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                         return -EFAULT;
  85                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  86                 __get_user(mask, &act->sa_mask);
  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                         return -EFAULT;
  97                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  98                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  99         }
 100
 101         return ret;
 102 }
 103
 104 asmlinkage long
 105 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 106                                         struct pt_regs *regs)
 107 {
 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         unsigned long old_mask = regs->psw.mask;
 117         _sigregs user_sregs;
 118
 119         save_access_regs(current->thread.acrs);
 120
 121         /* Copy a 'clean' PSW mask to the user to avoid leaking
 122            information about whether PER is currently on.  */
 123         regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
 124         memcpy(&user_sregs.regs.psw, &regs->psw, sizeof(sregs->regs.psw) +
 125                sizeof(sregs->regs.gprs));
 126         regs->psw.mask = old_mask;
 127         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 128                sizeof(sregs->regs.acrs));
 129         /*
 130          * We have to store the fp registers to current->thread.fp_regs
 131          * to merge them with the emulated registers.
 132          */
 133         save_fp_regs(&current->thread.fp_regs);
 134         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 135                sizeof(s390_fp_regs));
 136         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 137 }
 138
 139 /* Returns positive number on error */
 140 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 141 {
 142         unsigned long old_mask = regs->psw.mask;
 143         int err;
 144         _sigregs user_sregs;
 145
 146         /* Alwys make any pending restarted system call return -EINTR */
 147         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 148
 149         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 150         regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);
 151         regs->psw.addr |= PSW_ADDR_AMODE;
 152         if (err)
 153                 return err;
 154         memcpy(&regs->psw, &user_sregs.regs.psw, sizeof(sregs->regs.psw) +
 155                sizeof(sregs->regs.gprs));
 156         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 157                sizeof(sregs->regs.acrs));
 158         restore_access_regs(current->thread.acrs);
 159
 160         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 161                sizeof(s390_fp_regs));
 162         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 163
 164         restore_fp_regs(&current->thread.fp_regs);
 165         regs->trap = -1;        /* disable syscall checks */
 166         return 0;
 167 }
 168
 169 asmlinkage long sys_sigreturn(struct pt_regs *regs)
 170 {
 171         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 172         sigset_t set;
 173
 174         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 175                 goto badframe;
 176         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 177                 goto badframe;
 178
 179         sigdelsetmask(&set, ~_BLOCKABLE);
 180         spin_lock_irq(&current->sighand->siglock);
 181         current->blocked = set;
 182         recalc_sigpending();
 183         spin_unlock_irq(&current->sighand->siglock);
 184
 185         if (restore_sigregs(regs, &frame->sregs))
 186                 goto badframe;
 187
 188         return regs->gprs[2];
 189
 190 badframe:
 191         force_sig(SIGSEGV, current);
 192         return 0;
 193 }
 194
 195 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 196 {
 197         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 198         sigset_t set;
 199
 200         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 201                 goto badframe;
 202         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 203                 goto badframe;
 204
 205         sigdelsetmask(&set, ~_BLOCKABLE);
 206         spin_lock_irq(&current->sighand->siglock);
 207         current->blocked = set;
 208         recalc_sigpending();
 209         spin_unlock_irq(&current->sighand->siglock);
 210
 211         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 212                 goto badframe;
 213
 214         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 215                            regs->gprs[15]) == -EFAULT)
 216                 goto badframe;
 217         return regs->gprs[2];
 218
 219 badframe:
 220         force_sig(SIGSEGV, current);
 221         return 0;
 222 }
 223
 224 /*
 225  * Set up a signal frame.
 226  */
 227
 228
 229 /*
 230  * Determine which stack to use..
 231  */
 232 static inline void __user *
 233 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 234 {
 235         unsigned long sp;
 236
 237         /* Default to using normal stack */
 238         sp = regs->gprs[15];
 239
 240         /* This is the X/Open sanctioned signal stack switching.  */
 241         if (ka->sa.sa_flags & SA_ONSTACK) {
 242                 if (! sas_ss_flags(sp))
 243                         sp = current->sas_ss_sp + current->sas_ss_size;
 244         }
 245
 246         /* This is the legacy signal stack switching. */
 247         else if (!user_mode(regs) &&
 248                  !(ka->sa.sa_flags & SA_RESTORER) &&
 249                  ka->sa.sa_restorer) {
 250                 sp = (unsigned long) ka->sa.sa_restorer;
 251         }
 252
 253         return (void __user *)((sp - frame_size) & -8ul);
 254 }
 255
 256 static inline int map_signal(int sig)
 257 {
 258         if (current_thread_info()->exec_domain
 259             && current_thread_info()->exec_domain->signal_invmap
 260             && sig < 32)
 261                 return current_thread_info()->exec_domain->signal_invmap[sig];
 262         else
 263                 return sig;
 264 }
 265
 266 static int setup_frame(int sig, struct k_sigaction *ka,
 267                        sigset_t *set, struct pt_regs * regs)
 268 {
 269         sigframe __user *frame;
 270
 271         frame = get_sigframe(ka, regs, sizeof(sigframe));
 272         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 273                 goto give_sigsegv;
 274
 275         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 276                 goto give_sigsegv;
 277
 278         if (save_sigregs(regs, &frame->sregs))
 279                 goto give_sigsegv;
 280         if (__put_user(&frame->sregs, &frame->sc.sregs))
 281                 goto give_sigsegv;
 282
 283         /* Set up to return from userspace.  If provided, use a stub
 284            already in userspace.  */
 285         if (ka->sa.sa_flags & SA_RESTORER) {
 286                 regs->gprs[14] = (unsigned long)
 287                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 288         } else {
 289                 regs->gprs[14] = (unsigned long)
 290                         frame->retcode | PSW_ADDR_AMODE;
 291                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 292                                (u16 __user *)(frame->retcode)))
 293                         goto give_sigsegv;
 294         }
 295
 296         /* Set up backchain. */
 297         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 298                 goto give_sigsegv;
 299
 300         /* Set up registers for signal handler */
 301         regs->gprs[15] = (unsigned long) frame;
 302         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 303
 304         regs->gprs[2] = map_signal(sig);
 305         regs->gprs[3] = (unsigned long) &frame->sc;
 306
 307         /* We forgot to include these in the sigcontext.
 308            To avoid breaking binary compatibility, they are passed as args. */
 309         regs->gprs[4] = current->thread.trap_no;
 310         regs->gprs[5] = current->thread.prot_addr;
 311
 312         /* Place signal number on stack to allow backtrace from handler.  */
 313         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 314                 goto give_sigsegv;
 315         return 0;
 316
 317 give_sigsegv:
 318         force_sigsegv(sig, current);
 319         return -EFAULT;
 320 }
 321
 322 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 323                            sigset_t *set, struct pt_regs * regs)
 324 {
 325         int err = 0;
 326         rt_sigframe __user *frame;
 327
 328         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 329         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 330                 goto give_sigsegv;
 331
 332         if (copy_siginfo_to_user(&frame->info, info))
 333                 goto give_sigsegv;
 334
 335         /* Create the ucontext.  */
 336         err |= __put_user(0, &frame->uc.uc_flags);
 337         err |= __put_user(NULL, &frame->uc.uc_link);
 338         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 339         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 340                           &frame->uc.uc_stack.ss_flags);
 341         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 342         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 343         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 344         if (err)
 345                 goto give_sigsegv;
 346
 347         /* Set up to return from userspace.  If provided, use a stub
 348            already in userspace.  */
 349         if (ka->sa.sa_flags & SA_RESTORER) {
 350                 regs->gprs[14] = (unsigned long)
 351                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 352         } else {
 353                 regs->gprs[14] = (unsigned long)
 354                         frame->retcode | PSW_ADDR_AMODE;
 355                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 356                                (u16 __user *)(frame->retcode)))
 357                         goto give_sigsegv;
 358         }
 359
 360         /* Set up backchain. */
 361         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 362                 goto give_sigsegv;
 363
 364         /* Set up registers for signal handler */
 365         regs->gprs[15] = (unsigned long) frame;
 366         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 367
 368         regs->gprs[2] = map_signal(sig);
 369         regs->gprs[3] = (unsigned long) &frame->info;
 370         regs->gprs[4] = (unsigned long) &frame->uc;
 371         return 0;
 372
 373 give_sigsegv:
 374         force_sigsegv(sig, current);
 375         return -EFAULT;
 376 }
 377
 378 /*
 379  * OK, we're invoking a handler
 380  */
 381
 382 static int
 383 handle_signal(unsigned long sig, struct k_sigaction *ka,
 384               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 385 {
 386         int ret;
 387
 388         /* Set up the stack frame */
 389         if (ka->sa.sa_flags & SA_SIGINFO)
 390                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 391         else
 392                 ret = setup_frame(sig, ka, oldset, regs);
 393
 394         if (ret == 0) {
 395                 spin_lock_irq(&current->sighand->siglock);
 396                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 397                 if (!(ka->sa.sa_flags & SA_NODEFER))
 398                         sigaddset(&current->blocked,sig);
 399                 recalc_sigpending();
 400                 spin_unlock_irq(&current->sighand->siglock);
 401         }
 402
 403         return ret;
 404 }
 405
 406 /*
 407  * Note that 'init' is a special process: it doesn't get signals it doesn't
 408  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 409  * mistake.
 410  *
 411  * Note that we go through the signals twice: once to check the signals that
 412  * the kernel can handle, and then we build all the user-level signal handling
 413  * stack-frames in one go after that.
 414  */
 415 void do_signal(struct pt_regs *regs)
 416 {
 417         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 418         siginfo_t info;
 419         int signr;
 420         struct k_sigaction ka;
 421         sigset_t *oldset;
 422
 423         /*
 424          * We want the common case to go fast, which
 425          * is why we may in certain cases get here from
 426          * kernel mode. Just return without doing anything
 427          * if so.
 428          */
 429         if (!user_mode(regs))
 430                 return;
 431
 432         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 433                 oldset = &current->saved_sigmask;
 434         else
 435                 oldset = &current->blocked;
 436
 437         /* Are we from a system call? */
 438         if (regs->trap == __LC_SVC_OLD_PSW) {
 439                 continue_addr = regs->psw.addr;
 440                 restart_addr = continue_addr - regs->ilc;
 441                 retval = regs->gprs[2];
 442
 443                 /* Prepare for system call restart.  We do this here so that a
 444                    debugger will see the already changed PSW. */
 445                 switch (retval) {
 446                 case -ERESTARTNOHAND:
 447                 case -ERESTARTSYS:
 448                 case -ERESTARTNOINTR:
 449                         regs->gprs[2] = regs->orig_gpr2;
 450                         regs->psw.addr = restart_addr;
 451                         break;
 452                 case -ERESTART_RESTARTBLOCK:
 453                         regs->gprs[2] = -EINTR;
 454                 }
 455                 regs->trap = -1;        /* Don't deal with this again. */
 456         }
 457
 458         /* Get signal to deliver.  When running under ptrace, at this point
 459            the debugger may change all our registers ... */
 460         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 461
 462         /* Depending on the signal settings we may need to revert the
 463            decision to restart the system call. */
 464         if (signr > 0 && regs->psw.addr == restart_addr) {
 465                 if (retval == -ERESTARTNOHAND
 466                     || (retval == -ERESTARTSYS
 467                          && !(current->sighand->action[signr-1].sa.sa_flags
 468                               & SA_RESTART))) {
 469                         regs->gprs[2] = -EINTR;
 470                         regs->psw.addr = continue_addr;
 471                 }
 472         }
 473
 474         if (signr > 0) {
 475                 /* Whee!  Actually deliver the signal.  */
 476 #ifdef CONFIG_COMPAT
 477                 if (test_thread_flag(TIF_31BIT)) {
 478                         extern int handle_signal32(unsigned long sig,
 479                                                    struct k_sigaction *ka,
 480                                                    siginfo_t *info,
 481                                                    sigset_t *oldset,
 482                                                    struct pt_regs *regs);
 483                         if (handle_signal32(
 484                                     signr, &ka, &info, oldset, regs) == 0) {
 485                                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 486                                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 487                         }
 488                         return;
 489                 }
 490 #endif
 491                 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
 492                         /*
 493                          * A signal was successfully delivered; the saved
 494                          * sigmask will have been stored in the signal frame,
 495                          * and will be restored by sigreturn, so we can simply
 496                          * clear the TIF_RESTORE_SIGMASK flag.
 497                          */
 498                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 499                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 500                 }
 501                 return;
 502         }
 503
 504         /*
 505          * If there's no signal to deliver, we just put the saved sigmask back.
 506          */
 507         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 508                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 509                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 510         }
 511
 512         /* Restart a different system call. */
 513         if (retval == -ERESTART_RESTARTBLOCK
 514             && regs->psw.addr == continue_addr) {
 515                 regs->gprs[2] = __NR_restart_syscall;
 516                 set_thread_flag(TIF_RESTART_SVC);
 517         }
 518 }