/*

   * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)

   * Licensed under the GPL
   */

  #include <linux/module.h>
  #include <linux/ptrace.h>
  #include <linux/sched.h>
  #include <asm/siginfo.h>
  #include <asm/signal.h>
  #include <asm/unistd.h>

  #include "frame_kern.h"

  #include "kern_util.h"

  
  EXPORT_SYMBOL(block_signals);
  EXPORT_SYMBOL(unblock_signals);
  
  #define _S(nr) (1<<((nr)-1))
  
  #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  
  /*
   * OK, we're invoking a handler

   */

  static int handle_signal(struct pt_regs *regs, unsigned long signr,
  			 struct k_sigaction *ka, siginfo_t *info,
  			 sigset_t *oldset)
  {
  	unsigned long sp;
  	int err;
  
  	/* Always make any pending restarted system calls return -EINTR */
  	current_thread_info()->restart_block.fn = do_no_restart_syscall;
  
  	/* Did we come from a system call? */

  	if (PT_REGS_SYSCALL_NR(regs) >= 0) {

  		/* If so, check system call restarting.. */

  		switch (PT_REGS_SYSCALL_RET(regs)) {

  		case -ERESTART_RESTARTBLOCK:
  		case -ERESTARTNOHAND:
  			PT_REGS_SYSCALL_RET(regs) = -EINTR;
  			break;
  
  		case -ERESTARTSYS:
  			if (!(ka->sa.sa_flags & SA_RESTART)) {
  				PT_REGS_SYSCALL_RET(regs) = -EINTR;
  				break;
  			}
  		/* fallthrough */
  		case -ERESTARTNOINTR:
  			PT_REGS_RESTART_SYSCALL(regs);
  			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  			break;
  		}
  	}
  
  	sp = PT_REGS_SP(regs);

  	if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))

  		sp = current->sas_ss_sp + current->sas_ss_size;
  
  #ifdef CONFIG_ARCH_HAS_SC_SIGNALS

  	if (!(ka->sa.sa_flags & SA_SIGINFO))

  		err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  	else
  #endif
  		err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);

  	if (err) {

  		spin_lock_irq(&current->sighand->siglock);
  		current->blocked = *oldset;
  		recalc_sigpending();
  		spin_unlock_irq(&current->sighand->siglock);
  		force_sigsegv(signr, current);

  	} else {

  		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, signr);

  		recalc_sigpending();
  		spin_unlock_irq(&current->sighand->siglock);
  	}
  
  	return err;
  }

  static int kern_do_signal(struct pt_regs *regs)

  {
  	struct k_sigaction ka_copy;
  	siginfo_t info;

  	sigset_t *oldset;

  	int sig, handled_sig = 0;

  	if (test_thread_flag(TIF_RESTORE_SIGMASK))
  		oldset = &current->saved_sigmask;
  	else
  		oldset = &current->blocked;

  	while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {

  		handled_sig = 1;
  		/* Whee!  Actually deliver the signal.  */

  		if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
  			/*
  			 * a signal was successfully delivered; the saved

  			 * sigmask will have been stored in the signal frame,
  			 * and will be restored by sigreturn, so we can simply

  			 * clear the TIF_RESTORE_SIGMASK flag
  			 */

  			if (test_thread_flag(TIF_RESTORE_SIGMASK))
  				clear_thread_flag(TIF_RESTORE_SIGMASK);

  			break;

  		}

  	}
  
  	/* Did we come from a system call? */

  	if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {

  		/* Restart the system call - no handlers present */

  		switch (PT_REGS_SYSCALL_RET(regs)) {

  		case -ERESTARTNOHAND:
  		case -ERESTARTSYS:
  		case -ERESTARTNOINTR:

  			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  			PT_REGS_RESTART_SYSCALL(regs);

  			break;
  		case -ERESTART_RESTARTBLOCK:

  			PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;

  			PT_REGS_RESTART_SYSCALL(regs);

  			break;

  		}

  	}

  	/*
  	 * This closes a way to execute a system call on the host.  If

  	 * you set a breakpoint on a system call instruction and singlestep
  	 * from it, the tracing thread used to PTRACE_SINGLESTEP the process
  	 * rather than PTRACE_SYSCALL it, allowing the system call to execute

  	 * on the host.  The tracing thread will check this flag and

  	 * PTRACE_SYSCALL if necessary.
  	 */

  	if (current->ptrace & PT_DTRACE)

  		current->thread.singlestep_syscall =
  			is_syscall(PT_REGS_IP(&current->thread.regs));

  	/*
  	 * if there's no signal to deliver, we just put the saved sigmask
  	 * back
  	 */

  	if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
  		clear_thread_flag(TIF_RESTORE_SIGMASK);
  		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
  	}

  	return handled_sig;

  }
  
  int do_signal(void)
  {

  	return kern_do_signal(&current->thread.regs);

  }
  
  /*
   * Atomically swap in the new signal mask, and wait for a signal.
   */
  long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  {

  	mask &= _BLOCKABLE;
  	spin_lock_irq(&current->sighand->siglock);

  	current->saved_sigmask = current->blocked;

  	siginitset(&current->blocked, mask);
  	recalc_sigpending();
  	spin_unlock_irq(&current->sighand->siglock);

  	current->state = TASK_INTERRUPTIBLE;
  	schedule();
  	set_thread_flag(TIF_RESTORE_SIGMASK);
  	return -ERESTARTNOHAND;

  }

  long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  {

  	return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));

  }