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/unistd.h>
  16 #include <linux/stddef.h>
  17 #include <linux/personality.h>
  18 #include <linux/suspend.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/elf.h>
  21 #include <linux/binfmts.h>
  22 #include <asm/processor.h>
  23 #include <asm/ucontext.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/i387.h>
  26 #include <asm/vdso.h>
  27 #include "sigframe_32.h"
  28
  29 #define DEBUG_SIG 0
  30
  31 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  32
  33 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  34                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  35                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  36                          X86_EFLAGS_CF)
  37
  38 #ifdef CONFIG_X86_32
  39 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  40 #else
  41 # define FIX_EFLAGS     __FIX_EFLAGS
  42 #endif
  43
  44 /*
  45  * Atomically swap in the new signal mask, and wait for a signal.
  46  */
  47 asmlinkage int
  48 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  49 {
  50         mask &= _BLOCKABLE;
  51         spin_lock_irq(&current->sighand->siglock);
  52         current->saved_sigmask = current->blocked;
  53         siginitset(&current->blocked, mask);
  54         recalc_sigpending();
  55         spin_unlock_irq(&current->sighand->siglock);
  56
  57         current->state = TASK_INTERRUPTIBLE;
  58         schedule();
  59         set_thread_flag(TIF_RESTORE_SIGMASK);
  60         return -ERESTARTNOHAND;
  61 }
  62
  63 asmlinkage int
  64 sys_sigaction(int sig, const struct old_sigaction __user *act,
  65               struct old_sigaction __user *oact)
  66 {
  67         struct k_sigaction new_ka, old_ka;
  68         int ret;
  69
  70         if (act) {
  71                 old_sigset_t mask;
  72                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  73                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  74                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  75                         return -EFAULT;
  76                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  77                 __get_user(mask, &act->sa_mask);
  78                 siginitset(&new_ka.sa.sa_mask, mask);
  79         }
  80
  81         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  82
  83         if (!ret && oact) {
  84                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  85                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  86                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  87                         return -EFAULT;
  88                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  89                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  90         }
  91
  92         return ret;
  93 }
  94
  95 asmlinkage int
  96 sys_sigaltstack(unsigned long bx)
  97 {
  98         /* This is needed to make gcc realize it doesn't own the "struct pt_regs" */
  99         struct pt_regs *regs = (struct pt_regs *)&bx;
 100         const stack_t __user *uss = (const stack_t __user *)bx;
 101         stack_t __user *uoss = (stack_t __user *)regs->cx;
 102
 103         return do_sigaltstack(uss, uoss, regs->sp);
 104 }
 105
 106
 107 /*
 108  * Do a signal return; undo the signal stack.
 109  */
 110
 111 static int
 112 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax)
 113 {
 114         unsigned int err = 0;
 115
 116         /* Always make any pending restarted system calls return -EINTR */
 117         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 118
 119 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 120
 121 #define COPY_SEG(seg)                                                   \
 122         { unsigned short tmp;                                           \
 123           err |= __get_user(tmp, &sc->seg);                             \
 124           regs->seg = tmp; }
 125
 126 #define COPY_SEG_STRICT(seg)                                            \
 127         { unsigned short tmp;                                           \
 128           err |= __get_user(tmp, &sc->seg);                             \
 129           regs->seg = tmp|3; }
 130
 131 #define GET_SEG(seg)                                                    \
 132         { unsigned short tmp;                                           \
 133           err |= __get_user(tmp, &sc->seg);                             \
 134           loadsegment(seg,tmp); }
 135
 136         GET_SEG(gs);
 137         COPY_SEG(fs);
 138         COPY_SEG(es);
 139         COPY_SEG(ds);
 140         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 141         COPY(dx); COPY(cx); COPY(ip);
 142         COPY_SEG_STRICT(cs);
 143         COPY_SEG_STRICT(ss);
 144
 145         {
 146                 unsigned int tmpflags;
 147                 err |= __get_user(tmpflags, &sc->flags);
 148                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 149                 regs->orig_ax = -1;             /* disable syscall checks */
 150         }
 151
 152         {
 153                 struct _fpstate __user * buf;
 154                 err |= __get_user(buf, &sc->fpstate);
 155                 if (buf) {
 156                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 157                                 goto badframe;
 158                         err |= restore_i387(buf);
 159                 } else {
 160                         struct task_struct *me = current;
 161                         if (used_math()) {
 162                                 clear_fpu(me);
 163                                 clear_used_math();
 164                         }
 165                 }
 166         }
 167
 168         err |= __get_user(*peax, &sc->ax);
 169         return err;
 170
 171 badframe:
 172         return 1;
 173 }
 174
 175 asmlinkage int sys_sigreturn(unsigned long __unused)
 176 {
 177         struct pt_regs *regs = (struct pt_regs *) &__unused;
 178         struct sigframe __user *frame = (struct sigframe __user *)(regs->sp - 8);
 179         sigset_t set;
 180         int ax;
 181
 182         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 183                 goto badframe;
 184         if (__get_user(set.sig[0], &frame->sc.oldmask)
 185             || (_NSIG_WORDS > 1
 186                 && __copy_from_user(&set.sig[1], &frame->extramask,
 187                                     sizeof(frame->extramask))))
 188                 goto badframe;
 189
 190         sigdelsetmask(&set, ~_BLOCKABLE);
 191         spin_lock_irq(&current->sighand->siglock);
 192         current->blocked = set;
 193         recalc_sigpending();
 194         spin_unlock_irq(&current->sighand->siglock);
 195
 196         if (restore_sigcontext(regs, &frame->sc, &ax))
 197                 goto badframe;
 198         return ax;
 199
 200 badframe:
 201         if (show_unhandled_signals && printk_ratelimit()) {
 202                 printk("%s%s[%d] bad frame in sigreturn frame:%p ip:%lx"
 203                        " sp:%lx oeax:%lx",
 204                     task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 205                     current->comm, task_pid_nr(current), frame, regs->ip,
 206                     regs->sp, regs->orig_ax);
 207                 print_vma_addr(" in ", regs->ip);
 208                 printk("\n");
 209         }
 210
 211         force_sig(SIGSEGV, current);
 212         return 0;
 213 }
 214
 215 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 216 {
 217         struct pt_regs *regs = (struct pt_regs *)&__unused;
 218         struct rt_sigframe __user *frame;
 219         sigset_t set;
 220         int ax;
 221
 222         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 223         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 224                 goto badframe;
 225         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 226                 goto badframe;
 227
 228         sigdelsetmask(&set, ~_BLOCKABLE);
 229         spin_lock_irq(&current->sighand->siglock);
 230         current->blocked = set;
 231         recalc_sigpending();
 232         spin_unlock_irq(&current->sighand->siglock);
 233
 234         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 235                 goto badframe;
 236
 237         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 238                 goto badframe;
 239
 240         return ax;
 241
 242 badframe:
 243         force_sig(SIGSEGV, current);
 244         return 0;
 245 }
 246
 247 /*
 248  * Set up a signal frame.
 249  */
 250
 251 static int
 252 setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 253                  struct pt_regs *regs, unsigned long mask)
 254 {
 255         int tmp, err = 0;
 256
 257         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 258         savesegment(gs, tmp);
 259         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 260
 261         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 262         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 263         err |= __put_user(regs->di, &sc->di);
 264         err |= __put_user(regs->si, &sc->si);
 265         err |= __put_user(regs->bp, &sc->bp);
 266         err |= __put_user(regs->sp, &sc->sp);
 267         err |= __put_user(regs->bx, &sc->bx);
 268         err |= __put_user(regs->dx, &sc->dx);
 269         err |= __put_user(regs->cx, &sc->cx);
 270         err |= __put_user(regs->ax, &sc->ax);
 271         err |= __put_user(current->thread.trap_no, &sc->trapno);
 272         err |= __put_user(current->thread.error_code, &sc->err);
 273         err |= __put_user(regs->ip, &sc->ip);
 274         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 275         err |= __put_user(regs->flags, &sc->flags);
 276         err |= __put_user(regs->sp, &sc->sp_at_signal);
 277         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 278
 279         tmp = save_i387(fpstate);
 280         if (tmp < 0)
 281           err = 1;
 282         else
 283           err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
 284
 285         /* non-iBCS2 extensions.. */
 286         err |= __put_user(mask, &sc->oldmask);
 287         err |= __put_user(current->thread.cr2, &sc->cr2);
 288
 289         return err;
 290 }
 291
 292 /*
 293  * Determine which stack to use..
 294  */
 295 static inline void __user *
 296 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 297 {
 298         unsigned long sp;
 299
 300         /* Default to using normal stack */
 301         sp = regs->sp;
 302
 303         /*
 304          * If we are on the alternate signal stack and would overflow it, don't.
 305          * Return an always-bogus address instead so we will die with SIGSEGV.
 306          */
 307         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 308                 return (void __user *) -1L;
 309
 310         /* This is the X/Open sanctioned signal stack switching.  */
 311         if (ka->sa.sa_flags & SA_ONSTACK) {
 312                 if (sas_ss_flags(sp) == 0)
 313                         sp = current->sas_ss_sp + current->sas_ss_size;
 314         }
 315
 316         /* This is the legacy signal stack switching. */
 317         else if ((regs->ss & 0xffff) != __USER_DS &&
 318                  !(ka->sa.sa_flags & SA_RESTORER) &&
 319                  ka->sa.sa_restorer) {
 320                 sp = (unsigned long) ka->sa.sa_restorer;
 321         }
 322
 323         sp -= frame_size;
 324         /* Align the stack pointer according to the i386 ABI,
 325          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 326         sp = ((sp + 4) & -16ul) - 4;
 327         return (void __user *) sp;
 328 }
 329
 330 /* These symbols are defined with the addresses in the vsyscall page.
 331    See vsyscall-sigreturn.S.  */
 332 extern void __user __kernel_sigreturn;
 333 extern void __user __kernel_rt_sigreturn;
 334
 335 static int setup_frame(int sig, struct k_sigaction *ka,
 336                        sigset_t *set, struct pt_regs * regs)
 337 {
 338         void __user *restorer;
 339         struct sigframe __user *frame;
 340         int err = 0;
 341         int usig;
 342
 343         frame = get_sigframe(ka, regs, sizeof(*frame));
 344
 345         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 346                 goto give_sigsegv;
 347
 348         usig = current_thread_info()->exec_domain
 349                 && current_thread_info()->exec_domain->signal_invmap
 350                 && sig < 32
 351                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 352                 : sig;
 353
 354         err = __put_user(usig, &frame->sig);
 355         if (err)
 356                 goto give_sigsegv;
 357
 358         err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
 359         if (err)
 360                 goto give_sigsegv;
 361
 362         if (_NSIG_WORDS > 1) {
 363                 err = __copy_to_user(&frame->extramask, &set->sig[1],
 364                                       sizeof(frame->extramask));
 365                 if (err)
 366                         goto give_sigsegv;
 367         }
 368
 369         if (current->mm->context.vdso)
 370                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 371         else
 372                 restorer = &frame->retcode;
 373         if (ka->sa.sa_flags & SA_RESTORER)
 374                 restorer = ka->sa.sa_restorer;
 375
 376         /* Set up to return from userspace.  */
 377         err |= __put_user(restorer, &frame->pretcode);
 378
 379         /*
 380          * This is popl %eax ; movl $,%eax ; int $0x80
 381          *
 382          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 383          * reasons and because gdb uses it as a signature to notice
 384          * signal handler stack frames.
 385          */
 386         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 387         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 388         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 389
 390         if (err)
 391                 goto give_sigsegv;
 392
 393         /* Set up registers for signal handler */
 394         regs->sp = (unsigned long) frame;
 395         regs->ip = (unsigned long) ka->sa.sa_handler;
 396         regs->ax = (unsigned long) sig;
 397         regs->dx = 0;
 398         regs->cx = 0;
 399
 400         regs->ds = __USER_DS;
 401         regs->es = __USER_DS;
 402         regs->ss = __USER_DS;
 403         regs->cs = __USER_CS;
 404
 405         /*
 406          * Clear TF when entering the signal handler, but
 407          * notify any tracer that was single-stepping it.
 408          * The tracer may want to single-step inside the
 409          * handler too.
 410          */
 411         regs->flags &= ~(TF_MASK | X86_EFLAGS_DF);
 412         if (test_thread_flag(TIF_SINGLESTEP))
 413                 ptrace_notify(SIGTRAP);
 414
 415 #if DEBUG_SIG
 416         printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n",
 417                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 418 #endif
 419
 420         return 0;
 421
 422 give_sigsegv:
 423         force_sigsegv(sig, current);
 424         return -EFAULT;
 425 }
 426
 427 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 428                            sigset_t *set, struct pt_regs * regs)
 429 {
 430         void __user *restorer;
 431         struct rt_sigframe __user *frame;
 432         int err = 0;
 433         int usig;
 434
 435         frame = get_sigframe(ka, regs, sizeof(*frame));
 436
 437         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 438                 goto give_sigsegv;
 439
 440         usig = current_thread_info()->exec_domain
 441                 && current_thread_info()->exec_domain->signal_invmap
 442                 && sig < 32
 443                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 444                 : sig;
 445
 446         err |= __put_user(usig, &frame->sig);
 447         err |= __put_user(&frame->info, &frame->pinfo);
 448         err |= __put_user(&frame->uc, &frame->puc);
 449         err |= copy_siginfo_to_user(&frame->info, info);
 450         if (err)
 451                 goto give_sigsegv;
 452
 453         /* Create the ucontext.  */
 454         err |= __put_user(0, &frame->uc.uc_flags);
 455         err |= __put_user(0, &frame->uc.uc_link);
 456         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 457         err |= __put_user(sas_ss_flags(regs->sp),
 458                           &frame->uc.uc_stack.ss_flags);
 459         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 460         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 461                                 regs, set->sig[0]);
 462         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 463         if (err)
 464                 goto give_sigsegv;
 465
 466         /* Set up to return from userspace.  */
 467         restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 468         if (ka->sa.sa_flags & SA_RESTORER)
 469                 restorer = ka->sa.sa_restorer;
 470         err |= __put_user(restorer, &frame->pretcode);
 471
 472         /*
 473          * This is movl $,%ax ; int $0x80
 474          *
 475          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 476          * reasons and because gdb uses it as a signature to notice
 477          * signal handler stack frames.
 478          */
 479         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 480         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 481         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 482
 483         if (err)
 484                 goto give_sigsegv;
 485
 486         /* Set up registers for signal handler */
 487         regs->sp = (unsigned long) frame;
 488         regs->ip = (unsigned long) ka->sa.sa_handler;
 489         regs->ax = (unsigned long) usig;
 490         regs->dx = (unsigned long) &frame->info;
 491         regs->cx = (unsigned long) &frame->uc;
 492
 493         regs->ds = __USER_DS;
 494         regs->es = __USER_DS;
 495         regs->ss = __USER_DS;
 496         regs->cs = __USER_CS;
 497
 498         /*
 499          * Clear TF when entering the signal handler, but
 500          * notify any tracer that was single-stepping it.
 501          * The tracer may want to single-step inside the
 502          * handler too.
 503          */
 504         regs->flags &= ~(TF_MASK | X86_EFLAGS_DF);
 505         if (test_thread_flag(TIF_SINGLESTEP))
 506                 ptrace_notify(SIGTRAP);
 507
 508 #if DEBUG_SIG
 509         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 510                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 511 #endif
 512
 513         return 0;
 514
 515 give_sigsegv:
 516         force_sigsegv(sig, current);
 517         return -EFAULT;
 518 }
 519
 520 /*
 521  * OK, we're invoking a handler
 522  */
 523
 524 static int
 525 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 526               sigset_t *oldset, struct pt_regs *regs)
 527 {
 528         int ret;
 529
 530         /* Are we from a system call? */
 531         if ((long)regs->orig_ax >= 0) {
 532                 /* If so, check system call restarting.. */
 533                 switch (regs->ax) {
 534                 case -ERESTART_RESTARTBLOCK:
 535                 case -ERESTARTNOHAND:
 536                         regs->ax = -EINTR;
 537                         break;
 538
 539                 case -ERESTARTSYS:
 540                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 541                                 regs->ax = -EINTR;
 542                                 break;
 543                         }
 544                 /* fallthrough */
 545                 case -ERESTARTNOINTR:
 546                         regs->ax = regs->orig_ax;
 547                         regs->ip -= 2;
 548                         break;
 549                 }
 550         }
 551
 552         /*
 553          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 554          * flag so that register information in the sigcontext is correct.
 555          */
 556         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 557             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 558                 regs->flags &= ~X86_EFLAGS_TF;
 559
 560         /* Set up the stack frame */
 561         if (ka->sa.sa_flags & SA_SIGINFO)
 562                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 563         else
 564                 ret = setup_frame(sig, ka, oldset, regs);
 565
 566         if (ret == 0) {
 567                 spin_lock_irq(&current->sighand->siglock);
 568                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 569                 if (!(ka->sa.sa_flags & SA_NODEFER))
 570                         sigaddset(&current->blocked,sig);
 571                 recalc_sigpending();
 572                 spin_unlock_irq(&current->sighand->siglock);
 573         }
 574
 575         return ret;
 576 }
 577
 578 /*
 579  * Note that 'init' is a special process: it doesn't get signals it doesn't
 580  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 581  * mistake.
 582  */
 583 static void do_signal(struct pt_regs *regs)
 584 {
 585         struct k_sigaction ka;
 586         siginfo_t info;
 587         int signr;
 588         sigset_t *oldset;
 589
 590         /*
 591          * We want the common case to go fast, which is why we may in certain
 592          * cases get here from kernel mode. Just return without doing anything
 593          * if so.
 594          * X86_32: vm86 regs switched out by assembly code before reaching
 595          * here, so testing against kernel CS suffices.
 596          */
 597         if (!user_mode(regs))
 598                 return;
 599
 600         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 601                 oldset = &current->saved_sigmask;
 602         else
 603                 oldset = &current->blocked;
 604
 605         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 606         if (signr > 0) {
 607                 /* Re-enable any watchpoints before delivering the
 608                  * signal to user space. The processor register will
 609                  * have been cleared if the watchpoint triggered
 610                  * inside the kernel.
 611                  */
 612                 if (current->thread.debugreg7)
 613                         set_debugreg(current->thread.debugreg7, 7);
 614
 615                 /* Whee!  Actually deliver the signal.  */
 616                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 617                         /* a signal was successfully delivered; the saved
 618                          * sigmask will have been stored in the signal frame,
 619                          * and will be restored by sigreturn, so we can simply
 620                          * clear the TIF_RESTORE_SIGMASK flag */
 621                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 622                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 623                 }
 624
 625                 return;
 626         }
 627
 628         /* Did we come from a system call? */
 629         if ((long)regs->orig_ax >= 0) {
 630                 /* Restart the system call - no handlers present */
 631                 switch (regs->ax) {
 632                 case -ERESTARTNOHAND:
 633                 case -ERESTARTSYS:
 634                 case -ERESTARTNOINTR:
 635                         regs->ax = regs->orig_ax;
 636                         regs->ip -= 2;
 637                         break;
 638
 639                 case -ERESTART_RESTARTBLOCK:
 640                         regs->ax = __NR_restart_syscall;
 641                         regs->ip -= 2;
 642                         break;
 643                 }
 644         }
 645
 646         /*
 647          * If there's no signal to deliver, we just put the saved sigmask
 648          * back.
 649          */
 650         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 651                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 652                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 653         }
 654 }
 655
 656 /*
 657  * notification of userspace execution resumption
 658  * - triggered by the TIF_WORK_MASK flags
 659  */
 660 void do_notify_resume(struct pt_regs *regs, void *unused,
 661                       __u32 thread_info_flags)
 662 {
 663         /* Pending single-step? */
 664         if (thread_info_flags & _TIF_SINGLESTEP) {
 665                 regs->flags |= X86_EFLAGS_TF;
 666                 clear_thread_flag(TIF_SINGLESTEP);
 667         }
 668
 669         /* deal with pending signal delivery */
 670         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 671                 do_signal(regs);
 672
 673         if (thread_info_flags & _TIF_HRTICK_RESCHED)
 674                 hrtick_resched();
 675
 676         clear_thread_flag(TIF_IRET);
 677 }