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