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