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_user_bits |
 120                 (regs->psw.mask & PSW_MASK_USER);
 121         user_sregs.regs.psw.addr = regs->psw.addr;
 122         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 123         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 124                sizeof(sregs->regs.acrs));
 125         /*
 126          * We have to store the fp registers to current->thread.fp_regs
 127          * to merge them with the emulated registers.
 128          */
 129         save_fp_regs(&current->thread.fp_regs);
 130         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 131                sizeof(s390_fp_regs));
 132         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 133 }
 134
 135 /* Returns positive number on error */
 136 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 137 {
 138         int err;
 139         _sigregs user_sregs;
 140
 141         /* Alwys make any pending restarted system call return -EINTR */
 142         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 143
 144         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 145         if (err)
 146                 return err;
 147         /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
 148         regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
 149                 (user_sregs.regs.psw.mask & PSW_MASK_USER);
 150         /* Check for invalid amode */
 151         if (regs->psw.mask & PSW_MASK_EA)
 152                 regs->psw.mask |= PSW_MASK_BA;
 153         regs->psw.addr = user_sregs.regs.psw.addr;
 154         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 155         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 156                sizeof(sregs->regs.acrs));
 157         restore_access_regs(current->thread.acrs);
 158
 159         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 160                sizeof(s390_fp_regs));
 161         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 162
 163         restore_fp_regs(&current->thread.fp_regs);
 164         clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 165         return 0;
 166 }
 167
 168 SYSCALL_DEFINE0(sigreturn)
 169 {
 170         struct pt_regs *regs = task_pt_regs(current);
 171         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 172         sigset_t set;
 173
 174         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 175                 goto badframe;
 176         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 177                 goto badframe;
 178         sigdelsetmask(&set, ~_BLOCKABLE);
 179         set_current_blocked(&set);
 180         if (restore_sigregs(regs, &frame->sregs))
 181                 goto badframe;
 182         return regs->gprs[2];
 183 badframe:
 184         force_sig(SIGSEGV, current);
 185         return 0;
 186 }
 187
 188 SYSCALL_DEFINE0(rt_sigreturn)
 189 {
 190         struct pt_regs *regs = task_pt_regs(current);
 191         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 192         sigset_t set;
 193
 194         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 195                 goto badframe;
 196         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 197                 goto badframe;
 198         sigdelsetmask(&set, ~_BLOCKABLE);
 199         set_current_blocked(&set);
 200         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 201                 goto badframe;
 202         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 203                            regs->gprs[15]) == -EFAULT)
 204                 goto badframe;
 205         return regs->gprs[2];
 206 badframe:
 207         force_sig(SIGSEGV, current);
 208         return 0;
 209 }
 210
 211 /*
 212  * Set up a signal frame.
 213  */
 214
 215
 216 /*
 217  * Determine which stack to use..
 218  */
 219 static inline void __user *
 220 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 221 {
 222         unsigned long sp;
 223
 224         /* Default to using normal stack */
 225         sp = regs->gprs[15];
 226
 227         /* Overflow on alternate signal stack gives SIGSEGV. */
 228         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 229                 return (void __user *) -1UL;
 230
 231         /* This is the X/Open sanctioned signal stack switching.  */
 232         if (ka->sa.sa_flags & SA_ONSTACK) {
 233                 if (! sas_ss_flags(sp))
 234                         sp = current->sas_ss_sp + current->sas_ss_size;
 235         }
 236
 237         /* This is the legacy signal stack switching. */
 238         else if (!user_mode(regs) &&
 239                  !(ka->sa.sa_flags & SA_RESTORER) &&
 240                  ka->sa.sa_restorer) {
 241                 sp = (unsigned long) ka->sa.sa_restorer;
 242         }
 243
 244         return (void __user *)((sp - frame_size) & -8ul);
 245 }
 246
 247 static inline int map_signal(int sig)
 248 {
 249         if (current_thread_info()->exec_domain
 250             && current_thread_info()->exec_domain->signal_invmap
 251             && sig < 32)
 252                 return current_thread_info()->exec_domain->signal_invmap[sig];
 253         else
 254                 return sig;
 255 }
 256
 257 static int setup_frame(int sig, struct k_sigaction *ka,
 258                        sigset_t *set, struct pt_regs * regs)
 259 {
 260         sigframe __user *frame;
 261
 262         frame = get_sigframe(ka, regs, sizeof(sigframe));
 263         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 264                 goto give_sigsegv;
 265
 266         if (frame == (void __user *) -1UL)
 267                 goto give_sigsegv;
 268
 269         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 270                 goto give_sigsegv;
 271
 272         if (save_sigregs(regs, &frame->sregs))
 273                 goto give_sigsegv;
 274         if (__put_user(&frame->sregs, &frame->sc.sregs))
 275                 goto give_sigsegv;
 276
 277         /* Set up to return from userspace.  If provided, use a stub
 278            already in userspace.  */
 279         if (ka->sa.sa_flags & SA_RESTORER) {
 280                 regs->gprs[14] = (unsigned long)
 281                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 282         } else {
 283                 regs->gprs[14] = (unsigned long)
 284                         frame->retcode | PSW_ADDR_AMODE;
 285                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 286                                (u16 __user *)(frame->retcode)))
 287                         goto give_sigsegv;
 288         }
 289
 290         /* Set up backchain. */
 291         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 292                 goto give_sigsegv;
 293
 294         /* Set up registers for signal handler */
 295         regs->gprs[15] = (unsigned long) frame;
 296         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 297         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 298
 299         regs->gprs[2] = map_signal(sig);
 300         regs->gprs[3] = (unsigned long) &frame->sc;
 301
 302         /* We forgot to include these in the sigcontext.
 303            To avoid breaking binary compatibility, they are passed as args. */
 304         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 305             sig == SIGTRAP || sig == SIGFPE) {
 306                 /* set extra registers only for synchronous signals */
 307                 regs->gprs[4] = regs->int_code & 127;
 308                 regs->gprs[5] = regs->int_parm_long;
 309                 regs->gprs[6] = task_thread_info(current)->last_break;
 310         }
 311
 312         /* Place signal number on stack to allow backtrace from handler.  */
 313         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 314                 goto give_sigsegv;
 315         return 0;
 316
 317 give_sigsegv:
 318         force_sigsegv(sig, current);
 319         return -EFAULT;
 320 }
 321
 322 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 323                            sigset_t *set, struct pt_regs * regs)
 324 {
 325         int err = 0;
 326         rt_sigframe __user *frame;
 327
 328         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 329         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 330                 goto give_sigsegv;
 331
 332         if (frame == (void __user *) -1UL)
 333                 goto give_sigsegv;
 334
 335         if (copy_siginfo_to_user(&frame->info, info))
 336                 goto give_sigsegv;
 337
 338         /* Create the ucontext.  */
 339         err |= __put_user(0, &frame->uc.uc_flags);
 340         err |= __put_user(NULL, &frame->uc.uc_link);
 341         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 342         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 343                           &frame->uc.uc_stack.ss_flags);
 344         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 345         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 346         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 347         if (err)
 348                 goto give_sigsegv;
 349
 350         /* Set up to return from userspace.  If provided, use a stub
 351            already in userspace.  */
 352         if (ka->sa.sa_flags & SA_RESTORER) {
 353                 regs->gprs[14] = (unsigned long)
 354                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 355         } else {
 356                 regs->gprs[14] = (unsigned long)
 357                         frame->retcode | PSW_ADDR_AMODE;
 358                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 359                                (u16 __user *)(frame->retcode)))
 360                         goto give_sigsegv;
 361         }
 362
 363         /* Set up backchain. */
 364         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 365                 goto give_sigsegv;
 366
 367         /* Set up registers for signal handler */
 368         regs->gprs[15] = (unsigned long) frame;
 369         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 370         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 371
 372         regs->gprs[2] = map_signal(sig);
 373         regs->gprs[3] = (unsigned long) &frame->info;
 374         regs->gprs[4] = (unsigned long) &frame->uc;
 375         regs->gprs[5] = task_thread_info(current)->last_break;
 376         return 0;
 377
 378 give_sigsegv:
 379         force_sigsegv(sig, current);
 380         return -EFAULT;
 381 }
 382
 383 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 384                          siginfo_t *info, sigset_t *oldset,
 385                          struct pt_regs *regs)
 386 {
 387         sigset_t blocked;
 388         int ret;
 389
 390         /* Set up the stack frame */
 391         if (ka->sa.sa_flags & SA_SIGINFO)
 392                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 393         else
 394                 ret = setup_frame(sig, ka, oldset, regs);
 395         if (ret)
 396                 return ret;
 397         sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
 398         if (!(ka->sa.sa_flags & SA_NODEFER))
 399                 sigaddset(&blocked, sig);
 400         set_current_blocked(&blocked);
 401         return 0;
 402 }
 403
 404 /*
 405  * Note that 'init' is a special process: it doesn't get signals it doesn't
 406  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 407  * mistake.
 408  *
 409  * Note that we go through the signals twice: once to check the signals that
 410  * the kernel can handle, and then we build all the user-level signal handling
 411  * stack-frames in one go after that.
 412  */
 413 void do_signal(struct pt_regs *regs)
 414 {
 415         siginfo_t info;
 416         int signr;
 417         struct k_sigaction ka;
 418         sigset_t *oldset;
 419
 420         /*
 421          * We want the common case to go fast, which
 422          * is why we may in certain cases get here from
 423          * kernel mode. Just return without doing anything
 424          * if so.
 425          */
 426         if (!user_mode(regs))
 427                 return;
 428
 429         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 430                 oldset = &current->saved_sigmask;
 431         else
 432                 oldset = &current->blocked;
 433
 434         /*
 435          * Get signal to deliver. When running under ptrace, at this point
 436          * the debugger may change all our registers, including the system
 437          * call information.
 438          */
 439         current_thread_info()->system_call =
 440                 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
 441         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 442
 443         if (signr > 0) {
 444                 /* Whee!  Actually deliver the signal.  */
 445                 if (current_thread_info()->system_call) {
 446                         regs->int_code = current_thread_info()->system_call;
 447                         /* Check for system call restarting. */
 448                         switch (regs->gprs[2]) {
 449                         case -ERESTART_RESTARTBLOCK:
 450                         case -ERESTARTNOHAND:
 451                                 regs->gprs[2] = -EINTR;
 452                                 break;
 453                         case -ERESTARTSYS:
 454                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 455                                         regs->gprs[2] = -EINTR;
 456                                         break;
 457                                 }
 458                         /* fallthrough */
 459                         case -ERESTARTNOINTR:
 460                                 regs->gprs[2] = regs->orig_gpr2;
 461                                 regs->psw.addr =
 462                                         __rewind_psw(regs->psw,
 463                                                      regs->int_code >> 16);
 464                                 break;
 465                         }
 466                 }
 467                 /* No longer in a system call */
 468                 clear_thread_flag(TIF_SYSCALL);
 469
 470                 if ((is_compat_task() ?
 471                      handle_signal32(signr, &ka, &info, oldset, regs) :
 472                      handle_signal(signr, &ka, &info, oldset, regs)) == 0) {
 473                         /*
 474                          * A signal was successfully delivered; the saved
 475                          * sigmask will have been stored in the signal frame,
 476                          * and will be restored by sigreturn, so we can simply
 477                          * clear the TIF_RESTORE_SIGMASK flag.
 478                          */
 479                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 480                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 481
 482                         /*
 483                          * Let tracing know that we've done the handler setup.
 484                          */
 485                         tracehook_signal_handler(signr, &info, &ka, regs,
 486                                          test_thread_flag(TIF_SINGLE_STEP));
 487                 }
 488                 return;
 489         }
 490
 491         /* No handlers present - check for system call restart */
 492         clear_thread_flag(TIF_SYSCALL);
 493         if (current_thread_info()->system_call) {
 494                 regs->int_code = current_thread_info()->system_call;
 495                 switch (regs->gprs[2]) {
 496                 case -ERESTART_RESTARTBLOCK:
 497                         /* Restart with sys_restart_syscall */
 498                         regs->int_code = __NR_restart_syscall;
 499                 /* fallthrough */
 500                 case -ERESTARTNOHAND:
 501                 case -ERESTARTSYS:
 502                 case -ERESTARTNOINTR:
 503                         /* Restart system call with magic TIF bit. */
 504                         regs->gprs[2] = regs->orig_gpr2;
 505                         set_thread_flag(TIF_SYSCALL);
 506                         break;
 507                 }
 508         }
 509
 510         /*
 511          * If there's no signal to deliver, we just put the saved sigmask back.
 512          */
 513         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 514                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 515                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 516         }
 517 }
 518
 519 void do_notify_resume(struct pt_regs *regs)
 520 {
 521         clear_thread_flag(TIF_NOTIFY_RESUME);
 522         tracehook_notify_resume(regs);
 523         if (current->replacement_session_keyring)
 524                 key_replace_session_keyring();
 525 }