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