arch/cris/arch-v32/kernel/signal.c - maze/linux - Git at Google

 /*
  * Copyright (C) 2003, Axis Communications AB.
  */

 #include <linux/sched.h>
 #include <linux/mm.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/syscalls.h>
 #include <linux/vmalloc.h>

 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 #include <arch/ptrace.h>
 #include <arch/hwregs/cpu_vect.h>

 extern unsigned long cris_signal_return_page;

 /* Flag to check if a signal is blockable. */
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

 /*
  * A syscall in CRIS is really a "break 13" instruction, which is 2
  * bytes. The registers is manipulated so upon return the instruction
  * will be executed again.
  *
  * This relies on that PC points to the instruction after the break call.
  */
 #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;

 /* Signal frames. */
 struct signal_frame {
 	struct sigcontext sc;
 	unsigned long extramask[_NSIG_WORDS - 1];
 	unsigned char retcode[8];	/* Trampoline code. */
 };

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

 void do_signal(int restart, struct pt_regs *regs);
 void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
 		      struct pt_regs *regs);
 /*
  * Swap in the new signal mask, and wait for a signal. Define some
  * dummy arguments to be able to reach the regs argument.
  */
 int
 sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
 	       long srp, struct pt_regs *regs)
 {
 	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;
 }

 int
 sys_sigaction(int signal, const struct old_sigaction *act,
 	      struct old_sigaction *oact)
 {
 	int retval;
 	struct k_sigaction newk;
 	struct k_sigaction oldk;

 	if (act) {
 		old_sigset_t mask;

 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 		    __get_user(newk.sa.sa_handler, &act->sa_handler) ||
 		    __get_user(newk.sa.sa_restorer, &act->sa_restorer))
 			return -EFAULT;

 		__get_user(newk.sa.sa_flags, &act->sa_flags);
 		__get_user(mask, &act->sa_mask);
 		siginitset(&newk.sa.sa_mask, mask);
 	}

 	retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);

 	if (!retval && oact) {
 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 		    __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
 		    __put_user(oldk.sa.sa_restorer, &oact->sa_restorer))
 			return -EFAULT;

 		__put_user(oldk.sa.sa_flags, &oact->sa_flags);
 		__put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask);
 	}

 	return retval;
 }

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

 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 registers from &sc->regs. sc is already checked
 	 * for VERIFY_READ since the signal_frame was previously
 	 * checked in sys_sigreturn().
 	 */
 	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
 		goto badframe;

 	/* Make that the user-mode flag is set. */
 	regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));

 	/* Restore the old USP. */
 	err |= __get_user(old_usp, &sc->usp);
 	wrusp(old_usp);

 	return err;

 badframe:
 	return 1;
 }

 /* Define some 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)
 {
 	sigset_t set;
 	struct signal_frame __user *frame;
 	unsigned long oldspc = regs->spc;
 	unsigned long oldccs = regs->ccs;

 	frame = (struct signal_frame *) rdusp();

 	/*
 	 * Since the signal is stacked on a dword boundary, the frame
 	 * should be dword aligned here as well. It it's not, then the
 	 * user is trying some funny business.
 	 */
 	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;

 	keep_debug_flags(oldccs, oldspc, regs);

 	return regs->r10;

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

 /* Define some dummy variables 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)
 {
 	sigset_t set;
 	struct rt_signal_frame __user *frame;
 	unsigned long oldspc = regs->spc;
 	unsigned long oldccs = regs->ccs;

 	frame = (struct rt_signal_frame *) rdusp();

 	/*
 	 * Since the signal is stacked on a dword boundary, the frame
 	 * should be dword aligned here as well. It it's not, then the
 	 * user is trying some funny business.
 	 */
 	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;

 	keep_debug_flags(oldccs, oldspc, regs);

 	return regs->r10;

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

 /* Setup a signal frame. */
 static int
 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 		 unsigned long mask)
 {
 	int err;
 	unsigned long usp;

 	err = 0;
 	usp = rdusp();

 	/*
 	 * Copy the registers. They are located first in sc, so it's
 	 * possible to use sc directly.
 	 */
 	err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));

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

 	return err;
 }

 /* Figure out where 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;

 	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 a lot of state-info is stacked, and arranged for the
  * user-mode program to return to the kernel using either a trampiline
  * which performs the syscall sigreturn(), or a provided user-mode
  * trampoline.
   */
 static int
 setup_frame(int sig, struct k_sigaction *ka,  sigset_t *set,
 	    struct pt_regs * regs)
 {
 	int err;
 	unsigned long return_ip;
 	struct signal_frame __user *frame;

 	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 user-space. If provided, use a stub
 	 * already located in user-space.
 	 */
 	if (ka->sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long)ka->sa.sa_restorer;
 	} else {
 		/* Trampoline - the desired return ip is in the signal return page. */
 		return_ip = cris_signal_return_page;

 		/*
 		 * This is movu.w __NR_sigreturn, r9; break 13;
 		 *
 		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 		 * reasons and because gdb uses it as a signature to notice
 		 * signal handler stack frames.
 		 */
 		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.
 	 *
 	 * Where the code enters now.
 	 * Where the code enter later.
 	 * First argument, signo.
 	 */
 	regs->erp = (unsigned long) ka->sa.sa_handler;
 	regs->srp = return_ip;
 	regs->r10 = sig;

 	/* Actually move the USP to reflect the stacked frame. */
 	wrusp((unsigned long)frame);

 	return 0;

 give_sigsegv:
 	if (sig == SIGSEGV)
 		ka->sa.sa_handler = SIG_DFL;

 	force_sig(SIGSEGV, current);
 	return -EFAULT;
 }

 static int
 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	       sigset_t *set, struct pt_regs * regs)
 {
 	int err;
 	unsigned long return_ip;
 	struct rt_signal_frame __user *frame;

 	err = 0;
 	frame = get_sigframe(ka, regs, sizeof(*frame));

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

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

 	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 user-space. If provided, use a stub
 	 * already located in user-space.
 	 */
 	if (ka->sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long) ka->sa.sa_restorer;
 	} else {
 		/* Trampoline - the desired return ip is in the signal return page. */
 		return_ip = cris_signal_return_page + 6;

 		/*
 		 * This is movu.w __NR_rt_sigreturn, r9; break 13;
 		 *
 		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 		 * reasons and because gdb uses it as a signature to notice
 		 * signal handler stack frames.
 		 */
 		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;

 	/*
 	 * Set up registers for signal handler.
 	 *
 	 * Where the code enters now.
 	 * Where the code enters later.
 	 * First argument is signo.
 	 * Second argument is (siginfo_t *).
 	 * Third argument is unused.
 	 */
 	regs->erp = (unsigned long) ka->sa.sa_handler;
 	regs->srp = return_ip;
 	regs->r10 = sig;
 	regs->r11 = (unsigned long) &frame->info;
 	regs->r12 = 0;

 	/* Actually move the usp to reflect the stacked frame. */
 	wrusp((unsigned long)frame);

 	return 0;

 give_sigsegv:
 	if (sig == SIGSEGV)
 		ka->sa.sa_handler = SIG_DFL;

 	force_sig(SIGSEGV, current);
 	return -EFAULT;
 }

 /* Invoke a signal handler to, well, handle the signal. */
 static inline int
 handle_signal(int canrestart, unsigned long sig,
 	      siginfo_t *info, struct k_sigaction *ka,
               sigset_t *oldset, struct pt_regs * regs)
 {
 	int ret;

 	/* Check if this got called from a system call. */
 	if (canrestart) {
 		/* If so, check system call restarting. */
 		switch (regs->r10) {
 			case -ERESTART_RESTARTBLOCK:
 			case -ERESTARTNOHAND:
 				/*
 				 * This means that the syscall should
 				 * only be restarted if there was no
 				 * handler for the signal, and since
 				 * this point isn't reached unless
 				 * there is a handler, there's no need
 				 * to restart.
 				 */
 				regs->r10 = -EINTR;
 				break;

                         case -ERESTARTSYS:
 				/*
 				 * This means 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;
 				}

 				/* Fall through. */

 			case -ERESTARTNOINTR:
 				/*
 				 * This means that the syscall should
                                  * be called again after the signal
                                  * handler returns.
 				 */
 				RESTART_CRIS_SYS(regs);
 				break;
                 }
         }

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

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

 	if (ret == 0) {
 		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);
 	}

 	return ret;
 }

 /*
  * 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.
  */
 void
 do_signal(int canrestart, struct pt_regs *regs)
 {
 	int signr;
 	siginfo_t info;
         struct k_sigaction ka;
 	sigset_t *oldset;

 	/*
 	 * The common case should go fast, which is why this point is
 	 * reached from kernel-mode. If that's the case, just return
 	 * without doing anything.
 	 */
 	if (!user_mode(regs))
 		return;

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

 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

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

 		return;
 	}

 	/* Got here 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->erp -= 2;
 		}
 	}

 	/* if there's no signal to deliver, we just put the saved sigmask
 	 * back */
 	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 		clear_thread_flag(TIF_RESTORE_SIGMASK);
 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 	}
 }

 asmlinkage void
 ugdb_trap_user(struct thread_info *ti, int sig)
 {
 	if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
 		/* Zero single-step PC if the reason we stopped wasn't a single
 		   step exception. This is to avoid relying on it when it isn't
 		   reliable. */
 		user_regs(ti)->spc = 0;
 	}
 	/* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
 	   not withing any configured h/w breakpoint range). Synchronize with
 	   what already exists for kernel debugging.  */
 	if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
 		/* Break 8: subtract 2 from ERP unless in a delay slot. */
 		if (!(user_regs(ti)->erp & 0x1))
 			user_regs(ti)->erp -= 2;
 	}
 	sys_kill(ti->task->pid, sig);
 }

 void
 keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
 		 struct pt_regs *regs)
 {
 	if (oldccs & (1 << Q_CCS_BITNR)) {
 		/* Pending single step due to single-stepping the break 13
 		   in the signal trampoline: keep the Q flag. */
 		regs->ccs |= (1 << Q_CCS_BITNR);
 		/* S flag should be set - complain if it's not. */
 		if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
 			printk("Q flag but no S flag?");
 		}
 		regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 		/* Assume the SPC is valid and interesting. */
 		regs->spc = oldspc;

 	} else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
 		/* If a h/w bp was set in the signal handler we need
 		   to keep the S flag. */
 		regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 		/* Don't keep the old SPC though; if we got here due to
 		   a single-step, the Q flag should have been set. */
 	} else if (regs->spc) {
 		/* If we were single-stepping *before* the signal was taken,
 		   we don't want to restore that state now, because GDB will
 		   have forgotten all about it. */
 		regs->spc = 0;
 		regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
 	}
 }

 /* Set up the trampolines on the signal return page. */
 int __init
 cris_init_signal(void)
 {
 	u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);

 	/* This is movu.w __NR_sigreturn, r9; break 13; */
 	data[0] = 0x9c5f;
 	data[1] = __NR_sigreturn;
 	data[2] = 0xe93d;
 	/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
 	data[3] = 0x9c5f;
 	data[4] = __NR_rt_sigreturn;
 	data[5] = 0xe93d;

 	/* Map to userspace with appropriate permissions (no write access...) */
 	cris_signal_return_page = (unsigned long)
           __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);

 	return 0;
 }

 __initcall(cris_init_signal);
	/*
	* Copyright (C) 2003, Axis Communications AB.
	*/

	#include <linux/sched.h>
	#include <linux/mm.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/syscalls.h>
	#include <linux/vmalloc.h>

	#include <asm/io.h>
	#include <asm/processor.h>
	#include <asm/ucontext.h>
	#include <asm/uaccess.h>
	#include <arch/ptrace.h>
	#include <arch/hwregs/cpu_vect.h>

	extern unsigned long cris_signal_return_page;

	/* Flag to check if a signal is blockable. */
	#define _BLOCKABLE (~(sigmask(SIGKILL) \| sigmask(SIGSTOP)))

	/*
	* A syscall in CRIS is really a "break 13" instruction, which is 2
	* bytes. The registers is manipulated so upon return the instruction
	* will be executed again.
	*
	* This relies on that PC points to the instruction after the break call.
	*/
	#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;

	/* Signal frames. */
	struct signal_frame {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS - 1];
	unsigned char retcode[8]; /* Trampoline code. */
	};

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

	void do_signal(int restart, struct pt_regs *regs);
	void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
	struct pt_regs *regs);
	/*
	* Swap in the new signal mask, and wait for a signal. Define some
	* dummy arguments to be able to reach the regs argument.
	*/
	int
	sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
	long srp, struct pt_regs *regs)
	{
	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;
	}

	int
	sys_sigaction(int signal, const struct old_sigaction *act,
	struct old_sigaction *oact)
	{
	int retval;
	struct k_sigaction newk;
	struct k_sigaction oldk;

	if (act) {
	old_sigset_t mask;

	if (!access_ok(VERIFY_READ, act, sizeof(*act)) \|\|
	__get_user(newk.sa.sa_handler, &act->sa_handler) \|\|
	__get_user(newk.sa.sa_restorer, &act->sa_restorer))
	return -EFAULT;

	__get_user(newk.sa.sa_flags, &act->sa_flags);
	__get_user(mask, &act->sa_mask);
	siginitset(&newk.sa.sa_mask, mask);
	}

	retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);

	if (!retval && oact) {
	if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) \|\|
	__put_user(oldk.sa.sa_handler, &oact->sa_handler) \|\|
	__put_user(oldk.sa.sa_restorer, &oact->sa_restorer))
	return -EFAULT;

	__put_user(oldk.sa.sa_flags, &oact->sa_flags);
	__put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return retval;
	}

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

	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 registers from &sc->regs. sc is already checked
	* for VERIFY_READ since the signal_frame was previously
	* checked in sys_sigreturn().
	*/
	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
	goto badframe;

	/* Make that the user-mode flag is set. */
	regs->ccs \|= (1 << (U_CCS_BITNR + CCS_SHIFT));

	/* Restore the old USP. */
	err \|= __get_user(old_usp, &sc->usp);
	wrusp(old_usp);

	return err;

	badframe:
	return 1;
	}

	/* Define some 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)
	{
	sigset_t set;
	struct signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct signal_frame *) rdusp();

	/*
	* Since the signal is stacked on a dword boundary, the frame
	* should be dword aligned here as well. It it's not, then the
	* user is trying some funny business.
	*/
	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;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

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

	/* Define some dummy variables 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)
	{
	sigset_t set;
	struct rt_signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct rt_signal_frame *) rdusp();

	/*
	* Since the signal is stacked on a dword boundary, the frame
	* should be dword aligned here as well. It it's not, then the
	* user is trying some funny business.
	*/
	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;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

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

	/* Setup a signal frame. */
	static int
	setup_sigcontext(struct sigcontext __user sc, struct pt_regs regs,
	unsigned long mask)
	{
	int err;
	unsigned long usp;

	err = 0;
	usp = rdusp();

	/*
	* Copy the registers. They are located first in sc, so it's
	* possible to use sc directly.
	*/
	err \|= __copy_to_user(sc, regs, sizeof(struct pt_regs));

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

	return err;
	}

	/* Figure out where 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;

	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 a lot of state-info is stacked, and arranged for the
	* user-mode program to return to the kernel using either a trampiline
	* which performs the syscall sigreturn(), or a provided user-mode
	* trampoline.
	*/
	static int
	setup_frame(int sig, struct k_sigaction ka, sigset_t set,
	struct pt_regs * regs)
	{
	int err;
	unsigned long return_ip;
	struct signal_frame __user *frame;

	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 user-space. If provided, use a stub
	* already located in user-space.
	*/
	if (ka->sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long)ka->sa.sa_restorer;
	} else {
	/* Trampoline - the desired return ip is in the signal return page. */
	return_ip = cris_signal_return_page;

	/*
	* This is movu.w __NR_sigreturn, r9; break 13;
	*
	* WE DO NOT USE IT ANY MORE! It's only left here for historical
	* reasons and because gdb uses it as a signature to notice
	* signal handler stack frames.
	*/
	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.
	*
	* Where the code enters now.
	* Where the code enter later.
	* First argument, signo.
	*/
	regs->erp = (unsigned long) ka->sa.sa_handler;
	regs->srp = return_ip;
	regs->r10 = sig;

	/* Actually move the USP to reflect the stacked frame. */
	wrusp((unsigned long)frame);

	return 0;

	give_sigsegv:
	if (sig == SIGSEGV)
	ka->sa.sa_handler = SIG_DFL;

	force_sig(SIGSEGV, current);
	return -EFAULT;
	}

	static int
	setup_rt_frame(int sig, struct k_sigaction ka, siginfo_t info,
	sigset_t set, struct pt_regs regs)
	{
	int err;
	unsigned long return_ip;
	struct rt_signal_frame __user *frame;

	err = 0;
	frame = get_sigframe(ka, regs, sizeof(*frame));

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

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

	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 user-space. If provided, use a stub
	* already located in user-space.
	*/
	if (ka->sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long) ka->sa.sa_restorer;
	} else {
	/* Trampoline - the desired return ip is in the signal return page. */
	return_ip = cris_signal_return_page + 6;

	/*
	* This is movu.w __NR_rt_sigreturn, r9; break 13;
	*
	* WE DO NOT USE IT ANY MORE! It's only left here for historical
	* reasons and because gdb uses it as a signature to notice
	* signal handler stack frames.
	*/
	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;

	/*
	* Set up registers for signal handler.
	*
	* Where the code enters now.
	* Where the code enters later.
	* First argument is signo.
	* Second argument is (siginfo_t *).
	* Third argument is unused.
	*/
	regs->erp = (unsigned long) ka->sa.sa_handler;
	regs->srp = return_ip;
	regs->r10 = sig;
	regs->r11 = (unsigned long) &frame->info;
	regs->r12 = 0;

	/* Actually move the usp to reflect the stacked frame. */
	wrusp((unsigned long)frame);

	return 0;

	give_sigsegv:
	if (sig == SIGSEGV)
	ka->sa.sa_handler = SIG_DFL;

	force_sig(SIGSEGV, current);
	return -EFAULT;
	}

	/* Invoke a signal handler to, well, handle the signal. */
	static inline int
	handle_signal(int canrestart, unsigned long sig,
	siginfo_t info, struct k_sigaction ka,
	sigset_t oldset, struct pt_regs regs)
	{
	int ret;

	/* Check if this got called from a system call. */
	if (canrestart) {
	/* If so, check system call restarting. */
	switch (regs->r10) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	/*
	* This means that the syscall should
	* only be restarted if there was no
	* handler for the signal, and since
	* this point isn't reached unless
	* there is a handler, there's no need
	* to restart.
	*/
	regs->r10 = -EINTR;
	break;

	case -ERESTARTSYS:
	/*
	* This means 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;
	}

	/* Fall through. */

	case -ERESTARTNOINTR:
	/*
	* This means that the syscall should
	* be called again after the signal
	* handler returns.
	*/
	RESTART_CRIS_SYS(regs);
	break;
	}
	}

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

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

	if (ret == 0) {
	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);
	}

	return ret;
	}

	/*
	* 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.
	*/
	void
	do_signal(int canrestart, struct pt_regs *regs)
	{
	int signr;
	siginfo_t info;
	struct k_sigaction ka;
	sigset_t *oldset;

	/*
	* The common case should go fast, which is why this point is
	* reached from kernel-mode. If that's the case, just return
	* without doing anything.
	*/
	if (!user_mode(regs))
	return;

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

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

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

	return;
	}

	/* Got here 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->erp -= 2;
	}
	}

	/* if there's no signal to deliver, we just put the saved sigmask
	* back */
	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
	clear_thread_flag(TIF_RESTORE_SIGMASK);
	sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
	}
	}

	asmlinkage void
	ugdb_trap_user(struct thread_info *ti, int sig)
	{
	if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
	/* Zero single-step PC if the reason we stopped wasn't a single
	step exception. This is to avoid relying on it when it isn't
	reliable. */
	user_regs(ti)->spc = 0;
	}
	/* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
	not withing any configured h/w breakpoint range). Synchronize with
	what already exists for kernel debugging. */
	if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
	/* Break 8: subtract 2 from ERP unless in a delay slot. */
	if (!(user_regs(ti)->erp & 0x1))
	user_regs(ti)->erp -= 2;
	}
	sys_kill(ti->task->pid, sig);
	}

	void
	keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
	struct pt_regs *regs)
	{
	if (oldccs & (1 << Q_CCS_BITNR)) {
	/* Pending single step due to single-stepping the break 13
	in the signal trampoline: keep the Q flag. */
	regs->ccs \|= (1 << Q_CCS_BITNR);
	/* S flag should be set - complain if it's not. */
	if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
	printk("Q flag but no S flag?");
	}
	regs->ccs \|= (1 << (S_CCS_BITNR + CCS_SHIFT));
	/* Assume the SPC is valid and interesting. */
	regs->spc = oldspc;

	} else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
	/* If a h/w bp was set in the signal handler we need
	to keep the S flag. */
	regs->ccs \|= (1 << (S_CCS_BITNR + CCS_SHIFT));
	/* Don't keep the old SPC though; if we got here due to
	a single-step, the Q flag should have been set. */
	} else if (regs->spc) {
	/* If we were single-stepping before the signal was taken,
	we don't want to restore that state now, because GDB will
	have forgotten all about it. */
	regs->spc = 0;
	regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
	}
	}

	/* Set up the trampolines on the signal return page. */
	int __init
	cris_init_signal(void)
	{
	u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);

	/* This is movu.w __NR_sigreturn, r9; break 13; */
	data[0] = 0x9c5f;
	data[1] = __NR_sigreturn;
	data[2] = 0xe93d;
	/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
	data[3] = 0x9c5f;
	data[4] = __NR_rt_sigreturn;
	data[5] = 0xe93d;

	/* Map to userspace with appropriate permissions (no write access...) */
	cris_signal_return_page = (unsigned long)
	__ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);

	return 0;
	}

	__initcall(cris_init_signal);