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