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signal.c

/*
 *  linux/arch/m68knommu/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

/*
 * Linux/m68k support by Hamish Macdonald
 *
 * 68060 fixes by Jesper Skov
 *
 * 1997-12-01  Modified for POSIX.1b signals by Andreas Schwab
 *
 * mathemu support by Roman Zippel
 *  (Note: fpstate in the signal context is completely ignored for the emulator
 *         and the internal floating point format is put on stack)
 */

/*
 * ++roman (07/09/96): implemented signal stacks (specially for tosemu on
 * Atari :-) Current limitation: Only one sigstack can be active at one time.
 * If a second signal with SA_ONSTACK set arrives while working on a sigstack,
 * SA_ONSTACK is ignored. This behaviour avoids lots of trouble with nested
 * signal handlers!
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/highuid.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>

#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/traps.h>
#include <asm/ucontext.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

void ret_from_user_signal(void);
void ret_from_user_rt_signal(void);
asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs);

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int do_sigsuspend(struct pt_regs *regs)
{
      old_sigset_t mask = regs->d3;
      sigset_t saveset;

      mask &= _BLOCKABLE;
      spin_lock_irq(&current->sighand->siglock);
      saveset = current->blocked;
      siginitset(&current->blocked, mask);
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

      regs->d0 = -EINTR;
      while (1) {
            current->state = TASK_INTERRUPTIBLE;
            schedule();
            if (do_signal(&saveset, regs))
                  return -EINTR;
      }
}

asmlinkage int
do_rt_sigsuspend(struct pt_regs *regs)
{
      sigset_t *unewset = (sigset_t *)regs->d1;
      size_t sigsetsize = (size_t)regs->d2;
      sigset_t saveset, newset;

      /* XXX: Don't preclude handling different sized sigset_t's.  */
      if (sigsetsize != sizeof(sigset_t))
            return -EINVAL;

      if (copy_from_user(&newset, unewset, sizeof(newset)))
            return -EFAULT;
      sigdelsetmask(&newset, ~_BLOCKABLE);

      spin_lock_irq(&current->sighand->siglock);
      saveset = current->blocked;
      current->blocked = newset;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

      regs->d0 = -EINTR;
      while (1) {
            current->state = TASK_INTERRUPTIBLE;
            schedule();
            if (do_signal(&saveset, regs))
                  return -EINTR;
      }
}

asmlinkage int 
sys_sigaction(int sig, const struct old_sigaction *act,
            struct old_sigaction *oact)
{
      struct k_sigaction new_ka, old_ka;
      int ret;

      if (act) {
            old_sigset_t mask;
            if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
                __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
                __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
                  return -EFAULT;
            __get_user(new_ka.sa.sa_flags, &act->sa_flags);
            __get_user(mask, &act->sa_mask);
            siginitset(&new_ka.sa.sa_mask, mask);
      }

      ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

      if (!ret && oact) {
            if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
                __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
                __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
                  return -EFAULT;
            __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
            __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
      }

      return ret;
}

asmlinkage int
sys_sigaltstack(const stack_t *uss, stack_t *uoss)
{
      return do_sigaltstack(uss, uoss, rdusp());
}


/*
 * Do a signal return; undo the signal stack.
 *
 * Keep the return code on the stack quadword aligned!
 * That makes the cache flush below easier.
 */

struct sigframe
{
      char *pretcode;
      int sig;
      int code;
      struct sigcontext *psc;
      char retcode[8];
      unsigned long extramask[_NSIG_WORDS-1];
      struct sigcontext sc;
};

struct rt_sigframe
{
      char *pretcode;
      int sig;
      struct siginfo *pinfo;
      void *puc;
      char retcode[8];
      struct siginfo info;
      struct ucontext uc;
};

#ifdef CONFIG_FPU

static unsigned char fpu_version = 0;     /* version number of fpu, set by setup_frame */

static inline int restore_fpu_state(struct sigcontext *sc)
{
      int err = 1;

      if (FPU_IS_EMU) {
          /* restore registers */
          memcpy(current->thread.fpcntl, sc->sc_fpcntl, 12);
          memcpy(current->thread.fp, sc->sc_fpregs, 24);
          return 0;
      }

      if (sc->sc_fpstate[0]) {
          /* Verify the frame format.  */
          if (sc->sc_fpstate[0] != fpu_version)
            goto out;

          __asm__ volatile (".chip 68k/68881\n\t"
                        "fmovemx %0,%/fp0-%/fp1\n\t"
                        "fmoveml %1,%/fpcr/%/fpsr/%/fpiar\n\t"
                        ".chip 68k"
                        : /* no outputs */
                        : "m" (*sc->sc_fpregs), "m" (*sc->sc_fpcntl));
      }
      __asm__ volatile (".chip 68k/68881\n\t"
                    "frestore %0\n\t"
                    ".chip 68k" : : "m" (*sc->sc_fpstate));
      err = 0;

out:
      return err;
}

#define FPCONTEXT_SIZE  216
#define uc_fpstate      uc_filler[0]
#define uc_formatvec    uc_filler[FPCONTEXT_SIZE/4]
#define uc_extra  uc_filler[FPCONTEXT_SIZE/4+1]

static inline int rt_restore_fpu_state(struct ucontext *uc)
{
      unsigned char fpstate[FPCONTEXT_SIZE];
      int context_size = 0;
      fpregset_t fpregs;
      int err = 1;

      if (FPU_IS_EMU) {
            /* restore fpu control register */
            if (__copy_from_user(current->thread.fpcntl,
                        &uc->uc_mcontext.fpregs.f_pcr, 12))
                  goto out;
            /* restore all other fpu register */
            if (__copy_from_user(current->thread.fp,
                        uc->uc_mcontext.fpregs.f_fpregs, 96))
                  goto out;
            return 0;
      }

      if (__get_user(*(long *)fpstate, (long *)&uc->uc_fpstate))
            goto out;
      if (fpstate[0]) {
            context_size = fpstate[1];

            /* Verify the frame format.  */
            if (fpstate[0] != fpu_version)
                  goto out;
            if (__copy_from_user(&fpregs, &uc->uc_mcontext.fpregs,
                 sizeof(fpregs)))
                  goto out;
            __asm__ volatile (".chip 68k/68881\n\t"
                          "fmovemx %0,%/fp0-%/fp7\n\t"
                          "fmoveml %1,%/fpcr/%/fpsr/%/fpiar\n\t"
                          ".chip 68k"
                          : /* no outputs */
                          : "m" (*fpregs.f_fpregs),
                            "m" (fpregs.f_pcr));
      }
      if (context_size &&
          __copy_from_user(fpstate + 4, (long *)&uc->uc_fpstate + 1,
                       context_size))
            goto out;
      __asm__ volatile (".chip 68k/68881\n\t"
                    "frestore %0\n\t"
                    ".chip 68k" : : "m" (*fpstate));
      err = 0;

out:
      return err;
}

#endif

static inline int
restore_sigcontext(struct pt_regs *regs, struct sigcontext *usc, void *fp,
               int *pd0)
{
      int formatvec;
      struct sigcontext context;
      int err = 0;

      /* Always make any pending restarted system calls return -EINTR */
      current_thread_info()->restart_block.fn = do_no_restart_syscall;

      /* get previous context */
      if (copy_from_user(&context, usc, sizeof(context)))
            goto badframe;
      
      /* restore passed registers */
      regs->d1 = context.sc_d1;
      regs->a0 = context.sc_a0;
      regs->a1 = context.sc_a1;
      ((struct switch_stack *)regs - 1)->a5 = context.sc_a5;
      regs->sr = (regs->sr & 0xff00) | (context.sc_sr & 0xff);
      regs->pc = context.sc_pc;
      regs->orig_d0 = -1;           /* disable syscall checks */
      wrusp(context.sc_usp);
      formatvec = context.sc_formatvec;
      regs->format = formatvec >> 12;
      regs->vector = formatvec & 0xfff;

#ifdef CONFIG_FPU
      err = restore_fpu_state(&context);
#endif

      *pd0 = context.sc_d0;
      return err;

badframe:
      return 1;
}

static inline int
rt_restore_ucontext(struct pt_regs *regs, struct switch_stack *sw,
                struct ucontext *uc, int *pd0)
{
      int temp;
      greg_t *gregs = uc->uc_mcontext.gregs;
      unsigned long usp;
      int err;

      /* Always make any pending restarted system calls return -EINTR */
      current_thread_info()->restart_block.fn = do_no_restart_syscall;

      err = __get_user(temp, &uc->uc_mcontext.version);
      if (temp != MCONTEXT_VERSION)
            goto badframe;
      /* restore passed registers */
      err |= __get_user(regs->d0, &gregs[0]);
      err |= __get_user(regs->d1, &gregs[1]);
      err |= __get_user(regs->d2, &gregs[2]);
      err |= __get_user(regs->d3, &gregs[3]);
      err |= __get_user(regs->d4, &gregs[4]);
      err |= __get_user(regs->d5, &gregs[5]);
      err |= __get_user(sw->d6, &gregs[6]);
      err |= __get_user(sw->d7, &gregs[7]);
      err |= __get_user(regs->a0, &gregs[8]);
      err |= __get_user(regs->a1, &gregs[9]);
      err |= __get_user(regs->a2, &gregs[10]);
      err |= __get_user(sw->a3, &gregs[11]);
      err |= __get_user(sw->a4, &gregs[12]);
      err |= __get_user(sw->a5, &gregs[13]);
      err |= __get_user(sw->a6, &gregs[14]);
      err |= __get_user(usp, &gregs[15]);
      wrusp(usp);
      err |= __get_user(regs->pc, &gregs[16]);
      err |= __get_user(temp, &gregs[17]);
      regs->sr = (regs->sr & 0xff00) | (temp & 0xff);
      regs->orig_d0 = -1;           /* disable syscall checks */
      regs->format = temp >> 12;
      regs->vector = temp & 0xfff;

      if (do_sigaltstack(&uc->uc_stack, NULL, usp) == -EFAULT)
            goto badframe;

      *pd0 = regs->d0;
      return err;

badframe:
      return 1;
}

asmlinkage int do_sigreturn(unsigned long __unused)
{
      struct switch_stack *sw = (struct switch_stack *) &__unused;
      struct pt_regs *regs = (struct pt_regs *) (sw + 1);
      unsigned long usp = rdusp();
      struct sigframe *frame = (struct sigframe *)(usp - 4);
      sigset_t set;
      int d0;

      if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
            goto badframe;
      if (__get_user(set.sig[0], &frame->sc.sc_mask) ||
          (_NSIG_WORDS > 1 &&
           __copy_from_user(&set.sig[1], &frame->extramask,
                        sizeof(frame->extramask))))
            goto badframe;

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
      
      if (restore_sigcontext(regs, &frame->sc, frame + 1, &d0))
            goto badframe;
      return d0;

badframe:
      force_sig(SIGSEGV, current);
      return 0;
}

asmlinkage int do_rt_sigreturn(unsigned long __unused)
{
      struct switch_stack *sw = (struct switch_stack *) &__unused;
      struct pt_regs *regs = (struct pt_regs *) (sw + 1);
      unsigned long usp = rdusp();
      struct rt_sigframe *frame = (struct rt_sigframe *)(usp - 4);
      sigset_t set;
      int d0;

      if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
            goto badframe;
      if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
            goto badframe;

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
      
      if (rt_restore_ucontext(regs, sw, &frame->uc, &d0))
            goto badframe;
      return d0;

badframe:
      force_sig(SIGSEGV, current);
      return 0;
}

#ifdef CONFIG_FPU
/*
 * Set up a signal frame.
 */

static inline void save_fpu_state(struct sigcontext *sc, struct pt_regs *regs)
{
      if (FPU_IS_EMU) {
            /* save registers */
            memcpy(sc->sc_fpcntl, current->thread.fpcntl, 12);
            memcpy(sc->sc_fpregs, current->thread.fp, 24);
            return;
      }

      __asm__ volatile (".chip 68k/68881\n\t"
                    "fsave %0\n\t"
                    ".chip 68k"
                    : : "m" (*sc->sc_fpstate) : "memory");

      if (sc->sc_fpstate[0]) {
            fpu_version = sc->sc_fpstate[0];
            __asm__ volatile (".chip 68k/68881\n\t"
                          "fmovemx %/fp0-%/fp1,%0\n\t"
                          "fmoveml %/fpcr/%/fpsr/%/fpiar,%1\n\t"
                          ".chip 68k"
                          : /* no outputs */
                          : "m" (*sc->sc_fpregs),
                            "m" (*sc->sc_fpcntl)
                          : "memory");
      }
}

static inline int rt_save_fpu_state(struct ucontext *uc, struct pt_regs *regs)
{
      unsigned char fpstate[FPCONTEXT_SIZE];
      int context_size = 0;
      int err = 0;

      if (FPU_IS_EMU) {
            /* save fpu control register */
            err |= copy_to_user(&uc->uc_mcontext.fpregs.f_pcr,
                        current->thread.fpcntl, 12);
            /* save all other fpu register */
            err |= copy_to_user(uc->uc_mcontext.fpregs.f_fpregs,
                        current->thread.fp, 96);
            return err;
      }

      __asm__ volatile (".chip 68k/68881\n\t"
                    "fsave %0\n\t"
                    ".chip 68k"
                    : : "m" (*fpstate) : "memory");

      err |= __put_user(*(long *)fpstate, (long *)&uc->uc_fpstate);
      if (fpstate[0]) {
            fpregset_t fpregs;
            context_size = fpstate[1];
            fpu_version = fpstate[0];
            __asm__ volatile (".chip 68k/68881\n\t"
                          "fmovemx %/fp0-%/fp7,%0\n\t"
                          "fmoveml %/fpcr/%/fpsr/%/fpiar,%1\n\t"
                          ".chip 68k"
                          : /* no outputs */
                          : "m" (*fpregs.f_fpregs),
                            "m" (fpregs.f_pcr)
                          : "memory");
            err |= copy_to_user(&uc->uc_mcontext.fpregs, &fpregs,
                            sizeof(fpregs));
      }
      if (context_size)
            err |= copy_to_user((long *)&uc->uc_fpstate + 1, fpstate + 4,
                            context_size);
      return err;
}

#endif

static void setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
                       unsigned long mask)
{
      sc->sc_mask = mask;
      sc->sc_usp = rdusp();
      sc->sc_d0 = regs->d0;
      sc->sc_d1 = regs->d1;
      sc->sc_a0 = regs->a0;
      sc->sc_a1 = regs->a1;
      sc->sc_a5 = ((struct switch_stack *)regs - 1)->a5;
      sc->sc_sr = regs->sr;
      sc->sc_pc = regs->pc;
      sc->sc_formatvec = regs->format << 12 | regs->vector;
#ifdef CONFIG_FPU
      save_fpu_state(sc, regs);
#endif
}

static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
{
      struct switch_stack *sw = (struct switch_stack *)regs - 1;
      greg_t *gregs = uc->uc_mcontext.gregs;
      int err = 0;

      err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
      err |= __put_user(regs->d0, &gregs[0]);
      err |= __put_user(regs->d1, &gregs[1]);
      err |= __put_user(regs->d2, &gregs[2]);
      err |= __put_user(regs->d3, &gregs[3]);
      err |= __put_user(regs->d4, &gregs[4]);
      err |= __put_user(regs->d5, &gregs[5]);
      err |= __put_user(sw->d6, &gregs[6]);
      err |= __put_user(sw->d7, &gregs[7]);
      err |= __put_user(regs->a0, &gregs[8]);
      err |= __put_user(regs->a1, &gregs[9]);
      err |= __put_user(regs->a2, &gregs[10]);
      err |= __put_user(sw->a3, &gregs[11]);
      err |= __put_user(sw->a4, &gregs[12]);
      err |= __put_user(sw->a5, &gregs[13]);
      err |= __put_user(sw->a6, &gregs[14]);
      err |= __put_user(rdusp(), &gregs[15]);
      err |= __put_user(regs->pc, &gregs[16]);
      err |= __put_user(regs->sr, &gregs[17]);
#ifdef CONFIG_FPU
      err |= rt_save_fpu_state(uc, regs);
#endif
      return err;
}

static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
      unsigned long usp;

      /* Default to using normal stack.  */
      usp = rdusp();

      /* This is the X/Open sanctioned signal stack switching.  */
      if (ka->sa.sa_flags & SA_ONSTACK) {
            if (!sas_ss_flags(usp))
                  usp = current->sas_ss_sp + current->sas_ss_size;
      }
      return (void *)((usp - frame_size) & -8UL);
}

static void setup_frame (int sig, struct k_sigaction *ka,
                   sigset_t *set, struct pt_regs *regs)
{
      struct sigframe *frame;
      struct sigcontext context;
      int err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));

      err |= __put_user((current_thread_info()->exec_domain
                     && current_thread_info()->exec_domain->signal_invmap
                     && sig < 32
                     ? current_thread_info()->exec_domain->signal_invmap[sig]
                     : sig),
                    &frame->sig);

      err |= __put_user(regs->vector, &frame->code);
      err |= __put_user(&frame->sc, &frame->psc);

      if (_NSIG_WORDS > 1)
            err |= copy_to_user(frame->extramask, &set->sig[1],
                            sizeof(frame->extramask));

      setup_sigcontext(&context, regs, set->sig[0]);
      err |= copy_to_user (&frame->sc, &context, sizeof(context));

      /* Set up to return from userspace.  */
      err |= __put_user((void *) ret_from_user_signal, &frame->pretcode);

      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler */
      wrusp ((unsigned long) frame);
      regs->pc = (unsigned long) ka->sa.sa_handler;
      ((struct switch_stack *)regs - 1)->a5 = current->mm->start_data;
      regs->format = 0x4; /*set format byte to make stack appear modulo 4 
                                    which it will be when doing the rte */

adjust_stack:
      /* Prepare to skip over the extra stuff in the exception frame.  */
      if (regs->stkadj) {
            struct pt_regs *tregs =
                  (struct pt_regs *)((ulong)regs + regs->stkadj);
#if defined(DEBUG)
            printk(KERN_DEBUG "Performing stackadjust=%04x\n", regs->stkadj);
#endif
            /* This must be copied with decreasing addresses to
                   handle overlaps.  */
            tregs->vector = 0;
            tregs->format = 0;
            tregs->pc = regs->pc;
            tregs->sr = regs->sr;
      }
      return;

give_sigsegv:
      force_sigsegv(sig, current);
      goto adjust_stack;
}

static void setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
                      sigset_t *set, struct pt_regs *regs)
{
      struct rt_sigframe *frame;
      int err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));

      err |= __put_user((current_thread_info()->exec_domain
                     && current_thread_info()->exec_domain->signal_invmap
                     && sig < 32
                     ? current_thread_info()->exec_domain->signal_invmap[sig]
                     : sig),
                    &frame->sig);
      err |= __put_user(&frame->info, &frame->pinfo);
      err |= __put_user(&frame->uc, &frame->puc);
      err |= copy_siginfo_to_user(&frame->info, info);

      /* Create the ucontext.  */
      err |= __put_user(0, &frame->uc.uc_flags);
      err |= __put_user(0, &frame->uc.uc_link);
      err |= __put_user((void *)current->sas_ss_sp,
                    &frame->uc.uc_stack.ss_sp);
      err |= __put_user(sas_ss_flags(rdusp()),
                    &frame->uc.uc_stack.ss_flags);
      err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
      err |= rt_setup_ucontext(&frame->uc, regs);
      err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));

      /* Set up to return from userspace.  */
      err |= __put_user((void *) ret_from_user_rt_signal, &frame->pretcode);

      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler */
      wrusp ((unsigned long) frame);
      regs->pc = (unsigned long) ka->sa.sa_handler;
      ((struct switch_stack *)regs - 1)->a5 = current->mm->start_data;
      regs->format = 0x4; /*set format byte to make stack appear modulo 4 
                                    which it will be when doing the rte */

adjust_stack:
      /* Prepare to skip over the extra stuff in the exception frame.  */
      if (regs->stkadj) {
            struct pt_regs *tregs =
                  (struct pt_regs *)((ulong)regs + regs->stkadj);
#if defined(DEBUG)
            printk(KERN_DEBUG "Performing stackadjust=%04x\n", regs->stkadj);
#endif
            /* This must be copied with decreasing addresses to
                   handle overlaps.  */
            tregs->vector = 0;
            tregs->format = 0;
            tregs->pc = regs->pc;
            tregs->sr = regs->sr;
      }
      return;

give_sigsegv:
      force_sigsegv(sig, current);
      goto adjust_stack;
}

static inline void
handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
{
      switch (regs->d0) {
      case -ERESTARTNOHAND:
            if (!has_handler)
                  goto do_restart;
            regs->d0 = -EINTR;
            break;

      case -ERESTART_RESTARTBLOCK:
            if (!has_handler) {
                  regs->d0 = __NR_restart_syscall;
                  regs->pc -= 2;
                  break;
            }
            regs->d0 = -EINTR;
            break;

      case -ERESTARTSYS:
            if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
                  regs->d0 = -EINTR;
                  break;
            }
      /* fallthrough */
      case -ERESTARTNOINTR:
      do_restart:
            regs->d0 = regs->orig_d0;
            regs->pc -= 2;
            break;
      }
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
            sigset_t *oldset, struct pt_regs *regs)
{
      /* are we from a system call? */
      if (regs->orig_d0 >= 0)
            /* If so, check system call restarting.. */
            handle_restart(regs, ka, 1);

      /* set up the stack frame */
      if (ka->sa.sa_flags & SA_SIGINFO)
            setup_rt_frame(sig, ka, info, oldset, regs);
      else
            setup_frame(sig, ka, oldset, regs);

      if (ka->sa.sa_flags & SA_ONESHOT)
            ka->sa.sa_handler = SIG_DFL;

      spin_lock_irq(&current->sighand->siglock);
      sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
      if (!(ka->sa.sa_flags & SA_NODEFER))
            sigaddset(&current->blocked,sig);
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
      struct k_sigaction ka;
      siginfo_t info;
      int signr;

      /*
       * We want the common case to go fast, which
       * is why we may in certain cases get here from
       * kernel mode. Just return without doing anything
       * if so.
       */
      if (!user_mode(regs))
            return 1;

      if (!oldset)
            oldset = &current->blocked;

      signr = get_signal_to_deliver(&info, &ka, regs, NULL);
      if (signr > 0) {
            /* Whee!  Actually deliver the signal.  */
            handle_signal(signr, &ka, &info, oldset, regs);
            return 1;
      }

      /* Did we come from a system call? */
      if (regs->orig_d0 >= 0) {
            /* Restart the system call - no handlers present */
            handle_restart(regs, NULL, 0);
      }
      return 0;
}

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