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/config.h>
  11 #include <linux/errno.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mm.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/sched.h>
  16 #include <linux/signal.h>
  17 #include <linux/smp.h>
  18 #include <linux/smp_lock.h>
  19 #include <linux/stddef.h>
  20 #include <linux/tty.h>
  21 #include <linux/binfmts.h>
  22 #include <linux/unistd.h>
  23 #include <linux/wait.h>
  24
  25 #include <asm/ia32.h>
  26 #include <asm/intrinsics.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/rse.h>
  29 #include <asm/sigcontext.h>
  30
  31 #include "sigframe.h"
  32
  33 #define DEBUG_SIG       0
  34 #define STACK_ALIGN     16              /* minimal alignment for stack pointer */
  35 #define _BLOCKABLE      (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  36
  37 #if _NSIG_WORDS > 1
  38 # define PUT_SIGSET(k,u)        __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
  39 # define GET_SIGSET(k,u)        __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
  40 #else
  41 # define PUT_SIGSET(k,u)        __put_user((k)->sig[0], &(u)->sig[0])
  42 # define GET_SIGSET(k,u)        __get_user((k)->sig[0], &(u)->sig[0])
  43 #endif
  44
  45 long
  46 ia64_rt_sigsuspend (sigset_t __user *uset, size_t sigsetsize, struct sigscratch *scr)
  47 {
  48         sigset_t oldset, set;
  49
  50         /* XXX: Don't preclude handling different sized sigset_t's.  */
  51         if (sigsetsize != sizeof(sigset_t))
  52                 return -EINVAL;
  53
  54         if (!access_ok(VERIFY_READ, uset, sigsetsize))
  55                 return -EFAULT;
  56
  57         if (GET_SIGSET(&set, uset))
  58                 return -EFAULT;
  59
  60         sigdelsetmask(&set, ~_BLOCKABLE);
  61
  62         spin_lock_irq(&current->sighand->siglock);
  63         {
  64                 oldset = current->blocked;
  65                 current->blocked = set;
  66                 recalc_sigpending();
  67         }
  68         spin_unlock_irq(&current->sighand->siglock);
  69
  70         /*
  71          * The return below usually returns to the signal handler.  We need to
  72          * pre-set the correct error code here to ensure that the right values
  73          * get saved in sigcontext by ia64_do_signal.
  74          */
  75         scr->pt.r8 = EINTR;
  76         scr->pt.r10 = -1;
  77
  78         while (1) {
  79                 current->state = TASK_INTERRUPTIBLE;
  80                 schedule();
  81                 if (ia64_do_signal(&oldset, scr, 1))
  82                         return -EINTR;
  83         }
  84 }
  85
  86 asmlinkage long
  87 sys_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, long arg2,
  88                  long arg3, long arg4, long arg5, long arg6, long arg7,
  89                  struct pt_regs regs)
  90 {
  91         return do_sigaltstack(uss, uoss, regs.r12);
  92 }
  93
  94 static long
  95 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
  96 {
  97         unsigned long ip, flags, nat, um, cfm;
  98         long err;
  99
 100         /* Always make any pending restarted system calls return -EINTR */
 101         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 102
 103         /* restore scratch that always needs gets updated during signal delivery: */
 104         err  = __get_user(flags, &sc->sc_flags);
 105         err |= __get_user(nat, &sc->sc_nat);
 106         err |= __get_user(ip, &sc->sc_ip);                      /* instruction pointer */
 107         err |= __get_user(cfm, &sc->sc_cfm);
 108         err |= __get_user(um, &sc->sc_um);                      /* user mask */
 109         err |= __get_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
 110         err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
 111         err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
 112         err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 113         err |= __get_user(scr->pt.pr, &sc->sc_pr);              /* predicates */
 114         err |= __get_user(scr->pt.b0, &sc->sc_br[0]);           /* b0 (rp) */
 115         err |= __get_user(scr->pt.b6, &sc->sc_br[6]);           /* b6 */
 116         err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
 117         err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);       /* r8-r11 */
 118         err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);     /* r12-r13 */
 119         err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);       /* r15 */
 120
 121         scr->pt.cr_ifs = cfm | (1UL << 63);
 122
 123         /* establish new instruction pointer: */
 124         scr->pt.cr_iip = ip & ~0x3UL;
 125         ia64_psr(&scr->pt)->ri = ip & 0x3;
 126         scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
 127
 128         scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
 129
 130         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 131                 /* Restore most scratch-state only when not in syscall. */
 132                 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 133                 err |= __get_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 134                 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 135                 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
 136                 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);       /* r2-r3 */
 137                 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);    /* r16-r31 */
 138         }
 139
 140         if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
 141                 struct ia64_psr *psr = ia64_psr(&scr->pt);
 142
 143                 __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
 144                 psr->mfh = 0;   /* drop signal handler's fph contents... */
 145                 if (psr->dfh)
 146                         ia64_drop_fpu(current);
 147                 else {
 148                         /* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
 149                         __ia64_load_fpu(current->thread.fph);
 150                         ia64_set_local_fpu_owner(current);
 151                 }
 152         }
 153         return err;
 154 }
 155
 156 int
 157 copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from)
 158 {
 159         if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))
 160                 return -EFAULT;
 161         if (from->si_code < 0) {
 162                 if (__copy_to_user(to, from, sizeof(siginfo_t)))
 163                         return -EFAULT;
 164                 return 0;
 165         } else {
 166                 int err;
 167
 168                 /*
 169                  * If you change siginfo_t structure, please be sure this code is fixed
 170                  * accordingly.  It should never copy any pad contained in the structure
 171                  * to avoid security leaks, but must copy the generic 3 ints plus the
 172                  * relevant union member.
 173                  */
 174                 err = __put_user(from->si_signo, &to->si_signo);
 175                 err |= __put_user(from->si_errno, &to->si_errno);
 176                 err |= __put_user((short)from->si_code, &to->si_code);
 177                 switch (from->si_code >> 16) {
 178                       case __SI_FAULT >> 16:
 179                         err |= __put_user(from->si_flags, &to->si_flags);
 180                         err |= __put_user(from->si_isr, &to->si_isr);
 181                       case __SI_POLL >> 16:
 182                         err |= __put_user(from->si_addr, &to->si_addr);
 183                         err |= __put_user(from->si_imm, &to->si_imm);
 184                         break;
 185                       case __SI_TIMER >> 16:
 186                         err |= __put_user(from->si_tid, &to->si_tid);
 187                         err |= __put_user(from->si_overrun, &to->si_overrun);
 188                         err |= __put_user(from->si_ptr, &to->si_ptr);
 189                         break;
 190                       case __SI_RT >> 16:       /* Not generated by the kernel as of now.  */
 191                       case __SI_MESGQ >> 16:
 192                         err |= __put_user(from->si_uid, &to->si_uid);
 193                         err |= __put_user(from->si_pid, &to->si_pid);
 194                         err |= __put_user(from->si_ptr, &to->si_ptr);
 195                         break;
 196                       case __SI_CHLD >> 16:
 197                         err |= __put_user(from->si_utime, &to->si_utime);
 198                         err |= __put_user(from->si_stime, &to->si_stime);
 199                         err |= __put_user(from->si_status, &to->si_status);
 200                       default:
 201                         err |= __put_user(from->si_uid, &to->si_uid);
 202                         err |= __put_user(from->si_pid, &to->si_pid);
 203                         break;
 204                 }
 205                 return err;
 206         }
 207 }
 208
 209 long
 210 ia64_rt_sigreturn (struct sigscratch *scr)
 211 {
 212         extern char ia64_strace_leave_kernel, ia64_leave_kernel;
 213         struct sigcontext __user *sc;
 214         struct siginfo si;
 215         sigset_t set;
 216         long retval;
 217
 218         sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
 219
 220         /*
 221          * When we return to the previously executing context, r8 and r10 have already
 222          * been setup the way we want them.  Indeed, if the signal wasn't delivered while
 223          * in a system call, we must not touch r8 or r10 as otherwise user-level state
 224          * could be corrupted.
 225          */
 226         retval = (long) &ia64_leave_kernel;
 227         if (test_thread_flag(TIF_SYSCALL_TRACE)
 228             || test_thread_flag(TIF_SYSCALL_AUDIT))
 229                 /*
 230                  * strace expects to be notified after sigreturn returns even though the
 231                  * context to which we return may not be in the middle of a syscall.
 232                  * Thus, the return-value that strace displays for sigreturn is
 233                  * meaningless.
 234                  */
 235                 retval = (long) &ia64_strace_leave_kernel;
 236
 237         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
 238                 goto give_sigsegv;
 239
 240         if (GET_SIGSET(&set, &sc->sc_mask))
 241                 goto give_sigsegv;
 242
 243         sigdelsetmask(&set, ~_BLOCKABLE);
 244
 245         spin_lock_irq(&current->sighand->siglock);
 246         {
 247                 current->blocked = set;
 248                 recalc_sigpending();
 249         }
 250         spin_unlock_irq(&current->sighand->siglock);
 251
 252         if (restore_sigcontext(sc, scr))
 253                 goto give_sigsegv;
 254
 255 #if DEBUG_SIG
 256         printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
 257                current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
 258 #endif
 259         /*
 260          * It is more difficult to avoid calling this function than to
 261          * call it and ignore errors.
 262          */
 263         do_sigaltstack(&sc->sc_stack, NULL, scr->pt.r12);
 264         return retval;
 265
 266   give_sigsegv:
 267         si.si_signo = SIGSEGV;
 268         si.si_errno = 0;
 269         si.si_code = SI_KERNEL;
 270         si.si_pid = current->pid;
 271         si.si_uid = current->uid;
 272         si.si_addr = sc;
 273         force_sig_info(SIGSEGV, &si, current);
 274         return retval;
 275 }
 276
 277 /*
 278  * This does just the minimum required setup of sigcontext.
 279  * Specifically, it only installs data that is either not knowable at
 280  * the user-level or that gets modified before execution in the
 281  * trampoline starts.  Everything else is done at the user-level.
 282  */
 283 static long
 284 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
 285 {
 286         unsigned long flags = 0, ifs, cfm, nat;
 287         long err;
 288
 289         ifs = scr->pt.cr_ifs;
 290
 291         if (on_sig_stack((unsigned long) sc))
 292                 flags |= IA64_SC_FLAG_ONSTACK;
 293         if ((ifs & (1UL << 63)) == 0)
 294                 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
 295                 flags |= IA64_SC_FLAG_IN_SYSCALL;
 296         cfm = ifs & ((1UL << 38) - 1);
 297         ia64_flush_fph(current);
 298         if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
 299                 flags |= IA64_SC_FLAG_FPH_VALID;
 300                 __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
 301         }
 302
 303         nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
 304
 305         err  = __put_user(flags, &sc->sc_flags);
 306         err |= __put_user(nat, &sc->sc_nat);
 307         err |= PUT_SIGSET(mask, &sc->sc_mask);
 308         err |= __put_user(cfm, &sc->sc_cfm);
 309         err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
 310         err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
 311         err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);            /* ar.unat */
 312         err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);            /* ar.fpsr */
 313         err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 314         err |= __put_user(scr->pt.pr, &sc->sc_pr);                      /* predicates */
 315         err |= __put_user(scr->pt.b0, &sc->sc_br[0]);                   /* b0 (rp) */
 316         err |= __put_user(scr->pt.b6, &sc->sc_br[6]);                   /* b6 */
 317         err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);           /* r1 */
 318         err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);         /* r8-r11 */
 319         err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);       /* r12-r13 */
 320         err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);         /* r15 */
 321         err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
 322
 323         if (flags & IA64_SC_FLAG_IN_SYSCALL) {
 324                 /* Clear scratch registers if the signal interrupted a system call. */
 325                 err |= __put_user(0, &sc->sc_ar_ccv);                           /* ar.ccv */
 326                 err |= __put_user(0, &sc->sc_br[7]);                            /* b7 */
 327                 err |= __put_user(0, &sc->sc_gr[14]);                           /* r14 */
 328                 err |= __clear_user(&sc->sc_ar25, 2*8);                 /* ar.csd & ar.ssd */
 329                 err |= __clear_user(&sc->sc_gr[2], 2*8);                        /* r2-r3 */
 330                 err |= __clear_user(&sc->sc_gr[16], 16*8);                      /* r16-r31 */
 331         } else {
 332                 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
 333                 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 334                 err |= __put_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 335                 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 336                 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
 337                 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);         /* r2-r3 */
 338                 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);      /* r16-r31 */
 339         }
 340         return err;
 341 }
 342
 343 /*
 344  * Check whether the register-backing store is already on the signal stack.
 345  */
 346 static inline int
 347 rbs_on_sig_stack (unsigned long bsp)
 348 {
 349         return (bsp - current->sas_ss_sp < current->sas_ss_size);
 350 }
 351
 352 static long
 353 force_sigsegv_info (int sig, void __user *addr)
 354 {
 355         unsigned long flags;
 356         struct siginfo si;
 357
 358         if (sig == SIGSEGV) {
 359                 /*
 360                  * Acquiring siglock around the sa_handler-update is almost
 361                  * certainly overkill, but this isn't a
 362                  * performance-critical path and I'd rather play it safe
 363                  * here than having to debug a nasty race if and when
 364                  * something changes in kernel/signal.c that would make it
 365                  * no longer safe to modify sa_handler without holding the
 366                  * lock.
 367                  */
 368                 spin_lock_irqsave(&current->sighand->siglock, flags);
 369                 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
 370                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 371         }
 372         si.si_signo = SIGSEGV;
 373         si.si_errno = 0;
 374         si.si_code = SI_KERNEL;
 375         si.si_pid = current->pid;
 376         si.si_uid = current->uid;
 377         si.si_addr = addr;
 378         force_sig_info(SIGSEGV, &si, current);
 379         return 0;
 380 }
 381
 382 static long
 383 setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
 384              struct sigscratch *scr)
 385 {
 386         extern char __kernel_sigtramp[];
 387         unsigned long tramp_addr, new_rbs = 0;
 388         struct sigframe __user *frame;
 389         long err;
 390
 391         frame = (void __user *) scr->pt.r12;
 392         tramp_addr = (unsigned long) __kernel_sigtramp;
 393         if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags((unsigned long) frame) == 0) {
 394                 frame = (void __user *) ((current->sas_ss_sp + current->sas_ss_size)
 395                                          & ~(STACK_ALIGN - 1));
 396                 /*
 397                  * We need to check for the register stack being on the signal stack
 398                  * separately, because it's switched separately (memory stack is switched
 399                  * in the kernel, register stack is switched in the signal trampoline).
 400                  */
 401                 if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 402                         new_rbs = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);
 403         }
 404         frame = (void __user *) frame - ((sizeof(*frame) + STACK_ALIGN - 1) & ~(STACK_ALIGN - 1));
 405
 406         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 407                 return force_sigsegv_info(sig, frame);
 408
 409         err  = __put_user(sig, &frame->arg0);
 410         err |= __put_user(&frame->info, &frame->arg1);
 411         err |= __put_user(&frame->sc, &frame->arg2);
 412         err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
 413         err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
 414         err |= __put_user(ka->sa.sa_handler, &frame->handler);
 415
 416         err |= copy_siginfo_to_user(&frame->info, info);
 417
 418         err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp);
 419         err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size);
 420         err |= __put_user(sas_ss_flags(scr->pt.r12), &frame->sc.sc_stack.ss_flags);
 421         err |= setup_sigcontext(&frame->sc, set, scr);
 422
 423         if (unlikely(err))
 424                 return force_sigsegv_info(sig, frame);
 425
 426         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
 427         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
 428         scr->pt.cr_iip = tramp_addr;
 429         ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
 430         ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
 431         /*
 432          * Force the interruption function mask to zero.  This has no effect when a
 433          * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
 434          * ignored), but it has the desirable effect of making it possible to deliver a
 435          * signal with an incomplete register frame (which happens when a mandatory RSE
 436          * load faults).  Furthermore, it has no negative effect on the getting the user's
 437          * dirty partition preserved, because that's governed by scr->pt.loadrs.
 438          */
 439         scr->pt.cr_ifs = (1UL << 63);
 440
 441         /*
 442          * Note: this affects only the NaT bits of the scratch regs (the ones saved in
 443          * pt_regs), which is exactly what we want.
 444          */
 445         scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
 446
 447 #if DEBUG_SIG
 448         printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
 449                current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
 450 #endif
 451         return 1;
 452 }
 453
 454 static long
 455 handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset,
 456                struct sigscratch *scr)
 457 {
 458         if (IS_IA32_PROCESS(&scr->pt)) {
 459                 /* send signal to IA-32 process */
 460                 if (!ia32_setup_frame1(sig, ka, info, oldset, &scr->pt))
 461                         return 0;
 462         } else
 463                 /* send signal to IA-64 process */
 464                 if (!setup_frame(sig, ka, info, oldset, scr))
 465                         return 0;
 466
 467         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 468                 spin_lock_irq(&current->sighand->siglock);
 469                 {
 470                         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 471                         sigaddset(&current->blocked, sig);
 472                         recalc_sigpending();
 473                 }
 474                 spin_unlock_irq(&current->sighand->siglock);
 475         }
 476         return 1;
 477 }
 478
 479 /*
 480  * Note that `init' is a special process: it doesn't get signals it doesn't want to
 481  * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 482  */
 483 long
 484 ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
 485 {
 486         struct k_sigaction ka;
 487         siginfo_t info;
 488         long restart = in_syscall;
 489         long errno = scr->pt.r8;
 490 #       define ERR_CODE(c)      (IS_IA32_PROCESS(&scr->pt) ? -(c) : (c))
 491
 492         /*
 493          * In the ia64_leave_kernel code path, we want the common case to go fast, which
 494          * is why we may in certain cases get here from kernel mode. Just return without
 495          * doing anything if so.
 496          */
 497         if (!user_mode(&scr->pt))
 498                 return 0;
 499
 500         if (!oldset)
 501                 oldset = &current->blocked;
 502
 503         /*
 504          * This only loops in the rare cases of handle_signal() failing, in which case we
 505          * need to push through a forced SIGSEGV.
 506          */
 507         while (1) {
 508                 int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL);
 509
 510                 /*
 511                  * get_signal_to_deliver() may have run a debugger (via notify_parent())
 512                  * and the debugger may have modified the state (e.g., to arrange for an
 513                  * inferior call), thus it's important to check for restarting _after_
 514                  * get_signal_to_deliver().
 515                  */
 516                 if (IS_IA32_PROCESS(&scr->pt)) {
 517                         if (in_syscall) {
 518                                 if (errno >= 0)
 519                                         restart = 0;
 520                                 else
 521                                         errno = -errno;
 522                         }
 523                 } else if ((long) scr->pt.r10 != -1)
 524                         /*
 525                          * A system calls has to be restarted only if one of the error codes
 526                          * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
 527                          * isn't -1 then r8 doesn't hold an error code and we don't need to
 528                          * restart the syscall, so we can clear the "restart" flag here.
 529                          */
 530                         restart = 0;
 531
 532                 if (signr <= 0)
 533                         break;
 534
 535                 if (unlikely(restart)) {
 536                         switch (errno) {
 537                               case ERESTART_RESTARTBLOCK:
 538                               case ERESTARTNOHAND:
 539                                 scr->pt.r8 = ERR_CODE(EINTR);
 540                                 /* note: scr->pt.r10 is already -1 */
 541                                 break;
 542
 543                               case ERESTARTSYS:
 544                                 if ((ka.sa.sa_flags & SA_RESTART) == 0) {
 545                                         scr->pt.r8 = ERR_CODE(EINTR);
 546                                         /* note: scr->pt.r10 is already -1 */
 547                                         break;
 548                                 }
 549                               case ERESTARTNOINTR:
 550                                 if (IS_IA32_PROCESS(&scr->pt)) {
 551                                         scr->pt.r8 = scr->pt.r1;
 552                                         scr->pt.cr_iip -= 2;
 553                                 } else
 554                                         ia64_decrement_ip(&scr->pt);
 555                                 restart = 0; /* don't restart twice if handle_signal() fails... */
 556                         }
 557                 }
 558
 559                 /*
 560                  * Whee!  Actually deliver the signal.  If the delivery failed, we need to
 561                  * continue to iterate in this loop so we can deliver the SIGSEGV...
 562                  */
 563                 if (handle_signal(signr, &ka, &info, oldset, scr))
 564                         return 1;
 565         }
 566
 567         /* Did we come from a system call? */
 568         if (restart) {
 569                 /* Restart the system call - no handlers present */
 570                 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
 571                     || errno == ERESTART_RESTARTBLOCK)
 572                 {
 573                         if (IS_IA32_PROCESS(&scr->pt)) {
 574                                 scr->pt.r8 = scr->pt.r1;
 575                                 scr->pt.cr_iip -= 2;
 576                                 if (errno == ERESTART_RESTARTBLOCK)
 577                                         scr->pt.r8 = 0; /* x86 version of __NR_restart_syscall */
 578                         } else {
 579                                 /*
 580                                  * Note: the syscall number is in r15 which is saved in
 581                                  * pt_regs so all we need to do here is adjust ip so that
 582                                  * the "break" instruction gets re-executed.
 583                                  */
 584                                 ia64_decrement_ip(&scr->pt);
 585                                 if (errno == ERESTART_RESTARTBLOCK)
 586                                         scr->pt.r15 = __NR_restart_syscall;
 587                         }
 588                 }
 589         }
 590         return 0;
 591 }
 592
 593 /* Set a delayed signal that was detected in MCA/INIT/NMI/PMI context where it
 594  * could not be delivered.  It is important that the target process is not
 595  * allowed to do any more work in user space.  Possible cases for the target
 596  * process:
 597  *
 598  * - It is sleeping and will wake up soon.  Store the data in the current task,
 599  *   the signal will be sent when the current task returns from the next
 600  *   interrupt.
 601  *
 602  * - It is running in user context.  Store the data in the current task, the
 603  *   signal will be sent when the current task returns from the next interrupt.
 604  *
 605  * - It is running in kernel context on this or another cpu and will return to
 606  *   user context.  Store the data in the target task, the signal will be sent
 607  *   to itself when the target task returns to user space.
 608  *
 609  * - It is running in kernel context on this cpu and will sleep before
 610  *   returning to user context.  Because this is also the current task, the
 611  *   signal will not get delivered and the task could sleep indefinitely.
 612  *   Store the data in the idle task for this cpu, the signal will be sent
 613  *   after the idle task processes its next interrupt.
 614  *
 615  * To cover all cases, store the data in the target task, the current task and
 616  * the idle task on this cpu.  Whatever happens, the signal will be delivered
 617  * to the target task before it can do any useful user space work.  Multiple
 618  * deliveries have no unwanted side effects.
 619  *
 620  * Note: This code is executed in MCA/INIT/NMI/PMI context, with interrupts
 621  * disabled.  It must not take any locks nor use kernel structures or services
 622  * that require locks.
 623  */
 624
 625 /* To ensure that we get the right pid, check its start time.  To avoid extra
 626  * include files in thread_info.h, convert the task start_time to unsigned long,
 627  * giving us a cycle time of > 580 years.
 628  */
 629 static inline unsigned long
 630 start_time_ul(const struct task_struct *t)
 631 {
 632         return t->start_time.tv_sec * NSEC_PER_SEC + t->start_time.tv_nsec;
 633 }
 634
 635 void
 636 set_sigdelayed(pid_t pid, int signo, int code, void __user *addr)
 637 {
 638         struct task_struct *t;
 639         unsigned long start_time =  0;
 640         int i;
 641
 642         for (i = 1; i <= 3; ++i) {
 643                 switch (i) {
 644                 case 1:
 645                         t = find_task_by_pid(pid);
 646                         if (t)
 647                                 start_time = start_time_ul(t);
 648                         break;
 649                 case 2:
 650                         t = current;
 651                         break;
 652                 default:
 653                         t = idle_task(smp_processor_id());
 654                         break;
 655                 }
 656
 657                 if (!t)
 658                         return;
 659                 t->thread_info->sigdelayed.signo = signo;
 660                 t->thread_info->sigdelayed.code = code;
 661                 t->thread_info->sigdelayed.addr = addr;
 662                 t->thread_info->sigdelayed.start_time = start_time;
 663                 t->thread_info->sigdelayed.pid = pid;
 664                 wmb();
 665                 set_tsk_thread_flag(t, TIF_SIGDELAYED);
 666         }
 667 }
 668
 669 /* Called from entry.S when it detects TIF_SIGDELAYED, a delayed signal that
 670  * was detected in MCA/INIT/NMI/PMI context where it could not be delivered.
 671  */
 672
 673 void
 674 do_sigdelayed(void)
 675 {
 676         struct siginfo siginfo;
 677         pid_t pid;
 678         struct task_struct *t;
 679
 680         clear_thread_flag(TIF_SIGDELAYED);
 681         memset(&siginfo, 0, sizeof(siginfo));
 682         siginfo.si_signo = current_thread_info()->sigdelayed.signo;
 683         siginfo.si_code = current_thread_info()->sigdelayed.code;
 684         siginfo.si_addr = current_thread_info()->sigdelayed.addr;
 685         pid = current_thread_info()->sigdelayed.pid;
 686         t = find_task_by_pid(pid);
 687         if (!t)
 688                 return;
 689         if (current_thread_info()->sigdelayed.start_time != start_time_ul(t))
 690                 return;
 691         force_sig_info(siginfo.si_signo, &siginfo, t);
 692 }