Message-ID: <00da01cba465$6d6e52f0$484af8d0$@mprc.pku.edu.cn>
Date:	Sun, 26 Dec 2010 02:56:24 +0800
From:	"Guan Xuetao" <guanxuetao@...c.pku.edu.cn>
To:	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc:	雪涛 管 <guanxuetao@...c.pku.edu.cn>
Subject: [PATCHv1 11/12] unicore32 core architecture: signals

From: Guan Xuetao <guanxuetao@...c.pku.edu.cn>

Patch 11 implements signals.

Signed-off-by: Guan Xuetao <guanxuetao@...c.pku.edu.cn>
---
 arch/unicore32/include/asm/sigcontext.h |   61 ++++
 arch/unicore32/kernel/signal.c          |  571 +++++++++++++++++++++++++++++++
 arch/unicore32/kernel/signal.h          |   16 +
 3 files changed, 648 insertions(+), 0 deletions(-)

diff --git a/arch/unicore32/include/asm/sigcontext.h b/arch/unicore32/include/asm/sigcontext.h
new file mode 100644
index 0000000..68e05e7
--- /dev/null
+++ b/arch/unicore32/include/asm/sigcontext.h
@@ -0,0 +1,61 @@
+/*
+ * linux/arch/unicore32/include/asm/sigcontext.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __UNICORE_SIGCONTEXT_H__
+#define __UNICORE_SIGCONTEXT_H__
+
+/*
+ * Signal context structure - contains all info to do with the state
+ * before the signal handler was invoked.  Note: only add new entries
+ * to the end of the structure.
+ */
+struct sigcontext {
+	unsigned long trap_no;
+	unsigned long error_code;
+	unsigned long oldmask;
+	unsigned long ucreg_00;
+	unsigned long ucreg_01;
+	unsigned long ucreg_02;
+	unsigned long ucreg_03;
+	unsigned long ucreg_04;
+	unsigned long ucreg_05;
+	unsigned long ucreg_06;
+	unsigned long ucreg_07;
+	unsigned long ucreg_08;
+	unsigned long ucreg_09;
+	unsigned long ucreg_10;
+	unsigned long ucreg_11;
+	unsigned long ucreg_12;
+	unsigned long ucreg_13;
+	unsigned long ucreg_14;
+	unsigned long ucreg_15;
+	unsigned long ucreg_16;
+	unsigned long ucreg_17;
+	unsigned long ucreg_18;
+	unsigned long ucreg_19;
+	unsigned long ucreg_20;
+	unsigned long ucreg_21;
+	unsigned long ucreg_22;
+	unsigned long ucreg_23;
+	unsigned long ucreg_24;
+	unsigned long ucreg_25;
+	unsigned long ucreg_26;
+	unsigned long ucreg_fp;
+	unsigned long ucreg_ip;
+	unsigned long ucreg_sp;
+	unsigned long ucreg_lr;
+	unsigned long ucreg_pc;
+	unsigned long ucreg_asr;
+	unsigned long fault_address;
+};
+
+
+#endif
diff --git a/arch/unicore32/kernel/signal.c b/arch/unicore32/kernel/signal.c
new file mode 100644
index 0000000..c7deecc
--- /dev/null
+++ b/arch/unicore32/kernel/signal.c
@@ -0,0 +1,571 @@
+/*
+ * linux/arch/unicore32/kernel/signal.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/freezer.h>
+#include <linux/uaccess.h>
+#include <linux/tracehook.h>
+#include <linux/elf.h>
+#include <linux/unistd.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ucontext.h>
+
+#include "ptrace.h"
+#include "signal.h"
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+/*
+ * For UniCore syscalls, we encode the syscall number into the instruction.
+ */
+#define SWI_SYS_SIGRETURN	(0xff000000 | (__NR_SYSCALL_BASE)	\
+					| (__NR_sigreturn))
+#define SWI_SYS_RT_SIGRETURN	(0xff000000 | (__NR_SYSCALL_BASE)	\
+					| (__NR_rt_sigreturn))
+#define SWI_SYS_RESTART		(0xff000000 | (__NR_SYSCALL_BASE)	\
+					| (__NR_restart_syscall))
+
+const unsigned long sigreturn_codes[3] = {
+	SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
+};
+
+const unsigned long syscall_restart_code[2] = {
+	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
+	0x69efc004,		/* ldr	pc, [sp], #4 */
+};
+
+/*
+ * atomically swap in the new signal mask, and wait for a signal.
+ */
+asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask,
+		old_sigset_t mask)
+{
+	mask &= _BLOCKABLE;
+	spin_lock_irq(&current->sighand->siglock);
+	current->saved_sigmask = current->blocked;
+	siginitset(&current->blocked, mask);
+	recalc_sigpending();
+	spin_unlock_irq(&current->sighand->siglock);
+
+	current->state = TASK_INTERRUPTIBLE;
+	schedule();
+	set_restore_sigmask();
+	return -ERESTARTNOHAND;
+}
+
+asmlinkage int sys_sigaction(int sig, const struct sigaction __user *act,
+	      struct sigaction __user *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))
+			return -EFAULT;
+		__get_user(new_ka.sa.sa_flags, &act->sa_flags);
+		__get_user(mask, &act->sa_mask.sig[0]);
+		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))
+			return -EFAULT;
+		__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
+		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask.sig[0]);
+		__put_user(old_ka.sa.sa_mask.sig[1], &oact->sa_mask.sig[1]);
+	}
+
+	return ret;
+}
+
+/*
+ * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
+ */
+struct sigframe {
+	struct ucontext uc;
+	unsigned long retcode[2];
+};
+
+struct rt_sigframe {
+	struct siginfo info;
+	struct sigframe sig;
+};
+
+static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
+{
+	sigset_t set;
+	int err;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0) {
+		sigdelsetmask(&set, ~_BLOCKABLE);
+		spin_lock_irq(&current->sighand->siglock);
+		current->blocked = set;
+		recalc_sigpending();
+		spin_unlock_irq(&current->sighand->siglock);
+	}
+
+	__get_user_error(regs->UCreg_00, &sf->uc.uc_mcontext.ucreg_00, err);
+	__get_user_error(regs->UCreg_01, &sf->uc.uc_mcontext.ucreg_01, err);
+	__get_user_error(regs->UCreg_02, &sf->uc.uc_mcontext.ucreg_02, err);
+	__get_user_error(regs->UCreg_03, &sf->uc.uc_mcontext.ucreg_03, err);
+	__get_user_error(regs->UCreg_04, &sf->uc.uc_mcontext.ucreg_04, err);
+	__get_user_error(regs->UCreg_05, &sf->uc.uc_mcontext.ucreg_05, err);
+	__get_user_error(regs->UCreg_06, &sf->uc.uc_mcontext.ucreg_06, err);
+	__get_user_error(regs->UCreg_07, &sf->uc.uc_mcontext.ucreg_07, err);
+	__get_user_error(regs->UCreg_08, &sf->uc.uc_mcontext.ucreg_08, err);
+	__get_user_error(regs->UCreg_09, &sf->uc.uc_mcontext.ucreg_09, err);
+	__get_user_error(regs->UCreg_10, &sf->uc.uc_mcontext.ucreg_10, err);
+	__get_user_error(regs->UCreg_11, &sf->uc.uc_mcontext.ucreg_11, err);
+	__get_user_error(regs->UCreg_12, &sf->uc.uc_mcontext.ucreg_12, err);
+	__get_user_error(regs->UCreg_13, &sf->uc.uc_mcontext.ucreg_13, err);
+	__get_user_error(regs->UCreg_14, &sf->uc.uc_mcontext.ucreg_14, err);
+	__get_user_error(regs->UCreg_15, &sf->uc.uc_mcontext.ucreg_15, err);
+	__get_user_error(regs->UCreg_16, &sf->uc.uc_mcontext.ucreg_16, err);
+	__get_user_error(regs->UCreg_17, &sf->uc.uc_mcontext.ucreg_17, err);
+	__get_user_error(regs->UCreg_18, &sf->uc.uc_mcontext.ucreg_18, err);
+	__get_user_error(regs->UCreg_19, &sf->uc.uc_mcontext.ucreg_19, err);
+	__get_user_error(regs->UCreg_20, &sf->uc.uc_mcontext.ucreg_20, err);
+	__get_user_error(regs->UCreg_21, &sf->uc.uc_mcontext.ucreg_21, err);
+	__get_user_error(regs->UCreg_22, &sf->uc.uc_mcontext.ucreg_22, err);
+	__get_user_error(regs->UCreg_23, &sf->uc.uc_mcontext.ucreg_23, err);
+	__get_user_error(regs->UCreg_24, &sf->uc.uc_mcontext.ucreg_24, err);
+	__get_user_error(regs->UCreg_25, &sf->uc.uc_mcontext.ucreg_25, err);
+	__get_user_error(regs->UCreg_26, &sf->uc.uc_mcontext.ucreg_26, err);
+	__get_user_error(regs->UCreg_fp, &sf->uc.uc_mcontext.ucreg_fp, err);
+	__get_user_error(regs->UCreg_ip, &sf->uc.uc_mcontext.ucreg_ip, err);
+	__get_user_error(regs->UCreg_sp, &sf->uc.uc_mcontext.ucreg_sp, err);
+	__get_user_error(regs->UCreg_lr, &sf->uc.uc_mcontext.ucreg_lr, err);
+	__get_user_error(regs->UCreg_pc, &sf->uc.uc_mcontext.ucreg_pc, err);
+	__get_user_error(regs->UCreg_asr, &sf->uc.uc_mcontext.ucreg_asr, err);
+
+	err |= !valid_user_regs(regs);
+
+	return err;
+}
+
+asmlinkage int sys_sigreturn(struct pt_regs *regs)
+{
+	struct sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 64-bit boundary,
+	 * then 'sp' should be word aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (regs->UCreg_sp & 7)
+		goto badframe;
+
+	frame = (struct sigframe __user *)regs->UCreg_sp;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, frame))
+		goto badframe;
+
+	single_step_trap(current);
+
+	return regs->UCreg_00;
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 64-bit boundary,
+	 * then 'sp' should be word aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (regs->UCreg_sp & 7)
+		goto badframe;
+
+	frame = (struct rt_sigframe __user *)regs->UCreg_sp;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, &frame->sig))
+		goto badframe;
+
+	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
+			== -EFAULT)
+		goto badframe;
+
+	single_step_trap(current);
+
+	return regs->UCreg_00;
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
+		sigset_t *set)
+{
+	int err = 0;
+
+	__put_user_error(regs->UCreg_00, &sf->uc.uc_mcontext.ucreg_00, err);
+	__put_user_error(regs->UCreg_01, &sf->uc.uc_mcontext.ucreg_01, err);
+	__put_user_error(regs->UCreg_02, &sf->uc.uc_mcontext.ucreg_02, err);
+	__put_user_error(regs->UCreg_03, &sf->uc.uc_mcontext.ucreg_03, err);
+	__put_user_error(regs->UCreg_04, &sf->uc.uc_mcontext.ucreg_04, err);
+	__put_user_error(regs->UCreg_05, &sf->uc.uc_mcontext.ucreg_05, err);
+	__put_user_error(regs->UCreg_06, &sf->uc.uc_mcontext.ucreg_06, err);
+	__put_user_error(regs->UCreg_07, &sf->uc.uc_mcontext.ucreg_07, err);
+	__put_user_error(regs->UCreg_08, &sf->uc.uc_mcontext.ucreg_08, err);
+	__put_user_error(regs->UCreg_09, &sf->uc.uc_mcontext.ucreg_09, err);
+	__put_user_error(regs->UCreg_10, &sf->uc.uc_mcontext.ucreg_10, err);
+	__put_user_error(regs->UCreg_11, &sf->uc.uc_mcontext.ucreg_11, err);
+	__put_user_error(regs->UCreg_12, &sf->uc.uc_mcontext.ucreg_12, err);
+	__put_user_error(regs->UCreg_13, &sf->uc.uc_mcontext.ucreg_13, err);
+	__put_user_error(regs->UCreg_14, &sf->uc.uc_mcontext.ucreg_14, err);
+	__put_user_error(regs->UCreg_15, &sf->uc.uc_mcontext.ucreg_15, err);
+	__put_user_error(regs->UCreg_16, &sf->uc.uc_mcontext.ucreg_16, err);
+	__put_user_error(regs->UCreg_17, &sf->uc.uc_mcontext.ucreg_17, err);
+	__put_user_error(regs->UCreg_18, &sf->uc.uc_mcontext.ucreg_18, err);
+	__put_user_error(regs->UCreg_19, &sf->uc.uc_mcontext.ucreg_19, err);
+	__put_user_error(regs->UCreg_20, &sf->uc.uc_mcontext.ucreg_20, err);
+	__put_user_error(regs->UCreg_21, &sf->uc.uc_mcontext.ucreg_21, err);
+	__put_user_error(regs->UCreg_22, &sf->uc.uc_mcontext.ucreg_22, err);
+	__put_user_error(regs->UCreg_23, &sf->uc.uc_mcontext.ucreg_23, err);
+	__put_user_error(regs->UCreg_24, &sf->uc.uc_mcontext.ucreg_24, err);
+	__put_user_error(regs->UCreg_25, &sf->uc.uc_mcontext.ucreg_25, err);
+	__put_user_error(regs->UCreg_26, &sf->uc.uc_mcontext.ucreg_26, err);
+	__put_user_error(regs->UCreg_fp, &sf->uc.uc_mcontext.ucreg_fp, err);
+	__put_user_error(regs->UCreg_ip, &sf->uc.uc_mcontext.ucreg_ip, err);
+	__put_user_error(regs->UCreg_sp, &sf->uc.uc_mcontext.ucreg_sp, err);
+	__put_user_error(regs->UCreg_lr, &sf->uc.uc_mcontext.ucreg_lr, err);
+	__put_user_error(regs->UCreg_pc, &sf->uc.uc_mcontext.ucreg_pc, err);
+	__put_user_error(regs->UCreg_asr, &sf->uc.uc_mcontext.ucreg_asr, err);
+
+	__put_user_error(current->thread.trap_no,
+			&sf->uc.uc_mcontext.trap_no, err);
+	__put_user_error(current->thread.error_code,
+			&sf->uc.uc_mcontext.error_code, err);
+	__put_user_error(current->thread.address,
+			&sf->uc.uc_mcontext.fault_address, err);
+	__put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	return err;
+}
+
+static inline void __user *get_sigframe(struct k_sigaction *ka,
+		struct pt_regs *regs, int framesize)
+{
+	unsigned long sp = regs->UCreg_sp;
+	void __user *frame;
+
+	/*
+	 * This is the X/Open sanctioned signal stack switching.
+	 */
+	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
+		sp = current->sas_ss_sp + current->sas_ss_size;
+
+	/*
+	 * ATPCS B01 mandates 8-byte alignment
+	 */
+	frame = (void __user *)((sp - framesize) & ~7);
+
+	/*
+	 * Check that we can actually write to the signal frame.
+	 */
+	if (!access_ok(VERIFY_WRITE, frame, framesize))
+		frame = NULL;
+
+	return frame;
+}
+
+static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+	     unsigned long __user *rc, void __user *frame, int usig)
+{
+	unsigned long handler = (unsigned long)ka->sa.sa_handler;
+	unsigned long retcode;
+	unsigned long asr = regs->UCreg_asr & ~PSR_f;
+
+	unsigned int idx = 0;
+
+	if (ka->sa.sa_flags & SA_SIGINFO)
+		idx += 1;
+
+	if (__put_user(sigreturn_codes[idx],   rc) ||
+	    __put_user(sigreturn_codes[idx+1], rc+1))
+		return 1;
+
+	retcode = KERN_SIGRETURN_CODE + (idx << 2);
+
+	regs->UCreg_00 = usig;
+	regs->UCreg_sp = (unsigned long)frame;
+	regs->UCreg_lr = retcode;
+	regs->UCreg_pc = handler;
+	regs->UCreg_asr = asr;
+
+	return 0;
+}
+
+static int setup_frame(int usig, struct k_sigaction *ka,
+		sigset_t *set, struct pt_regs *regs)
+{
+	struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	/*
+	 * Set uc.uc_flags to a value which sc.trap_no would never have.
+	 */
+	__put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
+
+	err |= setup_sigframe(frame, regs, set);
+	if (err == 0)
+		err = setup_return(regs, ka, frame->retcode, frame, usig);
+
+	return err;
+}
+
+static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
+	       sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame =
+			get_sigframe(ka, regs, sizeof(*frame));
+	stack_t stack;
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	err |= copy_siginfo_to_user(&frame->info, info);
+
+	__put_user_error(0, &frame->sig.uc.uc_flags, err);
+	__put_user_error(NULL, &frame->sig.uc.uc_link, err);
+
+	memset(&stack, 0, sizeof(stack));
+	stack.ss_sp = (void __user *)current->sas_ss_sp;
+	stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
+	stack.ss_size = current->sas_ss_size;
+	err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
+
+	err |= setup_sigframe(&frame->sig, regs, set);
+	if (err == 0)
+		err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
+
+	if (err == 0) {
+		/*
+		 * For realtime signals we must also set the second and third
+		 * arguments for the signal handler.
+		 */
+		regs->UCreg_01 = (unsigned long)&frame->info;
+		regs->UCreg_02 = (unsigned long)&frame->sig.uc;
+	}
+
+	return err;
+}
+
+static inline void setup_syscall_restart(struct pt_regs *regs)
+{
+	regs->UCreg_00 = regs->UCreg_ORIG_00;
+	regs->UCreg_pc -= 4;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static int handle_signal(unsigned long sig, struct k_sigaction *ka,
+	      siginfo_t *info, sigset_t *oldset,
+	      struct pt_regs *regs, int syscall)
+{
+	struct thread_info *thread = current_thread_info();
+	struct task_struct *tsk = current;
+	int usig = sig;
+	int ret;
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall) {
+		switch (regs->UCreg_00) {
+		case -ERESTART_RESTARTBLOCK:
+		case -ERESTARTNOHAND:
+			regs->UCreg_00 = -EINTR;
+			break;
+		case -ERESTARTSYS:
+			if (!(ka->sa.sa_flags & SA_RESTART)) {
+				regs->UCreg_00 = -EINTR;
+				break;
+			}
+			/* fallthrough */
+		case -ERESTARTNOINTR:
+			setup_syscall_restart(regs);
+		}
+	}
+
+	/*
+	 * translate the signal
+	 */
+	if (usig < 32 && thread->exec_domain
+			&& thread->exec_domain->signal_invmap)
+		usig = thread->exec_domain->signal_invmap[usig];
+
+	/*
+	 * Set up the stack frame
+	 */
+	if (ka->sa.sa_flags & SA_SIGINFO)
+		ret = setup_rt_frame(usig, ka, info, oldset, regs);
+	else
+		ret = setup_frame(usig, ka, oldset, regs);
+
+	/*
+	 * Check that the resulting registers are actually sane.
+	 */
+	ret |= !valid_user_regs(regs);
+
+	if (ret != 0) {
+		force_sigsegv(sig, tsk);
+		return ret;
+	}
+
+	/*
+	 * Block the signal if we were successful.
+	 */
+	spin_lock_irq(&tsk->sighand->siglock);
+	sigorsets(&tsk->blocked, &tsk->blocked,
+		  &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
+		sigaddset(&tsk->blocked, sig);
+	recalc_sigpending();
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	return 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.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static void do_signal(struct pt_regs *regs, int syscall)
+{
+	struct k_sigaction ka;
+	siginfo_t info;
+	int signr;
+
+	/*
+	 * 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 (try_to_freeze())
+		goto no_signal;
+
+	single_step_clear(current);
+
+	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+	if (signr > 0) {
+		sigset_t *oldset;
+
+		if (test_thread_flag(TIF_RESTORE_SIGMASK))
+			oldset = &current->saved_sigmask;
+		else
+			oldset = &current->blocked;
+		if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
+				== 0) {
+			/*
+			 * 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);
+		}
+		single_step_set(current);
+		return;
+	}
+
+ no_signal:
+	/*
+	 * No signal to deliver to the process - restart the syscall.
+	 */
+	if (syscall) {
+		if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
+				u32 __user *usp;
+
+				regs->UCreg_sp -= 4;
+				usp = (u32 __user *)regs->UCreg_sp;
+
+				if (put_user(regs->UCreg_pc, usp) == 0) {
+					regs->UCreg_pc = KERN_RESTART_CODE;
+				} else {
+					regs->UCreg_sp += 4;
+					force_sigsegv(0, current);
+				}
+		}
+		if (regs->UCreg_00 == -ERESTARTNOHAND ||
+		    regs->UCreg_00 == -ERESTARTSYS ||
+		    regs->UCreg_00 == -ERESTARTNOINTR) {
+			setup_syscall_restart(regs);
+		}
+
+		/* 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);
+		}
+	}
+	single_step_set(current);
+}
+
+asmlinkage void do_notify_resume(struct pt_regs *regs,
+		unsigned int thread_flags, int syscall)
+{
+	if (thread_flags & _TIF_SIGPENDING)
+		do_signal(regs, syscall);
+
+	if (thread_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+		if (current->replacement_session_keyring)
+			key_replace_session_keyring();
+	}
+}
diff --git a/arch/unicore32/kernel/signal.h b/arch/unicore32/kernel/signal.h
new file mode 100644
index 0000000..4b56698
--- /dev/null
+++ b/arch/unicore32/kernel/signal.h
@@ -0,0 +1,16 @@
+/*
+ * linux/arch/unicore32/kernel/signal.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#define KERN_SIGRETURN_CODE	(KUSER_VECPAGE_BASE + 0x00000500)
+#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
+
+extern const unsigned long sigreturn_codes[3];
+extern const unsigned long syscall_restart_code[2];

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