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/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 <linux/tracehook.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/lowcore.h>
  31 #include "entry.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                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  86                     __get_user(mask, &act->sa_mask))
  87                         return -EFAULT;
  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                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  98                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  99                         return -EFAULT;
 100         }
 101
 102         return ret;
 103 }
 104
 105 asmlinkage long
 106 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 107 {
 108         struct pt_regs *regs = task_pt_regs(current);
 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         _sigregs user_sregs;
 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         user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask);
 124         user_sregs.regs.psw.addr = regs->psw.addr;
 125         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 126         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 127                sizeof(sregs->regs.acrs));
 128         /*
 129          * We have to store the fp registers to current->thread.fp_regs
 130          * to merge them with the emulated registers.
 131          */
 132         save_fp_regs(&current->thread.fp_regs);
 133         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 134                sizeof(s390_fp_regs));
 135         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 136 }
 137
 138 /* Returns positive number on error */
 139 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 140 {
 141         int err;
 142         _sigregs user_sregs;
 143
 144         /* Alwys make any pending restarted system call return -EINTR */
 145         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 146
 147         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 148         if (err)
 149                 return err;
 150         regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
 151                                         user_sregs.regs.psw.mask);
 152         regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
 153         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 154         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 155                sizeof(sregs->regs.acrs));
 156         restore_access_regs(current->thread.acrs);
 157
 158         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 159                sizeof(s390_fp_regs));
 160         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 161
 162         restore_fp_regs(&current->thread.fp_regs);
 163         regs->svcnr = 0;        /* disable syscall checks */
 164         return 0;
 165 }
 166
 167 asmlinkage long sys_sigreturn(void)
 168 {
 169         struct pt_regs *regs = task_pt_regs(current);
 170         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 171         sigset_t set;
 172
 173         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 174                 goto badframe;
 175         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 176                 goto badframe;
 177
 178         sigdelsetmask(&set, ~_BLOCKABLE);
 179         spin_lock_irq(&current->sighand->siglock);
 180         current->blocked = set;
 181         recalc_sigpending();
 182         spin_unlock_irq(&current->sighand->siglock);
 183
 184         if (restore_sigregs(regs, &frame->sregs))
 185                 goto badframe;
 186
 187         return regs->gprs[2];
 188
 189 badframe:
 190         force_sig(SIGSEGV, current);
 191         return 0;
 192 }
 193
 194 asmlinkage long sys_rt_sigreturn(void)
 195 {
 196         struct pt_regs *regs = task_pt_regs(current);
 197         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 198         sigset_t set;
 199
 200         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 201                 goto badframe;
 202         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 203                 goto badframe;
 204
 205         sigdelsetmask(&set, ~_BLOCKABLE);
 206         spin_lock_irq(&current->sighand->siglock);
 207         current->blocked = set;
 208         recalc_sigpending();
 209         spin_unlock_irq(&current->sighand->siglock);
 210
 211         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 212                 goto badframe;
 213
 214         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 215                            regs->gprs[15]) == -EFAULT)
 216                 goto badframe;
 217         return regs->gprs[2];
 218
 219 badframe:
 220         force_sig(SIGSEGV, current);
 221         return 0;
 222 }
 223
 224 /*
 225  * Set up a signal frame.
 226  */
 227
 228
 229 /*
 230  * Determine which stack to use..
 231  */
 232 static inline void __user *
 233 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 234 {
 235         unsigned long sp;
 236
 237         /* Default to using normal stack */
 238         sp = regs->gprs[15];
 239
 240         /* Overflow on alternate signal stack gives SIGSEGV. */
 241         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 242                 return (void __user *) -1UL;
 243
 244         /* This is the X/Open sanctioned signal stack switching.  */
 245         if (ka->sa.sa_flags & SA_ONSTACK) {
 246                 if (! sas_ss_flags(sp))
 247                         sp = current->sas_ss_sp + current->sas_ss_size;
 248         }
 249
 250         /* This is the legacy signal stack switching. */
 251         else if (!user_mode(regs) &&
 252                  !(ka->sa.sa_flags & SA_RESTORER) &&
 253                  ka->sa.sa_restorer) {
 254                 sp = (unsigned long) ka->sa.sa_restorer;
 255         }
 256
 257         return (void __user *)((sp - frame_size) & -8ul);
 258 }
 259
 260 static inline int map_signal(int sig)
 261 {
 262         if (current_thread_info()->exec_domain
 263             && current_thread_info()->exec_domain->signal_invmap
 264             && sig < 32)
 265                 return current_thread_info()->exec_domain->signal_invmap[sig];
 266         else
 267                 return sig;
 268 }
 269
 270 static int setup_frame(int sig, struct k_sigaction *ka,
 271                        sigset_t *set, struct pt_regs * regs)
 272 {
 273         sigframe __user *frame;
 274
 275         frame = get_sigframe(ka, regs, sizeof(sigframe));
 276         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 277                 goto give_sigsegv;
 278
 279         if (frame == (void __user *) -1UL)
 280                 goto give_sigsegv;
 281
 282         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 283                 goto give_sigsegv;
 284
 285         if (save_sigregs(regs, &frame->sregs))
 286                 goto give_sigsegv;
 287         if (__put_user(&frame->sregs, &frame->sc.sregs))
 288                 goto give_sigsegv;
 289
 290         /* Set up to return from userspace.  If provided, use a stub
 291            already in userspace.  */
 292         if (ka->sa.sa_flags & SA_RESTORER) {
 293                 regs->gprs[14] = (unsigned long)
 294                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 295         } else {
 296                 regs->gprs[14] = (unsigned long)
 297                         frame->retcode | PSW_ADDR_AMODE;
 298                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 299                                (u16 __user *)(frame->retcode)))
 300                         goto give_sigsegv;
 301         }
 302
 303         /* Set up backchain. */
 304         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 305                 goto give_sigsegv;
 306
 307         /* Set up registers for signal handler */
 308         regs->gprs[15] = (unsigned long) frame;
 309         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 310
 311         regs->gprs[2] = map_signal(sig);
 312         regs->gprs[3] = (unsigned long) &frame->sc;
 313
 314         /* We forgot to include these in the sigcontext.
 315            To avoid breaking binary compatibility, they are passed as args. */
 316         regs->gprs[4] = current->thread.trap_no;
 317         regs->gprs[5] = current->thread.prot_addr;
 318
 319         /* Place signal number on stack to allow backtrace from handler.  */
 320         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 321                 goto give_sigsegv;
 322         return 0;
 323
 324 give_sigsegv:
 325         force_sigsegv(sig, current);
 326         return -EFAULT;
 327 }
 328
 329 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 330                            sigset_t *set, struct pt_regs * regs)
 331 {
 332         int err = 0;
 333         rt_sigframe __user *frame;
 334
 335         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 336         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 337                 goto give_sigsegv;
 338
 339         if (frame == (void __user *) -1UL)
 340                 goto give_sigsegv;
 341
 342         if (copy_siginfo_to_user(&frame->info, info))
 343                 goto give_sigsegv;
 344
 345         /* Create the ucontext.  */
 346         err |= __put_user(0, &frame->uc.uc_flags);
 347         err |= __put_user(NULL, &frame->uc.uc_link);
 348         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 349         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 350                           &frame->uc.uc_stack.ss_flags);
 351         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 352         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 353         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 354         if (err)
 355                 goto give_sigsegv;
 356
 357         /* Set up to return from userspace.  If provided, use a stub
 358            already in userspace.  */
 359         if (ka->sa.sa_flags & SA_RESTORER) {
 360                 regs->gprs[14] = (unsigned long)
 361                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 362         } else {
 363                 regs->gprs[14] = (unsigned long)
 364                         frame->retcode | PSW_ADDR_AMODE;
 365                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 366                                (u16 __user *)(frame->retcode)))
 367                         goto give_sigsegv;
 368         }
 369
 370         /* Set up backchain. */
 371         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 372                 goto give_sigsegv;
 373
 374         /* Set up registers for signal handler */
 375         regs->gprs[15] = (unsigned long) frame;
 376         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 377
 378         regs->gprs[2] = map_signal(sig);
 379         regs->gprs[3] = (unsigned long) &frame->info;
 380         regs->gprs[4] = (unsigned long) &frame->uc;
 381         return 0;
 382
 383 give_sigsegv:
 384         force_sigsegv(sig, current);
 385         return -EFAULT;
 386 }
 387
 388 /*
 389  * OK, we're invoking a handler
 390  */
 391
 392 static int
 393 handle_signal(unsigned long sig, struct k_sigaction *ka,
 394               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 395 {
 396         int ret;
 397
 398         /* Set up the stack frame */
 399         if (ka->sa.sa_flags & SA_SIGINFO)
 400                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 401         else
 402                 ret = setup_frame(sig, ka, oldset, regs);
 403
 404         if (ret == 0) {
 405                 spin_lock_irq(&current->sighand->siglock);
 406                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 407                 if (!(ka->sa.sa_flags & SA_NODEFER))
 408                         sigaddset(&current->blocked,sig);
 409                 recalc_sigpending();
 410                 spin_unlock_irq(&current->sighand->siglock);
 411         }
 412
 413         return ret;
 414 }
 415
 416 /*
 417  * Note that 'init' is a special process: it doesn't get signals it doesn't
 418  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 419  * mistake.
 420  *
 421  * Note that we go through the signals twice: once to check the signals that
 422  * the kernel can handle, and then we build all the user-level signal handling
 423  * stack-frames in one go after that.
 424  */
 425 void do_signal(struct pt_regs *regs)
 426 {
 427         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 428         siginfo_t info;
 429         int signr;
 430         struct k_sigaction ka;
 431         sigset_t *oldset;
 432
 433         /*
 434          * We want the common case to go fast, which
 435          * is why we may in certain cases get here from
 436          * kernel mode. Just return without doing anything
 437          * if so.
 438          */
 439         if (!user_mode(regs))
 440                 return;
 441
 442         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 443                 oldset = &current->saved_sigmask;
 444         else
 445                 oldset = &current->blocked;
 446
 447         /* Are we from a system call? */
 448         if (regs->svcnr) {
 449                 continue_addr = regs->psw.addr;
 450                 restart_addr = continue_addr - regs->ilc;
 451                 retval = regs->gprs[2];
 452
 453                 /* Prepare for system call restart.  We do this here so that a
 454                    debugger will see the already changed PSW. */
 455                 switch (retval) {
 456                 case -ERESTARTNOHAND:
 457                 case -ERESTARTSYS:
 458                 case -ERESTARTNOINTR:
 459                         regs->gprs[2] = regs->orig_gpr2;
 460                         regs->psw.addr = restart_addr;
 461                         break;
 462                 case -ERESTART_RESTARTBLOCK:
 463                         regs->gprs[2] = -EINTR;
 464                 }
 465                 regs->svcnr = 0;        /* Don't deal with this again. */
 466         }
 467
 468         /* Get signal to deliver.  When running under ptrace, at this point
 469            the debugger may change all our registers ... */
 470         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 471
 472         /* Depending on the signal settings we may need to revert the
 473            decision to restart the system call. */
 474         if (signr > 0 && regs->psw.addr == restart_addr) {
 475                 if (retval == -ERESTARTNOHAND
 476                     || (retval == -ERESTARTSYS
 477                          && !(current->sighand->action[signr-1].sa.sa_flags
 478                               & SA_RESTART))) {
 479                         regs->gprs[2] = -EINTR;
 480                         regs->psw.addr = continue_addr;
 481                 }
 482         }
 483
 484         if (signr > 0) {
 485                 /* Whee!  Actually deliver the signal.  */
 486                 int ret;
 487 #ifdef CONFIG_COMPAT
 488                 if (test_thread_flag(TIF_31BIT)) {
 489                         ret = handle_signal32(signr, &ka, &info, oldset, regs);
 490                 }
 491                 else
 492 #endif
 493                         ret = handle_signal(signr, &ka, &info, oldset, regs);
 494                 if (!ret) {
 495                         /*
 496                          * A signal was successfully delivered; the saved
 497                          * sigmask will have been stored in the signal frame,
 498                          * and will be restored by sigreturn, so we can simply
 499                          * clear the TIF_RESTORE_SIGMASK flag.
 500                          */
 501                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 502                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 503
 504                         /*
 505                          * If we would have taken a single-step trap
 506                          * for a normal instruction, act like we took
 507                          * one for the handler setup.
 508                          */
 509                         if (current->thread.per_info.single_step)
 510                                 set_thread_flag(TIF_SINGLE_STEP);
 511
 512                         /*
 513                          * Let tracing know that we've done the handler setup.
 514                          */
 515                         tracehook_signal_handler(signr, &info, &ka, regs,
 516                                          test_thread_flag(TIF_SINGLE_STEP));
 517                 }
 518                 return;
 519         }
 520
 521         /*
 522          * If there's no signal to deliver, we just put the saved sigmask back.
 523          */
 524         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 525                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 526                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 527         }
 528
 529         /* Restart a different system call. */
 530         if (retval == -ERESTART_RESTARTBLOCK
 531             && regs->psw.addr == continue_addr) {
 532                 regs->gprs[2] = __NR_restart_syscall;
 533                 set_thread_flag(TIF_RESTART_SVC);
 534         }
 535 }
 536
 537 void do_notify_resume(struct pt_regs *regs)
 538 {
 539         clear_thread_flag(TIF_NOTIFY_RESUME);
 540         tracehook_notify_resume(regs);
 541 }