arch/s390/kernel/signal.c

   1 /*
   2  *  arch/s390/kernel/signal.c
   3  *
   4  *    Copyright (C) IBM Corp. 1999,2006
   5  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   6  *
   7  *    Based on Intel version
   8  *
   9  *  Copyright (C) 1991, 1992  Linus Torvalds
  10  *
  11  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  12  */
  13
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/smp_lock.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/errno.h>
  21 #include <linux/wait.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/unistd.h>
  24 #include <linux/stddef.h>
  25 #include <linux/tty.h>
  26 #include <linux/personality.h>
  27 #include <linux/binfmts.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/lowcore.h>
  31
  32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  33
  34
  35 typedef struct
  36 {
  37         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  38         struct sigcontext sc;
  39         _sigregs sregs;
  40         int signo;
  41         __u8 retcode[S390_SYSCALL_SIZE];
  42 } sigframe;
  43
  44 typedef struct
  45 {
  46         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  47         __u8 retcode[S390_SYSCALL_SIZE];
  48         struct siginfo info;
  49         struct ucontext uc;
  50 } rt_sigframe;
  51
  52 /*
  53  * Atomically swap in the new signal mask, and wait for a signal.
  54  */
  55 asmlinkage int
  56 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  57 {
  58         mask &= _BLOCKABLE;
  59         spin_lock_irq(&current->sighand->siglock);
  60         current->saved_sigmask = current->blocked;
  61         siginitset(&current->blocked, mask);
  62         recalc_sigpending();
  63         spin_unlock_irq(&current->sighand->siglock);
  64
  65         current->state = TASK_INTERRUPTIBLE;
  66         schedule();
  67         set_thread_flag(TIF_RESTORE_SIGMASK);
  68
  69         return -ERESTARTNOHAND;
  70 }
  71
  72 asmlinkage long
  73 sys_sigaction(int sig, const struct old_sigaction __user *act,
  74               struct old_sigaction __user *oact)
  75 {
  76         struct k_sigaction new_ka, old_ka;
  77         int ret;
  78
  79         if (act) {
  80                 old_sigset_t mask;
  81                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  82                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  83                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  84                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  85                     __get_user(mask, &act->sa_mask))
  86                         return -EFAULT;
  87                 siginitset(&new_ka.sa.sa_mask, mask);
  88         }
  89
  90         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  91
  92         if (!ret && oact) {
  93                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  94                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  95                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  96                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  97                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  98                         return -EFAULT;
  99         }
 100
 101         return ret;
 102 }
 103
 104 asmlinkage long
 105 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 106 {
 107         struct pt_regs *regs = task_pt_regs(current);
 108         return do_sigaltstack(uss, uoss, regs->gprs[15]);
 109 }
 110
 111
 112
 113 /* Returns non-zero on fault. */
 114 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 115 {
 116         _sigregs user_sregs;
 117
 118         save_access_regs(current->thread.acrs);
 119
 120         /* Copy a 'clean' PSW mask to the user to avoid leaking
 121            information about whether PER is currently on.  */
 122         user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask);
 123         user_sregs.regs.psw.addr = regs->psw.addr;
 124         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 125         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 126                sizeof(sregs->regs.acrs));
 127         /*
 128          * We have to store the fp registers to current->thread.fp_regs
 129          * to merge them with the emulated registers.
 130          */
 131         save_fp_regs(&current->thread.fp_regs);
 132         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 133                sizeof(s390_fp_regs));
 134         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 135 }
 136
 137 /* Returns positive number on error */
 138 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 139 {
 140         int err;
 141         _sigregs user_sregs;
 142
 143         /* Alwys make any pending restarted system call return -EINTR */
 144         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 145
 146         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 147         if (err)
 148                 return err;
 149         regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
 150                                         user_sregs.regs.psw.mask);
 151         regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
 152         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 153         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 154                sizeof(sregs->regs.acrs));
 155         restore_access_regs(current->thread.acrs);
 156
 157         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 158                sizeof(s390_fp_regs));
 159         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 160
 161         restore_fp_regs(&current->thread.fp_regs);
 162         regs->trap = -1;        /* disable syscall checks */
 163         return 0;
 164 }
 165
 166 asmlinkage long sys_sigreturn(void)
 167 {
 168         struct pt_regs *regs = task_pt_regs(current);
 169         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 170         sigset_t set;
 171
 172         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 173                 goto badframe;
 174         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 175                 goto badframe;
 176
 177         sigdelsetmask(&set, ~_BLOCKABLE);
 178         spin_lock_irq(&current->sighand->siglock);
 179         current->blocked = set;
 180         recalc_sigpending();
 181         spin_unlock_irq(&current->sighand->siglock);
 182
 183         if (restore_sigregs(regs, &frame->sregs))
 184                 goto badframe;
 185
 186         return regs->gprs[2];
 187
 188 badframe:
 189         force_sig(SIGSEGV, current);
 190         return 0;
 191 }
 192
 193 asmlinkage long sys_rt_sigreturn(void)
 194 {
 195         struct pt_regs *regs = task_pt_regs(current);
 196         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 197         sigset_t set;
 198
 199         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 200                 goto badframe;
 201         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 202                 goto badframe;
 203
 204         sigdelsetmask(&set, ~_BLOCKABLE);
 205         spin_lock_irq(&current->sighand->siglock);
 206         current->blocked = set;
 207         recalc_sigpending();
 208         spin_unlock_irq(&current->sighand->siglock);
 209
 210         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 211                 goto badframe;
 212
 213         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 214                            regs->gprs[15]) == -EFAULT)
 215                 goto badframe;
 216         return regs->gprs[2];
 217
 218 badframe:
 219         force_sig(SIGSEGV, current);
 220         return 0;
 221 }
 222
 223 /*
 224  * Set up a signal frame.
 225  */
 226
 227
 228 /*
 229  * Determine which stack to use..
 230  */
 231 static inline void __user *
 232 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 233 {
 234         unsigned long sp;
 235
 236         /* Default to using normal stack */
 237         sp = regs->gprs[15];
 238
 239         /* This is the X/Open sanctioned signal stack switching.  */
 240         if (ka->sa.sa_flags & SA_ONSTACK) {
 241                 if (! sas_ss_flags(sp))
 242                         sp = current->sas_ss_sp + current->sas_ss_size;
 243         }
 244
 245         /* This is the legacy signal stack switching. */
 246         else if (!user_mode(regs) &&
 247                  !(ka->sa.sa_flags & SA_RESTORER) &&
 248                  ka->sa.sa_restorer) {
 249                 sp = (unsigned long) ka->sa.sa_restorer;
 250         }
 251
 252         return (void __user *)((sp - frame_size) & -8ul);
 253 }
 254
 255 static inline int map_signal(int sig)
 256 {
 257         if (current_thread_info()->exec_domain
 258             && current_thread_info()->exec_domain->signal_invmap
 259             && sig < 32)
 260                 return current_thread_info()->exec_domain->signal_invmap[sig];
 261         else
 262                 return sig;
 263 }
 264
 265 static int setup_frame(int sig, struct k_sigaction *ka,
 266                        sigset_t *set, struct pt_regs * regs)
 267 {
 268         sigframe __user *frame;
 269
 270         frame = get_sigframe(ka, regs, sizeof(sigframe));
 271         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 272                 goto give_sigsegv;
 273
 274         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 275                 goto give_sigsegv;
 276
 277         if (save_sigregs(regs, &frame->sregs))
 278                 goto give_sigsegv;
 279         if (__put_user(&frame->sregs, &frame->sc.sregs))
 280                 goto give_sigsegv;
 281
 282         /* Set up to return from userspace.  If provided, use a stub
 283            already in userspace.  */
 284         if (ka->sa.sa_flags & SA_RESTORER) {
 285                 regs->gprs[14] = (unsigned long)
 286                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 287         } else {
 288                 regs->gprs[14] = (unsigned long)
 289                         frame->retcode | PSW_ADDR_AMODE;
 290                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 291                                (u16 __user *)(frame->retcode)))
 292                         goto give_sigsegv;
 293         }
 294
 295         /* Set up backchain. */
 296         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 297                 goto give_sigsegv;
 298
 299         /* Set up registers for signal handler */
 300         regs->gprs[15] = (unsigned long) frame;
 301         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 302
 303         regs->gprs[2] = map_signal(sig);
 304         regs->gprs[3] = (unsigned long) &frame->sc;
 305
 306         /* We forgot to include these in the sigcontext.
 307            To avoid breaking binary compatibility, they are passed as args. */
 308         regs->gprs[4] = current->thread.trap_no;
 309         regs->gprs[5] = current->thread.prot_addr;
 310
 311         /* Place signal number on stack to allow backtrace from handler.  */
 312         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 313                 goto give_sigsegv;
 314         return 0;
 315
 316 give_sigsegv:
 317         force_sigsegv(sig, current);
 318         return -EFAULT;
 319 }
 320
 321 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 322                            sigset_t *set, struct pt_regs * regs)
 323 {
 324         int err = 0;
 325         rt_sigframe __user *frame;
 326
 327         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 328         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 329                 goto give_sigsegv;
 330
 331         if (copy_siginfo_to_user(&frame->info, info))
 332                 goto give_sigsegv;
 333
 334         /* Create the ucontext.  */
 335         err |= __put_user(0, &frame->uc.uc_flags);
 336         err |= __put_user(NULL, &frame->uc.uc_link);
 337         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 338         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 339                           &frame->uc.uc_stack.ss_flags);
 340         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 341         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 342         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 343         if (err)
 344                 goto give_sigsegv;
 345
 346         /* Set up to return from userspace.  If provided, use a stub
 347            already in userspace.  */
 348         if (ka->sa.sa_flags & SA_RESTORER) {
 349                 regs->gprs[14] = (unsigned long)
 350                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 351         } else {
 352                 regs->gprs[14] = (unsigned long)
 353                         frame->retcode | PSW_ADDR_AMODE;
 354                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 355                                (u16 __user *)(frame->retcode)))
 356                         goto give_sigsegv;
 357         }
 358
 359         /* Set up backchain. */
 360         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 361                 goto give_sigsegv;
 362
 363         /* Set up registers for signal handler */
 364         regs->gprs[15] = (unsigned long) frame;
 365         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 366
 367         regs->gprs[2] = map_signal(sig);
 368         regs->gprs[3] = (unsigned long) &frame->info;
 369         regs->gprs[4] = (unsigned long) &frame->uc;
 370         return 0;
 371
 372 give_sigsegv:
 373         force_sigsegv(sig, current);
 374         return -EFAULT;
 375 }
 376
 377 /*
 378  * OK, we're invoking a handler
 379  */
 380
 381 static int
 382 handle_signal(unsigned long sig, struct k_sigaction *ka,
 383               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 384 {
 385         int ret;
 386
 387         /* Set up the stack frame */
 388         if (ka->sa.sa_flags & SA_SIGINFO)
 389                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 390         else
 391                 ret = setup_frame(sig, ka, oldset, regs);
 392
 393         if (ret == 0) {
 394                 spin_lock_irq(&current->sighand->siglock);
 395                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 396                 if (!(ka->sa.sa_flags & SA_NODEFER))
 397                         sigaddset(&current->blocked,sig);
 398                 recalc_sigpending();
 399                 spin_unlock_irq(&current->sighand->siglock);
 400         }
 401
 402         return ret;
 403 }
 404
 405 /*
 406  * Note that 'init' is a special process: it doesn't get signals it doesn't
 407  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 408  * mistake.
 409  *
 410  * Note that we go through the signals twice: once to check the signals that
 411  * the kernel can handle, and then we build all the user-level signal handling
 412  * stack-frames in one go after that.
 413  */
 414 void do_signal(struct pt_regs *regs)
 415 {
 416         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 417         siginfo_t info;
 418         int signr;
 419         struct k_sigaction ka;
 420         sigset_t *oldset;
 421
 422         /*
 423          * We want the common case to go fast, which
 424          * is why we may in certain cases get here from
 425          * kernel mode. Just return without doing anything
 426          * if so.
 427          */
 428         if (!user_mode(regs))
 429                 return;
 430
 431         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 432                 oldset = &current->saved_sigmask;
 433         else
 434                 oldset = &current->blocked;
 435
 436         /* Are we from a system call? */
 437         if (regs->trap == __LC_SVC_OLD_PSW) {
 438                 continue_addr = regs->psw.addr;
 439                 restart_addr = continue_addr - regs->ilc;
 440                 retval = regs->gprs[2];
 441
 442                 /* Prepare for system call restart.  We do this here so that a
 443                    debugger will see the already changed PSW. */
 444                 switch (retval) {
 445                 case -ERESTARTNOHAND:
 446                 case -ERESTARTSYS:
 447                 case -ERESTARTNOINTR:
 448                         regs->gprs[2] = regs->orig_gpr2;
 449                         regs->psw.addr = restart_addr;
 450                         break;
 451                 case -ERESTART_RESTARTBLOCK:
 452                         regs->gprs[2] = -EINTR;
 453                 }
 454                 regs->trap = -1;        /* Don't deal with this again. */
 455         }
 456
 457         /* Get signal to deliver.  When running under ptrace, at this point
 458            the debugger may change all our registers ... */
 459         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 460
 461         /* Depending on the signal settings we may need to revert the
 462            decision to restart the system call. */
 463         if (signr > 0 && regs->psw.addr == restart_addr) {
 464                 if (retval == -ERESTARTNOHAND
 465                     || (retval == -ERESTARTSYS
 466                          && !(current->sighand->action[signr-1].sa.sa_flags
 467                               & SA_RESTART))) {
 468                         regs->gprs[2] = -EINTR;
 469                         regs->psw.addr = continue_addr;
 470                 }
 471         }
 472
 473         if (signr > 0) {
 474                 /* Whee!  Actually deliver the signal.  */
 475 #ifdef CONFIG_COMPAT
 476                 if (test_thread_flag(TIF_31BIT)) {
 477                         extern int handle_signal32(unsigned long sig,
 478                                                    struct k_sigaction *ka,
 479                                                    siginfo_t *info,
 480                                                    sigset_t *oldset,
 481                                                    struct pt_regs *regs);
 482                         if (handle_signal32(
 483                                     signr, &ka, &info, oldset, regs) == 0) {
 484                                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 485                                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 486                         }
 487                         return;
 488                 }
 489 #endif
 490                 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
 491                         /*
 492                          * A signal was successfully delivered; the saved
 493                          * sigmask will have been stored in the signal frame,
 494                          * and will be restored by sigreturn, so we can simply
 495                          * clear the TIF_RESTORE_SIGMASK flag.
 496                          */
 497                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 498                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 499                 }
 500                 return;
 501         }
 502
 503         /*
 504          * If there's no signal to deliver, we just put the saved sigmask back.
 505          */
 506         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 507                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 508                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 509         }
 510
 511         /* Restart a different system call. */
 512         if (retval == -ERESTART_RESTARTBLOCK
 513             && regs->psw.addr == continue_addr) {
 514                 regs->gprs[2] = __NR_restart_syscall;
 515                 set_thread_flag(TIF_RESTART_SVC);
 516         }
 517 }