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signal.c

/*
 *  linux/arch/h8300/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.
 */

/*
 * uClinux H8/300 support by Yoshinori Sato <ysato@users.sourceforge.jp>
 *                and David McCullough <davidm@snapgear.com>
 *
 * Based on
 * Linux/m68k by Hamish Macdonald
 */

/*
 * ++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/personality.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/freezer.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)))

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

/*
 * 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->er3;
      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->er0 = -EINTR;
      while (1) {
            current->state = TASK_INTERRUPTIBLE;
            schedule();
            if (do_signal(regs, &saveset))
                  return -EINTR;
      }
}

asmlinkage int
do_rt_sigsuspend(struct pt_regs *regs)
{
      sigset_t *unewset = (sigset_t *)regs->er1;
      size_t sigsetsize = (size_t)regs->er2;
      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->er0 = -EINTR;
      while (1) {
            current->state = TASK_INTERRUPTIBLE;
            schedule();
            if (do_signal(regs, &saveset))
                  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
{
      long dummy_er0;
      long dummy_vector;
#if defined(CONFIG_CPU_H8S)
      short dummy_exr;
#endif
      long dummy_pc;
      char *pretcode;
      unsigned char retcode[8];
      unsigned long extramask[_NSIG_WORDS-1];
      struct sigcontext sc;
      int sig;
} __attribute__((aligned(2),packed));

struct rt_sigframe
{
      long dummy_er0;
      long dummy_vector;
#if defined(CONFIG_CPU_H8S)
      short dummy_exr;
#endif
      long dummy_pc;
      char *pretcode;
      struct siginfo *pinfo;
      void *puc;
      unsigned char retcode[8];
      struct siginfo info;
      struct ucontext uc;
      int sig;
} __attribute__((aligned(2),packed));

static inline int
restore_sigcontext(struct pt_regs *regs, struct sigcontext *usc,
               int *pd0)
{
      int err = 0;
      unsigned int ccr;
      unsigned int usp;
      unsigned int er0;

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

#define COPY(r) err |= __get_user(regs->r, &usc->sc_##r)    /* restore passed registers */
      COPY(er1);
      COPY(er2);
      COPY(er3);
      COPY(er5);
      COPY(pc);
      ccr = regs->ccr & 0x10;
      COPY(ccr);
#undef COPY
      regs->ccr &= 0xef;
      regs->ccr |= ccr;
      regs->orig_er0 = -1;          /* disable syscall checks */
      err |= __get_user(usp, &usc->sc_usp);
      wrusp(usp);

      err |= __get_user(er0, &usc->sc_er0);
      *pd0 = er0;
      return err;
}

asmlinkage int do_sigreturn(unsigned long __unused,...)
{
      struct pt_regs *regs = (struct pt_regs *) (&__unused - 1);
      unsigned long usp = rdusp();
      struct sigframe *frame = (struct sigframe *)(usp - 4);
      sigset_t set;
      int er0;

      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, &er0))
            goto badframe;
      return er0;

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

asmlinkage int do_rt_sigreturn(unsigned long __unused,...)
{
      struct pt_regs *regs = (struct pt_regs *) &__unused;
      unsigned long usp = rdusp();
      struct rt_sigframe *frame = (struct rt_sigframe *)(usp - 4);
      sigset_t set;
      int er0;

      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_unlock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_lock_irq(&current->sighand->siglock);
      
      if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &er0))
            goto badframe;

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

      return er0;

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

static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
                       unsigned long mask)
{
      int err = 0;

      err |= __put_user(regs->er0, &sc->sc_er0);
      err |= __put_user(regs->er1, &sc->sc_er1);
      err |= __put_user(regs->er2, &sc->sc_er2);
      err |= __put_user(regs->er3, &sc->sc_er3);
      err |= __put_user(regs->er4, &sc->sc_er4);
      err |= __put_user(regs->er5, &sc->sc_er5);
      err |= __put_user(regs->er6, &sc->sc_er6);
      err |= __put_user(rdusp(),   &sc->sc_usp);
      err |= __put_user(regs->pc,  &sc->sc_pc);
      err |= __put_user(regs->ccr, &sc->sc_ccr);
      err |= __put_user(mask,      &sc->sc_mask);

      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;
      int err = 0;
      int usig;
      unsigned char *ret;

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

      if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
            goto give_sigsegv;

      usig = current_thread_info()->exec_domain
            && current_thread_info()->exec_domain->signal_invmap
            && sig < 32
            ? current_thread_info()->exec_domain->signal_invmap[sig]
            : sig;

      err |= __put_user(usig, &frame->sig);
      if (err)
            goto give_sigsegv;

      err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
      if (err)
            goto give_sigsegv;

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

      ret = frame->retcode;
      if (ka->sa.sa_flags & SA_RESTORER)
            ret = (unsigned char *)(ka->sa.sa_restorer);
      else {
            /* sub.l er0,er0; mov.b #__NR_sigreturn,r0l; trapa #0 */
            err |= __put_user(0x1a80f800 + (__NR_sigreturn & 0xff),
                          (unsigned long *)(frame->retcode + 0));
            err |= __put_user(0x5700, (unsigned short *)(frame->retcode + 4));
      }

      /* Set up to return from userspace.  */
      err |= __put_user(ret, &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;
      regs->er0 = (current_thread_info()->exec_domain
                     && current_thread_info()->exec_domain->signal_invmap
                     && sig < 32
                     ? current_thread_info()->exec_domain->signal_invmap[sig]
                      : sig);
      regs->er1 = (unsigned long)&(frame->sc);
      regs->er5 = current->mm->start_data;      /* GOT base */

      return;

give_sigsegv:
      force_sigsegv(sig, current);
}

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;
      int usig;
      unsigned char *ret;

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

      if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
            goto give_sigsegv;

      usig = current_thread_info()->exec_domain
            && current_thread_info()->exec_domain->signal_invmap
            && sig < 32
            ? current_thread_info()->exec_domain->signal_invmap[sig]
            : sig;

      err |= __put_user(usig, &frame->sig);
      if (err)
            goto give_sigsegv;

      err |= __put_user(&frame->info, &frame->pinfo);
      err |= __put_user(&frame->uc, &frame->puc);
      err |= copy_siginfo_to_user(&frame->info, info);
      if (err)
            goto give_sigsegv;

      /* 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 |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
      err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));
      if (err)
            goto give_sigsegv;

      /* Set up to return from userspace.  */
      ret = frame->retcode;
      if (ka->sa.sa_flags & SA_RESTORER)
            ret = (unsigned char *)(ka->sa.sa_restorer);
      else {
            /* sub.l er0,er0; mov.b #__NR_sigreturn,r0l; trapa #0 */
            err |= __put_user(0x1a80f800 + (__NR_sigreturn & 0xff),
                          (unsigned long *)(frame->retcode + 0));
            err |= __put_user(0x5700, (unsigned short *)(frame->retcode + 4));
      }
      err |= __put_user(ret, &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;
      regs->er0 = (current_thread_info()->exec_domain
                 && current_thread_info()->exec_domain->signal_invmap
                 && sig < 32
                 ? current_thread_info()->exec_domain->signal_invmap[sig]
                 : sig);
      regs->er1 = (unsigned long)&(frame->info);
      regs->er2 = (unsigned long)&frame->uc;
      regs->er5 = current->mm->start_data;      /* GOT base */

      return;

give_sigsegv:
      force_sigsegv(sig, current);
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
            sigset_t *oldset, struct pt_regs * regs)
{
      /* are we from a system call? */
      if (regs->orig_er0 >= 0) {
            switch (regs->er0) {
                    case -ERESTART_RESTARTBLOCK:
                  case -ERESTARTNOHAND:
                        regs->er0 = -EINTR;
                        break;

                  case -ERESTARTSYS:
                        if (!(ka->sa.sa_flags & SA_RESTART)) {
                              regs->er0 = -EINTR;
                              break;
                        }
                  /* fallthrough */
                  case -ERESTARTNOINTR:
                        regs->er0 = regs->orig_er0;
                        regs->pc -= 2;
            }
      }

      /* 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);

      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(struct pt_regs *regs, sigset_t *oldset)
{
      siginfo_t info;
      int signr;
      struct k_sigaction ka;

      /*
       * 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 ((regs->ccr & 0x10))
            return 1;

      if (try_to_freeze())
            goto no_signal;

      current->thread.esp0 = (unsigned long) regs;

      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, &info, &ka, oldset, regs);
            return 1;
      }
 no_signal:
      /* Did we come from a system call? */
      if (regs->orig_er0 >= 0) {
            /* Restart the system call - no handlers present */
            if (regs->er0 == -ERESTARTNOHAND ||
                regs->er0 == -ERESTARTSYS ||
                regs->er0 == -ERESTARTNOINTR) {
                  regs->er0 = regs->orig_er0;
                  regs->pc -= 2;
            }
            if (regs->er0 == -ERESTART_RESTARTBLOCK){
                  regs->er0 = __NR_restart_syscall;
                  regs->pc -= 2;
            }
      }
      return 0;
}

asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
{
      if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
            do_signal(regs, NULL);
}

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