arch/cris/arch-v10/kernel/signal.c - maze/linux - Git at Google

 /*
  *  linux/arch/cris/kernel/signal.c
  *
  *  Based on arch/i386/kernel/signal.c by
  *     Copyright (C) 1991, 1992  Linus Torvalds
  *     1997-11-28  Modified for POSIX.1b signals by Richard Henderson *
  *
  *  Ideas also taken from arch/arm.
  *
  *  Copyright (C) 2000, 2001 Axis Communications AB
  *
  *  Authors:  Bjorn Wesen (bjornw@axis.com)
  *
  */

 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.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 <asm/processor.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>

 #define DEBUG_SIG 0

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

 /* a syscall in Linux/CRIS is a break 13 instruction which is 2 bytes */
 /* manipulate regs so that upon return, it will be re-executed */

 /* We rely on that pc points to the instruction after "break 13", so the
  * library must never do strange things like putting it in a delay slot.
  */
 #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->irp -= 2;

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

 /*
  * Atomically swap in the new signal mask, and wait for a signal.  Define
  * dummy arguments to be able to reach the regs argument.  (Note that this
  * arrangement relies on old_sigset_t occupying one register.)
  */
 int
 sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
                long srp, 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->r10 = -EINTR;
 	while (1) {
 		current->state = TASK_INTERRUPTIBLE;
 		schedule();
 		if (do_signal(0, &saveset, regs))
 			/* We will get here twice: once to call the signal
 			   handler, then again to return from the
 			   sigsuspend system call.  When calling the
 			   signal handler, R10 holds the signal number as
 			   set through do_signal.  The sigsuspend call
 			   will return with the restored value set above;
 			   always -EINTR.  */
 			return regs->r10;
 	}
 }

 /* Define dummy arguments to be able to reach the regs argument.  (Note that
  * this arrangement relies on size_t occupying one register.)
  */
 int
 sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r12, long r13,
                   long mof, long srp, 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->r10 = -EINTR;
 	while (1) {
 		current->state = TASK_INTERRUPTIBLE;
 		schedule();
 		if (do_signal(0, &saveset, regs))
 			/* We will get here twice: once to call the signal
 			   handler, then again to return from the
 			   sigsuspend system call.  When calling the
 			   signal handler, R10 holds the signal number as
 			   set through do_signal.  The sigsuspend call
 			   will return with the restored value set above;
 			   always -EINTR.  */
 			return regs->r10;
 	}
 }

 int
 sys_sigaction(int sig, const struct old_sigaction __user *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;
 }

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


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

 struct sigframe {
 	struct sigcontext sc;
 	unsigned long extramask[_NSIG_WORDS-1];
 	unsigned char retcode[8];  /* trampoline code */
 };

 struct rt_sigframe {
 	struct siginfo *pinfo;
 	void *puc;
 	struct siginfo info;
 	struct ucontext uc;
 	unsigned char retcode[8];  /* trampoline code */
 };


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

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

 	/* restore the regs from &sc->regs (same as sc, since regs is first)
 	 * (sc is already checked for VERIFY_READ since the sigframe was
 	 *  checked in sys_sigreturn previously)
 	 */

 	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
                 goto badframe;

 	/* make sure the U-flag is set so user-mode cannot fool us */

 	regs->dccr |= 1 << 8;

 	/* restore the old USP as it was before we stacked the sc etc.
 	 * (we cannot just pop the sigcontext since we aligned the sp and
 	 *  stuff after pushing it)
 	 */

 	err |= __get_user(old_usp, &sc->usp);

 	wrusp(old_usp);

 	/* TODO: the other ports use regs->orig_XX to disable syscall checks
 	 * after this completes, but we don't use that mechanism. maybe we can
 	 * use it now ?
 	 */

 	return err;

 badframe:
 	return 1;
 }

 /* Define dummy arguments to be able to reach the regs argument.  */

 asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
                              long srp, struct pt_regs *regs)
 {
 	struct sigframe __user *frame = (struct sigframe *)rdusp();
 	sigset_t set;

         /*
          * Since we stacked the signal on a dword boundary,
          * then frame should be dword aligned here.  If it's
          * not, then the user is trying to mess with us.
          */
         if (((long)frame) & 3)
                 goto badframe;

 	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))
 		goto badframe;

 	/* TODO: SIGTRAP when single-stepping as in arm ? */

 	return regs->r10;

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

 /* Define dummy arguments to be able to reach the regs argument.  */

 asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
                                 long mof, long srp, struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame = (struct rt_sigframe *)rdusp();
 	sigset_t set;

         /*
          * Since we stacked the signal on a dword boundary,
          * then frame should be dword aligned here.  If it's
          * not, then the user is trying to mess with us.
          */
         if (((long)frame) & 3)
                 goto badframe;

 	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))
 		goto badframe;

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

 	return regs->r10;

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

 /*
  * Set up a signal frame.
  */

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

 	/* copy the regs. they are first in sc so we can use sc directly */

 	err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));

         /* Set the frametype to CRIS_FRAME_NORMAL for the execution of
            the signal handler. The frametype will be restored to its previous
            value in restore_sigcontext. */
         regs->frametype = CRIS_FRAME_NORMAL;

 	/* then some other stuff */

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

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

 	return err;
 }

 /* figure out where we want to put the new signal frame - usually on the stack */

 static inline void __user *
 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 {
 	unsigned long sp = rdusp();

 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
 		if (! on_sig_stack(sp))
 			sp = current->sas_ss_sp + current->sas_ss_size;
 	}

 	/* make sure the frame is dword-aligned */

 	sp &= ~3;

 	return (void __user*)(sp - frame_size);
 }

 /* grab and setup a signal frame.
  *
  * basically we stack a lot of state info, and arrange for the
  * user-mode program to return to the kernel using either a
  * trampoline which performs the syscall sigreturn, or a provided
  * user-mode trampoline.
  */

 static void setup_frame(int sig, struct k_sigaction *ka,
 			sigset_t *set, struct pt_regs * regs)
 {
 	struct sigframe __user *frame;
 	unsigned long return_ip;
 	int err = 0;

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

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

 	/* Set up to return from userspace.  If provided, use a stub
 	   already in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long)ka->sa.sa_restorer;
 	} else {
 		/* trampoline - the desired return ip is the retcode itself */
 		return_ip = (unsigned long)&frame->retcode;
 		/* This is movu.w __NR_sigreturn, r9; break 13; */
 		err |= __put_user(0x9c5f,         (short __user*)(frame->retcode+0));
 		err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
 		err |= __put_user(0xe93d,         (short __user*)(frame->retcode+4));
 	}

 	if (err)
 		goto give_sigsegv;

 	/* Set up registers for signal handler */

 	regs->irp = (unsigned long) ka->sa.sa_handler;  /* what we enter NOW   */
 	regs->srp = return_ip;                          /* what we enter LATER */
 	regs->r10 = sig;                                /* first argument is signo */

 	/* actually move the usp to reflect the stacked frame */

 	wrusp((unsigned long)frame);

 	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 __user *frame;
 	unsigned long return_ip;
 	int err = 0;

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

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

 	/* Clear all the bits of the ucontext we don't use.  */
         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));

 	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.  If provided, use a stub
 	   already in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long)ka->sa.sa_restorer;
 	} else {
 		/* trampoline - the desired return ip is the retcode itself */
 		return_ip = (unsigned long)&frame->retcode;
 		/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
 		err |= __put_user(0x9c5f,            (short __user*)(frame->retcode+0));
 		err |= __put_user(__NR_rt_sigreturn, (short __user*)(frame->retcode+2));
 		err |= __put_user(0xe93d,            (short __user*)(frame->retcode+4));
 	}

 	if (err)
 		goto give_sigsegv;

 	/* TODO what is the current->exec_domain stuff and invmap ? */

 	/* Set up registers for signal handler */

 	regs->irp = (unsigned long) ka->sa.sa_handler;  /* what we enter NOW   */
 	regs->srp = return_ip;                          /* what we enter LATER */
 	regs->r10 = sig;                                /* first argument is signo */
         regs->r11 = (unsigned long) &frame->info;       /* second argument is (siginfo_t *) */
         regs->r12 = 0;                                  /* third argument is unused */

 	/* actually move the usp to reflect the stacked frame */

 	wrusp((unsigned long)frame);

 	return;

 give_sigsegv:
 	force_sigsegv(sig, current);
 }

 /*
  * OK, we're invoking a handler
  */

 static inline void
 handle_signal(int canrestart, unsigned long sig,
 	      siginfo_t *info, struct k_sigaction *ka,
               sigset_t *oldset, struct pt_regs * regs)
 {
 	/* Are we from a system call? */
 	if (canrestart) {
 		/* If so, check system call restarting.. */
 		switch (regs->r10) {
 			case -ERESTART_RESTARTBLOCK:
 			case -ERESTARTNOHAND:
 				/* ERESTARTNOHAND means that the syscall should only be
 				   restarted if there was no handler for the signal, and since
 				   we only get here if there is a handler, we don't restart */
 				regs->r10 = -EINTR;
 				break;

 			case -ERESTARTSYS:
 				/* ERESTARTSYS means to restart the syscall if there is no
 				   handler or the handler was registered with SA_RESTART */
 				if (!(ka->sa.sa_flags & SA_RESTART)) {
 					regs->r10 = -EINTR;
 					break;
 				}
 			/* fallthrough */
 			case -ERESTARTNOINTR:
 				/* ERESTARTNOINTR means that the syscall should be called again
 				   after the signal handler returns. */
 				RESTART_CRIS_SYS(regs);
 		}
 	}

 	/* 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.
  *
  * Also note that the regs structure given here as an argument, is the latest
  * pushed pt_regs. It may or may not be the same as the first pushed registers
  * when the initial usermode->kernelmode transition took place. Therefore
  * we can use user_mode(regs) to see if we came directly from kernel or user
  * mode below.
  */

 int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
 {
 	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(canrestart, signr, &info, &ka, oldset, regs);
 		return 1;
 	}

 	/* Did we come from a system call? */
 	if (canrestart) {
 		/* Restart the system call - no handlers present */
 		if (regs->r10 == -ERESTARTNOHAND ||
 		    regs->r10 == -ERESTARTSYS ||
 		    regs->r10 == -ERESTARTNOINTR) {
 			RESTART_CRIS_SYS(regs);
 		}
 		if (regs->r10 == -ERESTART_RESTARTBLOCK){
 			regs->r10 = __NR_restart_syscall;
 			regs->irp -= 2;
 		}
 	}
 	return 0;
 }
	/*
	* linux/arch/cris/kernel/signal.c
	*
	* Based on arch/i386/kernel/signal.c by
	* Copyright (C) 1991, 1992 Linus Torvalds
	* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson *
	*
	* Ideas also taken from arch/arm.
	*
	* Copyright (C) 2000, 2001 Axis Communications AB
	*
	* Authors: Bjorn Wesen (bjornw@axis.com)
	*
	*/

	#include <linux/sched.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.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 <asm/processor.h>
	#include <asm/ucontext.h>
	#include <asm/uaccess.h>

	#define DEBUG_SIG 0

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

	/* a syscall in Linux/CRIS is a break 13 instruction which is 2 bytes */
	/* manipulate regs so that upon return, it will be re-executed */

	/* We rely on that pc points to the instruction after "break 13", so the
	* library must never do strange things like putting it in a delay slot.
	*/
	#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->irp -= 2;

	int do_signal(int canrestart, sigset_t oldset, struct pt_regs regs);

	/*
	* Atomically swap in the new signal mask, and wait for a signal. Define
	* dummy arguments to be able to reach the regs argument. (Note that this
	* arrangement relies on old_sigset_t occupying one register.)
	*/
	int
	sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
	long srp, 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->r10 = -EINTR;
	while (1) {
	current->state = TASK_INTERRUPTIBLE;
	schedule();
	if (do_signal(0, &saveset, regs))
	/* We will get here twice: once to call the signal
	handler, then again to return from the
	sigsuspend system call. When calling the
	signal handler, R10 holds the signal number as
	set through do_signal. The sigsuspend call
	will return with the restored value set above;
	always -EINTR. */
	return regs->r10;
	}
	}

	/* Define dummy arguments to be able to reach the regs argument. (Note that
	* this arrangement relies on size_t occupying one register.)
	*/
	int
	sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r12, long r13,
	long mof, long srp, 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->r10 = -EINTR;
	while (1) {
	current->state = TASK_INTERRUPTIBLE;
	schedule();
	if (do_signal(0, &saveset, regs))
	/* We will get here twice: once to call the signal
	handler, then again to return from the
	sigsuspend system call. When calling the
	signal handler, R10 holds the signal number as
	set through do_signal. The sigsuspend call
	will return with the restored value set above;
	always -EINTR. */
	return regs->r10;
	}
	}

	int
	sys_sigaction(int sig, const struct old_sigaction __user *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;
	}

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


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

	struct sigframe {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	unsigned char retcode[8]; /* trampoline code */
	};

	struct rt_sigframe {
	struct siginfo *pinfo;
	void *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned char retcode[8]; /* trampoline code */
	};


	static int
	restore_sigcontext(struct pt_regs regs, struct sigcontext __user sc)
	{
	unsigned int err = 0;
	unsigned long old_usp;

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

	/* restore the regs from &sc->regs (same as sc, since regs is first)
	* (sc is already checked for VERIFY_READ since the sigframe was
	* checked in sys_sigreturn previously)
	*/

	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
	goto badframe;

	/* make sure the U-flag is set so user-mode cannot fool us */

	regs->dccr \|= 1 << 8;

	/* restore the old USP as it was before we stacked the sc etc.
	* (we cannot just pop the sigcontext since we aligned the sp and
	* stuff after pushing it)
	*/

	err \|= __get_user(old_usp, &sc->usp);

	wrusp(old_usp);

	/* TODO: the other ports use regs->orig_XX to disable syscall checks
	* after this completes, but we don't use that mechanism. maybe we can
	* use it now ?
	*/

	return err;

	badframe:
	return 1;
	}

	/* Define dummy arguments to be able to reach the regs argument. */

	asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
	long srp, struct pt_regs *regs)
	{
	struct sigframe __user frame = (struct sigframe )rdusp();
	sigset_t set;

	/*
	* Since we stacked the signal on a dword boundary,
	* then frame should be dword aligned here. If it's
	* not, then the user is trying to mess with us.
	*/
	if (((long)frame) & 3)
	goto badframe;

	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))
	goto badframe;

	/* TODO: SIGTRAP when single-stepping as in arm ? */

	return regs->r10;

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

	/* Define dummy arguments to be able to reach the regs argument. */

	asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
	long mof, long srp, struct pt_regs *regs)
	{
	struct rt_sigframe __user frame = (struct rt_sigframe )rdusp();
	sigset_t set;

	/*
	* Since we stacked the signal on a dword boundary,
	* then frame should be dword aligned here. If it's
	* not, then the user is trying to mess with us.
	*/
	if (((long)frame) & 3)
	goto badframe;

	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))
	goto badframe;

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

	return regs->r10;

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

	/*
	* Set up a signal frame.
	*/

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

	/* copy the regs. they are first in sc so we can use sc directly */

	err \|= __copy_to_user(sc, regs, sizeof(struct pt_regs));

	/* Set the frametype to CRIS_FRAME_NORMAL for the execution of
	the signal handler. The frametype will be restored to its previous
	value in restore_sigcontext. */
	regs->frametype = CRIS_FRAME_NORMAL;

	/* then some other stuff */

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

	err \|= __put_user(usp, &sc->usp);

	return err;
	}

	/* figure out where we want to put the new signal frame - usually on the stack */

	static inline void __user *
	get_sigframe(struct k_sigaction ka, struct pt_regs regs, size_t frame_size)
	{
	unsigned long sp = rdusp();

	/* This is the X/Open sanctioned signal stack switching. */
	if (ka->sa.sa_flags & SA_ONSTACK) {
	if (! on_sig_stack(sp))
	sp = current->sas_ss_sp + current->sas_ss_size;
	}

	/* make sure the frame is dword-aligned */

	sp &= ~3;

	return (void __user*)(sp - frame_size);
	}

	/* grab and setup a signal frame.
	*
	* basically we stack a lot of state info, and arrange for the
	* user-mode program to return to the kernel using either a
	* trampoline which performs the syscall sigreturn, or a provided
	* user-mode trampoline.
	*/

	static void setup_frame(int sig, struct k_sigaction *ka,
	sigset_t set, struct pt_regs regs)
	{
	struct sigframe __user *frame;
	unsigned long return_ip;
	int err = 0;

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

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

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ka->sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long)ka->sa.sa_restorer;
	} else {
	/* trampoline - the desired return ip is the retcode itself */
	return_ip = (unsigned long)&frame->retcode;
	/* This is movu.w __NR_sigreturn, r9; break 13; */
	err \|= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
	err \|= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
	err \|= __put_user(0xe93d, (short __user*)(frame->retcode+4));
	}

	if (err)
	goto give_sigsegv;

	/* Set up registers for signal handler */

	regs->irp = (unsigned long) ka->sa.sa_handler; /* what we enter NOW */
	regs->srp = return_ip; /* what we enter LATER */
	regs->r10 = sig; /* first argument is signo */

	/* actually move the usp to reflect the stacked frame */

	wrusp((unsigned long)frame);

	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 __user *frame;
	unsigned long return_ip;
	int err = 0;

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

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

	/* Clear all the bits of the ucontext we don't use. */
	err \|= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));

	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. If provided, use a stub
	already in userspace. */
	if (ka->sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long)ka->sa.sa_restorer;
	} else {
	/* trampoline - the desired return ip is the retcode itself */
	return_ip = (unsigned long)&frame->retcode;
	/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
	err \|= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
	err \|= __put_user(__NR_rt_sigreturn, (short __user*)(frame->retcode+2));
	err \|= __put_user(0xe93d, (short __user*)(frame->retcode+4));
	}

	if (err)
	goto give_sigsegv;

	/* TODO what is the current->exec_domain stuff and invmap ? */

	/* Set up registers for signal handler */

	regs->irp = (unsigned long) ka->sa.sa_handler; /* what we enter NOW */
	regs->srp = return_ip; /* what we enter LATER */
	regs->r10 = sig; /* first argument is signo */
	regs->r11 = (unsigned long) &frame->info; /* second argument is (siginfo_t ) /
	regs->r12 = 0; /* third argument is unused */

	/* actually move the usp to reflect the stacked frame */

	wrusp((unsigned long)frame);

	return;

	give_sigsegv:
	force_sigsegv(sig, current);
	}

	/*
	* OK, we're invoking a handler
	*/

	static inline void
	handle_signal(int canrestart, unsigned long sig,
	siginfo_t info, struct k_sigaction ka,
	sigset_t oldset, struct pt_regs regs)
	{
	/* Are we from a system call? */
	if (canrestart) {
	/* If so, check system call restarting.. */
	switch (regs->r10) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	/* ERESTARTNOHAND means that the syscall should only be
	restarted if there was no handler for the signal, and since
	we only get here if there is a handler, we don't restart */
	regs->r10 = -EINTR;
	break;

	case -ERESTARTSYS:
	/* ERESTARTSYS means to restart the syscall if there is no
	handler or the handler was registered with SA_RESTART */
	if (!(ka->sa.sa_flags & SA_RESTART)) {
	regs->r10 = -EINTR;
	break;
	}
	/* fallthrough */
	case -ERESTARTNOINTR:
	/* ERESTARTNOINTR means that the syscall should be called again
	after the signal handler returns. */
	RESTART_CRIS_SYS(regs);
	}
	}

	/* 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.
	*
	* Also note that the regs structure given here as an argument, is the latest
	* pushed pt_regs. It may or may not be the same as the first pushed registers
	* when the initial usermode->kernelmode transition took place. Therefore
	* we can use user_mode(regs) to see if we came directly from kernel or user
	* mode below.
	*/

	int do_signal(int canrestart, sigset_t oldset, struct pt_regs regs)
	{
	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(canrestart, signr, &info, &ka, oldset, regs);
	return 1;
	}

	/* Did we come from a system call? */
	if (canrestart) {
	/* Restart the system call - no handlers present */
	if (regs->r10 == -ERESTARTNOHAND \|\|
	regs->r10 == -ERESTARTSYS \|\|
	regs->r10 == -ERESTARTNOINTR) {
	RESTART_CRIS_SYS(regs);
	}
	if (regs->r10 == -ERESTART_RESTARTBLOCK){
	regs->r10 = __NR_restart_syscall;
	regs->irp -= 2;
	}
	}
	return 0;
	}