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