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         mask &= _BLOCKABLE;
  61         spin_lock_irq(&current->sighand->siglock);
  62         current->saved_sigmask = current->blocked;
  63         siginitset(&current->blocked, mask);
  64         recalc_sigpending();
  65         spin_unlock_irq(&current->sighand->siglock);
  66
  67         current->state = TASK_INTERRUPTIBLE;
  68         schedule();
  69         set_thread_flag(TIF_RESTORE_SIGMASK);
  70
  71         return -ERESTARTNOHAND;
  72 }
  73
  74 SYSCALL_DEFINE3(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 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
 106                 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 /* 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->svcnr = 0;        /* disable syscall checks */
 162         return 0;
 163 }
 164
 165 SYSCALL_DEFINE0(sigreturn)
 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 SYSCALL_DEFINE0(rt_sigreturn)
 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         /* Overflow on alternate signal stack gives SIGSEGV. */
 239         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 240                 return (void __user *) -1UL;
 241
 242         /* This is the X/Open sanctioned signal stack switching.  */
 243         if (ka->sa.sa_flags & SA_ONSTACK) {
 244                 if (! sas_ss_flags(sp))
 245                         sp = current->sas_ss_sp + current->sas_ss_size;
 246         }
 247
 248         /* This is the legacy signal stack switching. */
 249         else if (!user_mode(regs) &&
 250                  !(ka->sa.sa_flags & SA_RESTORER) &&
 251                  ka->sa.sa_restorer) {
 252                 sp = (unsigned long) ka->sa.sa_restorer;
 253         }
 254
 255         return (void __user *)((sp - frame_size) & -8ul);
 256 }
 257
 258 static inline int map_signal(int sig)
 259 {
 260         if (current_thread_info()->exec_domain
 261             && current_thread_info()->exec_domain->signal_invmap
 262             && sig < 32)
 263                 return current_thread_info()->exec_domain->signal_invmap[sig];
 264         else
 265                 return sig;
 266 }
 267
 268 static int setup_frame(int sig, struct k_sigaction *ka,
 269                        sigset_t *set, struct pt_regs * regs)
 270 {
 271         sigframe __user *frame;
 272
 273         frame = get_sigframe(ka, regs, sizeof(sigframe));
 274         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 275                 goto give_sigsegv;
 276
 277         if (frame == (void __user *) -1UL)
 278                 goto give_sigsegv;
 279
 280         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 281                 goto give_sigsegv;
 282
 283         if (save_sigregs(regs, &frame->sregs))
 284                 goto give_sigsegv;
 285         if (__put_user(&frame->sregs, &frame->sc.sregs))
 286                 goto give_sigsegv;
 287
 288         /* Set up to return from userspace.  If provided, use a stub
 289            already in userspace.  */
 290         if (ka->sa.sa_flags & SA_RESTORER) {
 291                 regs->gprs[14] = (unsigned long)
 292                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 293         } else {
 294                 regs->gprs[14] = (unsigned long)
 295                         frame->retcode | PSW_ADDR_AMODE;
 296                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 297                                (u16 __user *)(frame->retcode)))
 298                         goto give_sigsegv;
 299         }
 300
 301         /* Set up backchain. */
 302         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 303                 goto give_sigsegv;
 304
 305         /* Set up registers for signal handler */
 306         regs->gprs[15] = (unsigned long) frame;
 307         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 308
 309         regs->gprs[2] = map_signal(sig);
 310         regs->gprs[3] = (unsigned long) &frame->sc;
 311
 312         /* We forgot to include these in the sigcontext.
 313            To avoid breaking binary compatibility, they are passed as args. */
 314         regs->gprs[4] = current->thread.trap_no;
 315         regs->gprs[5] = current->thread.prot_addr;
 316
 317         /* Place signal number on stack to allow backtrace from handler.  */
 318         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 319                 goto give_sigsegv;
 320         return 0;
 321
 322 give_sigsegv:
 323         force_sigsegv(sig, current);
 324         return -EFAULT;
 325 }
 326
 327 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 328                            sigset_t *set, struct pt_regs * regs)
 329 {
 330         int err = 0;
 331         rt_sigframe __user *frame;
 332
 333         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 334         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 335                 goto give_sigsegv;
 336
 337         if (frame == (void __user *) -1UL)
 338                 goto give_sigsegv;
 339
 340         if (copy_siginfo_to_user(&frame->info, info))
 341                 goto give_sigsegv;
 342
 343         /* Create the ucontext.  */
 344         err |= __put_user(0, &frame->uc.uc_flags);
 345         err |= __put_user(NULL, &frame->uc.uc_link);
 346         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 347         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 348                           &frame->uc.uc_stack.ss_flags);
 349         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 350         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 351         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 352         if (err)
 353                 goto give_sigsegv;
 354
 355         /* Set up to return from userspace.  If provided, use a stub
 356            already in userspace.  */
 357         if (ka->sa.sa_flags & SA_RESTORER) {
 358                 regs->gprs[14] = (unsigned long)
 359                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 360         } else {
 361                 regs->gprs[14] = (unsigned long)
 362                         frame->retcode | PSW_ADDR_AMODE;
 363                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 364                                (u16 __user *)(frame->retcode)))
 365                         goto give_sigsegv;
 366         }
 367
 368         /* Set up backchain. */
 369         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 370                 goto give_sigsegv;
 371
 372         /* Set up registers for signal handler */
 373         regs->gprs[15] = (unsigned long) frame;
 374         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 375
 376         regs->gprs[2] = map_signal(sig);
 377         regs->gprs[3] = (unsigned long) &frame->info;
 378         regs->gprs[4] = (unsigned long) &frame->uc;
 379         return 0;
 380
 381 give_sigsegv:
 382         force_sigsegv(sig, current);
 383         return -EFAULT;
 384 }
 385
 386 /*
 387  * OK, we're invoking a handler
 388  */
 389
 390 static int
 391 handle_signal(unsigned long sig, struct k_sigaction *ka,
 392               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 393 {
 394         int ret;
 395
 396         /* Set up the stack frame */
 397         if (ka->sa.sa_flags & SA_SIGINFO)
 398                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 399         else
 400                 ret = setup_frame(sig, ka, oldset, regs);
 401
 402         if (ret == 0) {
 403                 spin_lock_irq(&current->sighand->siglock);
 404                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 405                 if (!(ka->sa.sa_flags & SA_NODEFER))
 406                         sigaddset(&current->blocked,sig);
 407                 recalc_sigpending();
 408                 spin_unlock_irq(&current->sighand->siglock);
 409         }
 410
 411         return ret;
 412 }
 413
 414 /*
 415  * Note that 'init' is a special process: it doesn't get signals it doesn't
 416  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 417  * mistake.
 418  *
 419  * Note that we go through the signals twice: once to check the signals that
 420  * the kernel can handle, and then we build all the user-level signal handling
 421  * stack-frames in one go after that.
 422  */
 423 void do_signal(struct pt_regs *regs)
 424 {
 425         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 426         siginfo_t info;
 427         int signr;
 428         struct k_sigaction ka;
 429         sigset_t *oldset;
 430
 431         /*
 432          * We want the common case to go fast, which
 433          * is why we may in certain cases get here from
 434          * kernel mode. Just return without doing anything
 435          * if so.
 436          */
 437         if (!user_mode(regs))
 438                 return;
 439
 440         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 441                 oldset = &current->saved_sigmask;
 442         else
 443                 oldset = &current->blocked;
 444
 445         /* Are we from a system call? */
 446         if (regs->svcnr) {
 447                 continue_addr = regs->psw.addr;
 448                 restart_addr = continue_addr - regs->ilc;
 449                 retval = regs->gprs[2];
 450
 451                 /* Prepare for system call restart.  We do this here so that a
 452                    debugger will see the already changed PSW. */
 453                 switch (retval) {
 454                 case -ERESTARTNOHAND:
 455                 case -ERESTARTSYS:
 456                 case -ERESTARTNOINTR:
 457                         regs->gprs[2] = regs->orig_gpr2;
 458                         regs->psw.addr = restart_addr;
 459                         break;
 460                 case -ERESTART_RESTARTBLOCK:
 461                         regs->gprs[2] = -EINTR;
 462                 }
 463                 regs->svcnr = 0;        /* Don't deal with this again. */
 464         }
 465
 466         /* Get signal to deliver.  When running under ptrace, at this point
 467            the debugger may change all our registers ... */
 468         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 469
 470         /* Depending on the signal settings we may need to revert the
 471            decision to restart the system call. */
 472         if (signr > 0 && regs->psw.addr == restart_addr) {
 473                 if (retval == -ERESTARTNOHAND
 474                     || (retval == -ERESTARTSYS
 475                          && !(current->sighand->action[signr-1].sa.sa_flags
 476                               & SA_RESTART))) {
 477                         regs->gprs[2] = -EINTR;
 478                         regs->psw.addr = continue_addr;
 479                 }
 480         }
 481
 482         if (signr > 0) {
 483                 /* Whee!  Actually deliver the signal.  */
 484                 int ret;
 485 #ifdef CONFIG_COMPAT
 486                 if (is_compat_task()) {
 487                         ret = handle_signal32(signr, &ka, &info, oldset, regs);
 488                 }
 489                 else
 490 #endif
 491                         ret = handle_signal(signr, &ka, &info, oldset, regs);
 492                 if (!ret) {
 493                         /*
 494                          * A signal was successfully delivered; the saved
 495                          * sigmask will have been stored in the signal frame,
 496                          * and will be restored by sigreturn, so we can simply
 497                          * clear the TIF_RESTORE_SIGMASK flag.
 498                          */
 499                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 500                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 501
 502                         /*
 503                          * If we would have taken a single-step trap
 504                          * for a normal instruction, act like we took
 505                          * one for the handler setup.
 506                          */
 507                         if (current->thread.per_info.single_step)
 508                                 set_thread_flag(TIF_SINGLE_STEP);
 509
 510                         /*
 511                          * Let tracing know that we've done the handler setup.
 512                          */
 513                         tracehook_signal_handler(signr, &info, &ka, regs,
 514                                          test_thread_flag(TIF_SINGLE_STEP));
 515                 }
 516                 return;
 517         }
 518
 519         /*
 520          * If there's no signal to deliver, we just put the saved sigmask back.
 521          */
 522         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 523                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 524                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 525         }
 526
 527         /* Restart a different system call. */
 528         if (retval == -ERESTART_RESTARTBLOCK
 529             && regs->psw.addr == continue_addr) {
 530                 regs->gprs[2] = __NR_restart_syscall;
 531                 set_thread_flag(TIF_RESTART_SVC);
 532         }
 533 }
 534
 535 void do_notify_resume(struct pt_regs *regs)
 536 {
 537         clear_thread_flag(TIF_NOTIFY_RESUME);
 538         tracehook_notify_resume(regs);
 539         if (current->replacement_session_keyring)
 540                 key_replace_session_keyring();
 541 }