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