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 <linux/syscalls.h>
  29 #include <linux/compat.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/lowcore.h>
  33 #include "entry.h"
  34
  35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  36
  37
  38 typedef struct
  39 {
  40         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  41         struct sigcontext sc;
  42         _sigregs sregs;
  43         int signo;
  44         __u8 retcode[S390_SYSCALL_SIZE];
  45 } sigframe;
  46
  47 typedef struct
  48 {
  49         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  50         __u8 retcode[S390_SYSCALL_SIZE];
  51         struct siginfo info;
  52         struct ucontext uc;
  53 } rt_sigframe;
  54
  55 /*
  56  * Atomically swap in the new signal mask, and wait for a signal.
  57  */
  58 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask)
  59 {
  60         sigset_t blocked;
  61
  62         current->saved_sigmask = current->blocked;
  63         mask &= _BLOCKABLE;
  64         siginitset(&blocked, mask);
  65         set_current_blocked(&blocked);
  66         set_current_state(TASK_INTERRUPTIBLE);
  67         schedule();
  68         set_restore_sigmask();
  69         return -ERESTARTNOHAND;
  70 }
  71
  72 SYSCALL_DEFINE3(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 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
 104                 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 /* Returns non-zero on fault. */
 111 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 112 {
 113         _sigregs user_sregs;
 114
 115         save_access_regs(current->thread.acrs);
 116
 117         /* Copy a 'clean' PSW mask to the user to avoid leaking
 118            information about whether PER is currently on.  */
 119         user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask);
 120         user_sregs.regs.psw.addr = regs->psw.addr;
 121         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 122         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 123                sizeof(sregs->regs.acrs));
 124         /*
 125          * We have to store the fp registers to current->thread.fp_regs
 126          * to merge them with the emulated registers.
 127          */
 128         save_fp_regs(&current->thread.fp_regs);
 129         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 130                sizeof(s390_fp_regs));
 131         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 132 }
 133
 134 /* Returns positive number on error */
 135 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 136 {
 137         int err;
 138         _sigregs user_sregs;
 139
 140         /* Alwys make any pending restarted system call return -EINTR */
 141         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 142
 143         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 144         if (err)
 145                 return err;
 146         regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
 147                                         user_sregs.regs.psw.mask);
 148         regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
 149         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 150         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 151                sizeof(sregs->regs.acrs));
 152         restore_access_regs(current->thread.acrs);
 153
 154         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 155                sizeof(s390_fp_regs));
 156         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 157
 158         restore_fp_regs(&current->thread.fp_regs);
 159         regs->svcnr = 0;        /* disable syscall checks */
 160         return 0;
 161 }
 162
 163 SYSCALL_DEFINE0(sigreturn)
 164 {
 165         struct pt_regs *regs = task_pt_regs(current);
 166         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 167         sigset_t set;
 168
 169         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 170                 goto badframe;
 171         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 172                 goto badframe;
 173         sigdelsetmask(&set, ~_BLOCKABLE);
 174         set_current_blocked(&set);
 175         if (restore_sigregs(regs, &frame->sregs))
 176                 goto badframe;
 177         return regs->gprs[2];
 178 badframe:
 179         force_sig(SIGSEGV, current);
 180         return 0;
 181 }
 182
 183 SYSCALL_DEFINE0(rt_sigreturn)
 184 {
 185         struct pt_regs *regs = task_pt_regs(current);
 186         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 187         sigset_t set;
 188
 189         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 190                 goto badframe;
 191         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 192                 goto badframe;
 193         sigdelsetmask(&set, ~_BLOCKABLE);
 194         set_current_blocked(&set);
 195         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 196                 goto badframe;
 197         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 198                            regs->gprs[15]) == -EFAULT)
 199                 goto badframe;
 200         return regs->gprs[2];
 201 badframe:
 202         force_sig(SIGSEGV, current);
 203         return 0;
 204 }
 205
 206 /*
 207  * Set up a signal frame.
 208  */
 209
 210
 211 /*
 212  * Determine which stack to use..
 213  */
 214 static inline void __user *
 215 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 216 {
 217         unsigned long sp;
 218
 219         /* Default to using normal stack */
 220         sp = regs->gprs[15];
 221
 222         /* Overflow on alternate signal stack gives SIGSEGV. */
 223         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 224                 return (void __user *) -1UL;
 225
 226         /* This is the X/Open sanctioned signal stack switching.  */
 227         if (ka->sa.sa_flags & SA_ONSTACK) {
 228                 if (! sas_ss_flags(sp))
 229                         sp = current->sas_ss_sp + current->sas_ss_size;
 230         }
 231
 232         /* This is the legacy signal stack switching. */
 233         else if (!user_mode(regs) &&
 234                  !(ka->sa.sa_flags & SA_RESTORER) &&
 235                  ka->sa.sa_restorer) {
 236                 sp = (unsigned long) ka->sa.sa_restorer;
 237         }
 238
 239         return (void __user *)((sp - frame_size) & -8ul);
 240 }
 241
 242 static inline int map_signal(int sig)
 243 {
 244         if (current_thread_info()->exec_domain
 245             && current_thread_info()->exec_domain->signal_invmap
 246             && sig < 32)
 247                 return current_thread_info()->exec_domain->signal_invmap[sig];
 248         else
 249                 return sig;
 250 }
 251
 252 static int setup_frame(int sig, struct k_sigaction *ka,
 253                        sigset_t *set, struct pt_regs * regs)
 254 {
 255         sigframe __user *frame;
 256
 257         frame = get_sigframe(ka, regs, sizeof(sigframe));
 258         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 259                 goto give_sigsegv;
 260
 261         if (frame == (void __user *) -1UL)
 262                 goto give_sigsegv;
 263
 264         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 265                 goto give_sigsegv;
 266
 267         if (save_sigregs(regs, &frame->sregs))
 268                 goto give_sigsegv;
 269         if (__put_user(&frame->sregs, &frame->sc.sregs))
 270                 goto give_sigsegv;
 271
 272         /* Set up to return from userspace.  If provided, use a stub
 273            already in userspace.  */
 274         if (ka->sa.sa_flags & SA_RESTORER) {
 275                 regs->gprs[14] = (unsigned long)
 276                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 277         } else {
 278                 regs->gprs[14] = (unsigned long)
 279                         frame->retcode | PSW_ADDR_AMODE;
 280                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 281                                (u16 __user *)(frame->retcode)))
 282                         goto give_sigsegv;
 283         }
 284
 285         /* Set up backchain. */
 286         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 287                 goto give_sigsegv;
 288
 289         /* Set up registers for signal handler */
 290         regs->gprs[15] = (unsigned long) frame;
 291         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 292
 293         regs->gprs[2] = map_signal(sig);
 294         regs->gprs[3] = (unsigned long) &frame->sc;
 295
 296         /* We forgot to include these in the sigcontext.
 297            To avoid breaking binary compatibility, they are passed as args. */
 298         regs->gprs[4] = current->thread.trap_no;
 299         regs->gprs[5] = current->thread.prot_addr;
 300         regs->gprs[6] = task_thread_info(current)->last_break;
 301
 302         /* Place signal number on stack to allow backtrace from handler.  */
 303         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 304                 goto give_sigsegv;
 305         return 0;
 306
 307 give_sigsegv:
 308         force_sigsegv(sig, current);
 309         return -EFAULT;
 310 }
 311
 312 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 313                            sigset_t *set, struct pt_regs * regs)
 314 {
 315         int err = 0;
 316         rt_sigframe __user *frame;
 317
 318         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 319         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 320                 goto give_sigsegv;
 321
 322         if (frame == (void __user *) -1UL)
 323                 goto give_sigsegv;
 324
 325         if (copy_siginfo_to_user(&frame->info, info))
 326                 goto give_sigsegv;
 327
 328         /* Create the ucontext.  */
 329         err |= __put_user(0, &frame->uc.uc_flags);
 330         err |= __put_user(NULL, &frame->uc.uc_link);
 331         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 332         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 333                           &frame->uc.uc_stack.ss_flags);
 334         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 335         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 336         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 337         if (err)
 338                 goto give_sigsegv;
 339
 340         /* Set up to return from userspace.  If provided, use a stub
 341            already in userspace.  */
 342         if (ka->sa.sa_flags & SA_RESTORER) {
 343                 regs->gprs[14] = (unsigned long)
 344                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 345         } else {
 346                 regs->gprs[14] = (unsigned long)
 347                         frame->retcode | PSW_ADDR_AMODE;
 348                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 349                                (u16 __user *)(frame->retcode)))
 350                         goto give_sigsegv;
 351         }
 352
 353         /* Set up backchain. */
 354         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 355                 goto give_sigsegv;
 356
 357         /* Set up registers for signal handler */
 358         regs->gprs[15] = (unsigned long) frame;
 359         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 360
 361         regs->gprs[2] = map_signal(sig);
 362         regs->gprs[3] = (unsigned long) &frame->info;
 363         regs->gprs[4] = (unsigned long) &frame->uc;
 364         regs->gprs[5] = task_thread_info(current)->last_break;
 365         return 0;
 366
 367 give_sigsegv:
 368         force_sigsegv(sig, current);
 369         return -EFAULT;
 370 }
 371
 372 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 373                          siginfo_t *info, sigset_t *oldset,
 374                          struct pt_regs *regs)
 375 {
 376         sigset_t blocked;
 377         int ret;
 378
 379         /* Set up the stack frame */
 380         if (ka->sa.sa_flags & SA_SIGINFO)
 381                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 382         else
 383                 ret = setup_frame(sig, ka, oldset, regs);
 384         if (ret)
 385                 return ret;
 386         sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
 387         if (!(ka->sa.sa_flags & SA_NODEFER))
 388                 sigaddset(&blocked, sig);
 389         set_current_blocked(&blocked);
 390         return 0;
 391 }
 392
 393 /*
 394  * Note that 'init' is a special process: it doesn't get signals it doesn't
 395  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 396  * mistake.
 397  *
 398  * Note that we go through the signals twice: once to check the signals that
 399  * the kernel can handle, and then we build all the user-level signal handling
 400  * stack-frames in one go after that.
 401  */
 402 void do_signal(struct pt_regs *regs)
 403 {
 404         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 405         siginfo_t info;
 406         int signr;
 407         struct k_sigaction ka;
 408         sigset_t *oldset;
 409
 410         /*
 411          * We want the common case to go fast, which
 412          * is why we may in certain cases get here from
 413          * kernel mode. Just return without doing anything
 414          * if so.
 415          */
 416         if (!user_mode(regs))
 417                 return;
 418
 419         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 420                 oldset = &current->saved_sigmask;
 421         else
 422                 oldset = &current->blocked;
 423
 424         /* Are we from a system call? */
 425         if (regs->svcnr) {
 426                 continue_addr = regs->psw.addr;
 427                 restart_addr = continue_addr - regs->ilc;
 428                 retval = regs->gprs[2];
 429
 430                 /* Prepare for system call restart.  We do this here so that a
 431                    debugger will see the already changed PSW. */
 432                 switch (retval) {
 433                 case -ERESTARTNOHAND:
 434                 case -ERESTARTSYS:
 435                 case -ERESTARTNOINTR:
 436                         regs->gprs[2] = regs->orig_gpr2;
 437                         regs->psw.addr = restart_addr;
 438                         break;
 439                 case -ERESTART_RESTARTBLOCK:
 440                         regs->gprs[2] = -EINTR;
 441                 }
 442                 regs->svcnr = 0;        /* Don't deal with this again. */
 443         }
 444
 445         /* Get signal to deliver.  When running under ptrace, at this point
 446            the debugger may change all our registers ... */
 447         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 448
 449         /* Depending on the signal settings we may need to revert the
 450            decision to restart the system call. */
 451         if (signr > 0 && regs->psw.addr == restart_addr) {
 452                 if (retval == -ERESTARTNOHAND
 453                     || (retval == -ERESTARTSYS
 454                          && !(current->sighand->action[signr-1].sa.sa_flags
 455                               & SA_RESTART))) {
 456                         regs->gprs[2] = -EINTR;
 457                         regs->psw.addr = continue_addr;
 458                 }
 459         }
 460
 461         if (signr > 0) {
 462                 /* Whee!  Actually deliver the signal.  */
 463                 int ret;
 464 #ifdef CONFIG_COMPAT
 465                 if (is_compat_task()) {
 466                         ret = handle_signal32(signr, &ka, &info, oldset, regs);
 467                 }
 468                 else
 469 #endif
 470                         ret = handle_signal(signr, &ka, &info, oldset, regs);
 471                 if (!ret) {
 472                         /*
 473                          * A signal was successfully delivered; the saved
 474                          * sigmask will have been stored in the signal frame,
 475                          * and will be restored by sigreturn, so we can simply
 476                          * clear the TIF_RESTORE_SIGMASK flag.
 477                          */
 478                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 479                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 480
 481                         /*
 482                          * Let tracing know that we've done the handler setup.
 483                          */
 484                         tracehook_signal_handler(signr, &info, &ka, regs,
 485                                         test_thread_flag(TIF_SINGLE_STEP));
 486                 }
 487                 return;
 488         }
 489
 490         /*
 491          * If there's no signal to deliver, we just put the saved sigmask back.
 492          */
 493         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 494                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 495                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 496         }
 497
 498         /* Restart a different system call. */
 499         if (retval == -ERESTART_RESTARTBLOCK
 500             && regs->psw.addr == continue_addr) {
 501                 regs->gprs[2] = __NR_restart_syscall;
 502                 set_thread_flag(TIF_RESTART_SVC);
 503         }
 504 }
 505
 506 void do_notify_resume(struct pt_regs *regs)
 507 {
 508         clear_thread_flag(TIF_NOTIFY_RESUME);
 509         tracehook_notify_resume(regs);
 510         if (current->replacement_session_keyring)
 511                 key_replace_session_keyring();
 512 }