arch/x86/kernel/signal_32.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   5  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   6  */
   7
   8 #include <linux/sched.h>
   9 #include <linux/mm.h>
  10 #include <linux/smp.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/wait.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/tracehook.h>
  17 #include <linux/unistd.h>
  18 #include <linux/stddef.h>
  19 #include <linux/personality.h>
  20 #include <linux/uaccess.h>
  21
  22 #include <asm/processor.h>
  23 #include <asm/ucontext.h>
  24 #include <asm/i387.h>
  25 #include <asm/vdso.h>
  26
  27 #ifdef CONFIG_X86_64
  28 #include <asm/proto.h>
  29 #include <asm/ia32_unistd.h>
  30 #include <asm/mce.h>
  31 #endif /* CONFIG_X86_64 */
  32
  33 #include <asm/syscall.h>
  34 #include <asm/syscalls.h>
  35
  36 #include "sigframe.h"
  37
  38 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  39
  40 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  41                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  42                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  43                          X86_EFLAGS_CF)
  44
  45 #ifdef CONFIG_X86_32
  46 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  47 #else
  48 # define FIX_EFLAGS     __FIX_EFLAGS
  49 #endif
  50
  51 static const struct {
  52         u16 poplmovl;
  53         u32 val;
  54         u16 int80;
  55 } __attribute__((packed)) retcode = {
  56         0xb858,         /* popl %eax; movl $..., %eax */
  57         __NR_sigreturn,
  58         0x80cd,         /* int $0x80 */
  59 };
  60
  61 static const struct {
  62         u8  movl;
  63         u32 val;
  64         u16 int80;
  65         u8  pad;
  66 } __attribute__((packed)) rt_retcode = {
  67         0xb8,           /* movl $..., %eax */
  68         __NR_rt_sigreturn,
  69         0x80cd,         /* int $0x80 */
  70         0
  71 };
  72
  73 #define COPY(x)                 {               \
  74         err |= __get_user(regs->x, &sc->x);     \
  75 }
  76
  77 #define COPY_SEG(seg)           {                       \
  78                 unsigned short tmp;                     \
  79                 err |= __get_user(tmp, &sc->seg);       \
  80                 regs->seg = tmp;                        \
  81 }
  82
  83 #define COPY_SEG_CPL3(seg)      {                       \
  84                 unsigned short tmp;                     \
  85                 err |= __get_user(tmp, &sc->seg);       \
  86                 regs->seg = tmp | 3;                    \
  87 }
  88
  89 #define GET_SEG(seg)            {                       \
  90                 unsigned short tmp;                     \
  91                 err |= __get_user(tmp, &sc->seg);       \
  92                 loadsegment(seg, tmp);                  \
  93 }
  94
  95 static int
  96 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  97                    unsigned long *pax)
  98 {
  99         void __user *buf;
 100         unsigned int tmpflags;
 101         unsigned int err = 0;
 102
 103         /* Always make any pending restarted system calls return -EINTR */
 104         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 105
 106 #ifdef CONFIG_X86_32
 107         GET_SEG(gs);
 108         COPY_SEG(fs);
 109         COPY_SEG(es);
 110         COPY_SEG(ds);
 111 #endif /* CONFIG_X86_32 */
 112
 113         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 114         COPY(dx); COPY(cx); COPY(ip);
 115
 116 #ifdef CONFIG_X86_64
 117         COPY(r8);
 118         COPY(r9);
 119         COPY(r10);
 120         COPY(r11);
 121         COPY(r12);
 122         COPY(r13);
 123         COPY(r14);
 124         COPY(r15);
 125 #endif /* CONFIG_X86_64 */
 126
 127 #ifdef CONFIG_X86_32
 128         COPY_SEG_CPL3(cs);
 129         COPY_SEG_CPL3(ss);
 130 #else /* !CONFIG_X86_32 */
 131         /* Kernel saves and restores only the CS segment register on signals,
 132          * which is the bare minimum needed to allow mixed 32/64-bit code.
 133          * App's signal handler can save/restore other segments if needed. */
 134         COPY_SEG_CPL3(cs);
 135 #endif /* CONFIG_X86_32 */
 136
 137         err |= __get_user(tmpflags, &sc->flags);
 138         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 139         regs->orig_ax = -1;             /* disable syscall checks */
 140
 141         err |= __get_user(buf, &sc->fpstate);
 142         err |= restore_i387_xstate(buf);
 143
 144         err |= __get_user(*pax, &sc->ax);
 145         return err;
 146 }
 147
 148 static int
 149 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 150                  struct pt_regs *regs, unsigned long mask)
 151 {
 152         int err = 0;
 153
 154 #ifdef CONFIG_X86_32
 155         {
 156                 unsigned int tmp;
 157
 158                 savesegment(gs, tmp);
 159                 err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 160         }
 161         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 162         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 163         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 164 #endif /* CONFIG_X86_32 */
 165
 166         err |= __put_user(regs->di, &sc->di);
 167         err |= __put_user(regs->si, &sc->si);
 168         err |= __put_user(regs->bp, &sc->bp);
 169         err |= __put_user(regs->sp, &sc->sp);
 170         err |= __put_user(regs->bx, &sc->bx);
 171         err |= __put_user(regs->dx, &sc->dx);
 172         err |= __put_user(regs->cx, &sc->cx);
 173         err |= __put_user(regs->ax, &sc->ax);
 174 #ifdef CONFIG_X86_64
 175         err |= __put_user(regs->r8, &sc->r8);
 176         err |= __put_user(regs->r9, &sc->r9);
 177         err |= __put_user(regs->r10, &sc->r10);
 178         err |= __put_user(regs->r11, &sc->r11);
 179         err |= __put_user(regs->r12, &sc->r12);
 180         err |= __put_user(regs->r13, &sc->r13);
 181         err |= __put_user(regs->r14, &sc->r14);
 182         err |= __put_user(regs->r15, &sc->r15);
 183 #endif /* CONFIG_X86_64 */
 184
 185         err |= __put_user(current->thread.trap_no, &sc->trapno);
 186         err |= __put_user(current->thread.error_code, &sc->err);
 187         err |= __put_user(regs->ip, &sc->ip);
 188 #ifdef CONFIG_X86_32
 189         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 190         err |= __put_user(regs->flags, &sc->flags);
 191         err |= __put_user(regs->sp, &sc->sp_at_signal);
 192         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 193 #else /* !CONFIG_X86_32 */
 194         err |= __put_user(regs->flags, &sc->flags);
 195         err |= __put_user(regs->cs, &sc->cs);
 196         err |= __put_user(0, &sc->gs);
 197         err |= __put_user(0, &sc->fs);
 198 #endif /* CONFIG_X86_32 */
 199
 200         err |= __put_user(fpstate, &sc->fpstate);
 201
 202         /* non-iBCS2 extensions.. */
 203         err |= __put_user(mask, &sc->oldmask);
 204         err |= __put_user(current->thread.cr2, &sc->cr2);
 205
 206         return err;
 207 }
 208
 209 /*
 210  * Atomically swap in the new signal mask, and wait for a signal.
 211  */
 212 asmlinkage int
 213 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 214 {
 215         mask &= _BLOCKABLE;
 216         spin_lock_irq(&current->sighand->siglock);
 217         current->saved_sigmask = current->blocked;
 218         siginitset(&current->blocked, mask);
 219         recalc_sigpending();
 220         spin_unlock_irq(&current->sighand->siglock);
 221
 222         current->state = TASK_INTERRUPTIBLE;
 223         schedule();
 224         set_restore_sigmask();
 225
 226         return -ERESTARTNOHAND;
 227 }
 228
 229 asmlinkage int
 230 sys_sigaction(int sig, const struct old_sigaction __user *act,
 231               struct old_sigaction __user *oact)
 232 {
 233         struct k_sigaction new_ka, old_ka;
 234         int ret;
 235
 236         if (act) {
 237                 old_sigset_t mask;
 238
 239                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 240                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 241                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 242                         return -EFAULT;
 243
 244                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 245                 __get_user(mask, &act->sa_mask);
 246                 siginitset(&new_ka.sa.sa_mask, mask);
 247         }
 248
 249         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 250
 251         if (!ret && oact) {
 252                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 253                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 254                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 255                         return -EFAULT;
 256
 257                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 258                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 259         }
 260
 261         return ret;
 262 }
 263
 264 #ifdef CONFIG_X86_32
 265 asmlinkage int sys_sigaltstack(unsigned long bx)
 266 {
 267         /*
 268          * This is needed to make gcc realize it doesn't own the
 269          * "struct pt_regs"
 270          */
 271         struct pt_regs *regs = (struct pt_regs *)&bx;
 272         const stack_t __user *uss = (const stack_t __user *)bx;
 273         stack_t __user *uoss = (stack_t __user *)regs->cx;
 274
 275         return do_sigaltstack(uss, uoss, regs->sp);
 276 }
 277 #else /* !CONFIG_X86_32 */
 278 asmlinkage long
 279 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 280                 struct pt_regs *regs)
 281 {
 282         return do_sigaltstack(uss, uoss, regs->sp);
 283 }
 284 #endif /* CONFIG_X86_32 */
 285
 286 /*
 287  * Do a signal return; undo the signal stack.
 288  */
 289 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 290 {
 291         struct sigframe __user *frame;
 292         struct pt_regs *regs;
 293         unsigned long ax;
 294         sigset_t set;
 295
 296         regs = (struct pt_regs *) &__unused;
 297         frame = (struct sigframe __user *)(regs->sp - 8);
 298
 299         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 300                 goto badframe;
 301         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 302                 && __copy_from_user(&set.sig[1], &frame->extramask,
 303                                     sizeof(frame->extramask))))
 304                 goto badframe;
 305
 306         sigdelsetmask(&set, ~_BLOCKABLE);
 307         spin_lock_irq(&current->sighand->siglock);
 308         current->blocked = set;
 309         recalc_sigpending();
 310         spin_unlock_irq(&current->sighand->siglock);
 311
 312         if (restore_sigcontext(regs, &frame->sc, &ax))
 313                 goto badframe;
 314         return ax;
 315
 316 badframe:
 317         if (show_unhandled_signals && printk_ratelimit()) {
 318                 printk("%s%s[%d] bad frame in sigreturn frame:"
 319                         "%p ip:%lx sp:%lx oeax:%lx",
 320                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 321                     current->comm, task_pid_nr(current), frame, regs->ip,
 322                     regs->sp, regs->orig_ax);
 323                 print_vma_addr(" in ", regs->ip);
 324                 printk(KERN_CONT "\n");
 325         }
 326
 327         force_sig(SIGSEGV, current);
 328
 329         return 0;
 330 }
 331
 332 static long do_rt_sigreturn(struct pt_regs *regs)
 333 {
 334         struct rt_sigframe __user *frame;
 335         unsigned long ax;
 336         sigset_t set;
 337
 338         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 339         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 340                 goto badframe;
 341         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 342                 goto badframe;
 343
 344         sigdelsetmask(&set, ~_BLOCKABLE);
 345         spin_lock_irq(&current->sighand->siglock);
 346         current->blocked = set;
 347         recalc_sigpending();
 348         spin_unlock_irq(&current->sighand->siglock);
 349
 350         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 351                 goto badframe;
 352
 353         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 354                 goto badframe;
 355
 356         return ax;
 357
 358 badframe:
 359         signal_fault(regs, frame, "rt_sigreturn");
 360         return 0;
 361 }
 362
 363 #ifdef CONFIG_X86_32
 364 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 365 {
 366         struct pt_regs *regs = (struct pt_regs *)&__unused;
 367
 368         return do_rt_sigreturn(regs);
 369 }
 370 #else /* !CONFIG_X86_32 */
 371 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 372 {
 373         return do_rt_sigreturn(regs);
 374 }
 375 #endif /* CONFIG_X86_32 */
 376
 377 /*
 378  * Set up a signal frame.
 379  */
 380
 381 /*
 382  * Determine which stack to use..
 383  */
 384 static inline void __user *
 385 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 386              void **fpstate)
 387 {
 388         unsigned long sp;
 389
 390         /* Default to using normal stack */
 391         sp = regs->sp;
 392
 393         /*
 394          * If we are on the alternate signal stack and would overflow it, don't.
 395          * Return an always-bogus address instead so we will die with SIGSEGV.
 396          */
 397         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 398                 return (void __user *) -1L;
 399
 400         /* This is the X/Open sanctioned signal stack switching.  */
 401         if (ka->sa.sa_flags & SA_ONSTACK) {
 402                 if (sas_ss_flags(sp) == 0)
 403                         sp = current->sas_ss_sp + current->sas_ss_size;
 404         } else {
 405                 /* This is the legacy signal stack switching. */
 406                 if ((regs->ss & 0xffff) != __USER_DS &&
 407                         !(ka->sa.sa_flags & SA_RESTORER) &&
 408                                 ka->sa.sa_restorer)
 409                         sp = (unsigned long) ka->sa.sa_restorer;
 410         }
 411
 412         if (used_math()) {
 413                 sp = sp - sig_xstate_size;
 414                 *fpstate = (struct _fpstate *) sp;
 415                 if (save_i387_xstate(*fpstate) < 0)
 416                         return (void __user *)-1L;
 417         }
 418
 419         sp -= frame_size;
 420         /*
 421          * Align the stack pointer according to the i386 ABI,
 422          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 423          */
 424         sp = ((sp + 4) & -16ul) - 4;
 425
 426         return (void __user *) sp;
 427 }
 428
 429 static int
 430 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 431               struct pt_regs *regs)
 432 {
 433         struct sigframe __user *frame;
 434         void __user *restorer;
 435         int err = 0;
 436         void __user *fpstate = NULL;
 437
 438         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 439
 440         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 441                 return -EFAULT;
 442
 443         if (__put_user(sig, &frame->sig))
 444                 return -EFAULT;
 445
 446         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 447                 return -EFAULT;
 448
 449         if (_NSIG_WORDS > 1) {
 450                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 451                                    sizeof(frame->extramask)))
 452                         return -EFAULT;
 453         }
 454
 455         if (current->mm->context.vdso)
 456                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 457         else
 458                 restorer = &frame->retcode;
 459         if (ka->sa.sa_flags & SA_RESTORER)
 460                 restorer = ka->sa.sa_restorer;
 461
 462         /* Set up to return from userspace.  */
 463         err |= __put_user(restorer, &frame->pretcode);
 464
 465         /*
 466          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 467          *
 468          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 469          * reasons and because gdb uses it as a signature to notice
 470          * signal handler stack frames.
 471          */
 472         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 473
 474         if (err)
 475                 return -EFAULT;
 476
 477         /* Set up registers for signal handler */
 478         regs->sp = (unsigned long)frame;
 479         regs->ip = (unsigned long)ka->sa.sa_handler;
 480         regs->ax = (unsigned long)sig;
 481         regs->dx = 0;
 482         regs->cx = 0;
 483
 484         regs->ds = __USER_DS;
 485         regs->es = __USER_DS;
 486         regs->ss = __USER_DS;
 487         regs->cs = __USER_CS;
 488
 489         return 0;
 490 }
 491
 492 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 493                             sigset_t *set, struct pt_regs *regs)
 494 {
 495         struct rt_sigframe __user *frame;
 496         void __user *restorer;
 497         int err = 0;
 498         void __user *fpstate = NULL;
 499
 500         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 501
 502         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 503                 return -EFAULT;
 504
 505         err |= __put_user(sig, &frame->sig);
 506         err |= __put_user(&frame->info, &frame->pinfo);
 507         err |= __put_user(&frame->uc, &frame->puc);
 508         err |= copy_siginfo_to_user(&frame->info, info);
 509         if (err)
 510                 return -EFAULT;
 511
 512         /* Create the ucontext.  */
 513         if (cpu_has_xsave)
 514                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 515         else
 516                 err |= __put_user(0, &frame->uc.uc_flags);
 517         err |= __put_user(0, &frame->uc.uc_link);
 518         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 519         err |= __put_user(sas_ss_flags(regs->sp),
 520                           &frame->uc.uc_stack.ss_flags);
 521         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 522         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 523                                 regs, set->sig[0]);
 524         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 525         if (err)
 526                 return -EFAULT;
 527
 528         /* Set up to return from userspace.  */
 529         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 530         if (ka->sa.sa_flags & SA_RESTORER)
 531                 restorer = ka->sa.sa_restorer;
 532         err |= __put_user(restorer, &frame->pretcode);
 533
 534         /*
 535          * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 536          *
 537          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 538          * reasons and because gdb uses it as a signature to notice
 539          * signal handler stack frames.
 540          */
 541         err |= __put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 542
 543         if (err)
 544                 return -EFAULT;
 545
 546         /* Set up registers for signal handler */
 547         regs->sp = (unsigned long)frame;
 548         regs->ip = (unsigned long)ka->sa.sa_handler;
 549         regs->ax = (unsigned long)sig;
 550         regs->dx = (unsigned long)&frame->info;
 551         regs->cx = (unsigned long)&frame->uc;
 552
 553         regs->ds = __USER_DS;
 554         regs->es = __USER_DS;
 555         regs->ss = __USER_DS;
 556         regs->cs = __USER_CS;
 557
 558         return 0;
 559 }
 560
 561 /*
 562  * OK, we're invoking a handler:
 563  */
 564 static int signr_convert(int sig)
 565 {
 566 #ifdef CONFIG_X86_32
 567         struct thread_info *info = current_thread_info();
 568
 569         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 570                 return info->exec_domain->signal_invmap[sig];
 571 #endif /* CONFIG_X86_32 */
 572         return sig;
 573 }
 574
 575 #ifdef CONFIG_X86_32
 576
 577 #define is_ia32 1
 578 #define ia32_setup_frame        __setup_frame
 579 #define ia32_setup_rt_frame     __setup_rt_frame
 580
 581 #else /* !CONFIG_X86_32 */
 582
 583 #ifdef CONFIG_IA32_EMULATION
 584 #define is_ia32 test_thread_flag(TIF_IA32)
 585 #else /* !CONFIG_IA32_EMULATION */
 586 #define is_ia32 0
 587 #endif /* CONFIG_IA32_EMULATION */
 588
 589 #endif /* CONFIG_X86_32 */
 590
 591 static int
 592 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 593                sigset_t *set, struct pt_regs *regs)
 594 {
 595         int usig = signr_convert(sig);
 596         int ret;
 597
 598         /* Set up the stack frame */
 599         if (is_ia32) {
 600                 if (ka->sa.sa_flags & SA_SIGINFO)
 601                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 602                 else
 603                         ret = ia32_setup_frame(usig, ka, set, regs);
 604         } else
 605                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 606
 607         if (ret) {
 608                 force_sigsegv(sig, current);
 609                 return -EFAULT;
 610         }
 611
 612         return ret;
 613 }
 614
 615 static int
 616 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 617               sigset_t *oldset, struct pt_regs *regs)
 618 {
 619         int ret;
 620
 621         /* Are we from a system call? */
 622         if (syscall_get_nr(current, regs) >= 0) {
 623                 /* If so, check system call restarting.. */
 624                 switch (syscall_get_error(current, regs)) {
 625                 case -ERESTART_RESTARTBLOCK:
 626                 case -ERESTARTNOHAND:
 627                         regs->ax = -EINTR;
 628                         break;
 629
 630                 case -ERESTARTSYS:
 631                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 632                                 regs->ax = -EINTR;
 633                                 break;
 634                         }
 635                 /* fallthrough */
 636                 case -ERESTARTNOINTR:
 637                         regs->ax = regs->orig_ax;
 638                         regs->ip -= 2;
 639                         break;
 640                 }
 641         }
 642
 643         /*
 644          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 645          * flag so that register information in the sigcontext is correct.
 646          */
 647         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 648             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 649                 regs->flags &= ~X86_EFLAGS_TF;
 650
 651         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 652
 653         if (ret)
 654                 return ret;
 655
 656 #ifdef CONFIG_X86_64
 657         /*
 658          * This has nothing to do with segment registers,
 659          * despite the name.  This magic affects uaccess.h
 660          * macros' behavior.  Reset it to the normal setting.
 661          */
 662         set_fs(USER_DS);
 663 #endif
 664
 665         /*
 666          * Clear the direction flag as per the ABI for function entry.
 667          */
 668         regs->flags &= ~X86_EFLAGS_DF;
 669
 670         /*
 671          * Clear TF when entering the signal handler, but
 672          * notify any tracer that was single-stepping it.
 673          * The tracer may want to single-step inside the
 674          * handler too.
 675          */
 676         regs->flags &= ~X86_EFLAGS_TF;
 677
 678         spin_lock_irq(&current->sighand->siglock);
 679         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 680         if (!(ka->sa.sa_flags & SA_NODEFER))
 681                 sigaddset(&current->blocked, sig);
 682         recalc_sigpending();
 683         spin_unlock_irq(&current->sighand->siglock);
 684
 685         tracehook_signal_handler(sig, info, ka, regs,
 686                                  test_thread_flag(TIF_SINGLESTEP));
 687
 688         return 0;
 689 }
 690
 691 #ifdef CONFIG_X86_32
 692 #define NR_restart_syscall      __NR_restart_syscall
 693 #else /* !CONFIG_X86_32 */
 694 #define NR_restart_syscall      \
 695         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 696 #endif /* CONFIG_X86_32 */
 697
 698 /*
 699  * Note that 'init' is a special process: it doesn't get signals it doesn't
 700  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 701  * mistake.
 702  */
 703 static void do_signal(struct pt_regs *regs)
 704 {
 705         struct k_sigaction ka;
 706         siginfo_t info;
 707         int signr;
 708         sigset_t *oldset;
 709
 710         /*
 711          * We want the common case to go fast, which is why we may in certain
 712          * cases get here from kernel mode. Just return without doing anything
 713          * if so.
 714          * X86_32: vm86 regs switched out by assembly code before reaching
 715          * here, so testing against kernel CS suffices.
 716          */
 717         if (!user_mode(regs))
 718                 return;
 719
 720         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 721                 oldset = &current->saved_sigmask;
 722         else
 723                 oldset = &current->blocked;
 724
 725         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 726         if (signr > 0) {
 727                 /*
 728                  * Re-enable any watchpoints before delivering the
 729                  * signal to user space. The processor register will
 730                  * have been cleared if the watchpoint triggered
 731                  * inside the kernel.
 732                  */
 733                 if (current->thread.debugreg7)
 734                         set_debugreg(current->thread.debugreg7, 7);
 735
 736                 /* Whee! Actually deliver the signal.  */
 737                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 738                         /*
 739                          * A signal was successfully delivered; the saved
 740                          * sigmask will have been stored in the signal frame,
 741                          * and will be restored by sigreturn, so we can simply
 742                          * clear the TS_RESTORE_SIGMASK flag.
 743                          */
 744                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 745                 }
 746                 return;
 747         }
 748
 749         /* Did we come from a system call? */
 750         if (syscall_get_nr(current, regs) >= 0) {
 751                 /* Restart the system call - no handlers present */
 752                 switch (syscall_get_error(current, regs)) {
 753                 case -ERESTARTNOHAND:
 754                 case -ERESTARTSYS:
 755                 case -ERESTARTNOINTR:
 756                         regs->ax = regs->orig_ax;
 757                         regs->ip -= 2;
 758                         break;
 759
 760                 case -ERESTART_RESTARTBLOCK:
 761                         regs->ax = NR_restart_syscall;
 762                         regs->ip -= 2;
 763                         break;
 764                 }
 765         }
 766
 767         /*
 768          * If there's no signal to deliver, we just put the saved sigmask
 769          * back.
 770          */
 771         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 772                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 773                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 774         }
 775 }
 776
 777 /*
 778  * notification of userspace execution resumption
 779  * - triggered by the TIF_WORK_MASK flags
 780  */
 781 void
 782 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 783 {
 784 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 785         /* notify userspace of pending MCEs */
 786         if (thread_info_flags & _TIF_MCE_NOTIFY)
 787                 mce_notify_user();
 788 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 789
 790         /* deal with pending signal delivery */
 791         if (thread_info_flags & _TIF_SIGPENDING)
 792                 do_signal(regs);
 793
 794         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 795                 clear_thread_flag(TIF_NOTIFY_RESUME);
 796                 tracehook_notify_resume(regs);
 797         }
 798
 799 #ifdef CONFIG_X86_32
 800         clear_thread_flag(TIF_IRET);
 801 #endif /* CONFIG_X86_32 */
 802 }
 803
 804 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 805 {
 806         struct task_struct *me = current;
 807
 808         if (show_unhandled_signals && printk_ratelimit()) {
 809                 printk(KERN_INFO
 810                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 811                        me->comm, me->pid, where, frame,
 812                        regs->ip, regs->sp, regs->orig_ax);
 813                 print_vma_addr(" in ", regs->ip);
 814                 printk(KERN_CONT "\n");
 815         }
 816
 817         force_sig(SIGSEGV, me);
 818 }