arch/s390/kernel/signal.c

   1 /*
   2  *  arch/s390/kernel/signal.c
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   7  *
   8  *    Based on Intel version
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  *
  12  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  13  */
  14
  15 #include <linux/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/smp_lock.h>
  20 #include <linux/kernel.h>
  21 #include <linux/signal.h>
  22 #include <linux/errno.h>
  23 #include <linux/wait.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/unistd.h>
  26 #include <linux/stddef.h>
  27 #include <linux/tty.h>
  28 #include <linux/personality.h>
  29 #include <linux/binfmts.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/lowcore.h>
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36
  37 typedef struct
  38 {
  39         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  40         struct sigcontext sc;
  41         _sigregs sregs;
  42         int signo;
  43         __u8 retcode[S390_SYSCALL_SIZE];
  44 } sigframe;
  45
  46 typedef struct
  47 {
  48         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  49         __u8 retcode[S390_SYSCALL_SIZE];
  50         struct siginfo info;
  51         struct ucontext uc;
  52 } rt_sigframe;
  53
  54 int do_signal(struct pt_regs *regs, sigset_t *oldset);
  55
  56 /*
  57  * Atomically swap in the new signal mask, and wait for a signal.
  58  */
  59 asmlinkage int
  60 sys_sigsuspend(struct pt_regs * regs, int history0, int history1,
  61                old_sigset_t mask)
  62 {
  63         sigset_t saveset;
  64
  65         mask &= _BLOCKABLE;
  66         spin_lock_irq(&current->sighand->siglock);
  67         saveset = current->blocked;
  68         siginitset(&current->blocked, mask);
  69         recalc_sigpending();
  70         spin_unlock_irq(&current->sighand->siglock);
  71         regs->gprs[2] = -EINTR;
  72
  73         while (1) {
  74                 set_current_state(TASK_INTERRUPTIBLE);
  75                 schedule();
  76                 if (do_signal(regs, &saveset))
  77                         return -EINTR;
  78         }
  79 }
  80
  81 asmlinkage long
  82 sys_rt_sigsuspend(struct pt_regs *regs, sigset_t __user *unewset,
  83                                                 size_t sigsetsize)
  84 {
  85         sigset_t saveset, newset;
  86
  87         /* XXX: Don't preclude handling different sized sigset_t's.  */
  88         if (sigsetsize != sizeof(sigset_t))
  89                 return -EINVAL;
  90
  91         if (copy_from_user(&newset, unewset, sizeof(newset)))
  92                 return -EFAULT;
  93         sigdelsetmask(&newset, ~_BLOCKABLE);
  94
  95         spin_lock_irq(&current->sighand->siglock);
  96         saveset = current->blocked;
  97         current->blocked = newset;
  98         recalc_sigpending();
  99         spin_unlock_irq(&current->sighand->siglock);
 100         regs->gprs[2] = -EINTR;
 101
 102         while (1) {
 103                 set_current_state(TASK_INTERRUPTIBLE);
 104                 schedule();
 105                 if (do_signal(regs, &saveset))
 106                         return -EINTR;
 107         }
 108 }
 109
 110 asmlinkage long
 111 sys_sigaction(int sig, const struct old_sigaction __user *act,
 112               struct old_sigaction __user *oact)
 113 {
 114         struct k_sigaction new_ka, old_ka;
 115         int ret;
 116
 117         if (act) {
 118                 old_sigset_t mask;
 119                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 120                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 121                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 122                         return -EFAULT;
 123                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 124                 __get_user(mask, &act->sa_mask);
 125                 siginitset(&new_ka.sa.sa_mask, mask);
 126         }
 127
 128         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 129
 130         if (!ret && oact) {
 131                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 132                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 133                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 134                         return -EFAULT;
 135                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 136                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 137         }
 138
 139         return ret;
 140 }
 141
 142 asmlinkage long
 143 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 144                                         struct pt_regs *regs)
 145 {
 146         return do_sigaltstack(uss, uoss, regs->gprs[15]);
 147 }
 148
 149
 150
 151 /* Returns non-zero on fault. */
 152 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 153 {
 154         unsigned long old_mask = regs->psw.mask;
 155         int err;
 156
 157         save_access_regs(current->thread.acrs);
 158
 159         /* Copy a 'clean' PSW mask to the user to avoid leaking
 160            information about whether PER is currently on.  */
 161         regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
 162         err = __copy_to_user(&sregs->regs.psw, &regs->psw,
 163                              sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
 164         regs->psw.mask = old_mask;
 165         if (err != 0)
 166                 return err;
 167         err = __copy_to_user(&sregs->regs.acrs, current->thread.acrs,
 168                              sizeof(sregs->regs.acrs));
 169         if (err != 0)
 170                 return err;
 171         /*
 172          * We have to store the fp registers to current->thread.fp_regs
 173          * to merge them with the emulated registers.
 174          */
 175         save_fp_regs(&current->thread.fp_regs);
 176         return __copy_to_user(&sregs->fpregs, &current->thread.fp_regs,
 177                               sizeof(s390_fp_regs));
 178 }
 179
 180 /* Returns positive number on error */
 181 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 182 {
 183         unsigned long old_mask = regs->psw.mask;
 184         int err;
 185
 186         /* Alwys make any pending restarted system call return -EINTR */
 187         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 188
 189         err = __copy_from_user(&regs->psw, &sregs->regs.psw,
 190                                sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
 191         regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);
 192         regs->psw.addr |= PSW_ADDR_AMODE;
 193         if (err)
 194                 return err;
 195         err = __copy_from_user(&current->thread.acrs, &sregs->regs.acrs,
 196                                sizeof(sregs->regs.acrs));
 197         if (err)
 198                 return err;
 199         restore_access_regs(current->thread.acrs);
 200
 201         err = __copy_from_user(&current->thread.fp_regs, &sregs->fpregs,
 202                                sizeof(s390_fp_regs));
 203         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 204         if (err)
 205                 return err;
 206
 207         restore_fp_regs(&current->thread.fp_regs);
 208         regs->trap = -1;        /* disable syscall checks */
 209         return 0;
 210 }
 211
 212 asmlinkage long sys_sigreturn(struct pt_regs *regs)
 213 {
 214         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 215         sigset_t set;
 216
 217         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 218                 goto badframe;
 219         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 220                 goto badframe;
 221
 222         sigdelsetmask(&set, ~_BLOCKABLE);
 223         spin_lock_irq(&current->sighand->siglock);
 224         current->blocked = set;
 225         recalc_sigpending();
 226         spin_unlock_irq(&current->sighand->siglock);
 227
 228         if (restore_sigregs(regs, &frame->sregs))
 229                 goto badframe;
 230
 231         return regs->gprs[2];
 232
 233 badframe:
 234         force_sig(SIGSEGV, current);
 235         return 0;
 236 }
 237
 238 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 239 {
 240         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 241         sigset_t set;
 242
 243         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 244                 goto badframe;
 245         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 246                 goto badframe;
 247
 248         sigdelsetmask(&set, ~_BLOCKABLE);
 249         spin_lock_irq(&current->sighand->siglock);
 250         current->blocked = set;
 251         recalc_sigpending();
 252         spin_unlock_irq(&current->sighand->siglock);
 253
 254         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 255                 goto badframe;
 256
 257         /* It is more difficult to avoid calling this function than to
 258            call it and ignore errors.  */
 259         do_sigaltstack(&frame->uc.uc_stack, NULL, regs->gprs[15]);
 260         return regs->gprs[2];
 261
 262 badframe:
 263         force_sig(SIGSEGV, current);
 264         return 0;
 265 }
 266
 267 /*
 268  * Set up a signal frame.
 269  */
 270
 271
 272 /*
 273  * Determine which stack to use..
 274  */
 275 static inline void __user *
 276 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 277 {
 278         unsigned long sp;
 279
 280         /* Default to using normal stack */
 281         sp = regs->gprs[15];
 282
 283         /* This is the X/Open sanctioned signal stack switching.  */
 284         if (ka->sa.sa_flags & SA_ONSTACK) {
 285                 if (! sas_ss_flags(sp))
 286                         sp = current->sas_ss_sp + current->sas_ss_size;
 287         }
 288
 289         /* This is the legacy signal stack switching. */
 290         else if (!user_mode(regs) &&
 291                  !(ka->sa.sa_flags & SA_RESTORER) &&
 292                  ka->sa.sa_restorer) {
 293                 sp = (unsigned long) ka->sa.sa_restorer;
 294         }
 295
 296         return (void __user *)((sp - frame_size) & -8ul);
 297 }
 298
 299 static inline int map_signal(int sig)
 300 {
 301         if (current_thread_info()->exec_domain
 302             && current_thread_info()->exec_domain->signal_invmap
 303             && sig < 32)
 304                 return current_thread_info()->exec_domain->signal_invmap[sig];
 305         else
 306                 return sig;
 307 }
 308
 309 static void setup_frame(int sig, struct k_sigaction *ka,
 310                         sigset_t *set, struct pt_regs * regs)
 311 {
 312         sigframe __user *frame;
 313
 314         frame = get_sigframe(ka, regs, sizeof(sigframe));
 315         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 316                 goto give_sigsegv;
 317
 318         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 319                 goto give_sigsegv;
 320
 321         if (save_sigregs(regs, &frame->sregs))
 322                 goto give_sigsegv;
 323         if (__put_user(&frame->sregs, &frame->sc.sregs))
 324                 goto give_sigsegv;
 325
 326         /* Set up to return from userspace.  If provided, use a stub
 327            already in userspace.  */
 328         if (ka->sa.sa_flags & SA_RESTORER) {
 329                 regs->gprs[14] = (unsigned long)
 330                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 331         } else {
 332                 regs->gprs[14] = (unsigned long)
 333                         frame->retcode | PSW_ADDR_AMODE;
 334                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 335                                (u16 __user *)(frame->retcode)))
 336                         goto give_sigsegv;
 337         }
 338
 339         /* Set up backchain. */
 340         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 341                 goto give_sigsegv;
 342
 343         /* Set up registers for signal handler */
 344         regs->gprs[15] = (unsigned long) frame;
 345         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 346
 347         regs->gprs[2] = map_signal(sig);
 348         regs->gprs[3] = (unsigned long) &frame->sc;
 349
 350         /* We forgot to include these in the sigcontext.
 351            To avoid breaking binary compatibility, they are passed as args. */
 352         regs->gprs[4] = current->thread.trap_no;
 353         regs->gprs[5] = current->thread.prot_addr;
 354
 355         /* Place signal number on stack to allow backtrace from handler.  */
 356         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 357                 goto give_sigsegv;
 358         return;
 359
 360 give_sigsegv:
 361         force_sigsegv(sig, current);
 362 }
 363
 364 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 365                            sigset_t *set, struct pt_regs * regs)
 366 {
 367         int err = 0;
 368         rt_sigframe __user *frame;
 369
 370         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 371         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 372                 goto give_sigsegv;
 373
 374         if (copy_siginfo_to_user(&frame->info, info))
 375                 goto give_sigsegv;
 376
 377         /* Create the ucontext.  */
 378         err |= __put_user(0, &frame->uc.uc_flags);
 379         err |= __put_user(0, &frame->uc.uc_link);
 380         err |= __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 381         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 382                           &frame->uc.uc_stack.ss_flags);
 383         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 384         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 385         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 386         if (err)
 387                 goto give_sigsegv;
 388
 389         /* Set up to return from userspace.  If provided, use a stub
 390            already in userspace.  */
 391         if (ka->sa.sa_flags & SA_RESTORER) {
 392                 regs->gprs[14] = (unsigned long)
 393                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 394         } else {
 395                 regs->gprs[14] = (unsigned long)
 396                         frame->retcode | PSW_ADDR_AMODE;
 397                 err |= __put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 398                                   (u16 __user *)(frame->retcode));
 399         }
 400
 401         /* Set up backchain. */
 402         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 403                 goto give_sigsegv;
 404
 405         /* Set up registers for signal handler */
 406         regs->gprs[15] = (unsigned long) frame;
 407         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 408
 409         regs->gprs[2] = map_signal(sig);
 410         regs->gprs[3] = (unsigned long) &frame->info;
 411         regs->gprs[4] = (unsigned long) &frame->uc;
 412         return;
 413
 414 give_sigsegv:
 415         force_sigsegv(sig, current);
 416 }
 417
 418 /*
 419  * OK, we're invoking a handler
 420  */
 421
 422 static void
 423 handle_signal(unsigned long sig, struct k_sigaction *ka,
 424               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 425 {
 426         /* Set up the stack frame */
 427         if (ka->sa.sa_flags & SA_SIGINFO)
 428                 setup_rt_frame(sig, ka, info, oldset, regs);
 429         else
 430                 setup_frame(sig, ka, oldset, regs);
 431
 432         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 433                 spin_lock_irq(&current->sighand->siglock);
 434                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 435                 sigaddset(&current->blocked,sig);
 436                 recalc_sigpending();
 437                 spin_unlock_irq(&current->sighand->siglock);
 438         }
 439 }
 440
 441 /*
 442  * Note that 'init' is a special process: it doesn't get signals it doesn't
 443  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 444  * mistake.
 445  *
 446  * Note that we go through the signals twice: once to check the signals that
 447  * the kernel can handle, and then we build all the user-level signal handling
 448  * stack-frames in one go after that.
 449  */
 450 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 451 {
 452         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 453         siginfo_t info;
 454         int signr;
 455         struct k_sigaction ka;
 456
 457         /*
 458          * We want the common case to go fast, which
 459          * is why we may in certain cases get here from
 460          * kernel mode. Just return without doing anything
 461          * if so.
 462          */
 463         if (!user_mode(regs))
 464                 return 1;
 465
 466         if (!oldset)
 467                 oldset = &current->blocked;
 468
 469         /* Are we from a system call? */
 470         if (regs->trap == __LC_SVC_OLD_PSW) {
 471                 continue_addr = regs->psw.addr;
 472                 restart_addr = continue_addr - regs->ilc;
 473                 retval = regs->gprs[2];
 474
 475                 /* Prepare for system call restart.  We do this here so that a
 476                    debugger will see the already changed PSW. */
 477                 if (retval == -ERESTARTNOHAND ||
 478                     retval == -ERESTARTSYS ||
 479                     retval == -ERESTARTNOINTR) {
 480                         regs->gprs[2] = regs->orig_gpr2;
 481                         regs->psw.addr = restart_addr;
 482                 } else if (retval == -ERESTART_RESTARTBLOCK) {
 483                         regs->gprs[2] = -EINTR;
 484                 }
 485         }
 486
 487         /* Get signal to deliver.  When running under ptrace, at this point
 488            the debugger may change all our registers ... */
 489         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 490
 491         /* Depending on the signal settings we may need to revert the
 492            decision to restart the system call. */
 493         if (signr > 0 && regs->psw.addr == restart_addr) {
 494                 if (retval == -ERESTARTNOHAND
 495                     || (retval == -ERESTARTSYS
 496                          && !(current->sighand->action[signr-1].sa.sa_flags
 497                               & SA_RESTART))) {
 498                         regs->gprs[2] = -EINTR;
 499                         regs->psw.addr = continue_addr;
 500                 }
 501         }
 502
 503         if (signr > 0) {
 504                 /* Whee!  Actually deliver the signal.  */
 505 #ifdef CONFIG_S390_SUPPORT
 506                 if (test_thread_flag(TIF_31BIT)) {
 507                         extern void handle_signal32(unsigned long sig,
 508                                                     struct k_sigaction *ka,
 509                                                     siginfo_t *info,
 510                                                     sigset_t *oldset,
 511                                                     struct pt_regs *regs);
 512                         handle_signal32(signr, &ka, &info, oldset, regs);
 513                         return 1;
 514                 }
 515 #endif
 516                 handle_signal(signr, &ka, &info, oldset, regs);
 517                 return 1;
 518         }
 519
 520         /* Restart a different system call. */
 521         if (retval == -ERESTART_RESTARTBLOCK
 522             && regs->psw.addr == continue_addr) {
 523                 regs->gprs[2] = __NR_restart_syscall;
 524                 set_thread_flag(TIF_RESTART_SVC);
 525         }
 526         return 0;
 527 }