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signal.c

/*
 * arch/v850/kernel/signal.c -- Signal handling
 *
 *  Copyright (C) 2001,02,03  NEC Electronics Corporation
 *  Copyright (C) 2001,02,03  Miles Bader <miles@gnu.org>
 *  Copyright (C) 1999,2000,2002  Niibe Yutaka & Kaz Kojima
 *  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.
 *
 * 1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 * This file was derived from the sh version, arch/sh/kernel/signal.c
 */

#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/tty.h>

#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/thread_info.h>
#include <asm/cacheflush.h>

#define DEBUG_SIG 0

#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
sys_sigsuspend(old_sigset_t mask, struct pt_regs *regs)
{
      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->gpr[GPR_RVAL] = -EINTR;
      while (1) {
            current->state = TASK_INTERRUPTIBLE;
            schedule();
            if (do_signal(regs, &saveset))
                  return -EINTR;
      }
}

asmlinkage int
sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize,
              struct pt_regs *regs)
{
      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->gpr[GPR_RVAL] = -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,
            struct pt_regs *regs)
{
      return do_sigaltstack(uss, uoss, regs->gpr[GPR_SP]);
}


/*
 * Do a signal return; undo the signal stack.
 */

struct sigframe
{
      struct sigcontext sc;
      unsigned long extramask[_NSIG_WORDS-1];
      unsigned long tramp[2]; /* signal trampoline */
};

struct rt_sigframe
{
      struct siginfo info;
      struct ucontext uc;
      unsigned long tramp[2]; /* signal trampoline */
};

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc, int *rval_p)
{
      unsigned int err = 0;

#define COPY(x)         err |= __get_user(regs->x, &sc->regs.x)
      COPY(gpr[0]);     COPY(gpr[1]);     COPY(gpr[2]);     COPY(gpr[3]);
      COPY(gpr[4]);     COPY(gpr[5]);     COPY(gpr[6]);     COPY(gpr[7]);
      COPY(gpr[8]);     COPY(gpr[9]);     COPY(gpr[10]);    COPY(gpr[11]);
      COPY(gpr[12]);    COPY(gpr[13]);    COPY(gpr[14]);    COPY(gpr[15]);
      COPY(gpr[16]);    COPY(gpr[17]);    COPY(gpr[18]);    COPY(gpr[19]);
      COPY(gpr[20]);    COPY(gpr[21]);    COPY(gpr[22]);    COPY(gpr[23]);
      COPY(gpr[24]);    COPY(gpr[25]);    COPY(gpr[26]);    COPY(gpr[27]);
      COPY(gpr[28]);    COPY(gpr[29]);    COPY(gpr[30]);    COPY(gpr[31]);
      COPY(pc);   COPY(psw);
      COPY(ctpc); COPY(ctpsw);      COPY(ctbp);
#undef COPY

      return err;
}

asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
      struct sigframe *frame = (struct sigframe *)regs->gpr[GPR_SP];
      sigset_t set;
      int rval;

      if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
            goto badframe;

      if (__get_user(set.sig[0], &frame->sc.oldmask)
          || (_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, &rval))
            goto badframe;
      return rval;

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

asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
      struct rt_sigframe *frame = (struct rt_sigframe *)regs->gpr[GPR_SP];
      sigset_t set;
      stack_t st;
      int rval;

      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 (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
            goto badframe;

      if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
            goto badframe;
      /* It is more difficult to avoid calling this function than to
         call it and ignore errors.  */
      do_sigaltstack(&st, NULL, regs->gpr[GPR_SP]);

      return rval;

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

/*
 * Set up a signal frame.
 */

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

#define COPY(x)         err |= __put_user(regs->x, &sc->regs.x)
      COPY(gpr[0]);     COPY(gpr[1]);     COPY(gpr[2]);     COPY(gpr[3]);
      COPY(gpr[4]);     COPY(gpr[5]);     COPY(gpr[6]);     COPY(gpr[7]);
      COPY(gpr[8]);     COPY(gpr[9]);     COPY(gpr[10]);    COPY(gpr[11]);
      COPY(gpr[12]);    COPY(gpr[13]);    COPY(gpr[14]);    COPY(gpr[15]);
      COPY(gpr[16]);    COPY(gpr[17]);    COPY(gpr[18]);    COPY(gpr[19]);
      COPY(gpr[20]);    COPY(gpr[21]);    COPY(gpr[22]);    COPY(gpr[23]);
      COPY(gpr[24]);    COPY(gpr[25]);    COPY(gpr[26]);    COPY(gpr[27]);
      COPY(gpr[28]);    COPY(gpr[29]);    COPY(gpr[30]);    COPY(gpr[31]);
      COPY(pc);   COPY(psw);
      COPY(ctpc); COPY(ctpsw);      COPY(ctbp);
#undef COPY

      err |= __put_user(mask, &sc->oldmask);

      return err;
}

/*
 * Determine which stack to use..
 */
static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
      /* Default to using normal stack */
      unsigned long sp = regs->gpr[GPR_SP];

      if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
            sp = current->sas_ss_sp + current->sas_ss_size;

      return (void *)((sp - 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 signal;

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

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

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

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

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

      /* Set up to return from userspace.  If provided, use a stub
         already in userspace.  */
      if (ka->sa.sa_flags & SA_RESTORER) {
            regs->gpr[GPR_LP] = (unsigned long) ka->sa.sa_restorer;
      } else {
            /* Note, these encodings are _little endian_!  */

            /* addi  __NR_sigreturn, r0, r12  */
            err |= __put_user(0x6600 | (__NR_sigreturn << 16),
                          frame->tramp + 0);
            /* trap 0 */
            err |= __put_user(0x010007e0,
                          frame->tramp + 1);

            regs->gpr[GPR_LP] = (unsigned long)frame->tramp;

            flush_cache_sigtramp (regs->gpr[GPR_LP]);
      }

      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler.  */
      regs->pc = (v850_reg_t) ka->sa.sa_handler;
      regs->gpr[GPR_SP] = (v850_reg_t)frame;
      /* Signal handler args:  */
      regs->gpr[GPR_ARG0] = signal; /* arg 0: signum */
      regs->gpr[GPR_ARG1] = (v850_reg_t)&frame->sc;/* arg 1: sigcontext */

      set_fs(USER_DS);

#if DEBUG_SIG
      printk("SIG deliver (%s:%d): sp=%p pc=%08lx ra=%08lx\n",
            current->comm, current->pid, frame, regs->pc, );
#endif

      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 signal;

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

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

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

      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(regs->gpr[GPR_SP]),
                    &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));

      /* Set up to return from userspace.  If provided, use a stub
         already in userspace.  */
      if (ka->sa.sa_flags & SA_RESTORER) {
            regs->gpr[GPR_LP] = (unsigned long) ka->sa.sa_restorer;
      } else {
            /* Note, these encodings are _little endian_!  */

            /* addi  __NR_sigreturn, r0, r12  */
            err |= __put_user(0x6600 | (__NR_sigreturn << 16),
                          frame->tramp + 0);
            /* trap 0 */
            err |= __put_user(0x010007e0,
                          frame->tramp + 1);

            regs->gpr[GPR_LP] = (unsigned long)frame->tramp;

            flush_cache_sigtramp (regs->gpr[GPR_LP]);
      }

      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler.  */
      regs->pc = (v850_reg_t) ka->sa.sa_handler;
      regs->gpr[GPR_SP] = (v850_reg_t)frame;
      /* Signal handler args:  */
      regs->gpr[GPR_ARG0] = signal; /* arg 0: signum */
      regs->gpr[GPR_ARG1] = (v850_reg_t)&frame->info; /* arg 1: siginfo */
      regs->gpr[GPR_ARG2] = (v850_reg_t)&frame->uc; /* arg 2: ucontext */

      set_fs(USER_DS);

#if DEBUG_SIG
      printk("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
            current->comm, current->pid, frame, regs->pc, regs->pr);
#endif

      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 (PT_REGS_SYSCALL (regs)) {
            /* If so, check system call restarting.. */
            switch (regs->gpr[GPR_RVAL]) {
            case -ERESTART_RESTARTBLOCK:
                  current_thread_info()->restart_block.fn =
                        do_no_restart_syscall;
                  /* fall through */
            case -ERESTARTNOHAND:
                  regs->gpr[GPR_RVAL] = -EINTR;
                  break;

            case -ERESTARTSYS:
                  if (!(ka->sa.sa_flags & SA_RESTART)) {
                        regs->gpr[GPR_RVAL] = -EINTR;
                        break;
                  }
                  /* fallthrough */
            case -ERESTARTNOINTR:
                  regs->gpr[12] = PT_REGS_SYSCALL (regs);
                  regs->pc -= 4; /* Size of `trap 0' insn.  */
            }

            PT_REGS_SET_SYSCALL (regs, 0);
      }

      /* 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.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
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 (!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, &info, &ka, oldset, regs);
            return 1;
      }

      /* Did we come from a system call? */
      if (PT_REGS_SYSCALL (regs)) {
            int rval = (int)regs->gpr[GPR_RVAL];
            /* Restart the system call - no handlers present */
            if (rval == -ERESTARTNOHAND
                || rval == -ERESTARTSYS
                || rval == -ERESTARTNOINTR)
            {
                  regs->gpr[12] = PT_REGS_SYSCALL (regs);
                  regs->pc -= 4; /* Size of `trap 0' insn.  */
            }
            else if (rval == -ERESTART_RESTARTBLOCK) {
                  regs->gpr[12] = __NR_restart_syscall;
                  regs->pc -= 4; /* Size of `trap 0' insn.  */
            }
      }
      return 0;
}

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