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

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  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) 2000-2007 Axis Communications AB
  *
  *  Authors:  Bjorn Wesen (bjornw@axis.com)
  *
  */

 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #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 <asm/processor.h>
 #include <asm/ucontext.h>
 #include <linux/uaccess.h>
 #include <arch/system.h>

 #define DEBUG_SIG 0

 /* 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;

 void do_signal(int canrestart, struct pt_regs *regs);

 /*
  * 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->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;
 }

 asmlinkage int sys_sigreturn(void)
 {
 	struct pt_regs *regs = current_pt_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;

 	set_current_blocked(&set);

 	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;
 }

 asmlinkage int sys_rt_sigreturn(void)
 {
 	struct pt_regs *regs = current_pt_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;

 	set_current_blocked(&set);

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

 	if (restore_altstack(&frame->uc.uc_stack))
 		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 ksignal *ksig, size_t frame_size)
 {
 	unsigned long sp = sigsp(rdusp(), ksig);

 	/* 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 int setup_frame(struct ksignal *ksig, sigset_t *set,
 		       struct pt_regs *regs)
 {
 	struct sigframe __user *frame;
 	unsigned long return_ip;
 	int err = 0;

 	frame = get_sigframe(ksig, sizeof(*frame));

 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		return -EFAULT;

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

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

 	/* Set up to return from userspace.  If provided, use a stub
 	   already in userspace.  */
 	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long)ksig->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)
 		return -EFAULT;

 	/* Set up registers for signal handler */

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

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

 	wrusp((unsigned long)frame);

 	return 0;
 }

 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 			  struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame;
 	unsigned long return_ip;
 	int err = 0;

 	frame = get_sigframe(ksig, sizeof(*frame));

 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		return -EFAULT;

 	err |= __put_user(&frame->info, &frame->pinfo);
 	err |= __put_user(&frame->uc, &frame->puc);
 	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 	if (err)
 		return -EFAULT;

 	/* 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));

 	err |= __save_altstack(&frame->uc.uc_stack, rdusp());

 	if (err)
 		return -EFAULT;

 	/* Set up to return from userspace.  If provided, use a stub
 	   already in userspace.  */
 	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 		return_ip = (unsigned long)ksig->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)
 		return -EFAULT;

 	/* Set up registers for signal handler */

 	/* What we enter NOW   */
 	regs->irp = (unsigned long) ksig->ka.sa.sa_handler;
 	/* What we enter LATER */
 	regs->srp = return_ip;
 	/* First argument is signo */
 	regs->r10 = ksig->sig;
 	/* Second argument is (siginfo_t *) */
 	regs->r11 = (unsigned long)&frame->info;
 	/* Third argument is unused */
 	regs->r12 = 0;

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

 	return 0;
 }

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

 static inline void handle_signal(int canrestart, struct ksignal *ksig,
 				 struct pt_regs *regs)
 {
 	sigset_t *oldset = sigmask_to_save();
 	int ret;

 	/* 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 (!(ksig->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 (ksig->ka.sa.sa_flags & SA_SIGINFO)
 		ret = setup_rt_frame(ksig, oldset, regs);
 	else
 		ret = setup_frame(ksig, oldset, regs);

 	signal_setup_done(ret, ksig, 0);
 }

 /*
  * 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)
 {
 	struct ksignal ksig;

 	/*
 	 * 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;

 	if (get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.  */
 		handle_signal(canrestart, &ksig, regs);
 		return;
 	}

 	/* 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->r9 = __NR_restart_syscall;
 			regs->irp -= 2;
 		}
 	}

 	/* if there's no signal to deliver, we just put the saved sigmask
 	 * back */
 	restore_saved_sigmask();
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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) 2000-2007 Axis Communications AB
	*
	* Authors: Bjorn Wesen (bjornw@axis.com)
	*
	*/

	#include <linux/sched.h>
	#include <linux/sched/task_stack.h>
	#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 <asm/processor.h>
	#include <asm/ucontext.h>
	#include <linux/uaccess.h>
	#include <arch/system.h>

	#define DEBUG_SIG 0

	/* 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;

	void do_signal(int canrestart, struct pt_regs *regs);

	/*
	* 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->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;
	}

	asmlinkage int sys_sigreturn(void)
	{
	struct pt_regs *regs = current_pt_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;

	set_current_blocked(&set);

	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;
	}

	asmlinkage int sys_rt_sigreturn(void)
	{
	struct pt_regs *regs = current_pt_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;

	set_current_blocked(&set);

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

	if (restore_altstack(&frame->uc.uc_stack))
	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 ksignal *ksig, size_t frame_size)
	{
	unsigned long sp = sigsp(rdusp(), ksig);

	/* 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 int setup_frame(struct ksignal ksig, sigset_t set,
	struct pt_regs *regs)
	{
	struct sigframe __user *frame;
	unsigned long return_ip;
	int err = 0;

	frame = get_sigframe(ksig, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
	return -EFAULT;

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

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

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long)ksig->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)
	return -EFAULT;

	/* Set up registers for signal handler */

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

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

	wrusp((unsigned long)frame);

	return 0;
	}

	static int setup_rt_frame(struct ksignal ksig, sigset_t set,
	struct pt_regs *regs)
	{
	struct rt_sigframe __user *frame;
	unsigned long return_ip;
	int err = 0;

	frame = get_sigframe(ksig, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
	return -EFAULT;

	err \|= __put_user(&frame->info, &frame->pinfo);
	err \|= __put_user(&frame->uc, &frame->puc);
	err \|= copy_siginfo_to_user(&frame->info, &ksig->info);
	if (err)
	return -EFAULT;

	/* 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));

	err \|= __save_altstack(&frame->uc.uc_stack, rdusp());

	if (err)
	return -EFAULT;

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
	return_ip = (unsigned long)ksig->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)
	return -EFAULT;

	/* Set up registers for signal handler */

	/* What we enter NOW */
	regs->irp = (unsigned long) ksig->ka.sa.sa_handler;
	/* What we enter LATER */
	regs->srp = return_ip;
	/* First argument is signo */
	regs->r10 = ksig->sig;
	/* Second argument is (siginfo_t ) /
	regs->r11 = (unsigned long)&frame->info;
	/* Third argument is unused */
	regs->r12 = 0;

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

	return 0;
	}

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

	static inline void handle_signal(int canrestart, struct ksignal *ksig,
	struct pt_regs *regs)
	{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/* 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 (!(ksig->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 (ksig->ka.sa.sa_flags & SA_SIGINFO)
	ret = setup_rt_frame(ksig, oldset, regs);
	else
	ret = setup_frame(ksig, oldset, regs);

	signal_setup_done(ret, ksig, 0);
	}

	/*
	* 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)
	{
	struct ksignal ksig;

	/*
	* 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;

	if (get_signal(&ksig)) {
	/* Whee! Actually deliver the signal. */
	handle_signal(canrestart, &ksig, regs);
	return;
	}

	/* 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->r9 = __NR_restart_syscall;
	regs->irp -= 2;
	}
	}

	/* if there's no signal to deliver, we just put the saved sigmask
	* back */
	restore_saved_sigmask();
	}