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