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 <asm/compat.h>
  34 #include "entry.h"
  35
  36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  37
  38
  39 typedef struct
  40 {
  41         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  42         struct sigcontext sc;
  43         _sigregs sregs;
  44         int signo;
  45         __u8 retcode[S390_SYSCALL_SIZE];
  46 } sigframe;
  47
  48 typedef struct
  49 {
  50         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  51         __u8 retcode[S390_SYSCALL_SIZE];
  52         struct siginfo info;
  53         struct ucontext uc;
  54 } rt_sigframe;
  55
  56 /*
  57  * Atomically swap in the new signal mask, and wait for a signal.
  58  */
  59 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask)
  60 {
  61         sigset_t blocked;
  62
  63         current->saved_sigmask = current->blocked;
  64         mask &= _BLOCKABLE;
  65         siginitset(&blocked, mask);
  66         set_current_blocked(&blocked);
  67         set_current_state(TASK_INTERRUPTIBLE);
  68         schedule();
  69         set_restore_sigmask();
  70         return -ERESTARTNOHAND;
  71 }
  72
  73 SYSCALL_DEFINE3(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 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
 105                 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 /* Returns non-zero on fault. */
 112 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 113 {
 114         _sigregs user_sregs;
 115
 116         save_access_regs(current->thread.acrs);
 117
 118         /* Copy a 'clean' PSW mask to the user to avoid leaking
 119            information about whether PER is currently on.  */
 120         user_sregs.regs.psw.mask = psw_user_bits |
 121                 (regs->psw.mask & PSW_MASK_USER);
 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         /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
 149         regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
 150                 (user_sregs.regs.psw.mask & PSW_MASK_USER);
 151         /* Check for invalid amode */
 152         if (regs->psw.mask & PSW_MASK_EA)
 153                 regs->psw.mask |= PSW_MASK_BA;
 154         regs->psw.addr = user_sregs.regs.psw.addr;
 155         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 156         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 157                sizeof(sregs->regs.acrs));
 158         restore_access_regs(current->thread.acrs);
 159
 160         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 161                sizeof(s390_fp_regs));
 162         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 163
 164         restore_fp_regs(&current->thread.fp_regs);
 165         clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 166         return 0;
 167 }
 168
 169 SYSCALL_DEFINE0(sigreturn)
 170 {
 171         struct pt_regs *regs = task_pt_regs(current);
 172         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 173         sigset_t set;
 174
 175         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 176                 goto badframe;
 177         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 178                 goto badframe;
 179         sigdelsetmask(&set, ~_BLOCKABLE);
 180         set_current_blocked(&set);
 181         if (restore_sigregs(regs, &frame->sregs))
 182                 goto badframe;
 183         return regs->gprs[2];
 184 badframe:
 185         force_sig(SIGSEGV, current);
 186         return 0;
 187 }
 188
 189 SYSCALL_DEFINE0(rt_sigreturn)
 190 {
 191         struct pt_regs *regs = task_pt_regs(current);
 192         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 193         sigset_t set;
 194
 195         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 196                 goto badframe;
 197         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 198                 goto badframe;
 199         sigdelsetmask(&set, ~_BLOCKABLE);
 200         set_current_blocked(&set);
 201         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 202                 goto badframe;
 203         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 204                            regs->gprs[15]) == -EFAULT)
 205                 goto badframe;
 206         return regs->gprs[2];
 207 badframe:
 208         force_sig(SIGSEGV, current);
 209         return 0;
 210 }
 211
 212 /*
 213  * Set up a signal frame.
 214  */
 215
 216
 217 /*
 218  * Determine which stack to use..
 219  */
 220 static inline void __user *
 221 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 222 {
 223         unsigned long sp;
 224
 225         /* Default to using normal stack */
 226         sp = regs->gprs[15];
 227
 228         /* Overflow on alternate signal stack gives SIGSEGV. */
 229         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 230                 return (void __user *) -1UL;
 231
 232         /* This is the X/Open sanctioned signal stack switching.  */
 233         if (ka->sa.sa_flags & SA_ONSTACK) {
 234                 if (! sas_ss_flags(sp))
 235                         sp = current->sas_ss_sp + current->sas_ss_size;
 236         }
 237
 238         /* This is the legacy signal stack switching. */
 239         else if (!user_mode(regs) &&
 240                  !(ka->sa.sa_flags & SA_RESTORER) &&
 241                  ka->sa.sa_restorer) {
 242                 sp = (unsigned long) ka->sa.sa_restorer;
 243         }
 244
 245         return (void __user *)((sp - frame_size) & -8ul);
 246 }
 247
 248 static inline int map_signal(int sig)
 249 {
 250         if (current_thread_info()->exec_domain
 251             && current_thread_info()->exec_domain->signal_invmap
 252             && sig < 32)
 253                 return current_thread_info()->exec_domain->signal_invmap[sig];
 254         else
 255                 return sig;
 256 }
 257
 258 static int setup_frame(int sig, struct k_sigaction *ka,
 259                        sigset_t *set, struct pt_regs * regs)
 260 {
 261         sigframe __user *frame;
 262
 263         frame = get_sigframe(ka, regs, sizeof(sigframe));
 264         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 265                 goto give_sigsegv;
 266
 267         if (frame == (void __user *) -1UL)
 268                 goto give_sigsegv;
 269
 270         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 271                 goto give_sigsegv;
 272
 273         if (save_sigregs(regs, &frame->sregs))
 274                 goto give_sigsegv;
 275         if (__put_user(&frame->sregs, &frame->sc.sregs))
 276                 goto give_sigsegv;
 277
 278         /* Set up to return from userspace.  If provided, use a stub
 279            already in userspace.  */
 280         if (ka->sa.sa_flags & SA_RESTORER) {
 281                 regs->gprs[14] = (unsigned long)
 282                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 283         } else {
 284                 regs->gprs[14] = (unsigned long)
 285                         frame->retcode | PSW_ADDR_AMODE;
 286                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 287                                (u16 __user *)(frame->retcode)))
 288                         goto give_sigsegv;
 289         }
 290
 291         /* Set up backchain. */
 292         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 293                 goto give_sigsegv;
 294
 295         /* Set up registers for signal handler */
 296         regs->gprs[15] = (unsigned long) frame;
 297         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 298         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 299
 300         regs->gprs[2] = map_signal(sig);
 301         regs->gprs[3] = (unsigned long) &frame->sc;
 302
 303         /* We forgot to include these in the sigcontext.
 304            To avoid breaking binary compatibility, they are passed as args. */
 305         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 306             sig == SIGTRAP || sig == SIGFPE) {
 307                 /* set extra registers only for synchronous signals */
 308                 regs->gprs[4] = regs->int_code & 127;
 309                 regs->gprs[5] = regs->int_parm_long;
 310                 regs->gprs[6] = task_thread_info(current)->last_break;
 311         }
 312
 313         /* Place signal number on stack to allow backtrace from handler.  */
 314         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 315                 goto give_sigsegv;
 316         return 0;
 317
 318 give_sigsegv:
 319         force_sigsegv(sig, current);
 320         return -EFAULT;
 321 }
 322
 323 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 324                            sigset_t *set, struct pt_regs * regs)
 325 {
 326         int err = 0;
 327         rt_sigframe __user *frame;
 328
 329         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 330         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 331                 goto give_sigsegv;
 332
 333         if (frame == (void __user *) -1UL)
 334                 goto give_sigsegv;
 335
 336         if (copy_siginfo_to_user(&frame->info, info))
 337                 goto give_sigsegv;
 338
 339         /* Create the ucontext.  */
 340         err |= __put_user(0, &frame->uc.uc_flags);
 341         err |= __put_user(NULL, &frame->uc.uc_link);
 342         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 343         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 344                           &frame->uc.uc_stack.ss_flags);
 345         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 346         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 347         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 348         if (err)
 349                 goto give_sigsegv;
 350
 351         /* Set up to return from userspace.  If provided, use a stub
 352            already in userspace.  */
 353         if (ka->sa.sa_flags & SA_RESTORER) {
 354                 regs->gprs[14] = (unsigned long)
 355                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 356         } else {
 357                 regs->gprs[14] = (unsigned long)
 358                         frame->retcode | PSW_ADDR_AMODE;
 359                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 360                                (u16 __user *)(frame->retcode)))
 361                         goto give_sigsegv;
 362         }
 363
 364         /* Set up backchain. */
 365         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 366                 goto give_sigsegv;
 367
 368         /* Set up registers for signal handler */
 369         regs->gprs[15] = (unsigned long) frame;
 370         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 371         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 372
 373         regs->gprs[2] = map_signal(sig);
 374         regs->gprs[3] = (unsigned long) &frame->info;
 375         regs->gprs[4] = (unsigned long) &frame->uc;
 376         regs->gprs[5] = task_thread_info(current)->last_break;
 377         return 0;
 378
 379 give_sigsegv:
 380         force_sigsegv(sig, current);
 381         return -EFAULT;
 382 }
 383
 384 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 385                          siginfo_t *info, sigset_t *oldset,
 386                          struct pt_regs *regs)
 387 {
 388         sigset_t blocked;
 389         int ret;
 390
 391         /* Set up the stack frame */
 392         if (ka->sa.sa_flags & SA_SIGINFO)
 393                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 394         else
 395                 ret = setup_frame(sig, ka, oldset, regs);
 396         if (ret)
 397                 return ret;
 398         sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
 399         if (!(ka->sa.sa_flags & SA_NODEFER))
 400                 sigaddset(&blocked, sig);
 401         set_current_blocked(&blocked);
 402         return 0;
 403 }
 404
 405 /*
 406  * Note that 'init' is a special process: it doesn't get signals it doesn't
 407  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 408  * mistake.
 409  *
 410  * Note that we go through the signals twice: once to check the signals that
 411  * the kernel can handle, and then we build all the user-level signal handling
 412  * stack-frames in one go after that.
 413  */
 414 void do_signal(struct pt_regs *regs)
 415 {
 416         siginfo_t info;
 417         int signr;
 418         struct k_sigaction ka;
 419         sigset_t *oldset;
 420
 421         /*
 422          * We want the common case to go fast, which
 423          * is why we may in certain cases get here from
 424          * kernel mode. Just return without doing anything
 425          * if so.
 426          */
 427         if (!user_mode(regs))
 428                 return;
 429
 430         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 431                 oldset = &current->saved_sigmask;
 432         else
 433                 oldset = &current->blocked;
 434
 435         /*
 436          * Get signal to deliver. When running under ptrace, at this point
 437          * the debugger may change all our registers, including the system
 438          * call information.
 439          */
 440         current_thread_info()->system_call =
 441                 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
 442         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 443
 444         if (signr > 0) {
 445                 /* Whee!  Actually deliver the signal.  */
 446                 if (current_thread_info()->system_call) {
 447                         regs->int_code = current_thread_info()->system_call;
 448                         /* Check for system call restarting. */
 449                         switch (regs->gprs[2]) {
 450                         case -ERESTART_RESTARTBLOCK:
 451                         case -ERESTARTNOHAND:
 452                                 regs->gprs[2] = -EINTR;
 453                                 break;
 454                         case -ERESTARTSYS:
 455                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 456                                         regs->gprs[2] = -EINTR;
 457                                         break;
 458                                 }
 459                         /* fallthrough */
 460                         case -ERESTARTNOINTR:
 461                                 regs->gprs[2] = regs->orig_gpr2;
 462                                 regs->psw.addr =
 463                                         __rewind_psw(regs->psw,
 464                                                      regs->int_code >> 16);
 465                                 break;
 466                         }
 467                 }
 468                 /* No longer in a system call */
 469                 clear_thread_flag(TIF_SYSCALL);
 470
 471                 if ((is_compat_task() ?
 472                      handle_signal32(signr, &ka, &info, oldset, regs) :
 473                      handle_signal(signr, &ka, &info, oldset, regs)) == 0) {
 474                         /*
 475                          * A signal was successfully delivered; the saved
 476                          * sigmask will have been stored in the signal frame,
 477                          * and will be restored by sigreturn, so we can simply
 478                          * clear the TIF_RESTORE_SIGMASK flag.
 479                          */
 480                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 481                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 482
 483                         /*
 484                          * Let tracing know that we've done the handler setup.
 485                          */
 486                         tracehook_signal_handler(signr, &info, &ka, regs,
 487                                          test_thread_flag(TIF_SINGLE_STEP));
 488                 }
 489                 return;
 490         }
 491
 492         /* No handlers present - check for system call restart */
 493         clear_thread_flag(TIF_SYSCALL);
 494         if (current_thread_info()->system_call) {
 495                 regs->int_code = current_thread_info()->system_call;
 496                 switch (regs->gprs[2]) {
 497                 case -ERESTART_RESTARTBLOCK:
 498                         /* Restart with sys_restart_syscall */
 499                         regs->int_code = __NR_restart_syscall;
 500                 /* fallthrough */
 501                 case -ERESTARTNOHAND:
 502                 case -ERESTARTSYS:
 503                 case -ERESTARTNOINTR:
 504                         /* Restart system call with magic TIF bit. */
 505                         regs->gprs[2] = regs->orig_gpr2;
 506                         set_thread_flag(TIF_SYSCALL);
 507                         break;
 508                 }
 509         }
 510
 511         /*
 512          * If there's no signal to deliver, we just put the saved sigmask back.
 513          */
 514         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 515                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 516                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 517         }
 518 }
 519
 520 void do_notify_resume(struct pt_regs *regs)
 521 {
 522         clear_thread_flag(TIF_NOTIFY_RESUME);
 523         tracehook_notify_resume(regs);
 524         if (current->replacement_session_keyring)
 525                 key_replace_session_keyring();
 526 }