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 <asm/ucontext.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/lowcore.h>
  32 #include "entry.h"
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36
  37 typedef struct
  38 {
  39         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  40         struct sigcontext sc;
  41         _sigregs sregs;
  42         int signo;
  43         __u8 retcode[S390_SYSCALL_SIZE];
  44 } sigframe;
  45
  46 typedef struct
  47 {
  48         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  49         __u8 retcode[S390_SYSCALL_SIZE];
  50         struct siginfo info;
  51         struct ucontext uc;
  52 } rt_sigframe;
  53
  54 /*
  55  * Atomically swap in the new signal mask, and wait for a signal.
  56  */
  57 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask)
  58 {
  59         mask &= _BLOCKABLE;
  60         spin_lock_irq(&current->sighand->siglock);
  61         current->saved_sigmask = current->blocked;
  62         siginitset(&current->blocked, mask);
  63         recalc_sigpending();
  64         spin_unlock_irq(&current->sighand->siglock);
  65
  66         current->state = TASK_INTERRUPTIBLE;
  67         schedule();
  68         set_thread_flag(TIF_RESTORE_SIGMASK);
  69
  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->svcnr = 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
 175         sigdelsetmask(&set, ~_BLOCKABLE);
 176         spin_lock_irq(&current->sighand->siglock);
 177         current->blocked = set;
 178         recalc_sigpending();
 179         spin_unlock_irq(&current->sighand->siglock);
 180
 181         if (restore_sigregs(regs, &frame->sregs))
 182                 goto badframe;
 183
 184         return regs->gprs[2];
 185
 186 badframe:
 187         force_sig(SIGSEGV, current);
 188         return 0;
 189 }
 190
 191 SYSCALL_DEFINE0(rt_sigreturn)
 192 {
 193         struct pt_regs *regs = task_pt_regs(current);
 194         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 195         sigset_t set;
 196
 197         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 198                 goto badframe;
 199         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 200                 goto badframe;
 201
 202         sigdelsetmask(&set, ~_BLOCKABLE);
 203         spin_lock_irq(&current->sighand->siglock);
 204         current->blocked = set;
 205         recalc_sigpending();
 206         spin_unlock_irq(&current->sighand->siglock);
 207
 208         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 209                 goto badframe;
 210
 211         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 212                            regs->gprs[15]) == -EFAULT)
 213                 goto badframe;
 214         return regs->gprs[2];
 215
 216 badframe:
 217         force_sig(SIGSEGV, current);
 218         return 0;
 219 }
 220
 221 /*
 222  * Set up a signal frame.
 223  */
 224
 225
 226 /*
 227  * Determine which stack to use..
 228  */
 229 static inline void __user *
 230 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 231 {
 232         unsigned long sp;
 233
 234         /* Default to using normal stack */
 235         sp = regs->gprs[15];
 236
 237         /* Overflow on alternate signal stack gives SIGSEGV. */
 238         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 239                 return (void __user *) -1UL;
 240
 241         /* This is the X/Open sanctioned signal stack switching.  */
 242         if (ka->sa.sa_flags & SA_ONSTACK) {
 243                 if (! sas_ss_flags(sp))
 244                         sp = current->sas_ss_sp + current->sas_ss_size;
 245         }
 246
 247         /* This is the legacy signal stack switching. */
 248         else if (!user_mode(regs) &&
 249                  !(ka->sa.sa_flags & SA_RESTORER) &&
 250                  ka->sa.sa_restorer) {
 251                 sp = (unsigned long) ka->sa.sa_restorer;
 252         }
 253
 254         return (void __user *)((sp - frame_size) & -8ul);
 255 }
 256
 257 static inline int map_signal(int sig)
 258 {
 259         if (current_thread_info()->exec_domain
 260             && current_thread_info()->exec_domain->signal_invmap
 261             && sig < 32)
 262                 return current_thread_info()->exec_domain->signal_invmap[sig];
 263         else
 264                 return sig;
 265 }
 266
 267 static int setup_frame(int sig, struct k_sigaction *ka,
 268                        sigset_t *set, struct pt_regs * regs)
 269 {
 270         sigframe __user *frame;
 271
 272         frame = get_sigframe(ka, regs, sizeof(sigframe));
 273         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 274                 goto give_sigsegv;
 275
 276         if (frame == (void __user *) -1UL)
 277                 goto give_sigsegv;
 278
 279         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 280                 goto give_sigsegv;
 281
 282         if (save_sigregs(regs, &frame->sregs))
 283                 goto give_sigsegv;
 284         if (__put_user(&frame->sregs, &frame->sc.sregs))
 285                 goto give_sigsegv;
 286
 287         /* Set up to return from userspace.  If provided, use a stub
 288            already in userspace.  */
 289         if (ka->sa.sa_flags & SA_RESTORER) {
 290                 regs->gprs[14] = (unsigned long)
 291                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 292         } else {
 293                 regs->gprs[14] = (unsigned long)
 294                         frame->retcode | PSW_ADDR_AMODE;
 295                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 296                                (u16 __user *)(frame->retcode)))
 297                         goto give_sigsegv;
 298         }
 299
 300         /* Set up backchain. */
 301         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 302                 goto give_sigsegv;
 303
 304         /* Set up registers for signal handler */
 305         regs->gprs[15] = (unsigned long) frame;
 306         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 307
 308         regs->gprs[2] = map_signal(sig);
 309         regs->gprs[3] = (unsigned long) &frame->sc;
 310
 311         /* We forgot to include these in the sigcontext.
 312            To avoid breaking binary compatibility, they are passed as args. */
 313         regs->gprs[4] = current->thread.trap_no;
 314         regs->gprs[5] = current->thread.prot_addr;
 315
 316         /* Place signal number on stack to allow backtrace from handler.  */
 317         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 318                 goto give_sigsegv;
 319         return 0;
 320
 321 give_sigsegv:
 322         force_sigsegv(sig, current);
 323         return -EFAULT;
 324 }
 325
 326 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 327                            sigset_t *set, struct pt_regs * regs)
 328 {
 329         int err = 0;
 330         rt_sigframe __user *frame;
 331
 332         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 333         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 334                 goto give_sigsegv;
 335
 336         if (frame == (void __user *) -1UL)
 337                 goto give_sigsegv;
 338
 339         if (copy_siginfo_to_user(&frame->info, info))
 340                 goto give_sigsegv;
 341
 342         /* Create the ucontext.  */
 343         err |= __put_user(0, &frame->uc.uc_flags);
 344         err |= __put_user(NULL, &frame->uc.uc_link);
 345         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 346         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 347                           &frame->uc.uc_stack.ss_flags);
 348         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 349         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 350         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 351         if (err)
 352                 goto give_sigsegv;
 353
 354         /* Set up to return from userspace.  If provided, use a stub
 355            already in userspace.  */
 356         if (ka->sa.sa_flags & SA_RESTORER) {
 357                 regs->gprs[14] = (unsigned long)
 358                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 359         } else {
 360                 regs->gprs[14] = (unsigned long)
 361                         frame->retcode | PSW_ADDR_AMODE;
 362                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 363                                (u16 __user *)(frame->retcode)))
 364                         goto give_sigsegv;
 365         }
 366
 367         /* Set up backchain. */
 368         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 369                 goto give_sigsegv;
 370
 371         /* Set up registers for signal handler */
 372         regs->gprs[15] = (unsigned long) frame;
 373         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 374
 375         regs->gprs[2] = map_signal(sig);
 376         regs->gprs[3] = (unsigned long) &frame->info;
 377         regs->gprs[4] = (unsigned long) &frame->uc;
 378         return 0;
 379
 380 give_sigsegv:
 381         force_sigsegv(sig, current);
 382         return -EFAULT;
 383 }
 384
 385 /*
 386  * OK, we're invoking a handler
 387  */
 388
 389 static int
 390 handle_signal(unsigned long sig, struct k_sigaction *ka,
 391               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 392 {
 393         int ret;
 394
 395         /* Set up the stack frame */
 396         if (ka->sa.sa_flags & SA_SIGINFO)
 397                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 398         else
 399                 ret = setup_frame(sig, ka, oldset, regs);
 400
 401         if (ret == 0) {
 402                 spin_lock_irq(&current->sighand->siglock);
 403                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 404                 if (!(ka->sa.sa_flags & SA_NODEFER))
 405                         sigaddset(&current->blocked,sig);
 406                 recalc_sigpending();
 407                 spin_unlock_irq(&current->sighand->siglock);
 408         }
 409
 410         return ret;
 411 }
 412
 413 /*
 414  * Note that 'init' is a special process: it doesn't get signals it doesn't
 415  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 416  * mistake.
 417  *
 418  * Note that we go through the signals twice: once to check the signals that
 419  * the kernel can handle, and then we build all the user-level signal handling
 420  * stack-frames in one go after that.
 421  */
 422 void do_signal(struct pt_regs *regs)
 423 {
 424         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 425         siginfo_t info;
 426         int signr;
 427         struct k_sigaction ka;
 428         sigset_t *oldset;
 429
 430         /*
 431          * We want the common case to go fast, which
 432          * is why we may in certain cases get here from
 433          * kernel mode. Just return without doing anything
 434          * if so.
 435          */
 436         if (!user_mode(regs))
 437                 return;
 438
 439         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 440                 oldset = &current->saved_sigmask;
 441         else
 442                 oldset = &current->blocked;
 443
 444         /* Are we from a system call? */
 445         if (regs->svcnr) {
 446                 continue_addr = regs->psw.addr;
 447                 restart_addr = continue_addr - regs->ilc;
 448                 retval = regs->gprs[2];
 449
 450                 /* Prepare for system call restart.  We do this here so that a
 451                    debugger will see the already changed PSW. */
 452                 switch (retval) {
 453                 case -ERESTARTNOHAND:
 454                 case -ERESTARTSYS:
 455                 case -ERESTARTNOINTR:
 456                         regs->gprs[2] = regs->orig_gpr2;
 457                         regs->psw.addr = restart_addr;
 458                         break;
 459                 case -ERESTART_RESTARTBLOCK:
 460                         regs->gprs[2] = -EINTR;
 461                 }
 462                 regs->svcnr = 0;        /* Don't deal with this again. */
 463         }
 464
 465         /* Get signal to deliver.  When running under ptrace, at this point
 466            the debugger may change all our registers ... */
 467         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 468
 469         /* Depending on the signal settings we may need to revert the
 470            decision to restart the system call. */
 471         if (signr > 0 && regs->psw.addr == restart_addr) {
 472                 if (retval == -ERESTARTNOHAND
 473                     || (retval == -ERESTARTSYS
 474                          && !(current->sighand->action[signr-1].sa.sa_flags
 475                               & SA_RESTART))) {
 476                         regs->gprs[2] = -EINTR;
 477                         regs->psw.addr = continue_addr;
 478                 }
 479         }
 480
 481         if (signr > 0) {
 482                 /* Whee!  Actually deliver the signal.  */
 483                 int ret;
 484 #ifdef CONFIG_COMPAT
 485                 if (test_thread_flag(TIF_31BIT)) {
 486                         ret = handle_signal32(signr, &ka, &info, oldset, regs);
 487                 }
 488                 else
 489 #endif
 490                         ret = handle_signal(signr, &ka, &info, oldset, regs);
 491                 if (!ret) {
 492                         /*
 493                          * A signal was successfully delivered; the saved
 494                          * sigmask will have been stored in the signal frame,
 495                          * and will be restored by sigreturn, so we can simply
 496                          * clear the TIF_RESTORE_SIGMASK flag.
 497                          */
 498                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 499                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 500
 501                         /*
 502                          * If we would have taken a single-step trap
 503                          * for a normal instruction, act like we took
 504                          * one for the handler setup.
 505                          */
 506                         if (current->thread.per_info.single_step)
 507                                 set_thread_flag(TIF_SINGLE_STEP);
 508
 509                         /*
 510                          * Let tracing know that we've done the handler setup.
 511                          */
 512                         tracehook_signal_handler(signr, &info, &ka, regs,
 513                                          test_thread_flag(TIF_SINGLE_STEP));
 514                 }
 515                 return;
 516         }
 517
 518         /*
 519          * If there's no signal to deliver, we just put the saved sigmask back.
 520          */
 521         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 522                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 523                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 524         }
 525
 526         /* Restart a different system call. */
 527         if (retval == -ERESTART_RESTARTBLOCK
 528             && regs->psw.addr == continue_addr) {
 529                 regs->gprs[2] = __NR_restart_syscall;
 530                 set_thread_flag(TIF_RESTART_SVC);
 531         }
 532 }
 533
 534 void do_notify_resume(struct pt_regs *regs)
 535 {
 536         clear_thread_flag(TIF_NOTIFY_RESUME);
 537         tracehook_notify_resume(regs);
 538 }