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         regs->gprs[4] = current->thread.trap_no;
 306         regs->gprs[5] = current->thread.prot_addr;
 307         regs->gprs[6] = task_thread_info(current)->last_break;
 308
 309         /* Place signal number on stack to allow backtrace from handler.  */
 310         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 311                 goto give_sigsegv;
 312         return 0;
 313
 314 give_sigsegv:
 315         force_sigsegv(sig, current);
 316         return -EFAULT;
 317 }
 318
 319 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 320                            sigset_t *set, struct pt_regs * regs)
 321 {
 322         int err = 0;
 323         rt_sigframe __user *frame;
 324
 325         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 326         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 327                 goto give_sigsegv;
 328
 329         if (frame == (void __user *) -1UL)
 330                 goto give_sigsegv;
 331
 332         if (copy_siginfo_to_user(&frame->info, info))
 333                 goto give_sigsegv;
 334
 335         /* Create the ucontext.  */
 336         err |= __put_user(0, &frame->uc.uc_flags);
 337         err |= __put_user(NULL, &frame->uc.uc_link);
 338         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 339         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 340                           &frame->uc.uc_stack.ss_flags);
 341         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 342         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 343         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 344         if (err)
 345                 goto give_sigsegv;
 346
 347         /* Set up to return from userspace.  If provided, use a stub
 348            already in userspace.  */
 349         if (ka->sa.sa_flags & SA_RESTORER) {
 350                 regs->gprs[14] = (unsigned long)
 351                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 352         } else {
 353                 regs->gprs[14] = (unsigned long)
 354                         frame->retcode | PSW_ADDR_AMODE;
 355                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 356                                (u16 __user *)(frame->retcode)))
 357                         goto give_sigsegv;
 358         }
 359
 360         /* Set up backchain. */
 361         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 362                 goto give_sigsegv;
 363
 364         /* Set up registers for signal handler */
 365         regs->gprs[15] = (unsigned long) frame;
 366         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 367         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 368
 369         regs->gprs[2] = map_signal(sig);
 370         regs->gprs[3] = (unsigned long) &frame->info;
 371         regs->gprs[4] = (unsigned long) &frame->uc;
 372         regs->gprs[5] = task_thread_info(current)->last_break;
 373         return 0;
 374
 375 give_sigsegv:
 376         force_sigsegv(sig, current);
 377         return -EFAULT;
 378 }
 379
 380 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 381                          siginfo_t *info, sigset_t *oldset,
 382                          struct pt_regs *regs)
 383 {
 384         sigset_t blocked;
 385         int ret;
 386
 387         /* Set up the stack frame */
 388         if (ka->sa.sa_flags & SA_SIGINFO)
 389                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 390         else
 391                 ret = setup_frame(sig, ka, oldset, regs);
 392         if (ret)
 393                 return ret;
 394         sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
 395         if (!(ka->sa.sa_flags & SA_NODEFER))
 396                 sigaddset(&blocked, sig);
 397         set_current_blocked(&blocked);
 398         return 0;
 399 }
 400
 401 /*
 402  * Note that 'init' is a special process: it doesn't get signals it doesn't
 403  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 404  * mistake.
 405  *
 406  * Note that we go through the signals twice: once to check the signals that
 407  * the kernel can handle, and then we build all the user-level signal handling
 408  * stack-frames in one go after that.
 409  */
 410 void do_signal(struct pt_regs *regs)
 411 {
 412         siginfo_t info;
 413         int signr;
 414         struct k_sigaction ka;
 415         sigset_t *oldset;
 416
 417         /*
 418          * We want the common case to go fast, which
 419          * is why we may in certain cases get here from
 420          * kernel mode. Just return without doing anything
 421          * if so.
 422          */
 423         if (!user_mode(regs))
 424                 return;
 425
 426         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 427                 oldset = &current->saved_sigmask;
 428         else
 429                 oldset = &current->blocked;
 430
 431         /*
 432          * Get signal to deliver. When running under ptrace, at this point
 433          * the debugger may change all our registers, including the system
 434          * call information.
 435          */
 436         current_thread_info()->system_call =
 437                 test_thread_flag(TIF_SYSCALL) ? regs->svc_code : 0;
 438         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 439
 440         if (signr > 0) {
 441                 /* Whee!  Actually deliver the signal.  */
 442                 if (current_thread_info()->system_call) {
 443                         regs->svc_code = current_thread_info()->system_call;
 444                         /* Check for system call restarting. */
 445                         switch (regs->gprs[2]) {
 446                         case -ERESTART_RESTARTBLOCK:
 447                         case -ERESTARTNOHAND:
 448                                 regs->gprs[2] = -EINTR;
 449                                 break;
 450                         case -ERESTARTSYS:
 451                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 452                                         regs->gprs[2] = -EINTR;
 453                                         break;
 454                                 }
 455                         /* fallthrough */
 456                         case -ERESTARTNOINTR:
 457                                 regs->gprs[2] = regs->orig_gpr2;
 458                                 regs->psw.addr =
 459                                         __rewind_psw(regs->psw,
 460                                                      regs->svc_code >> 16);
 461                                 break;
 462                         }
 463                 }
 464                 /* No longer in a system call */
 465                 clear_thread_flag(TIF_SYSCALL);
 466
 467                 if ((is_compat_task() ?
 468                      handle_signal32(signr, &ka, &info, oldset, regs) :
 469                      handle_signal(signr, &ka, &info, oldset, regs)) == 0) {
 470                         /*
 471                          * A signal was successfully delivered; the saved
 472                          * sigmask will have been stored in the signal frame,
 473                          * and will be restored by sigreturn, so we can simply
 474                          * clear the TIF_RESTORE_SIGMASK flag.
 475                          */
 476                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 477                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 478
 479                         /*
 480                          * Let tracing know that we've done the handler setup.
 481                          */
 482                         tracehook_signal_handler(signr, &info, &ka, regs,
 483                                          test_thread_flag(TIF_SINGLE_STEP));
 484                 }
 485                 return;
 486         }
 487
 488         /* No handlers present - check for system call restart */
 489         clear_thread_flag(TIF_SYSCALL);
 490         if (current_thread_info()->system_call) {
 491                 regs->svc_code = current_thread_info()->system_call;
 492                 switch (regs->gprs[2]) {
 493                 case -ERESTART_RESTARTBLOCK:
 494                         /* Restart with sys_restart_syscall */
 495                         regs->svc_code = __NR_restart_syscall;
 496                 /* fallthrough */
 497                 case -ERESTARTNOHAND:
 498                 case -ERESTARTSYS:
 499                 case -ERESTARTNOINTR:
 500                         /* Restart system call with magic TIF bit. */
 501                         regs->gprs[2] = regs->orig_gpr2;
 502                         set_thread_flag(TIF_SYSCALL);
 503                         break;
 504                 }
 505         }
 506
 507         /*
 508          * If there's no signal to deliver, we just put the saved sigmask back.
 509          */
 510         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 511                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 512                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 513         }
 514 }
 515
 516 void do_notify_resume(struct pt_regs *regs)
 517 {
 518         clear_thread_flag(TIF_NOTIFY_RESUME);
 519         tracehook_notify_resume(regs);
 520         if (current->replacement_session_keyring)
 521                 key_replace_session_keyring();
 522 }