patch-2.3.48 linux/arch/mips64/kernel/signal.c

• Lines: 658
• Date: Thu Feb 24 22:53:35 2000
• Orig file: v2.3.47/linux/arch/mips64/kernel/signal.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.47/linux/arch/mips64/kernel/signal.c linux/arch/mips64/kernel/signal.c
@@ -0,0 +1,657 @@
+/* $Id: signal.c,v 1.5 2000/02/04 07:40:24 ralf Exp $
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1991, 1992  Linus Torvalds
+ * Copyright (C) 1994 - 1999  Ralf Baechle
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ */
+#include <linux/config.h>
+#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 <asm/asm.h>
+#include <asm/bitops.h>
+#include <asm/pgalloc.h>
+#include <asm/stackframe.h>
+#include <asm/uaccess.h>
+#include <asm/ucontext.h>
+
+#define DEBUG_SIG 0
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+extern asmlinkage int sys_wait4(pid_t pid, unsigned long *stat_addr,
+                         int options, unsigned long *ru);
+extern asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs);
+extern asmlinkage int save_fp_context(struct sigcontext *sc);
+extern asmlinkage int restore_fp_context(struct sigcontext *sc);
+
+/*
+ * Atomically swap in the new signal mask, and wait for a signal.
+ */
+asmlinkage inline int
+sys_sigsuspend(abi64_no_regargs, struct pt_regs regs)
+{
+	sigset_t *uset, saveset, newset;
+
+	save_static(&regs);
+	uset = (sigset_t *) regs.regs[4];
+	if (copy_from_user(&newset, uset, sizeof(sigset_t)))
+		return -EFAULT;
+	sigdelsetmask(&newset, ~_BLOCKABLE);
+
+	spin_lock_irq(&current->sigmask_lock);
+	saveset = current->blocked;
+	current->blocked = newset;
+	recalc_sigpending(current);
+	spin_unlock_irq(&current->sigmask_lock);
+
+	regs.regs[2] = EINTR;
+	regs.regs[7] = 1;
+	while (1) {
+		current->state = TASK_INTERRUPTIBLE;
+		schedule();
+		if (do_signal(&saveset, &regs))
+			return -EINTR;
+	}
+}
+
+asmlinkage int
+sys_rt_sigsuspend(abi64_no_regargs, struct pt_regs regs)
+{
+	sigset_t *unewset, saveset, newset;
+        size_t sigsetsize;
+
+	save_static(&regs);
+
+	/* XXX Don't preclude handling different sized sigset_t's.  */
+	sigsetsize = regs.regs[5];
+	if (sigsetsize != sizeof(sigset_t))
+		return -EINVAL;
+
+	unewset = (sigset_t *) regs.regs[4];
+	if (copy_from_user(&newset, unewset, sizeof(newset)))
+		return -EFAULT;
+	sigdelsetmask(&newset, ~_BLOCKABLE);
+
+	spin_lock_irq(&current->sigmask_lock);
+	saveset = current->blocked;
+	current->blocked = newset;
+        recalc_sigpending(current);
+	spin_unlock_irq(&current->sigmask_lock);
+
+	regs.regs[2] = EINTR;
+	regs.regs[7] = 1;
+	while (1) {
+		current->state = TASK_INTERRUPTIBLE;
+		schedule();
+		if (do_signal(&saveset, &regs))
+			return -EINTR;
+	}
+}
+
+asmlinkage int 
+sys_sigaction(int sig, const struct sigaction *act, struct sigaction *oact)
+{
+	struct k_sigaction new_ka, old_ka;
+	int ret;
+	int err = 0;
+
+	if (act) {
+		old_sigset_t mask;
+
+		if (!access_ok(VERIFY_READ, act, sizeof(*act)))
+			return -EFAULT;
+		err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
+		err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
+		err |= __get_user(mask, &act->sa_mask.sig[0]);
+		err |= __get_user(new_ka.sa.sa_restorer, &act->sa_restorer);
+		if (err)
+			return -EFAULT;
+
+		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)))
+                        return -EFAULT;
+		err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
+		err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
+		err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
+                err |= __put_user(0, &oact->sa_mask.sig[1]);
+                err |= __put_user(0, &oact->sa_mask.sig[2]);
+                err |= __put_user(0, &oact->sa_mask.sig[3]);
+		err |= __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer);
+                if (err)
+			return -EFAULT;
+	}
+
+	return ret;
+}
+
+asmlinkage int
+sys_sigaltstack(abi64_no_regargs, struct pt_regs regs)
+{
+	const stack_t *uss = (const stack_t *) regs.regs[4];
+	stack_t *uoss = (stack_t *) regs.regs[5];
+	unsigned long usp = regs.regs[29];
+
+	return do_sigaltstack(uss, uoss, usp);
+}
+
+asmlinkage int
+restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
+{
+	int owned_fp;
+	int err = 0;
+
+	err |= __get_user(regs->cp0_epc, &sc->sc_pc);
+	err |= __get_user(regs->hi, &sc->sc_mdhi);
+	err |= __get_user(regs->lo, &sc->sc_mdlo);
+
+#define restore_gp_reg(i) do {						\
+	err |= __get_user(regs->regs[i], &sc->sc_regs[i]);		\
+} while(0)
+	restore_gp_reg( 1); restore_gp_reg( 2); restore_gp_reg( 3);
+	restore_gp_reg( 4); restore_gp_reg( 5); restore_gp_reg( 6);
+	restore_gp_reg( 7); restore_gp_reg( 8); restore_gp_reg( 9);
+	restore_gp_reg(10); restore_gp_reg(11); restore_gp_reg(12);
+	restore_gp_reg(13); restore_gp_reg(14); restore_gp_reg(15);
+	restore_gp_reg(16); restore_gp_reg(17); restore_gp_reg(18);
+	restore_gp_reg(19); restore_gp_reg(20); restore_gp_reg(21);
+	restore_gp_reg(22); restore_gp_reg(23); restore_gp_reg(24);
+	restore_gp_reg(25); restore_gp_reg(26); restore_gp_reg(27);
+	restore_gp_reg(28); restore_gp_reg(29); restore_gp_reg(30);
+	restore_gp_reg(31);
+#undef restore_gp_reg
+
+	err |= __get_user(owned_fp, &sc->sc_ownedfp);
+	if (owned_fp) {
+		err |= restore_fp_context(sc);
+		last_task_used_math = current;
+	}
+
+	return err;
+}
+
+struct sigframe {
+	u32 sf_ass[4];			/* argument save space for o32 */
+	u32 sf_code[2];			/* signal trampoline */
+	struct sigcontext sf_sc;
+	sigset_t sf_mask;
+};
+
+struct rt_sigframe {
+	u32 rs_ass[4];			/* argument save space for o32 */
+	u32 rs_code[2];			/* signal trampoline */
+	struct siginfo rs_info;
+	struct ucontext rs_uc;
+};
+
+asmlinkage void
+sys_sigreturn(abi64_no_regargs, struct pt_regs regs)
+{
+	struct sigframe *frame;
+	sigset_t blocked;
+
+	frame = (struct sigframe *) regs.regs[29];
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+	if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
+		goto badframe;
+
+	sigdelsetmask(&blocked, ~_BLOCKABLE);
+	spin_lock_irq(&current->sigmask_lock);
+	current->blocked = blocked;
+	recalc_sigpending(current);
+	spin_unlock_irq(&current->sigmask_lock);
+
+	if (restore_sigcontext(&regs, &frame->sf_sc))
+		goto badframe;
+
+	/*
+	 * Don't let your children do this ...
+	 */
+	__asm__ __volatile__(
+		"move\t$29, %0\n\t"
+		"j\tret_from_sys_call"
+		:/* no outputs */
+		:"r" (&regs));
+	/* Unreached */
+
+badframe:
+	force_sig(SIGSEGV, current);
+}
+
+asmlinkage void
+sys_rt_sigreturn(abi64_no_regargs, struct pt_regs regs)
+{
+	struct rt_sigframe *frame;
+	sigset_t set;
+	stack_t st;
+
+	frame = (struct rt_sigframe *) regs.regs[29];
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+	if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+
+	sigdelsetmask(&set, ~_BLOCKABLE);
+	spin_lock_irq(&current->sigmask_lock);
+	current->blocked = set;
+	recalc_sigpending(current);
+	spin_unlock_irq(&current->sigmask_lock);
+
+	if (restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext))
+		goto badframe;
+
+	if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
+		goto badframe;
+	/* It is more difficult to avoid calling this function than to
+	   call it and ignore errors.  */
+	do_sigaltstack(&st, NULL, regs.regs[29]);
+
+	/*
+	 * Don't let your children do this ...
+	 */
+	__asm__ __volatile__(
+		"move\t$29, %0\n\t"
+		"j\tret_from_sys_call"
+		:/* no outputs */
+		:"r" (&regs));
+	/* Unreached */
+
+badframe:
+	force_sig(SIGSEGV, current);
+}
+
+static int inline
+setup_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
+{
+	int owned_fp;
+	int err = 0;
+
+	err |= __put_user(regs->cp0_epc, &sc->sc_pc);
+	err |= __put_user(regs->cp0_status, &sc->sc_status);
+
+#define save_gp_reg(i) {						\
+	err |= __put_user(regs->regs[i], &sc->sc_regs[i]);		\
+} while(0)
+	__put_user(0, &sc->sc_regs[0]); save_gp_reg(1); save_gp_reg(2);
+	save_gp_reg(3); save_gp_reg(4); save_gp_reg(5); save_gp_reg(6);
+	save_gp_reg(7); save_gp_reg(8); save_gp_reg(9); save_gp_reg(10);
+	save_gp_reg(11); save_gp_reg(12); save_gp_reg(13); save_gp_reg(14);
+	save_gp_reg(15); save_gp_reg(16); save_gp_reg(17); save_gp_reg(18);
+	save_gp_reg(19); save_gp_reg(20); save_gp_reg(21); save_gp_reg(22);
+	save_gp_reg(23); save_gp_reg(24); save_gp_reg(25); save_gp_reg(26);
+	save_gp_reg(27); save_gp_reg(28); save_gp_reg(29); save_gp_reg(30);
+	save_gp_reg(31);
+#undef save_gp_reg
+
+	err |= __put_user(regs->hi, &sc->sc_mdhi);
+	err |= __put_user(regs->lo, &sc->sc_mdlo);
+	err |= __put_user(regs->cp0_cause, &sc->sc_cause);
+	err |= __put_user(regs->cp0_badvaddr, &sc->sc_badvaddr);
+
+	owned_fp = (current == last_task_used_math);
+	err |= __put_user(owned_fp, &sc->sc_ownedfp);
+
+	if (current->used_math) {	/* fp is active.  */
+		set_cp0_status(ST0_CU1, ST0_CU1);
+		err |= save_fp_context(sc);
+		last_task_used_math = NULL;
+		regs->cp0_status &= ~ST0_CU1;
+		current->used_math = 0;
+	}
+
+	return err;
+}
+
+/*
+ * Determine which stack to use..
+ */
+static inline void *
+get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
+{
+	unsigned long sp;
+
+	/* Default to using normal stack */
+	sp = regs->regs[29];
+
+	/* This is the X/Open sanctioned signal stack switching.  */
+	if ((ka->sa.sa_flags & SA_ONSTACK) && ! on_sig_stack(sp))
+		sp = current->sas_ss_sp + current->sas_ss_size;
+
+	return (void *)((sp - frame_size) & ALMASK);
+}
+
+static void inline
+setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
+            int signr, sigset_t *set)
+{
+	struct sigframe *frame;
+	int err = 0;
+
+	frame = get_sigframe(ka, regs, sizeof(*frame));
+	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
+		goto give_sigsegv;
+
+	/* Set up to return from userspace.  If provided, use a stub already
+	   in userspace.  */
+	if (ka->sa.sa_flags & SA_RESTORER)
+		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+	else {
+		/*
+		 * Set up the return code ...
+		 *
+		 *         li      v0, __NR_sigreturn
+		 *         syscall
+		 */
+		err |= __put_user(0x24020000 + __NR_sigreturn,
+		                  frame->sf_code + 0);
+		err |= __put_user(0x0000000c                 ,
+		                  frame->sf_code + 1);
+		flush_cache_sigtramp((unsigned long) frame->sf_code);
+	}
+
+	err |= setup_sigcontext(regs, &frame->sf_sc);
+	err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
+	if (err)
+		goto give_sigsegv;
+
+	/*
+	 * Arguments to signal handler:
+	 *
+	 *   a0 = signal number
+	 *   a1 = 0 (should be cause)
+	 *   a2 = pointer to struct sigcontext
+	 *
+	 * $25 and c0_epc point to the signal handler, $29 points to the
+	 * struct sigframe.
+	 */
+	regs->regs[ 4] = signr;
+	regs->regs[ 5] = 0;
+	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
+	regs->regs[29] = (unsigned long) frame;
+	regs->regs[31] = (unsigned long) frame->sf_code;
+	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
+
+#if DEBUG_SIG
+	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%p ra=0x%p\n",
+	       current->comm, current->pid, frame, regs->cp0_epc, frame->code);
+#endif
+        return;
+
+give_sigsegv:
+	if (signr == SIGSEGV)
+		ka->sa.sa_handler = SIG_DFL;
+	force_sig(SIGSEGV, current);
+}
+
+static void inline
+setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
+               int signr, sigset_t *set, siginfo_t *info)
+{
+	struct rt_sigframe *frame;
+	int err = 0;
+
+	frame = get_sigframe(ka, regs, sizeof(*frame));
+	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
+		goto give_sigsegv;
+
+	/* Set up to return from userspace.  If provided, use a stub already
+	   in userspace.  */
+	if (ka->sa.sa_flags & SA_RESTORER)
+		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+	else {
+		/*
+		 * Set up the return code ...
+		 *
+		 *         li      v0, __NR_sigreturn
+		 *         syscall
+		 */
+		err |= __put_user(0x24020000 + __NR_sigreturn,
+		                  frame->rs_code + 0);
+		err |= __put_user(0x0000000c                 ,
+		                  frame->rs_code + 1);
+		flush_cache_sigtramp((unsigned long) frame->rs_code);
+	}
+
+	/* Create siginfo.  */
+	err |= __copy_to_user(&frame->rs_info, info, sizeof(*info));
+
+	/* Create the ucontext.  */
+	err |= __put_user(0, &frame->rs_uc.uc_flags);
+	err |= __put_user(0, &frame->rs_uc.uc_link);
+	err |= __put_user((void *)current->sas_ss_sp,
+	                  &frame->rs_uc.uc_stack.ss_sp);
+	err |= __put_user(sas_ss_flags(regs->regs[29]),
+	                  &frame->rs_uc.uc_stack.ss_flags);
+	err |= __put_user(current->sas_ss_size,
+	                  &frame->rs_uc.uc_stack.ss_size);
+	err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
+	err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		goto give_sigsegv;
+
+	/*
+	 * Arguments to signal handler:
+	 *
+	 *   a0 = signal number
+	 *   a1 = 0 (should be cause)
+	 *   a2 = pointer to ucontext
+	 *
+	 * $25 and c0_epc point to the signal handler, $29 points to
+	 * the struct rt_sigframe.
+	 */
+	regs->regs[ 4] = signr;
+	regs->regs[ 5] = (unsigned long) &frame->rs_info;
+	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
+	regs->regs[29] = (unsigned long) frame;
+	regs->regs[31] = (unsigned long) frame->rs_code;
+	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
+
+#if DEBUG_SIG
+	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%p ra=0x%p\n",
+	       current->comm, current->pid, frame, regs->cp0_epc, frame->code);
+#endif
+	return;
+
+give_sigsegv:
+	if (signr == SIGSEGV)
+		ka->sa.sa_handler = SIG_DFL;
+	force_sig(SIGSEGV, current);
+}
+
+static inline void
+handle_signal(unsigned long sig, struct k_sigaction *ka,
+	siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
+{
+	if (ka->sa.sa_flags & SA_SIGINFO)
+		setup_rt_frame(ka, regs, sig, oldset, info);
+	else
+		setup_frame(ka, regs, sig, oldset);
+
+	if (ka->sa.sa_flags & SA_ONESHOT)
+		ka->sa.sa_handler = SIG_DFL;
+	if (!(ka->sa.sa_flags & SA_NODEFER)) {
+		spin_lock_irq(&current->sigmask_lock);
+		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+		sigaddset(&current->blocked,sig);
+		recalc_sigpending(current);
+		spin_unlock_irq(&current->sigmask_lock);
+	}
+}
+
+static inline void
+syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
+{
+	switch(regs->regs[0]) {
+	case ERESTARTNOHAND:
+		regs->regs[2] = EINTR;
+		break;
+	case ERESTARTSYS:
+		if(!(ka->sa.sa_flags & SA_RESTART)) {
+			regs->regs[2] = EINTR;
+			break;
+		}
+	/* fallthrough */
+	case ERESTARTNOINTR:		/* Userland will reload $v0.  */
+		regs->regs[7] = regs->regs[26];
+		regs->cp0_epc -= 8;
+	}
+
+	regs->regs[0] = 0;		/* Don't deal with this again.  */
+}
+
+extern int do_irix_signal(sigset_t *oldset, struct pt_regs *regs);
+extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
+
+asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
+{
+	struct k_sigaction *ka;
+	siginfo_t info;
+
+#ifdef CONFIG_BINFMT_ELF32
+	if (current->thread.mflags & MF_32BIT) {
+		return do_signal32(oldset, regs);
+	}
+#endif
+
+#ifdef CONFIG_BINFMT_IRIX
+	if (current->personality != PER_LINUX)
+		return do_irix_signal(oldset, regs);
+#endif
+
+	if (!oldset)
+		oldset = &current->blocked;
+
+	for (;;) {
+		unsigned long signr;
+
+		spin_lock_irq(&current->sigmask_lock);
+		signr = dequeue_signal(&current->blocked, &info);
+		spin_unlock_irq(&current->sigmask_lock);
+
+		if (!signr)
+			break;
+
+		if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
+			/* Let the debugger run.  */
+			current->exit_code = signr;
+			current->state = TASK_STOPPED;
+			notify_parent(current, SIGCHLD);
+			schedule();
+
+			/* We're back.  Did the debugger cancel the sig?  */
+			if (!(signr = current->exit_code))
+				continue;
+			current->exit_code = 0;
+
+			/* The debugger continued.  Ignore SIGSTOP.  */
+			if (signr == SIGSTOP)
+				continue;
+
+			/* Update the siginfo structure.  Is this good?  */
+			if (signr != info.si_signo) {
+				info.si_signo = signr;
+				info.si_errno = 0;
+				info.si_code = SI_USER;
+				info.si_pid = current->p_pptr->pid;
+				info.si_uid = current->p_pptr->uid;
+			}
+
+			/* If the (new) signal is now blocked, requeue it.  */
+			if (sigismember(&current->blocked, signr)) {
+				send_sig_info(signr, &info, current);
+				continue;
+			}
+		}
+
+		ka = &current->sig->action[signr-1];
+		if (ka->sa.sa_handler == SIG_IGN) {
+			if (signr != SIGCHLD)
+				continue;
+			/* Check for SIGCHLD: it's special.  */
+			while (sys_wait4(-1, NULL, WNOHANG, NULL) > 0)
+				/* nothing */;
+			continue;
+		}
+
+		if (ka->sa.sa_handler == SIG_DFL) {
+			int exit_code = signr;
+
+			/* Init gets no signals it doesn't want.  */
+			if (current->pid == 1)
+				continue;
+
+			switch (signr) {
+			case SIGCONT: case SIGCHLD: case SIGWINCH:
+				continue;
+
+			case SIGTSTP: case SIGTTIN: case SIGTTOU:
+				if (is_orphaned_pgrp(current->pgrp))
+					continue;
+				/* FALLTHRU */
+
+			case SIGSTOP:
+				current->state = TASK_STOPPED;
+				current->exit_code = signr;
+				if (!(current->p_pptr->sig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
+					notify_parent(current, SIGCHLD);
+				schedule();
+				continue;
+
+			case SIGQUIT: case SIGILL: case SIGTRAP:
+			case SIGABRT: case SIGFPE: case SIGSEGV:
+			case SIGBUS: case SIGSYS: case SIGXCPU: case SIGXFSZ:
+				if (do_coredump(signr, regs))
+					exit_code |= 0x80;
+				/* FALLTHRU */
+
+			default:
+				lock_kernel();
+				sigaddset(&current->signal, signr);
+				recalc_sigpending(current);
+				current->flags |= PF_SIGNALED;
+				do_exit(exit_code);
+				/* NOTREACHED */
+			}
+		}
+
+		if (regs->regs[0])
+			syscall_restart(regs, ka);
+		/* Whee!  Actually deliver the signal.  */
+		handle_signal(signr, ka, &info, oldset, regs);
+		return 1;
+	}
+
+	/*
+	 * Who's code doesn't conform to the restartable syscall convention
+	 * dies here!!!  The li instruction, a single machine instruction,
+	 * must directly be followed by the syscall instruction.
+	 */
+	if (regs->regs[0]) {
+		if (regs->regs[2] == ERESTARTNOHAND ||
+		    regs->regs[2] == ERESTARTSYS ||
+		    regs->regs[2] == ERESTARTNOINTR) {
+			regs->regs[7] = regs->regs[26];
+			regs->cp0_epc -= 8;
+		}
+	}
+	return 0;
+}