arch/s390/kernel/signal.c

   1 /*
   2  *  arch/s390/kernel/signal.c
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   7  *
   8  *    Based on Intel version
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  *
  12  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  13  */
  14
  15 #include <linux/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/smp_lock.h>
  20 #include <linux/kernel.h>
  21 #include <linux/signal.h>
  22 #include <linux/errno.h>
  23 #include <linux/wait.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/unistd.h>
  26 #include <linux/stddef.h>
  27 #include <linux/tty.h>
  28 #include <linux/personality.h>
  29 #include <linux/binfmts.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/lowcore.h>
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36
  37 typedef struct
  38 {
  39         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  40         struct sigcontext sc;
  41         _sigregs sregs;
  42         __u8 retcode[S390_SYSCALL_SIZE];
  43 } sigframe;
  44
  45 typedef struct
  46 {
  47         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  48         __u8 retcode[S390_SYSCALL_SIZE];
  49         struct siginfo info;
  50         struct ucontext uc;
  51 } rt_sigframe;
  52
  53 int do_signal(struct pt_regs *regs, sigset_t *oldset);
  54
  55 /*
  56  * Atomically swap in the new signal mask, and wait for a signal.
  57  */
  58 asmlinkage int
  59 sys_sigsuspend(struct pt_regs * regs, int history0, int history1,
  60                old_sigset_t mask)
  61 {
  62         sigset_t saveset;
  63
  64         mask &= _BLOCKABLE;
  65         spin_lock_irq(&current->sighand->siglock);
  66         saveset = current->blocked;
  67         siginitset(&current->blocked, mask);
  68         recalc_sigpending();
  69         spin_unlock_irq(&current->sighand->siglock);
  70         regs->gprs[2] = -EINTR;
  71
  72         while (1) {
  73                 set_current_state(TASK_INTERRUPTIBLE);
  74                 schedule();
  75                 if (do_signal(regs, &saveset))
  76                         return -EINTR;
  77         }
  78 }
  79
  80 asmlinkage int
  81 sys_rt_sigsuspend(struct pt_regs * regs,sigset_t *unewset, size_t sigsetsize)
  82 {
  83         sigset_t saveset, newset;
  84
  85         /* XXX: Don't preclude handling different sized sigset_t's.  */
  86         if (sigsetsize != sizeof(sigset_t))
  87                 return -EINVAL;
  88
  89         if (copy_from_user(&newset, unewset, sizeof(newset)))
  90                 return -EFAULT;
  91         sigdelsetmask(&newset, ~_BLOCKABLE);
  92
  93         spin_lock_irq(&current->sighand->siglock);
  94         saveset = current->blocked;
  95         current->blocked = newset;
  96         recalc_sigpending();
  97         spin_unlock_irq(&current->sighand->siglock);
  98         regs->gprs[2] = -EINTR;
  99
 100         while (1) {
 101                 set_current_state(TASK_INTERRUPTIBLE);
 102                 schedule();
 103                 if (do_signal(regs, &saveset))
 104                         return -EINTR;
 105         }
 106 }
 107
 108 asmlinkage int
 109 sys_sigaction(int sig, const struct old_sigaction *act,
 110               struct old_sigaction *oact)
 111 {
 112         struct k_sigaction new_ka, old_ka;
 113         int ret;
 114
 115         if (act) {
 116                 old_sigset_t mask;
 117                 if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
 118                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 119                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 120                         return -EFAULT;
 121                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 122                 __get_user(mask, &act->sa_mask);
 123                 siginitset(&new_ka.sa.sa_mask, mask);
 124         }
 125
 126         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 127
 128         if (!ret && oact) {
 129                 if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
 130                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 131                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 132                         return -EFAULT;
 133                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 134                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 135         }
 136
 137         return ret;
 138 }
 139
 140 asmlinkage int
 141 sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs)
 142 {
 143         return do_sigaltstack(uss, uoss, regs->gprs[15]);
 144 }
 145
 146
 147
 148 /* Returns non-zero on fault. */
 149 static int save_sigregs(struct pt_regs *regs, _sigregs *sregs)
 150 {
 151         unsigned long old_mask = regs->psw.mask;
 152         int err;
 153
 154         save_access_regs(current->thread.acrs);
 155
 156         /* Copy a 'clean' PSW mask to the user to avoid leaking
 157            information about whether PER is currently on.  */
 158         regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
 159         err = __copy_to_user(&sregs->regs.psw, &regs->psw,
 160                              sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
 161         regs->psw.mask = old_mask;
 162         if (err != 0)
 163                 return err;
 164         err = __copy_to_user(&sregs->regs.acrs, current->thread.acrs,
 165                              sizeof(sregs->regs.acrs));
 166         if (err != 0)
 167                 return err;
 168         /*
 169          * We have to store the fp registers to current->thread.fp_regs
 170          * to merge them with the emulated registers.
 171          */
 172         save_fp_regs(&current->thread.fp_regs);
 173         return __copy_to_user(&sregs->fpregs, &current->thread.fp_regs,
 174                               sizeof(s390_fp_regs));
 175 }
 176
 177 /* Returns positive number on error */
 178 static int restore_sigregs(struct pt_regs *regs, _sigregs *sregs)
 179 {
 180         unsigned long old_mask = regs->psw.mask;
 181         int err;
 182
 183         /* Alwys make any pending restarted system call return -EINTR */
 184         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 185
 186         err = __copy_from_user(&regs->psw, &sregs->regs.psw,
 187                                sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
 188         regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);
 189         regs->psw.addr |= PSW_ADDR_AMODE;
 190         if (err)
 191                 return err;
 192         err = __copy_from_user(&current->thread.acrs, &sregs->regs.acrs,
 193                                sizeof(sregs->regs.acrs));
 194         if (err)
 195                 return err;
 196         restore_access_regs(current->thread.acrs);
 197
 198         err = __copy_from_user(&current->thread.fp_regs, &sregs->fpregs,
 199                                sizeof(s390_fp_regs));
 200         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 201         if (err)
 202                 return err;
 203
 204         restore_fp_regs(&current->thread.fp_regs);
 205         regs->trap = -1;        /* disable syscall checks */
 206         return 0;
 207 }
 208
 209 asmlinkage long sys_sigreturn(struct pt_regs *regs)
 210 {
 211         sigframe *frame = (sigframe *)regs->gprs[15];
 212         sigset_t set;
 213
 214         if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
 215                 goto badframe;
 216         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 217                 goto badframe;
 218
 219         sigdelsetmask(&set, ~_BLOCKABLE);
 220         spin_lock_irq(&current->sighand->siglock);
 221         current->blocked = set;
 222         recalc_sigpending();
 223         spin_unlock_irq(&current->sighand->siglock);
 224
 225         if (restore_sigregs(regs, &frame->sregs))
 226                 goto badframe;
 227
 228         return regs->gprs[2];
 229
 230 badframe:
 231         force_sig(SIGSEGV, current);
 232         return 0;
 233 }
 234
 235 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 236 {
 237         rt_sigframe *frame = (rt_sigframe *)regs->gprs[15];
 238         sigset_t set;
 239
 240         if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
 241                 goto badframe;
 242         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 243                 goto badframe;
 244
 245         sigdelsetmask(&set, ~_BLOCKABLE);
 246         spin_lock_irq(&current->sighand->siglock);
 247         current->blocked = set;
 248         recalc_sigpending();
 249         spin_unlock_irq(&current->sighand->siglock);
 250
 251         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 252                 goto badframe;
 253
 254         /* It is more difficult to avoid calling this function than to
 255            call it and ignore errors.  */
 256         do_sigaltstack(&frame->uc.uc_stack, NULL, regs->gprs[15]);
 257         return regs->gprs[2];
 258
 259 badframe:
 260         force_sig(SIGSEGV, current);
 261         return 0;
 262 }
 263
 264 /*
 265  * Set up a signal frame.
 266  */
 267
 268
 269 /*
 270  * Determine which stack to use..
 271  */
 272 static inline void *
 273 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 274 {
 275         unsigned long sp;
 276
 277         /* Default to using normal stack */
 278         sp = regs->gprs[15];
 279
 280         /* This is the X/Open sanctioned signal stack switching.  */
 281         if (ka->sa.sa_flags & SA_ONSTACK) {
 282                 if (! on_sig_stack(sp))
 283                         sp = current->sas_ss_sp + current->sas_ss_size;
 284         }
 285
 286         /* This is the legacy signal stack switching. */
 287         else if (!user_mode(regs) &&
 288                  !(ka->sa.sa_flags & SA_RESTORER) &&
 289                  ka->sa.sa_restorer) {
 290                 sp = (unsigned long) ka->sa.sa_restorer;
 291         }
 292
 293         return (void *)((sp - frame_size) & -8ul);
 294 }
 295
 296 static inline int map_signal(int sig)
 297 {
 298         if (current_thread_info()->exec_domain
 299             && current_thread_info()->exec_domain->signal_invmap
 300             && sig < 32)
 301                 return current_thread_info()->exec_domain->signal_invmap[sig];
 302         else
 303                 return sig;
 304 }
 305
 306 static void setup_frame(int sig, struct k_sigaction *ka,
 307                         sigset_t *set, struct pt_regs * regs)
 308 {
 309         sigframe *frame = get_sigframe(ka, regs, sizeof(sigframe));
 310         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 311                 goto give_sigsegv;
 312
 313         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 314                 goto give_sigsegv;
 315
 316         if (save_sigregs(regs, &frame->sregs))
 317                 goto give_sigsegv;
 318         if (__put_user(&frame->sregs, &frame->sc.sregs))
 319                 goto give_sigsegv;
 320
 321         /* Set up to return from userspace.  If provided, use a stub
 322            already in userspace.  */
 323         if (ka->sa.sa_flags & SA_RESTORER) {
 324                 regs->gprs[14] = (unsigned long)
 325                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 326         } else {
 327                 regs->gprs[14] = (unsigned long)
 328                         frame->retcode | PSW_ADDR_AMODE;
 329                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 330                                (u16 *)(frame->retcode)))
 331                         goto give_sigsegv;
 332         }
 333
 334         /* Set up backchain. */
 335         if (__put_user(regs->gprs[15], (addr_t *) frame))
 336                 goto give_sigsegv;
 337
 338         /* Set up registers for signal handler */
 339         regs->gprs[15] = (unsigned long) frame;
 340         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 341
 342         regs->gprs[2] = map_signal(sig);
 343         regs->gprs[3] = (unsigned long) &frame->sc;
 344
 345         /* We forgot to include these in the sigcontext.
 346            To avoid breaking binary compatibility, they are passed as args. */
 347         regs->gprs[4] = current->thread.trap_no;
 348         regs->gprs[5] = current->thread.prot_addr;
 349         return;
 350
 351 give_sigsegv:
 352         if (sig == SIGSEGV)
 353                 ka->sa.sa_handler = SIG_DFL;
 354         force_sig(SIGSEGV, current);
 355 }
 356
 357 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 358                            sigset_t *set, struct pt_regs * regs)
 359 {
 360         int err = 0;
 361         rt_sigframe *frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 362         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 363                 goto give_sigsegv;
 364
 365         if (copy_siginfo_to_user(&frame->info, info))
 366                 goto give_sigsegv;
 367
 368         /* Create the ucontext.  */
 369         err |= __put_user(0, &frame->uc.uc_flags);
 370         err |= __put_user(0, &frame->uc.uc_link);
 371         err |= __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 372         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 373                           &frame->uc.uc_stack.ss_flags);
 374         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 375         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 376         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 377         if (err)
 378                 goto give_sigsegv;
 379
 380         /* Set up to return from userspace.  If provided, use a stub
 381            already in userspace.  */
 382         if (ka->sa.sa_flags & SA_RESTORER) {
 383                 regs->gprs[14] = (unsigned long)
 384                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 385         } else {
 386                 regs->gprs[14] = (unsigned long)
 387                         frame->retcode | PSW_ADDR_AMODE;
 388                 err |= __put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 389                                   (u16 *)(frame->retcode));
 390         }
 391
 392         /* Set up backchain. */
 393         if (__put_user(regs->gprs[15], (addr_t *) frame))
 394                 goto give_sigsegv;
 395
 396         /* Set up registers for signal handler */
 397         regs->gprs[15] = (unsigned long) frame;
 398         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 399
 400         regs->gprs[2] = map_signal(sig);
 401         regs->gprs[3] = (unsigned long) &frame->info;
 402         regs->gprs[4] = (unsigned long) &frame->uc;
 403         return;
 404
 405 give_sigsegv:
 406         if (sig == SIGSEGV)
 407                 ka->sa.sa_handler = SIG_DFL;
 408         force_sig(SIGSEGV, current);
 409 }
 410
 411 /*
 412  * OK, we're invoking a handler
 413  */
 414
 415 static void
 416 handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 417         struct pt_regs * regs)
 418 {
 419         struct k_sigaction *ka = &current->sighand->action[sig-1];
 420
 421         /* Set up the stack frame */
 422         if (ka->sa.sa_flags & SA_SIGINFO)
 423                 setup_rt_frame(sig, ka, info, oldset, regs);
 424         else
 425                 setup_frame(sig, ka, oldset, regs);
 426
 427         if (ka->sa.sa_flags & SA_ONESHOT)
 428                 ka->sa.sa_handler = SIG_DFL;
 429
 430         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 431                 spin_lock_irq(&current->sighand->siglock);
 432                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 433                 sigaddset(&current->blocked,sig);
 434                 recalc_sigpending();
 435                 spin_unlock_irq(&current->sighand->siglock);
 436         }
 437 }
 438
 439 /*
 440  * Note that 'init' is a special process: it doesn't get signals it doesn't
 441  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 442  * mistake.
 443  *
 444  * Note that we go through the signals twice: once to check the signals that
 445  * the kernel can handle, and then we build all the user-level signal handling
 446  * stack-frames in one go after that.
 447  */
 448 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 449 {
 450         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 451         siginfo_t info;
 452         int signr;
 453
 454         /*
 455          * We want the common case to go fast, which
 456          * is why we may in certain cases get here from
 457          * kernel mode. Just return without doing anything
 458          * if so.
 459          */
 460         if (!user_mode(regs))
 461                 return 1;
 462
 463         if (!oldset)
 464                 oldset = &current->blocked;
 465
 466         /* Are we from a system call? */
 467         if (regs->trap == __LC_SVC_OLD_PSW) {
 468                 continue_addr = regs->psw.addr;
 469                 restart_addr = continue_addr - regs->ilc;
 470                 retval = regs->gprs[2];
 471
 472                 /* Prepare for system call restart.  We do this here so that a
 473                    debugger will see the already changed PSW. */
 474                 if (retval == -ERESTARTNOHAND ||
 475                     retval == -ERESTARTSYS ||
 476                     retval == -ERESTARTNOINTR) {
 477                         regs->gprs[2] = regs->orig_gpr2;
 478                         regs->psw.addr = restart_addr;
 479                 } else if (retval == -ERESTART_RESTARTBLOCK) {
 480                         regs->gprs[2] = -EINTR;
 481                 }
 482         }
 483
 484         /* Get signal to deliver.  When running under ptrace, at this point
 485            the debugger may change all our registers ... */
 486         signr = get_signal_to_deliver(&info, regs, NULL);
 487
 488         /* Depending on the signal settings we may need to revert the
 489            decision to restart the system call. */
 490         if (signr > 0 && regs->psw.addr == restart_addr) {
 491                 if (retval == -ERESTARTNOHAND
 492                     || (retval == -ERESTARTSYS
 493                          && !(current->sighand->action[signr-1].sa.sa_flags
 494                               & SA_RESTART))) {
 495                         regs->gprs[2] = -EINTR;
 496                         regs->psw.addr = continue_addr;
 497                 }
 498         }
 499
 500         if (signr > 0) {
 501                 /* Whee!  Actually deliver the signal.  */
 502 #ifdef CONFIG_S390_SUPPORT
 503                 if (test_thread_flag(TIF_31BIT)) {
 504                         extern void handle_signal32(unsigned long sig,
 505                                                     siginfo_t *info,
 506                                                     sigset_t *oldset,
 507                                                     struct pt_regs *regs);
 508                         handle_signal32(signr, &info, oldset, regs);
 509                         return 1;
 510                 }
 511 #endif
 512                 handle_signal(signr, &info, oldset, regs);
 513                 return 1;
 514         }
 515
 516         /* Restart a different system call. */
 517         if (retval == -ERESTART_RESTARTBLOCK
 518             && regs->psw.addr == continue_addr) {
 519                 regs->gprs[2] = __NR_restart_syscall;
 520                 set_thread_flag(TIF_RESTART_SVC);
 521         }
 522         return 0;
 523 }