arch/frv/kernel/signal.c

   1 /* signal.c: FRV specific bits of signal handling
   2  *
   3  * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  * - Derived from arch/m68k/kernel/signal.c
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/kernel.h>
  17 #include <linux/signal.h>
  18 #include <linux/errno.h>
  19 #include <linux/wait.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/unistd.h>
  22 #include <linux/personality.h>
  23 #include <linux/freezer.h>
  24 #include <linux/tracehook.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/cacheflush.h>
  28
  29 #define DEBUG_SIG 0
  30
  31 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  32
  33 struct fdpic_func_descriptor {
  34         unsigned long   text;
  35         unsigned long   GOT;
  36 };
  37
  38 /*
  39  * Atomically swap in the new signal mask, and wait for a signal.
  40  */
  41 asmlinkage int sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  42 {
  43         mask &= _BLOCKABLE;
  44         spin_lock_irq(&current->sighand->siglock);
  45         current->saved_sigmask = current->blocked;
  46         siginitset(&current->blocked, mask);
  47         recalc_sigpending();
  48         spin_unlock_irq(&current->sighand->siglock);
  49
  50         current->state = TASK_INTERRUPTIBLE;
  51         schedule();
  52         set_thread_flag(TIF_RESTORE_SIGMASK);
  53         return -ERESTARTNOHAND;
  54 }
  55
  56 asmlinkage int sys_sigaction(int sig,
  57                              const struct old_sigaction __user *act,
  58                              struct old_sigaction __user *oact)
  59 {
  60         struct k_sigaction new_ka, old_ka;
  61         int ret;
  62
  63         if (act) {
  64                 old_sigset_t mask;
  65                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  66                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  67                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  68                         return -EFAULT;
  69                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  70                 __get_user(mask, &act->sa_mask);
  71                 siginitset(&new_ka.sa.sa_mask, mask);
  72         }
  73
  74         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  75
  76         if (!ret && oact) {
  77                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  78                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  79                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  80                         return -EFAULT;
  81                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  82                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  83         }
  84
  85         return ret;
  86 }
  87
  88 asmlinkage
  89 int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  90 {
  91         return do_sigaltstack(uss, uoss, __frame->sp);
  92 }
  93
  94
  95 /*
  96  * Do a signal return; undo the signal stack.
  97  */
  98
  99 struct sigframe
 100 {
 101         __sigrestore_t pretcode;
 102         int sig;
 103         struct sigcontext sc;
 104         unsigned long extramask[_NSIG_WORDS-1];
 105         uint32_t retcode[2];
 106 };
 107
 108 struct rt_sigframe
 109 {
 110         __sigrestore_t pretcode;
 111         int sig;
 112         struct siginfo __user *pinfo;
 113         void __user *puc;
 114         struct siginfo info;
 115         struct ucontext uc;
 116         uint32_t retcode[2];
 117 };
 118
 119 static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
 120 {
 121         struct user_context *user = current->thread.user;
 122         unsigned long tbr, psr;
 123
 124         tbr = user->i.tbr;
 125         psr = user->i.psr;
 126         if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
 127                 goto badframe;
 128         user->i.tbr = tbr;
 129         user->i.psr = psr;
 130
 131         restore_user_regs(user);
 132
 133         user->i.syscallno = -1;         /* disable syscall checks */
 134
 135         *_gr8 = user->i.gr[8];
 136         return 0;
 137
 138  badframe:
 139         return 1;
 140 }
 141
 142 asmlinkage int sys_sigreturn(void)
 143 {
 144         struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
 145         sigset_t set;
 146         int gr8;
 147
 148         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 149                 goto badframe;
 150         if (__get_user(set.sig[0], &frame->sc.sc_oldmask))
 151                 goto badframe;
 152
 153         if (_NSIG_WORDS > 1 &&
 154             __copy_from_user(&set.sig[1], &frame->extramask, sizeof(frame->extramask)))
 155                 goto badframe;
 156
 157         sigdelsetmask(&set, ~_BLOCKABLE);
 158         spin_lock_irq(&current->sighand->siglock);
 159         current->blocked = set;
 160         recalc_sigpending();
 161         spin_unlock_irq(&current->sighand->siglock);
 162
 163         if (restore_sigcontext(&frame->sc, &gr8))
 164                 goto badframe;
 165         return gr8;
 166
 167  badframe:
 168         force_sig(SIGSEGV, current);
 169         return 0;
 170 }
 171
 172 asmlinkage int sys_rt_sigreturn(void)
 173 {
 174         struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
 175         sigset_t set;
 176         int gr8;
 177
 178         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 179                 goto badframe;
 180         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 181                 goto badframe;
 182
 183         sigdelsetmask(&set, ~_BLOCKABLE);
 184         spin_lock_irq(&current->sighand->siglock);
 185         current->blocked = set;
 186         recalc_sigpending();
 187         spin_unlock_irq(&current->sighand->siglock);
 188
 189         if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
 190                 goto badframe;
 191
 192         if (do_sigaltstack(&frame->uc.uc_stack, NULL, __frame->sp) == -EFAULT)
 193                 goto badframe;
 194
 195         return gr8;
 196
 197 badframe:
 198         force_sig(SIGSEGV, current);
 199         return 0;
 200 }
 201
 202 /*
 203  * Set up a signal frame
 204  */
 205 static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
 206 {
 207         save_user_regs(current->thread.user);
 208
 209         if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
 210                 goto badframe;
 211
 212         /* non-iBCS2 extensions.. */
 213         if (__put_user(mask, &sc->sc_oldmask) < 0)
 214                 goto badframe;
 215
 216         return 0;
 217
 218  badframe:
 219         return 1;
 220 }
 221
 222 /*****************************************************************************/
 223 /*
 224  * Determine which stack to use..
 225  */
 226 static inline void __user *get_sigframe(struct k_sigaction *ka,
 227                                         size_t frame_size)
 228 {
 229         unsigned long sp;
 230
 231         /* Default to using normal stack */
 232         sp = __frame->sp;
 233
 234         /* This is the X/Open sanctioned signal stack switching.  */
 235         if (ka->sa.sa_flags & SA_ONSTACK) {
 236                 if (! sas_ss_flags(sp))
 237                         sp = current->sas_ss_sp + current->sas_ss_size;
 238         }
 239
 240         return (void __user *) ((sp - frame_size) & ~7UL);
 241
 242 } /* end get_sigframe() */
 243
 244 /*****************************************************************************/
 245 /*
 246  *
 247  */
 248 static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 249 {
 250         struct sigframe __user *frame;
 251         int rsig;
 252
 253         frame = get_sigframe(ka, sizeof(*frame));
 254
 255         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 256                 goto give_sigsegv;
 257
 258         rsig = sig;
 259         if (sig < 32 &&
 260             __current_thread_info->exec_domain &&
 261             __current_thread_info->exec_domain->signal_invmap)
 262                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 263
 264         if (__put_user(rsig, &frame->sig) < 0)
 265                 goto give_sigsegv;
 266
 267         if (setup_sigcontext(&frame->sc, set->sig[0]))
 268                 goto give_sigsegv;
 269
 270         if (_NSIG_WORDS > 1) {
 271                 if (__copy_to_user(frame->extramask, &set->sig[1],
 272                                    sizeof(frame->extramask)))
 273                         goto give_sigsegv;
 274         }
 275
 276         /* Set up to return from userspace.  If provided, use a stub
 277          * already in userspace.  */
 278         if (ka->sa.sa_flags & SA_RESTORER) {
 279                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode) < 0)
 280                         goto give_sigsegv;
 281         }
 282         else {
 283                 /* Set up the following code on the stack:
 284                  *      setlos  #__NR_sigreturn,gr7
 285                  *      tira    gr0,0
 286                  */
 287                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 288                     __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
 289                     __put_user(0xc0700000, &frame->retcode[1]))
 290                         goto give_sigsegv;
 291
 292                 flush_icache_range((unsigned long) frame->retcode,
 293                                    (unsigned long) (frame->retcode + 2));
 294         }
 295
 296         /* set up registers for signal handler */
 297         __frame->sp   = (unsigned long) frame;
 298         __frame->lr   = (unsigned long) &frame->retcode;
 299         __frame->gr8  = sig;
 300
 301         if (current->personality & FDPIC_FUNCPTRS) {
 302                 struct fdpic_func_descriptor __user *funcptr =
 303                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 304                 __get_user(__frame->pc, &funcptr->text);
 305                 __get_user(__frame->gr15, &funcptr->GOT);
 306         } else {
 307                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 308                 __frame->gr15 = 0;
 309         }
 310
 311         set_fs(USER_DS);
 312
 313         /* the tracer may want to single-step inside the handler */
 314         if (test_thread_flag(TIF_SINGLESTEP))
 315                 ptrace_notify(SIGTRAP);
 316
 317 #if DEBUG_SIG
 318         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 319                sig, current->comm, current->pid, frame, __frame->pc,
 320                frame->pretcode);
 321 #endif
 322
 323         return 0;
 324
 325 give_sigsegv:
 326         force_sig(SIGSEGV, current);
 327         return -EFAULT;
 328
 329 } /* end setup_frame() */
 330
 331 /*****************************************************************************/
 332 /*
 333  *
 334  */
 335 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 336                           sigset_t *set)
 337 {
 338         struct rt_sigframe __user *frame;
 339         int rsig;
 340
 341         frame = get_sigframe(ka, sizeof(*frame));
 342
 343         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 344                 goto give_sigsegv;
 345
 346         rsig = sig;
 347         if (sig < 32 &&
 348             __current_thread_info->exec_domain &&
 349             __current_thread_info->exec_domain->signal_invmap)
 350                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 351
 352         if (__put_user(rsig,            &frame->sig) ||
 353             __put_user(&frame->info,    &frame->pinfo) ||
 354             __put_user(&frame->uc,      &frame->puc))
 355                 goto give_sigsegv;
 356
 357         if (copy_siginfo_to_user(&frame->info, info))
 358                 goto give_sigsegv;
 359
 360         /* Create the ucontext.  */
 361         if (__put_user(0, &frame->uc.uc_flags) ||
 362             __put_user(NULL, &frame->uc.uc_link) ||
 363             __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp) ||
 364             __put_user(sas_ss_flags(__frame->sp), &frame->uc.uc_stack.ss_flags) ||
 365             __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size))
 366                 goto give_sigsegv;
 367
 368         if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
 369                 goto give_sigsegv;
 370
 371         if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
 372                 goto give_sigsegv;
 373
 374         /* Set up to return from userspace.  If provided, use a stub
 375          * already in userspace.  */
 376         if (ka->sa.sa_flags & SA_RESTORER) {
 377                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
 378                         goto give_sigsegv;
 379         }
 380         else {
 381                 /* Set up the following code on the stack:
 382                  *      setlos  #__NR_sigreturn,gr7
 383                  *      tira    gr0,0
 384                  */
 385                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 386                     __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
 387                     __put_user(0xc0700000, &frame->retcode[1]))
 388                         goto give_sigsegv;
 389
 390                 flush_icache_range((unsigned long) frame->retcode,
 391                                    (unsigned long) (frame->retcode + 2));
 392         }
 393
 394         /* Set up registers for signal handler */
 395         __frame->sp  = (unsigned long) frame;
 396         __frame->lr   = (unsigned long) &frame->retcode;
 397         __frame->gr8 = sig;
 398         __frame->gr9 = (unsigned long) &frame->info;
 399
 400         if (current->personality & FDPIC_FUNCPTRS) {
 401                 struct fdpic_func_descriptor __user *funcptr =
 402                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 403                 __get_user(__frame->pc, &funcptr->text);
 404                 __get_user(__frame->gr15, &funcptr->GOT);
 405         } else {
 406                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 407                 __frame->gr15 = 0;
 408         }
 409
 410         set_fs(USER_DS);
 411
 412         /* the tracer may want to single-step inside the handler */
 413         if (test_thread_flag(TIF_SINGLESTEP))
 414                 ptrace_notify(SIGTRAP);
 415
 416 #if DEBUG_SIG
 417         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 418                sig, current->comm, current->pid, frame, __frame->pc,
 419                frame->pretcode);
 420 #endif
 421
 422         return 0;
 423
 424 give_sigsegv:
 425         force_sig(SIGSEGV, current);
 426         return -EFAULT;
 427
 428 } /* end setup_rt_frame() */
 429
 430 /*****************************************************************************/
 431 /*
 432  * OK, we're invoking a handler
 433  */
 434 static int handle_signal(unsigned long sig, siginfo_t *info,
 435                          struct k_sigaction *ka, sigset_t *oldset)
 436 {
 437         int ret;
 438
 439         /* Are we from a system call? */
 440         if (in_syscall(__frame)) {
 441                 /* If so, check system call restarting.. */
 442                 switch (__frame->gr8) {
 443                 case -ERESTART_RESTARTBLOCK:
 444                 case -ERESTARTNOHAND:
 445                         __frame->gr8 = -EINTR;
 446                         break;
 447
 448                 case -ERESTARTSYS:
 449                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 450                                 __frame->gr8 = -EINTR;
 451                                 break;
 452                         }
 453
 454                         /* fallthrough */
 455                 case -ERESTARTNOINTR:
 456                         __frame->gr8 = __frame->orig_gr8;
 457                         __frame->pc -= 4;
 458                 }
 459         }
 460
 461         /* Set up the stack frame */
 462         if (ka->sa.sa_flags & SA_SIGINFO)
 463                 ret = setup_rt_frame(sig, ka, info, oldset);
 464         else
 465                 ret = setup_frame(sig, ka, oldset);
 466
 467         if (ret == 0) {
 468                 spin_lock_irq(&current->sighand->siglock);
 469                 sigorsets(&current->blocked, &current->blocked,
 470                           &ka->sa.sa_mask);
 471                 if (!(ka->sa.sa_flags & SA_NODEFER))
 472                         sigaddset(&current->blocked, sig);
 473                 recalc_sigpending();
 474                 spin_unlock_irq(&current->sighand->siglock);
 475         }
 476
 477         return ret;
 478
 479 } /* end handle_signal() */
 480
 481 /*****************************************************************************/
 482 /*
 483  * Note that 'init' is a special process: it doesn't get signals it doesn't
 484  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 485  * mistake.
 486  */
 487 static void do_signal(void)
 488 {
 489         struct k_sigaction ka;
 490         siginfo_t info;
 491         sigset_t *oldset;
 492         int signr;
 493
 494         /*
 495          * We want the common case to go fast, which
 496          * is why we may in certain cases get here from
 497          * kernel mode. Just return without doing anything
 498          * if so.
 499          */
 500         if (!user_mode(__frame))
 501                 return;
 502
 503         if (try_to_freeze())
 504                 goto no_signal;
 505
 506         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 507                 oldset = &current->saved_sigmask;
 508         else
 509                 oldset = &current->blocked;
 510
 511         signr = get_signal_to_deliver(&info, &ka, __frame, NULL);
 512         if (signr > 0) {
 513                 if (handle_signal(signr, &info, &ka, oldset) == 0) {
 514                         /* a signal was successfully delivered; the saved
 515                          * sigmask will have been stored in the signal frame,
 516                          * and will be restored by sigreturn, so we can simply
 517                          * clear the TIF_RESTORE_SIGMASK flag */
 518                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 519                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 520
 521                         tracehook_signal_handler(signr, &info, &ka, __frame,
 522                                                  test_thread_flag(TIF_SINGLESTEP));
 523                 }
 524
 525                 return;
 526         }
 527
 528 no_signal:
 529         /* Did we come from a system call? */
 530         if (__frame->syscallno != -1) {
 531                 /* Restart the system call - no handlers present */
 532                 switch (__frame->gr8) {
 533                 case -ERESTARTNOHAND:
 534                 case -ERESTARTSYS:
 535                 case -ERESTARTNOINTR:
 536                         __frame->gr8 = __frame->orig_gr8;
 537                         __frame->pc -= 4;
 538                         break;
 539
 540                 case -ERESTART_RESTARTBLOCK:
 541                         __frame->gr8 = __NR_restart_syscall;
 542                         __frame->pc -= 4;
 543                         break;
 544                 }
 545         }
 546
 547         /* if there's no signal to deliver, we just put the saved sigmask
 548          * back */
 549         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 550                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 551                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 552         }
 553
 554 } /* end do_signal() */
 555
 556 /*****************************************************************************/
 557 /*
 558  * notification of userspace execution resumption
 559  * - triggered by the TIF_WORK_MASK flags
 560  */
 561 asmlinkage void do_notify_resume(__u32 thread_info_flags)
 562 {
 563         /* pending single-step? */
 564         if (thread_info_flags & _TIF_SINGLESTEP)
 565                 clear_thread_flag(TIF_SINGLESTEP);
 566
 567         /* deal with pending signal delivery */
 568         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 569                 do_signal();
 570
 571         /* deal with notification on about to resume userspace execution */
 572         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 573                 clear_thread_flag(TIF_NOTIFY_RESUME);
 574                 tracehook_notify_resume(__frame);
 575                 if (current->replacement_session_keyring)
 576                         key_replace_session_keyring();
 577         }
 578
 579 } /* end do_notify_resume() */