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         /* Always make any pending restarted system calls return -EINTR */
 125         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 126
 127         tbr = user->i.tbr;
 128         psr = user->i.psr;
 129         if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
 130                 goto badframe;
 131         user->i.tbr = tbr;
 132         user->i.psr = psr;
 133
 134         restore_user_regs(user);
 135
 136         user->i.syscallno = -1;         /* disable syscall checks */
 137
 138         *_gr8 = user->i.gr[8];
 139         return 0;
 140
 141  badframe:
 142         return 1;
 143 }
 144
 145 asmlinkage int sys_sigreturn(void)
 146 {
 147         struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
 148         sigset_t set;
 149         int gr8;
 150
 151         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 152                 goto badframe;
 153         if (__get_user(set.sig[0], &frame->sc.sc_oldmask))
 154                 goto badframe;
 155
 156         if (_NSIG_WORDS > 1 &&
 157             __copy_from_user(&set.sig[1], &frame->extramask, sizeof(frame->extramask)))
 158                 goto badframe;
 159
 160         sigdelsetmask(&set, ~_BLOCKABLE);
 161         spin_lock_irq(&current->sighand->siglock);
 162         current->blocked = set;
 163         recalc_sigpending();
 164         spin_unlock_irq(&current->sighand->siglock);
 165
 166         if (restore_sigcontext(&frame->sc, &gr8))
 167                 goto badframe;
 168         return gr8;
 169
 170  badframe:
 171         force_sig(SIGSEGV, current);
 172         return 0;
 173 }
 174
 175 asmlinkage int sys_rt_sigreturn(void)
 176 {
 177         struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
 178         sigset_t set;
 179         int gr8;
 180
 181         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 182                 goto badframe;
 183         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 184                 goto badframe;
 185
 186         sigdelsetmask(&set, ~_BLOCKABLE);
 187         spin_lock_irq(&current->sighand->siglock);
 188         current->blocked = set;
 189         recalc_sigpending();
 190         spin_unlock_irq(&current->sighand->siglock);
 191
 192         if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
 193                 goto badframe;
 194
 195         if (do_sigaltstack(&frame->uc.uc_stack, NULL, __frame->sp) == -EFAULT)
 196                 goto badframe;
 197
 198         return gr8;
 199
 200 badframe:
 201         force_sig(SIGSEGV, current);
 202         return 0;
 203 }
 204
 205 /*
 206  * Set up a signal frame
 207  */
 208 static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
 209 {
 210         save_user_regs(current->thread.user);
 211
 212         if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
 213                 goto badframe;
 214
 215         /* non-iBCS2 extensions.. */
 216         if (__put_user(mask, &sc->sc_oldmask) < 0)
 217                 goto badframe;
 218
 219         return 0;
 220
 221  badframe:
 222         return 1;
 223 }
 224
 225 /*****************************************************************************/
 226 /*
 227  * Determine which stack to use..
 228  */
 229 static inline void __user *get_sigframe(struct k_sigaction *ka,
 230                                         size_t frame_size)
 231 {
 232         unsigned long sp;
 233
 234         /* Default to using normal stack */
 235         sp = __frame->sp;
 236
 237         /* This is the X/Open sanctioned signal stack switching.  */
 238         if (ka->sa.sa_flags & SA_ONSTACK) {
 239                 if (! sas_ss_flags(sp))
 240                         sp = current->sas_ss_sp + current->sas_ss_size;
 241         }
 242
 243         return (void __user *) ((sp - frame_size) & ~7UL);
 244
 245 } /* end get_sigframe() */
 246
 247 /*****************************************************************************/
 248 /*
 249  *
 250  */
 251 static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 252 {
 253         struct sigframe __user *frame;
 254         int rsig;
 255
 256         set_fs(USER_DS);
 257
 258         frame = get_sigframe(ka, sizeof(*frame));
 259
 260         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 261                 goto give_sigsegv;
 262
 263         rsig = sig;
 264         if (sig < 32 &&
 265             __current_thread_info->exec_domain &&
 266             __current_thread_info->exec_domain->signal_invmap)
 267                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 268
 269         if (__put_user(rsig, &frame->sig) < 0)
 270                 goto give_sigsegv;
 271
 272         if (setup_sigcontext(&frame->sc, set->sig[0]))
 273                 goto give_sigsegv;
 274
 275         if (_NSIG_WORDS > 1) {
 276                 if (__copy_to_user(frame->extramask, &set->sig[1],
 277                                    sizeof(frame->extramask)))
 278                         goto give_sigsegv;
 279         }
 280
 281         /* Set up to return from userspace.  If provided, use a stub
 282          * already in userspace.  */
 283         if (ka->sa.sa_flags & SA_RESTORER) {
 284                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode) < 0)
 285                         goto give_sigsegv;
 286         }
 287         else {
 288                 /* Set up the following code on the stack:
 289                  *      setlos  #__NR_sigreturn,gr7
 290                  *      tira    gr0,0
 291                  */
 292                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 293                     __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
 294                     __put_user(0xc0700000, &frame->retcode[1]))
 295                         goto give_sigsegv;
 296
 297                 flush_icache_range((unsigned long) frame->retcode,
 298                                    (unsigned long) (frame->retcode + 2));
 299         }
 300
 301         /* Set up registers for the signal handler */
 302         if (current->personality & FDPIC_FUNCPTRS) {
 303                 struct fdpic_func_descriptor __user *funcptr =
 304                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 305                 struct fdpic_func_descriptor desc;
 306                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 307                         goto give_sigsegv;
 308                 __frame->pc = desc.text;
 309                 __frame->gr15 = desc.GOT;
 310         } else {
 311                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 312                 __frame->gr15 = 0;
 313         }
 314
 315         __frame->sp   = (unsigned long) frame;
 316         __frame->lr   = (unsigned long) &frame->retcode;
 317         __frame->gr8  = sig;
 318
 319         /* the tracer may want to single-step inside the handler */
 320         if (test_thread_flag(TIF_SINGLESTEP))
 321                 ptrace_notify(SIGTRAP);
 322
 323 #if DEBUG_SIG
 324         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 325                sig, current->comm, current->pid, frame, __frame->pc,
 326                frame->pretcode);
 327 #endif
 328
 329         return 0;
 330
 331 give_sigsegv:
 332         force_sigsegv(sig, current);
 333         return -EFAULT;
 334
 335 } /* end setup_frame() */
 336
 337 /*****************************************************************************/
 338 /*
 339  *
 340  */
 341 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 342                           sigset_t *set)
 343 {
 344         struct rt_sigframe __user *frame;
 345         int rsig;
 346
 347         set_fs(USER_DS);
 348
 349         frame = get_sigframe(ka, sizeof(*frame));
 350
 351         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 352                 goto give_sigsegv;
 353
 354         rsig = sig;
 355         if (sig < 32 &&
 356             __current_thread_info->exec_domain &&
 357             __current_thread_info->exec_domain->signal_invmap)
 358                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 359
 360         if (__put_user(rsig,            &frame->sig) ||
 361             __put_user(&frame->info,    &frame->pinfo) ||
 362             __put_user(&frame->uc,      &frame->puc))
 363                 goto give_sigsegv;
 364
 365         if (copy_siginfo_to_user(&frame->info, info))
 366                 goto give_sigsegv;
 367
 368         /* Create the ucontext.  */
 369         if (__put_user(0, &frame->uc.uc_flags) ||
 370             __put_user(NULL, &frame->uc.uc_link) ||
 371             __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp) ||
 372             __put_user(sas_ss_flags(__frame->sp), &frame->uc.uc_stack.ss_flags) ||
 373             __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size))
 374                 goto give_sigsegv;
 375
 376         if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
 377                 goto give_sigsegv;
 378
 379         if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
 380                 goto give_sigsegv;
 381
 382         /* Set up to return from userspace.  If provided, use a stub
 383          * already in userspace.  */
 384         if (ka->sa.sa_flags & SA_RESTORER) {
 385                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
 386                         goto give_sigsegv;
 387         }
 388         else {
 389                 /* Set up the following code on the stack:
 390                  *      setlos  #__NR_sigreturn,gr7
 391                  *      tira    gr0,0
 392                  */
 393                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 394                     __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
 395                     __put_user(0xc0700000, &frame->retcode[1]))
 396                         goto give_sigsegv;
 397
 398                 flush_icache_range((unsigned long) frame->retcode,
 399                                    (unsigned long) (frame->retcode + 2));
 400         }
 401
 402         /* Set up registers for signal handler */
 403         if (current->personality & FDPIC_FUNCPTRS) {
 404                 struct fdpic_func_descriptor __user *funcptr =
 405                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 406                 struct fdpic_func_descriptor desc;
 407                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 408                         goto give_sigsegv;
 409                 __frame->pc = desc.text;
 410                 __frame->gr15 = desc.GOT;
 411         } else {
 412                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 413                 __frame->gr15 = 0;
 414         }
 415
 416         __frame->sp  = (unsigned long) frame;
 417         __frame->lr  = (unsigned long) &frame->retcode;
 418         __frame->gr8 = sig;
 419         __frame->gr9 = (unsigned long) &frame->info;
 420
 421         /* the tracer may want to single-step inside the handler */
 422         if (test_thread_flag(TIF_SINGLESTEP))
 423                 ptrace_notify(SIGTRAP);
 424
 425 #if DEBUG_SIG
 426         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 427                sig, current->comm, current->pid, frame, __frame->pc,
 428                frame->pretcode);
 429 #endif
 430
 431         return 0;
 432
 433 give_sigsegv:
 434         force_sigsegv(sig, current);
 435         return -EFAULT;
 436
 437 } /* end setup_rt_frame() */
 438
 439 /*****************************************************************************/
 440 /*
 441  * OK, we're invoking a handler
 442  */
 443 static int handle_signal(unsigned long sig, siginfo_t *info,
 444                          struct k_sigaction *ka, sigset_t *oldset)
 445 {
 446         int ret;
 447
 448         /* Are we from a system call? */
 449         if (in_syscall(__frame)) {
 450                 /* If so, check system call restarting.. */
 451                 switch (__frame->gr8) {
 452                 case -ERESTART_RESTARTBLOCK:
 453                 case -ERESTARTNOHAND:
 454                         __frame->gr8 = -EINTR;
 455                         break;
 456
 457                 case -ERESTARTSYS:
 458                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 459                                 __frame->gr8 = -EINTR;
 460                                 break;
 461                         }
 462
 463                         /* fallthrough */
 464                 case -ERESTARTNOINTR:
 465                         __frame->gr8 = __frame->orig_gr8;
 466                         __frame->pc -= 4;
 467                 }
 468         }
 469
 470         /* Set up the stack frame */
 471         if (ka->sa.sa_flags & SA_SIGINFO)
 472                 ret = setup_rt_frame(sig, ka, info, oldset);
 473         else
 474                 ret = setup_frame(sig, ka, oldset);
 475
 476         if (ret == 0) {
 477                 spin_lock_irq(&current->sighand->siglock);
 478                 sigorsets(&current->blocked, &current->blocked,
 479                           &ka->sa.sa_mask);
 480                 if (!(ka->sa.sa_flags & SA_NODEFER))
 481                         sigaddset(&current->blocked, sig);
 482                 recalc_sigpending();
 483                 spin_unlock_irq(&current->sighand->siglock);
 484         }
 485
 486         return ret;
 487
 488 } /* end handle_signal() */
 489
 490 /*****************************************************************************/
 491 /*
 492  * Note that 'init' is a special process: it doesn't get signals it doesn't
 493  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 494  * mistake.
 495  */
 496 static void do_signal(void)
 497 {
 498         struct k_sigaction ka;
 499         siginfo_t info;
 500         sigset_t *oldset;
 501         int signr;
 502
 503         /*
 504          * We want the common case to go fast, which
 505          * is why we may in certain cases get here from
 506          * kernel mode. Just return without doing anything
 507          * if so.
 508          */
 509         if (!user_mode(__frame))
 510                 return;
 511
 512         if (try_to_freeze())
 513                 goto no_signal;
 514
 515         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 516                 oldset = &current->saved_sigmask;
 517         else
 518                 oldset = &current->blocked;
 519
 520         signr = get_signal_to_deliver(&info, &ka, __frame, NULL);
 521         if (signr > 0) {
 522                 if (handle_signal(signr, &info, &ka, oldset) == 0) {
 523                         /* a signal was successfully delivered; the saved
 524                          * sigmask will have been stored in the signal frame,
 525                          * and will be restored by sigreturn, so we can simply
 526                          * clear the TIF_RESTORE_SIGMASK flag */
 527                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 528                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 529
 530                         tracehook_signal_handler(signr, &info, &ka, __frame,
 531                                                  test_thread_flag(TIF_SINGLESTEP));
 532                 }
 533
 534                 return;
 535         }
 536
 537 no_signal:
 538         /* Did we come from a system call? */
 539         if (__frame->syscallno != -1) {
 540                 /* Restart the system call - no handlers present */
 541                 switch (__frame->gr8) {
 542                 case -ERESTARTNOHAND:
 543                 case -ERESTARTSYS:
 544                 case -ERESTARTNOINTR:
 545                         __frame->gr8 = __frame->orig_gr8;
 546                         __frame->pc -= 4;
 547                         break;
 548
 549                 case -ERESTART_RESTARTBLOCK:
 550                         __frame->gr7 = __NR_restart_syscall;
 551                         __frame->pc -= 4;
 552                         break;
 553                 }
 554         }
 555
 556         /* if there's no signal to deliver, we just put the saved sigmask
 557          * back */
 558         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 559                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 560                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 561         }
 562
 563 } /* end do_signal() */
 564
 565 /*****************************************************************************/
 566 /*
 567  * notification of userspace execution resumption
 568  * - triggered by the TIF_WORK_MASK flags
 569  */
 570 asmlinkage void do_notify_resume(__u32 thread_info_flags)
 571 {
 572         /* pending single-step? */
 573         if (thread_info_flags & _TIF_SINGLESTEP)
 574                 clear_thread_flag(TIF_SINGLESTEP);
 575
 576         /* deal with pending signal delivery */
 577         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 578                 do_signal();
 579
 580         /* deal with notification on about to resume userspace execution */
 581         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 582                 clear_thread_flag(TIF_NOTIFY_RESUME);
 583                 tracehook_notify_resume(__frame);
 584                 if (current->replacement_session_keyring)
 585                         key_replace_session_keyring();
 586         }
 587
 588 } /* end do_notify_resume() */