arch/ia64/kernel/signal.c

   1 /*
   2  * Architecture-specific signal handling support.
   3  *
   4  * Copyright (C) 1999-2004 Hewlett-Packard Co
   5  *      David Mosberger-Tang <davidm@hpl.hp.com>
   6  *
   7  * Derived from i386 and Alpha versions.
   8  */
   9
  10 #include <linux/errno.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/tracehook.h>
  15 #include <linux/sched.h>
  16 #include <linux/signal.h>
  17 #include <linux/smp.h>
  18 #include <linux/stddef.h>
  19 #include <linux/tty.h>
  20 #include <linux/binfmts.h>
  21 #include <linux/unistd.h>
  22 #include <linux/wait.h>
  23
  24 #include <asm/intrinsics.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/rse.h>
  27 #include <asm/sigcontext.h>
  28
  29 #include "sigframe.h"
  30
  31 #define DEBUG_SIG       0
  32 #define STACK_ALIGN     16              /* minimal alignment for stack pointer */
  33 #define _BLOCKABLE      (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  34
  35 #if _NSIG_WORDS > 1
  36 # define PUT_SIGSET(k,u)        __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
  37 # define GET_SIGSET(k,u)        __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
  38 #else
  39 # define PUT_SIGSET(k,u)        __put_user((k)->sig[0], &(u)->sig[0])
  40 # define GET_SIGSET(k,u)        __get_user((k)->sig[0], &(u)->sig[0])
  41 #endif
  42
  43 asmlinkage long
  44 sys_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, long arg2,
  45                  long arg3, long arg4, long arg5, long arg6, long arg7,
  46                  struct pt_regs regs)
  47 {
  48         return do_sigaltstack(uss, uoss, regs.r12);
  49 }
  50
  51 static long
  52 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
  53 {
  54         unsigned long ip, flags, nat, um, cfm, rsc;
  55         long err;
  56
  57         /* Always make any pending restarted system calls return -EINTR */
  58         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  59
  60         /* restore scratch that always needs gets updated during signal delivery: */
  61         err  = __get_user(flags, &sc->sc_flags);
  62         err |= __get_user(nat, &sc->sc_nat);
  63         err |= __get_user(ip, &sc->sc_ip);                      /* instruction pointer */
  64         err |= __get_user(cfm, &sc->sc_cfm);
  65         err |= __get_user(um, &sc->sc_um);                      /* user mask */
  66         err |= __get_user(rsc, &sc->sc_ar_rsc);
  67         err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
  68         err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
  69         err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
  70         err |= __get_user(scr->pt.pr, &sc->sc_pr);              /* predicates */
  71         err |= __get_user(scr->pt.b0, &sc->sc_br[0]);           /* b0 (rp) */
  72         err |= __get_user(scr->pt.b6, &sc->sc_br[6]);           /* b6 */
  73         err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
  74         err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);       /* r8-r11 */
  75         err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);     /* r12-r13 */
  76         err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);       /* r15 */
  77
  78         scr->pt.cr_ifs = cfm | (1UL << 63);
  79         scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
  80
  81         /* establish new instruction pointer: */
  82         scr->pt.cr_iip = ip & ~0x3UL;
  83         ia64_psr(&scr->pt)->ri = ip & 0x3;
  84         scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
  85
  86         scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
  87
  88         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
  89                 /* Restore most scratch-state only when not in syscall. */
  90                 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
  91                 err |= __get_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
  92                 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
  93                 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
  94                 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);       /* r2-r3 */
  95                 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);    /* r16-r31 */
  96         }
  97
  98         if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
  99                 struct ia64_psr *psr = ia64_psr(&scr->pt);
 100
 101                 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
 102                 psr->mfh = 0;   /* drop signal handler's fph contents... */
 103                 preempt_disable();
 104                 if (psr->dfh)
 105                         ia64_drop_fpu(current);
 106                 else {
 107                         /* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
 108                         __ia64_load_fpu(current->thread.fph);
 109                         ia64_set_local_fpu_owner(current);
 110                 }
 111                 preempt_enable();
 112         }
 113         return err;
 114 }
 115
 116 int
 117 copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from)
 118 {
 119         if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))
 120                 return -EFAULT;
 121         if (from->si_code < 0) {
 122                 if (__copy_to_user(to, from, sizeof(siginfo_t)))
 123                         return -EFAULT;
 124                 return 0;
 125         } else {
 126                 int err;
 127
 128                 /*
 129                  * If you change siginfo_t structure, please be sure this code is fixed
 130                  * accordingly.  It should never copy any pad contained in the structure
 131                  * to avoid security leaks, but must copy the generic 3 ints plus the
 132                  * relevant union member.
 133                  */
 134                 err = __put_user(from->si_signo, &to->si_signo);
 135                 err |= __put_user(from->si_errno, &to->si_errno);
 136                 err |= __put_user((short)from->si_code, &to->si_code);
 137                 switch (from->si_code >> 16) {
 138                       case __SI_FAULT >> 16:
 139                         err |= __put_user(from->si_flags, &to->si_flags);
 140                         err |= __put_user(from->si_isr, &to->si_isr);
 141                       case __SI_POLL >> 16:
 142                         err |= __put_user(from->si_addr, &to->si_addr);
 143                         err |= __put_user(from->si_imm, &to->si_imm);
 144                         break;
 145                       case __SI_TIMER >> 16:
 146                         err |= __put_user(from->si_tid, &to->si_tid);
 147                         err |= __put_user(from->si_overrun, &to->si_overrun);
 148                         err |= __put_user(from->si_ptr, &to->si_ptr);
 149                         break;
 150                       case __SI_RT >> 16:       /* Not generated by the kernel as of now.  */
 151                       case __SI_MESGQ >> 16:
 152                         err |= __put_user(from->si_uid, &to->si_uid);
 153                         err |= __put_user(from->si_pid, &to->si_pid);
 154                         err |= __put_user(from->si_ptr, &to->si_ptr);
 155                         break;
 156                       case __SI_CHLD >> 16:
 157                         err |= __put_user(from->si_utime, &to->si_utime);
 158                         err |= __put_user(from->si_stime, &to->si_stime);
 159                         err |= __put_user(from->si_status, &to->si_status);
 160                       default:
 161                         err |= __put_user(from->si_uid, &to->si_uid);
 162                         err |= __put_user(from->si_pid, &to->si_pid);
 163                         break;
 164                 }
 165                 return err;
 166         }
 167 }
 168
 169 long
 170 ia64_rt_sigreturn (struct sigscratch *scr)
 171 {
 172         extern char ia64_strace_leave_kernel, ia64_leave_kernel;
 173         struct sigcontext __user *sc;
 174         struct siginfo si;
 175         sigset_t set;
 176         long retval;
 177
 178         sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
 179
 180         /*
 181          * When we return to the previously executing context, r8 and r10 have already
 182          * been setup the way we want them.  Indeed, if the signal wasn't delivered while
 183          * in a system call, we must not touch r8 or r10 as otherwise user-level state
 184          * could be corrupted.
 185          */
 186         retval = (long) &ia64_leave_kernel;
 187         if (test_thread_flag(TIF_SYSCALL_TRACE)
 188             || test_thread_flag(TIF_SYSCALL_AUDIT))
 189                 /*
 190                  * strace expects to be notified after sigreturn returns even though the
 191                  * context to which we return may not be in the middle of a syscall.
 192                  * Thus, the return-value that strace displays for sigreturn is
 193                  * meaningless.
 194                  */
 195                 retval = (long) &ia64_strace_leave_kernel;
 196
 197         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
 198                 goto give_sigsegv;
 199
 200         if (GET_SIGSET(&set, &sc->sc_mask))
 201                 goto give_sigsegv;
 202
 203         sigdelsetmask(&set, ~_BLOCKABLE);
 204         set_current_blocked(&set);
 205
 206         if (restore_sigcontext(sc, scr))
 207                 goto give_sigsegv;
 208
 209 #if DEBUG_SIG
 210         printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
 211                current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
 212 #endif
 213         /*
 214          * It is more difficult to avoid calling this function than to
 215          * call it and ignore errors.
 216          */
 217         do_sigaltstack(&sc->sc_stack, NULL, scr->pt.r12);
 218         return retval;
 219
 220   give_sigsegv:
 221         si.si_signo = SIGSEGV;
 222         si.si_errno = 0;
 223         si.si_code = SI_KERNEL;
 224         si.si_pid = task_pid_vnr(current);
 225         si.si_uid = current_uid();
 226         si.si_addr = sc;
 227         force_sig_info(SIGSEGV, &si, current);
 228         return retval;
 229 }
 230
 231 /*
 232  * This does just the minimum required setup of sigcontext.
 233  * Specifically, it only installs data that is either not knowable at
 234  * the user-level or that gets modified before execution in the
 235  * trampoline starts.  Everything else is done at the user-level.
 236  */
 237 static long
 238 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
 239 {
 240         unsigned long flags = 0, ifs, cfm, nat;
 241         long err = 0;
 242
 243         ifs = scr->pt.cr_ifs;
 244
 245         if (on_sig_stack((unsigned long) sc))
 246                 flags |= IA64_SC_FLAG_ONSTACK;
 247         if ((ifs & (1UL << 63)) == 0)
 248                 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
 249                 flags |= IA64_SC_FLAG_IN_SYSCALL;
 250         cfm = ifs & ((1UL << 38) - 1);
 251         ia64_flush_fph(current);
 252         if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
 253                 flags |= IA64_SC_FLAG_FPH_VALID;
 254                 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
 255         }
 256
 257         nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
 258
 259         err |= __put_user(flags, &sc->sc_flags);
 260         err |= __put_user(nat, &sc->sc_nat);
 261         err |= PUT_SIGSET(mask, &sc->sc_mask);
 262         err |= __put_user(cfm, &sc->sc_cfm);
 263         err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
 264         err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
 265         err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);            /* ar.unat */
 266         err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);            /* ar.fpsr */
 267         err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 268         err |= __put_user(scr->pt.pr, &sc->sc_pr);                      /* predicates */
 269         err |= __put_user(scr->pt.b0, &sc->sc_br[0]);                   /* b0 (rp) */
 270         err |= __put_user(scr->pt.b6, &sc->sc_br[6]);                   /* b6 */
 271         err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);           /* r1 */
 272         err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);         /* r8-r11 */
 273         err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);       /* r12-r13 */
 274         err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);         /* r15 */
 275         err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
 276
 277         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 278                 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
 279                 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 280                 err |= __put_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 281                 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 282                 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
 283                 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);         /* r2-r3 */
 284                 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);      /* r16-r31 */
 285         }
 286         return err;
 287 }
 288
 289 /*
 290  * Check whether the register-backing store is already on the signal stack.
 291  */
 292 static inline int
 293 rbs_on_sig_stack (unsigned long bsp)
 294 {
 295         return (bsp - current->sas_ss_sp < current->sas_ss_size);
 296 }
 297
 298 static long
 299 force_sigsegv_info (int sig, void __user *addr)
 300 {
 301         unsigned long flags;
 302         struct siginfo si;
 303
 304         if (sig == SIGSEGV) {
 305                 /*
 306                  * Acquiring siglock around the sa_handler-update is almost
 307                  * certainly overkill, but this isn't a
 308                  * performance-critical path and I'd rather play it safe
 309                  * here than having to debug a nasty race if and when
 310                  * something changes in kernel/signal.c that would make it
 311                  * no longer safe to modify sa_handler without holding the
 312                  * lock.
 313                  */
 314                 spin_lock_irqsave(&current->sighand->siglock, flags);
 315                 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
 316                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 317         }
 318         si.si_signo = SIGSEGV;
 319         si.si_errno = 0;
 320         si.si_code = SI_KERNEL;
 321         si.si_pid = task_pid_vnr(current);
 322         si.si_uid = current_uid();
 323         si.si_addr = addr;
 324         force_sig_info(SIGSEGV, &si, current);
 325         return 0;
 326 }
 327
 328 static long
 329 setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
 330              struct sigscratch *scr)
 331 {
 332         extern char __kernel_sigtramp[];
 333         unsigned long tramp_addr, new_rbs = 0, new_sp;
 334         struct sigframe __user *frame;
 335         long err;
 336
 337         new_sp = scr->pt.r12;
 338         tramp_addr = (unsigned long) __kernel_sigtramp;
 339         if (ka->sa.sa_flags & SA_ONSTACK) {
 340                 int onstack = sas_ss_flags(new_sp);
 341
 342                 if (onstack == 0) {
 343                         new_sp = current->sas_ss_sp + current->sas_ss_size;
 344                         /*
 345                          * We need to check for the register stack being on the
 346                          * signal stack separately, because it's switched
 347                          * separately (memory stack is switched in the kernel,
 348                          * register stack is switched in the signal trampoline).
 349                          */
 350                         if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 351                                 new_rbs = ALIGN(current->sas_ss_sp,
 352                                                 sizeof(long));
 353                 } else if (onstack == SS_ONSTACK) {
 354                         unsigned long check_sp;
 355
 356                         /*
 357                          * If we are on the alternate signal stack and would
 358                          * overflow it, don't. Return an always-bogus address
 359                          * instead so we will die with SIGSEGV.
 360                          */
 361                         check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
 362                         if (!likely(on_sig_stack(check_sp)))
 363                                 return force_sigsegv_info(sig, (void __user *)
 364                                                           check_sp);
 365                 }
 366         }
 367         frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 368
 369         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 370                 return force_sigsegv_info(sig, frame);
 371
 372         err  = __put_user(sig, &frame->arg0);
 373         err |= __put_user(&frame->info, &frame->arg1);
 374         err |= __put_user(&frame->sc, &frame->arg2);
 375         err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
 376         err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
 377         err |= __put_user(ka->sa.sa_handler, &frame->handler);
 378
 379         err |= copy_siginfo_to_user(&frame->info, info);
 380
 381         err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp);
 382         err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size);
 383         err |= __put_user(sas_ss_flags(scr->pt.r12), &frame->sc.sc_stack.ss_flags);
 384         err |= setup_sigcontext(&frame->sc, set, scr);
 385
 386         if (unlikely(err))
 387                 return force_sigsegv_info(sig, frame);
 388
 389         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
 390         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
 391         scr->pt.cr_iip = tramp_addr;
 392         ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
 393         ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
 394         /*
 395          * Force the interruption function mask to zero.  This has no effect when a
 396          * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
 397          * ignored), but it has the desirable effect of making it possible to deliver a
 398          * signal with an incomplete register frame (which happens when a mandatory RSE
 399          * load faults).  Furthermore, it has no negative effect on the getting the user's
 400          * dirty partition preserved, because that's governed by scr->pt.loadrs.
 401          */
 402         scr->pt.cr_ifs = (1UL << 63);
 403
 404         /*
 405          * Note: this affects only the NaT bits of the scratch regs (the ones saved in
 406          * pt_regs), which is exactly what we want.
 407          */
 408         scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
 409
 410 #if DEBUG_SIG
 411         printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
 412                current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
 413 #endif
 414         return 1;
 415 }
 416
 417 static long
 418 handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset,
 419                struct sigscratch *scr)
 420 {
 421         if (!setup_frame(sig, ka, info, oldset, scr))
 422                 return 0;
 423
 424         block_sigmask(ka, sig);
 425
 426         /*
 427          * Let tracing know that we've done the handler setup.
 428          */
 429         tracehook_signal_handler(sig, info, ka, &scr->pt,
 430                                  test_thread_flag(TIF_SINGLESTEP));
 431
 432         return 1;
 433 }
 434
 435 /*
 436  * Note that `init' is a special process: it doesn't get signals it doesn't want to
 437  * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 438  */
 439 void
 440 ia64_do_signal (struct sigscratch *scr, long in_syscall)
 441 {
 442         struct k_sigaction ka;
 443         sigset_t *oldset;
 444         siginfo_t info;
 445         long restart = in_syscall;
 446         long errno = scr->pt.r8;
 447
 448         /*
 449          * In the ia64_leave_kernel code path, we want the common case to go fast, which
 450          * is why we may in certain cases get here from kernel mode. Just return without
 451          * doing anything if so.
 452          */
 453         if (!user_mode(&scr->pt))
 454                 return;
 455
 456         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 457                 oldset = &current->saved_sigmask;
 458         else
 459                 oldset = &current->blocked;
 460
 461         /*
 462          * This only loops in the rare cases of handle_signal() failing, in which case we
 463          * need to push through a forced SIGSEGV.
 464          */
 465         while (1) {
 466                 int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL);
 467
 468                 /*
 469                  * get_signal_to_deliver() may have run a debugger (via notify_parent())
 470                  * and the debugger may have modified the state (e.g., to arrange for an
 471                  * inferior call), thus it's important to check for restarting _after_
 472                  * get_signal_to_deliver().
 473                  */
 474                 if ((long) scr->pt.r10 != -1)
 475                         /*
 476                          * A system calls has to be restarted only if one of the error codes
 477                          * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
 478                          * isn't -1 then r8 doesn't hold an error code and we don't need to
 479                          * restart the syscall, so we can clear the "restart" flag here.
 480                          */
 481                         restart = 0;
 482
 483                 if (signr <= 0)
 484                         break;
 485
 486                 if (unlikely(restart)) {
 487                         switch (errno) {
 488                               case ERESTART_RESTARTBLOCK:
 489                               case ERESTARTNOHAND:
 490                                 scr->pt.r8 = EINTR;
 491                                 /* note: scr->pt.r10 is already -1 */
 492                                 break;
 493
 494                               case ERESTARTSYS:
 495                                 if ((ka.sa.sa_flags & SA_RESTART) == 0) {
 496                                         scr->pt.r8 = EINTR;
 497                                         /* note: scr->pt.r10 is already -1 */
 498                                         break;
 499                                 }
 500                               case ERESTARTNOINTR:
 501                                 ia64_decrement_ip(&scr->pt);
 502                                 restart = 0; /* don't restart twice if handle_signal() fails... */
 503                         }
 504                 }
 505
 506                 /*
 507                  * Whee!  Actually deliver the signal.  If the delivery failed, we need to
 508                  * continue to iterate in this loop so we can deliver the SIGSEGV...
 509                  */
 510                 if (handle_signal(signr, &ka, &info, oldset, scr)) {
 511                         /*
 512                          * A signal was successfully delivered; the saved
 513                          * sigmask will have been stored in the signal frame,
 514                          * and will be restored by sigreturn, so we can simply
 515                          * clear the TS_RESTORE_SIGMASK flag.
 516                          */
 517                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 518                         return;
 519                 }
 520         }
 521
 522         /* Did we come from a system call? */
 523         if (restart) {
 524                 /* Restart the system call - no handlers present */
 525                 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
 526                     || errno == ERESTART_RESTARTBLOCK)
 527                 {
 528                         /*
 529                          * Note: the syscall number is in r15 which is saved in
 530                          * pt_regs so all we need to do here is adjust ip so that
 531                          * the "break" instruction gets re-executed.
 532                          */
 533                         ia64_decrement_ip(&scr->pt);
 534                         if (errno == ERESTART_RESTARTBLOCK)
 535                                 scr->pt.r15 = __NR_restart_syscall;
 536                 }
 537         }
 538
 539         /* if there's no signal to deliver, we just put the saved sigmask
 540          * back */
 541         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 542                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 543                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 544         }
 545 }