301         regs->ip = (unsigned long)ka->sa.sa_handler;
 302         regs->ax = (unsigned long)sig;
 303         regs->dx = 0;
 304         regs->cx = 0;
 305
 306         regs->ds = __USER_DS;
 307         regs->es = __USER_DS;
 308         regs->ss = __USER_DS;
 309         regs->cs = __USER_CS;
 310
 311         return 0;
 312 }
 313
 314 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 315                             sigset_t *set, struct pt_regs *regs)
 316 {
 317         struct rt_sigframe __user *frame;
 318         void __user *restorer;
 319         int err = 0;
 320         void __user *fpstate = NULL;
 321
 322         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 323
 324         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 325                 return -EFAULT;
 326
 327         err |= __put_user(sig, &frame->sig);
 328         err |= __put_user(&frame->info, &frame->pinfo);
 329         err |= __put_user(&frame->uc, &frame->puc);
 330         err |= copy_siginfo_to_user(&frame->info, info);
 331         if (err)
 332                 return -EFAULT;
 333
 334         /* Create the ucontext.  */
 335         if (cpu_has_xsave)
 336                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 337         else
 338                 err |= __put_user(0, &frame->uc.uc_flags);
 339         err |= __put_user(0, &frame->uc.uc_link);
 340         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 341         err |= __put_user(sas_ss_flags(regs->sp),
 342                           &frame->uc.uc_stack.ss_flags);
 343         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 344         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 345                                 regs, set->sig[0]);
 346         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 347         if (err)
 348                 return -EFAULT;
 349
 350         /* Set up to return from userspace.  */
 351         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 352         if (ka->sa.sa_flags & SA_RESTORER)
 353                 restorer = ka->sa.sa_restorer;
 354         err |= __put_user(restorer, &frame->pretcode);
 355
 356         /*
 357          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 358          *
 359          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 360          * reasons and because gdb uses it as a signature to notice
 361          * signal handler stack frames.
 362          */
 363         err |= __put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 364
 365         if (err)
 366                 return -EFAULT;
 367
 368         /* Set up registers for signal handler */
 369         regs->sp = (unsigned long)frame;
 370         regs->ip = (unsigned long)ka->sa.sa_handler;
 371         regs->ax = (unsigned long)sig;
 372         regs->dx = (unsigned long)&frame->info;
 373         regs->cx = (unsigned long)&frame->uc;
 374
 375         regs->ds = __USER_DS;
 376         regs->es = __USER_DS;
 377         regs->ss = __USER_DS;
 378         regs->cs = __USER_CS;
 379
 380         return 0;
 381 }
 382 #else /* !CONFIG_X86_32 */
 383 /*
 384  * Determine which stack to use..
 385  */
 386 static void __user *
 387 get_stack(struct k_sigaction *ka, unsigned long sp, unsigned long size)
 388 {
 389         /* Default to using normal stack - redzone*/
 390         sp -= 128;
 391
 392         /* This is the X/Open sanctioned signal stack switching.  */
 393         if (ka->sa.sa_flags & SA_ONSTACK) {
 394                 if (sas_ss_flags(sp) == 0)
 395                         sp = current->sas_ss_sp + current->sas_ss_size;
 396         }
 397
 398         return (void __user *)round_down(sp - size, 64);
 399 }
 400
 401 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 402                             sigset_t *set, struct pt_regs *regs)
 403 {
 404         struct rt_sigframe __user *frame;
 405         void __user *fp = NULL;
 406         int err = 0;
 407         struct task_struct *me = current;
 408
 409         if (used_math()) {
 410                 fp = get_stack(ka, regs->sp, sig_xstate_size);
 411                 frame = (void __user *)round_down(
 412                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 413
 414                 if (save_i387_xstate(fp) < 0)
 415                         return -EFAULT;
 416         } else
 417                 frame = get_stack(ka, regs->sp, sizeof(struct rt_sigframe)) - 8;
 418
 419         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 420                 return -EFAULT;
 421
 422         if (ka->sa.sa_flags & SA_SIGINFO) {
 423                 if (copy_siginfo_to_user(&frame->info, info))
 424                         return -EFAULT;
 425         }
 426
 427         /* Create the ucontext.  */
 428         if (cpu_has_xsave)
 429                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 430         else
 431                 err |= __put_user(0, &frame->uc.uc_flags);
 432         err |= __put_user(0, &frame->uc.uc_link);
 433         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 434         err |= __put_user(sas_ss_flags(regs->sp),
 435                           &frame->uc.uc_stack.ss_flags);
 436         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 437         err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 438         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 439
 440         /* Set up to return from userspace.  If provided, use a stub
 441            already in userspace.  */
 442         /* x86-64 should always use SA_RESTORER. */
 443         if (ka->sa.sa_flags & SA_RESTORER) {
 444                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 445         } else {
 446                 /* could use a vstub here */
 447                 return -EFAULT;
 448         }
 449
 450         if (err)
 451                 return -EFAULT;
 452
 453         /* Set up registers for signal handler */
 454         regs->di = sig;
 455         /* In case the signal handler was declared without prototypes */
 456         regs->ax = 0;
 457
 458         /* This also works for non SA_SIGINFO handlers because they expect the
 459            next argument after the signal number on the stack. */
 460         regs->si = (unsigned long)&frame->info;
 461         regs->dx = (unsigned long)&frame->uc;
 462         regs->ip = (unsigned long) ka->sa.sa_handler;
 463
 464         regs->sp = (unsigned long)frame;
 465
 466         /* Set up the CS register to run signal handlers in 64-bit mode,
 467            even if the handler happens to be interrupting 32-bit code. */
 468         regs->cs = __USER_CS;
 469
 470         return 0;
 471 }
 472 #endif /* CONFIG_X86_32 */
 473
 474 #ifdef CONFIG_X86_32
 475 asmlinkage int sys_sigaltstack(unsigned long bx)
 476 {
 477         /*
 478          * This is needed to make gcc realize it doesn't own the
 479          * "struct pt_regs"
 480          */
 481         struct pt_regs *regs = (struct pt_regs *)&bx;
 482         const stack_t __user *uss = (const stack_t __user *)bx;
 483         stack_t __user *uoss = (stack_t __user *)regs->cx;
 484
 485         return do_sigaltstack(uss, uoss, regs->sp);
 486 }
 487 #else /* !CONFIG_X86_32 */
 488 asmlinkage long
 489 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 490                 struct pt_regs *regs)
 491 {
 492         return do_sigaltstack(uss, uoss, regs->sp);
 493 }
 494 #endif /* CONFIG_X86_32 */
 495
 496 /*
 497  * Do a signal return; undo the signal stack.
 498  */
 499 static long do_rt_sigreturn(struct pt_regs *regs)
 500 {
 501         struct rt_sigframe __user *frame;
 502         unsigned long ax;
 503         sigset_t set;
 504
 505         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 506         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 507                 goto badframe;
 508         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 509                 goto badframe;
 510
 511         sigdelsetmask(&set, ~_BLOCKABLE);
 512         spin_lock_irq(&current->sighand->siglock);
 513         current->blocked = set;
 514         recalc_sigpending();
 515         spin_unlock_irq(&current->sighand->siglock);
 516
 517         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 518                 goto badframe;
 519
 520         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 521                 goto badframe;
 522
 523         return ax;
 524
 525 badframe:
 526         signal_fault(regs, frame, "rt_sigreturn");
 527         return 0;
 528 }
 529
 530 #ifdef CONFIG_X86_32
 531 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 532 {
 533         struct pt_regs *regs = (struct pt_regs *)&__unused;
 534
 535         return do_rt_sigreturn(regs);
 536 }
 537 #else /* !CONFIG_X86_32 */
 538 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 539 {
 540         return do_rt_sigreturn(regs);
 541 }
 542 #endif /* CONFIG_X86_32 */
 543
 544 /*
 545  * OK, we're invoking a handler
 546  */
 547 static int signr_convert(int sig)
 548 {
 549 #ifdef CONFIG_X86_32
 550         struct thread_info *info = current_thread_info();
 551
 552         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 553                 return info->exec_domain->signal_invmap[sig];
 554 #endif /* CONFIG_X86_32 */
 555         return sig;
 556 }
 557
 558 #ifdef CONFIG_X86_32
 559
 560 #define is_ia32 1
 561 #define ia32_setup_frame        __setup_frame
 562 #define ia32_setup_rt_frame     __setup_rt_frame
 563
 564 #else /* !CONFIG_X86_32 */
 565
 566 #ifdef CONFIG_IA32_EMULATION
 567 #define is_ia32 test_thread_flag(TIF_IA32)
 568 #else /* !CONFIG_IA32_EMULATION */
 569 #define is_ia32 0
 570 #endif /* CONFIG_IA32_EMULATION */
 571
 572 #endif /* CONFIG_X86_32 */
 573
 574 static int
 575 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 576                sigset_t *set, struct pt_regs *regs)
 577 {
 578         int usig = signr_convert(sig);
 579         int ret;
 580
 581         /* Set up the stack frame */
 582         if (is_ia32) {
 583                 if (ka->sa.sa_flags & SA_SIGINFO)
 584                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 585                 else
 586                         ret = ia32_setup_frame(usig, ka, set, regs);
 587         } else
 588                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 589
 590         if (ret) {
 591                 force_sigsegv(sig, current);
 592                 return -EFAULT;
 593         }
 594
 595         return ret;
 596 }
 597
 598 static int
 599 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 600               sigset_t *oldset, struct pt_regs *regs)
 601 {
 602         int ret;
 603
 604         /* Are we from a system call? */
 605         if (syscall_get_nr(current, regs) >= 0) {
 606                 /* If so, check system call restarting.. */
 607                 switch (syscall_get_error(current, regs)) {
 608                 case -ERESTART_RESTARTBLOCK:
 609                 case -ERESTARTNOHAND:
 610                         regs->ax = -EINTR;
 611                         break;
 612
 613                 case -ERESTARTSYS:
 614                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 615                                 regs->ax = -EINTR;
 616                                 break;
 617                         }
 618                 /* fallthrough */
 619                 case -ERESTARTNOINTR:
 620                         regs->ax = regs->orig_ax;
 621                         regs->ip -= 2;
 622                         break;
 623                 }
 624         }
 625
 626         /*
 627          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 628          * flag so that register information in the sigcontext is correct.
 629          */
 630         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 631             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 632                 regs->flags &= ~X86_EFLAGS_TF;
 633
 634         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 635
 636         if (ret)
 637                 return ret;
 638
 639 #ifdef CONFIG_X86_64
 640         /*
 641          * This has nothing to do with segment registers,
 642          * despite the name.  This magic affects uaccess.h
 643          * macros' behavior.  Reset it to the normal setting.
 644          */
 645         set_fs(USER_DS);
 646 #endif
 647
 648         /*
 649          * Clear the direction flag as per the ABI for function entry.
 650          */
 651         regs->flags &= ~X86_EFLAGS_DF;
 652
 653         /*
 654          * Clear TF when entering the signal handler, but
 655          * notify any tracer that was single-stepping it.
 656          * The tracer may want to single-step inside the
 657          * handler too.
 658          */
 659         regs->flags &= ~X86_EFLAGS_TF;
 660
 661         spin_lock_irq(&current->sighand->siglock);
 662         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 663         if (!(ka->sa.sa_flags & SA_NODEFER))
 664                 sigaddset(&current->blocked, sig);
 665         recalc_sigpending();
 666         spin_unlock_irq(&current->sighand->siglock);
 667
 668         tracehook_signal_handler(sig, info, ka, regs,
 669                                  test_thread_flag(TIF_SINGLESTEP));
 670
 671         return 0;
 672 }
 673
 674 #ifdef CONFIG_X86_32
 675 #define NR_restart_syscall      __NR_restart_syscall
 676 #else /* !CONFIG_X86_32 */
 677 #define NR_restart_syscall      \
 678         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 679 #endif /* CONFIG_X86_32 */
 680
 681 /*
 682  * Note that 'init' is a special process: it doesn't get signals it doesn't
 683  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 684  * mistake.
 685  */
 686 static void do_signal(struct pt_regs *regs)
 687 {
 688         struct k_sigaction ka;
 689         siginfo_t info;
 690         int signr;
 691         sigset_t *oldset;
 692
 693         /*
 694          * We want the common case to go fast, which is why we may in certain
 695          * cases get here from kernel mode. Just return without doing anything
 696          * if so.
 697          * X86_32: vm86 regs switched out by assembly code before reaching
 698          * here, so testing against kernel CS suffices.
 699          */
 700         if (!user_mode(regs))
 701                 return;
 702
 703         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 704                 oldset = &current->saved_sigmask;
 705         else
 706                 oldset = &current->blocked;
 707
 708         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 709         if (signr > 0) {
 710                 /*
 711                  * Re-enable any watchpoints before delivering the
 712                  * signal to user space. The processor register will
 713                  * have been cleared if the watchpoint triggered
 714                  * inside the kernel.
 715                  */
 716                 if (current->thread.debugreg7)
 717                         set_debugreg(current->thread.debugreg7, 7);
 718
 719                 /* Whee! Actually deliver the signal.  */
 720                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 721                         /*
 722                          * A signal was successfully delivered; the saved
 723                          * sigmask will have been stored in the signal frame,
 724                          * and will be restored by sigreturn, so we can simply
 725                          * clear the TS_RESTORE_SIGMASK flag.
 726                          */
 727                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 728                 }
 729                 return;
 730         }
 731
 732         /* Did we come from a system call? */
 733         if (syscall_get_nr(current, regs) >= 0) {
 734                 /* Restart the system call - no handlers present */
 735                 switch (syscall_get_error(current, regs)) {
 736                 case -ERESTARTNOHAND:
 737                 case -ERESTARTSYS:
 738                 case -ERESTARTNOINTR:
 739                         regs->ax = regs->orig_ax;
 740                         regs->ip -= 2;
 741                         break;
 742
 743                 case -ERESTART_RESTARTBLOCK:
 744                         regs->ax = NR_restart_syscall;
 745                         regs->ip -= 2;
 746                         break;
 747                 }
 748         }
 749
 750         /*
 751          * If there's no signal to deliver, we just put the saved sigmask
 752          * back.
 753          */
 754         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 755                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 756                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 757         }
 758 }
 759
 760 /*
 761  * notification of userspace execution resumption
 762  * - triggered by the TIF_WORK_MASK flags
 763  */
 764 void
 765 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 766 {
 767 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 768         /* notify userspace of pending MCEs */
 769         if (thread_info_flags & _TIF_MCE_NOTIFY)
 770                 mce_notify_user();
 771 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 772
 773         /* deal with pending signal delivery */
 774         if (thread_info_flags & _TIF_SIGPENDING)
 775                 do_signal(regs);
 776
 777         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 778                 clear_thread_flag(TIF_NOTIFY_RESUME);
 779                 tracehook_notify_resume(regs);
 780         }
 781
 782 #ifdef CONFIG_X86_32
 783         clear_thread_flag(TIF_IRET);
 784 #endif /* CONFIG_X86_32 */
 785 }
 786
 787 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 788 {
 789         struct task_struct *me = current;
 790
 791         if (show_unhandled_signals && printk_ratelimit()) {
 792                 printk(KERN_INFO
 793                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 794                        me->comm, me->pid, where, frame,
 795                        regs->ip, regs->sp, regs->orig_ax);
 796                 print_vma_addr(" in ", regs->ip);
 797                 printk(KERN_CONT "\n");
 798         }
 799
 800         force_sig(SIGSEGV, me);
 801 }