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