linux/arch/s390/kernel/signal.c
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   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 <asm/ucontext.h>
  29#include <asm/uaccess.h>
  30#include <asm/lowcore.h>
  31#include "entry.h"
  32
  33#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  34
  35
  36typedef struct 
  37{
  38        __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  39        struct sigcontext sc;
  40        _sigregs sregs;
  41        int signo;
  42        __u8 retcode[S390_SYSCALL_SIZE];
  43} sigframe;
  44
  45typedef struct 
  46{
  47        __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  48        __u8 retcode[S390_SYSCALL_SIZE];
  49        struct siginfo info;
  50        struct ucontext uc;
  51} rt_sigframe;
  52
  53/*
  54 * Atomically swap in the new signal mask, and wait for a signal.
  55 */
  56asmlinkage int
  57sys_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
  73asmlinkage long
  74sys_sigaction(int sig, const struct old_sigaction __user *act,
  75              struct old_sigaction __user *oact)
  76{
  77        struct k_sigaction new_ka, old_ka;
  78        int ret;
  79
  80        if (act) {
  81                old_sigset_t mask;
  82                if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  83                    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  84                    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  85                    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  86                    __get_user(mask, &act->sa_mask))
  87                        return -EFAULT;
  88                siginitset(&new_ka.sa.sa_mask, mask);
  89        }
  90
  91        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  92
  93        if (!ret && oact) {
  94                if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  95                    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  96                    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  97                    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  98                    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  99                        return -EFAULT;
 100        }
 101
 102        return ret;
 103}
 104
 105asmlinkage long
 106sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 107{
 108        struct pt_regs *regs = task_pt_regs(current);
 109        return do_sigaltstack(uss, uoss, regs->gprs[15]);
 110}
 111
 112
 113
 114/* Returns non-zero on fault. */
 115static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 116{
 117        _sigregs user_sregs;
 118
 119        save_access_regs(current->thread.acrs);
 120
 121        /* Copy a 'clean' PSW mask to the user to avoid leaking
 122           information about whether PER is currently on.  */
 123        user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask);
 124        user_sregs.regs.psw.addr = regs->psw.addr;
 125        memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 126        memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 127               sizeof(sregs->regs.acrs));
 128        /* 
 129         * We have to store the fp registers to current->thread.fp_regs
 130         * to merge them with the emulated registers.
 131         */
 132        save_fp_regs(&current->thread.fp_regs);
 133        memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 134               sizeof(s390_fp_regs));
 135        return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 136}
 137
 138/* Returns positive number on error */
 139static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 140{
 141        int err;
 142        _sigregs user_sregs;
 143
 144        /* Alwys make any pending restarted system call return -EINTR */
 145        current_thread_info()->restart_block.fn = do_no_restart_syscall;
 146
 147        err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 148        if (err)
 149                return err;
 150        regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
 151                                        user_sregs.regs.psw.mask);
 152        regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
 153        memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 154        memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 155               sizeof(sregs->regs.acrs));
 156        restore_access_regs(current->thread.acrs);
 157
 158        memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 159               sizeof(s390_fp_regs));
 160        current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 161
 162        restore_fp_regs(&current->thread.fp_regs);
 163        regs->svcnr = 0;        /* disable syscall checks */
 164        return 0;
 165}
 166
 167asmlinkage long sys_sigreturn(void)
 168{
 169        struct pt_regs *regs = task_pt_regs(current);
 170        sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 171        sigset_t set;
 172
 173        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 174                goto badframe;
 175        if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 176                goto badframe;
 177
 178        sigdelsetmask(&set, ~_BLOCKABLE);
 179        spin_lock_irq(&current->sighand->siglock);
 180        current->blocked = set;
 181        recalc_sigpending();
 182        spin_unlock_irq(&current->sighand->siglock);
 183
 184        if (restore_sigregs(regs, &frame->sregs))
 185                goto badframe;
 186
 187        return regs->gprs[2];
 188
 189badframe:
 190        force_sig(SIGSEGV, current);
 191        return 0;
 192}
 193
 194asmlinkage long sys_rt_sigreturn(void)
 195{
 196        struct pt_regs *regs = task_pt_regs(current);
 197        rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 198        sigset_t set;
 199
 200        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 201                goto badframe;
 202        if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 203                goto badframe;
 204
 205        sigdelsetmask(&set, ~_BLOCKABLE);
 206        spin_lock_irq(&current->sighand->siglock);
 207        current->blocked = set;
 208        recalc_sigpending();
 209        spin_unlock_irq(&current->sighand->siglock);
 210
 211        if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 212                goto badframe;
 213
 214        if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 215                           regs->gprs[15]) == -EFAULT)
 216                goto badframe;
 217        return regs->gprs[2];
 218
 219badframe:
 220        force_sig(SIGSEGV, current);
 221        return 0;
 222}
 223
 224/*
 225 * Set up a signal frame.
 226 */
 227
 228
 229/*
 230 * Determine which stack to use..
 231 */
 232static inline void __user *
 233get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 234{
 235        unsigned long sp;
 236
 237        /* Default to using normal stack */
 238        sp = regs->gprs[15];
 239
 240        /* Overflow on alternate signal stack gives SIGSEGV. */
 241        if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 242                return (void __user *) -1UL;
 243
 244        /* This is the X/Open sanctioned signal stack switching.  */
 245        if (ka->sa.sa_flags & SA_ONSTACK) {
 246                if (! sas_ss_flags(sp))
 247                        sp = current->sas_ss_sp + current->sas_ss_size;
 248        }
 249
 250        /* This is the legacy signal stack switching. */
 251        else if (!user_mode(regs) &&
 252                 !(ka->sa.sa_flags & SA_RESTORER) &&
 253                 ka->sa.sa_restorer) {
 254                sp = (unsigned long) ka->sa.sa_restorer;
 255        }
 256
 257        return (void __user *)((sp - frame_size) & -8ul);
 258}
 259
 260static inline int map_signal(int sig)
 261{
 262        if (current_thread_info()->exec_domain
 263            && current_thread_info()->exec_domain->signal_invmap
 264            && sig < 32)
 265                return current_thread_info()->exec_domain->signal_invmap[sig];
 266        else
 267                return sig;
 268}
 269
 270static int setup_frame(int sig, struct k_sigaction *ka,
 271                       sigset_t *set, struct pt_regs * regs)
 272{
 273        sigframe __user *frame;
 274
 275        frame = get_sigframe(ka, regs, sizeof(sigframe));
 276        if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 277                goto give_sigsegv;
 278
 279        if (frame == (void __user *) -1UL)
 280                goto give_sigsegv;
 281
 282        if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 283                goto give_sigsegv;
 284
 285        if (save_sigregs(regs, &frame->sregs))
 286                goto give_sigsegv;
 287        if (__put_user(&frame->sregs, &frame->sc.sregs))
 288                goto give_sigsegv;
 289
 290        /* Set up to return from userspace.  If provided, use a stub
 291           already in userspace.  */
 292        if (ka->sa.sa_flags & SA_RESTORER) {
 293                regs->gprs[14] = (unsigned long)
 294                        ka->sa.sa_restorer | PSW_ADDR_AMODE;
 295        } else {
 296                regs->gprs[14] = (unsigned long)
 297                        frame->retcode | PSW_ADDR_AMODE;
 298                if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 299                               (u16 __user *)(frame->retcode)))
 300                        goto give_sigsegv;
 301        }
 302
 303        /* Set up backchain. */
 304        if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 305                goto give_sigsegv;
 306
 307        /* Set up registers for signal handler */
 308        regs->gprs[15] = (unsigned long) frame;
 309        regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 310
 311        regs->gprs[2] = map_signal(sig);
 312        regs->gprs[3] = (unsigned long) &frame->sc;
 313
 314        /* We forgot to include these in the sigcontext.
 315           To avoid breaking binary compatibility, they are passed as args. */
 316        regs->gprs[4] = current->thread.trap_no;
 317        regs->gprs[5] = current->thread.prot_addr;
 318
 319        /* Place signal number on stack to allow backtrace from handler.  */
 320        if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 321                goto give_sigsegv;
 322        return 0;
 323
 324give_sigsegv:
 325        force_sigsegv(sig, current);
 326        return -EFAULT;
 327}
 328
 329static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 330                           sigset_t *set, struct pt_regs * regs)
 331{
 332        int err = 0;
 333        rt_sigframe __user *frame;
 334
 335        frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 336        if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 337                goto give_sigsegv;
 338
 339        if (frame == (void __user *) -1UL)
 340                goto give_sigsegv;
 341
 342        if (copy_siginfo_to_user(&frame->info, info))
 343                goto give_sigsegv;
 344
 345        /* Create the ucontext.  */
 346        err |= __put_user(0, &frame->uc.uc_flags);
 347        err |= __put_user(NULL, &frame->uc.uc_link);
 348        err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 349        err |= __put_user(sas_ss_flags(regs->gprs[15]),
 350                          &frame->uc.uc_stack.ss_flags);
 351        err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 352        err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 353        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 354        if (err)
 355                goto give_sigsegv;
 356
 357        /* Set up to return from userspace.  If provided, use a stub
 358           already in userspace.  */
 359        if (ka->sa.sa_flags & SA_RESTORER) {
 360                regs->gprs[14] = (unsigned long)
 361                        ka->sa.sa_restorer | PSW_ADDR_AMODE;
 362        } else {
 363                regs->gprs[14] = (unsigned long)
 364                        frame->retcode | PSW_ADDR_AMODE;
 365                if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 366                               (u16 __user *)(frame->retcode)))
 367                        goto give_sigsegv;
 368        }
 369
 370        /* Set up backchain. */
 371        if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 372                goto give_sigsegv;
 373
 374        /* Set up registers for signal handler */
 375        regs->gprs[15] = (unsigned long) frame;
 376        regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 377
 378        regs->gprs[2] = map_signal(sig);
 379        regs->gprs[3] = (unsigned long) &frame->info;
 380        regs->gprs[4] = (unsigned long) &frame->uc;
 381        return 0;
 382
 383give_sigsegv:
 384        force_sigsegv(sig, current);
 385        return -EFAULT;
 386}
 387
 388/*
 389 * OK, we're invoking a handler
 390 */     
 391
 392static int
 393handle_signal(unsigned long sig, struct k_sigaction *ka,
 394              siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
 395{
 396        int ret;
 397
 398        /* Set up the stack frame */
 399        if (ka->sa.sa_flags & SA_SIGINFO)
 400                ret = setup_rt_frame(sig, ka, info, oldset, regs);
 401        else
 402                ret = setup_frame(sig, ka, oldset, regs);
 403
 404        if (ret == 0) {
 405                spin_lock_irq(&current->sighand->siglock);
 406                sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 407                if (!(ka->sa.sa_flags & SA_NODEFER))
 408                        sigaddset(&current->blocked,sig);
 409                recalc_sigpending();
 410                spin_unlock_irq(&current->sighand->siglock);
 411        }
 412
 413        return ret;
 414}
 415
 416/*
 417 * Note that 'init' is a special process: it doesn't get signals it doesn't
 418 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 419 * mistake.
 420 *
 421 * Note that we go through the signals twice: once to check the signals that
 422 * the kernel can handle, and then we build all the user-level signal handling
 423 * stack-frames in one go after that.
 424 */
 425void do_signal(struct pt_regs *regs)
 426{
 427        unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
 428        siginfo_t info;
 429        int signr;
 430        struct k_sigaction ka;
 431        sigset_t *oldset;
 432
 433        /*
 434         * We want the common case to go fast, which
 435         * is why we may in certain cases get here from
 436         * kernel mode. Just return without doing anything
 437         * if so.
 438         */
 439        if (!user_mode(regs))
 440                return;
 441
 442        if (test_thread_flag(TIF_RESTORE_SIGMASK))
 443                oldset = &current->saved_sigmask;
 444        else
 445                oldset = &current->blocked;
 446
 447        /* Are we from a system call? */
 448        if (regs->svcnr) {
 449                continue_addr = regs->psw.addr;
 450                restart_addr = continue_addr - regs->ilc;
 451                retval = regs->gprs[2];
 452
 453                /* Prepare for system call restart.  We do this here so that a
 454                   debugger will see the already changed PSW. */
 455                switch (retval) {
 456                case -ERESTARTNOHAND:
 457                case -ERESTARTSYS:
 458                case -ERESTARTNOINTR:
 459                        regs->gprs[2] = regs->orig_gpr2;
 460                        regs->psw.addr = restart_addr;
 461                        break;
 462                case -ERESTART_RESTARTBLOCK:
 463                        regs->gprs[2] = -EINTR;
 464                }
 465                regs->svcnr = 0;        /* Don't deal with this again. */
 466        }
 467
 468        /* Get signal to deliver.  When running under ptrace, at this point
 469           the debugger may change all our registers ... */
 470        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 471
 472        /* Depending on the signal settings we may need to revert the
 473           decision to restart the system call. */
 474        if (signr > 0 && regs->psw.addr == restart_addr) {
 475                if (retval == -ERESTARTNOHAND
 476                    || (retval == -ERESTARTSYS
 477                         && !(current->sighand->action[signr-1].sa.sa_flags
 478                              & SA_RESTART))) {
 479                        regs->gprs[2] = -EINTR;
 480                        regs->psw.addr = continue_addr;
 481                }
 482        }
 483
 484        if (signr > 0) {
 485                /* Whee!  Actually deliver the signal.  */
 486                int ret;
 487#ifdef CONFIG_COMPAT
 488                if (test_thread_flag(TIF_31BIT)) {
 489                        ret = handle_signal32(signr, &ka, &info, oldset, regs);
 490                }
 491                else
 492#endif
 493                        ret = handle_signal(signr, &ka, &info, oldset, regs);
 494                if (!ret) {
 495                        /*
 496                         * A signal was successfully delivered; the saved
 497                         * sigmask will have been stored in the signal frame,
 498                         * and will be restored by sigreturn, so we can simply
 499                         * clear the TIF_RESTORE_SIGMASK flag.
 500                         */
 501                        if (test_thread_flag(TIF_RESTORE_SIGMASK))
 502                                clear_thread_flag(TIF_RESTORE_SIGMASK);
 503
 504                        /*
 505                         * If we would have taken a single-step trap
 506                         * for a normal instruction, act like we took
 507                         * one for the handler setup.
 508                         */
 509                        if (current->thread.per_info.single_step)
 510                                set_thread_flag(TIF_SINGLE_STEP);
 511
 512                        /*
 513                         * Let tracing know that we've done the handler setup.
 514                         */
 515                        tracehook_signal_handler(signr, &info, &ka, regs,
 516                                         test_thread_flag(TIF_SINGLE_STEP));
 517                }
 518                return;
 519        }
 520
 521        /*
 522         * If there's no signal to deliver, we just put the saved sigmask back.
 523         */
 524        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 525                clear_thread_flag(TIF_RESTORE_SIGMASK);
 526                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 527        }
 528
 529        /* Restart a different system call. */
 530        if (retval == -ERESTART_RESTARTBLOCK
 531            && regs->psw.addr == continue_addr) {
 532                regs->gprs[2] = __NR_restart_syscall;
 533                set_thread_flag(TIF_RESTART_SVC);
 534        }
 535}
 536
 537void do_notify_resume(struct pt_regs *regs)
 538{
 539        clear_thread_flag(TIF_NOTIFY_RESUME);
 540        tracehook_notify_resume(regs);
 541}
 542