nds32: Exception handling

This patch includes the exception/interrupt entries, pt_reg structure and
related accessors.

/* Unaligned accessing handling*/
Andes processors cannot load/store information which is not naturally
aligned on the bus, i.e., loading a 4 byte data whose start address must
be divisible by 4. If unaligned data accessing is happened, data
unaligned exception will be triggered and user will get SIGSEGV or
kernel oops according to the unaligned address. In order to make user be
able to load/store data from an unaligned address, software load/store
emulation is implemented in arch/nds32/mm/alignment.c to address data
unaligned exception.

Unaligned accessing handling is disabled by default because it is not a
normal case. User can enable this feature by following steps.

A. Compile time:
    1. Enable kernel config CONFIG_ALIGNMENT_TRAP
B. Run time:
    1. Enter /proc/sys/nds32/unaligned_acess folder
    2. Write 1 to file enable_mode to enable unaligned accessing
       handling. User can disable it by writing 0 to this file.
    3. Write 1 to file debug to show which unaligned address is under
       processing. User can disable it by writing 0 to this file.

However, unaligned accessing handler cannot work if this unaligned
address is not accessible such as protection violation. On this
condition, the default behaviors for addressing data unaligned exception
still happen

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

6 files changed, 1483 insertions, 0 deletions

diff --git a/arch/nds32/include/asm/ptrace.h b/arch/nds32/include/asm/ptrace.h
new file mode 100644
index 000000000000..c4538839055c
--- /dev/null
+++ b/arch/nds32/include/asm/ptrace.h
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef __ASM_NDS32_PTRACE_H
+#define __ASM_NDS32_PTRACE_H
+
+#include <uapi/asm/ptrace.h>
+
+/*
+ * If pt_regs.syscallno == NO_SYSCALL, then the thread is not executing
+ * a syscall -- i.e., its most recent entry into the kernel from
+ * userspace was not via syscall, or otherwise a tracer cancelled the
+ * syscall.
+ *
+ * This must have the value -1, for ABI compatibility with ptrace etc.
+ */
+#define NO_SYSCALL (-1)
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
+struct pt_regs {
+	union {
+		struct user_pt_regs user_regs;
+		struct {
+			long uregs[26];
+			long fp;
+			long gp;
+			long lp;
+			long sp;
+			long ipc;
+#if defined(CONFIG_HWZOL)
+			long lb;
+			long le;
+			long lc;
+#else
+			long dummy[3];
+#endif
+			long syscallno;
+		};
+	};
+	long orig_r0;
+	long ir0;
+	long ipsw;
+	long pipsw;
+	long pipc;
+	long pp0;
+	long pp1;
+	long fucop_ctl;
+	long osp;
+};
+
+static inline bool in_syscall(struct pt_regs const *regs)
+{
+	return regs->syscallno != NO_SYSCALL;
+}
+
+static inline void forget_syscall(struct pt_regs *regs)
+{
+	regs->syscallno = NO_SYSCALL;
+}
+static inline unsigned long regs_return_value(struct pt_regs *regs)
+{
+	return regs->uregs[0];
+}
+extern void show_regs(struct pt_regs *);
+/* Avoid circular header include via sched.h */
+struct task_struct;
+
+#define arch_has_single_step()		(1)
+#define user_mode(regs)			(((regs)->ipsw & PSW_mskPOM) == 0)
+#define interrupts_enabled(regs)	(!!((regs)->ipsw & PSW_mskGIE))
+#define user_stack_pointer(regs)	((regs)->sp)
+#define instruction_pointer(regs)	((regs)->ipc)
+#define profile_pc(regs) 		instruction_pointer(regs)
+
+#endif /* __ASSEMBLY__ */
+#endif
diff --git a/arch/nds32/kernel/ex-entry.S b/arch/nds32/kernel/ex-entry.S
new file mode 100644
index 000000000000..a72e83d804f5
--- /dev/null
+++ b/arch/nds32/kernel/ex-entry.S
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/linkage.h>
+#include <asm/memory.h>
+#include <asm/nds32.h>
+#include <asm/errno.h>
+#include <asm/asm-offsets.h>
+#include <asm/page.h>
+
+#ifdef CONFIG_HWZOL
+	.macro push_zol
+	mfusr	$r14, $LB
+	mfusr	$r15, $LE
+	mfusr	$r16, $LC
+	.endm
+#endif
+
+	.macro	save_user_regs
+
+	smw.adm $sp, [$sp], $sp, #0x1
+	/* move $SP to the bottom of pt_regs */
+	addi    $sp, $sp, -OSP_OFFSET
+
+	/* push $r0 ~ $r25 */
+	smw.bim $r0, [$sp], $r25
+	/* push $fp, $gp, $lp */
+	smw.bim $sp, [$sp], $sp, #0xe
+
+	mfsr	$r12, $SP_USR
+	mfsr	$r13, $IPC
+#ifdef CONFIG_HWZOL
+	push_zol
+#endif
+	movi	$r17, -1
+	move	$r18, $r0
+	mfsr	$r19, $PSW
+	mfsr	$r20, $IPSW
+	mfsr	$r21, $P_IPSW
+	mfsr	$r22, $P_IPC
+	mfsr	$r23, $P_P0
+	mfsr	$r24, $P_P1
+	smw.bim $r12, [$sp], $r24, #0
+	addi	$sp, $sp, -FUCOP_CTL_OFFSET
+
+	/* Initialize kernel space $fp */
+	andi    $p0, $r20, #PSW_mskPOM
+	movi    $p1, #0x0
+	cmovz   $fp, $p1, $p0
+
+	andi	$r16, $r19, #PSW_mskINTL
+	slti	$r17, $r16, #4
+	bnez	$r17, 1f
+	addi	$r17, $r19, #-2
+	mtsr	$r17, $PSW
+	isb
+1:
+	/* If it was superuser mode, we don't need to update $r25 */
+	bnez	$p0, 2f
+	la	$p0, __entry_task
+	lw	$r25, [$p0]
+2:
+	.endm
+
+	.text
+
+/*
+ * Exception Vector
+ */
+exception_handlers:
+	.long	unhandled_exceptions	!Reset/NMI
+	.long	unhandled_exceptions	!TLB fill
+	.long	do_page_fault		!PTE not present
+	.long	do_dispatch_tlb_misc	!TLB misc
+	.long	unhandled_exceptions	!TLB VLPT
+	.long	unhandled_exceptions	!Machine Error
+	.long	do_debug_trap		!Debug related
+	.long	do_dispatch_general	!General exception
+	.long	eh_syscall		!Syscall
+	.long	asm_do_IRQ		!IRQ
+
+common_exception_handler:
+	save_user_regs
+	mfsr	$p0, $ITYPE
+	andi	$p0, $p0, #ITYPE_mskVECTOR
+	srli	$p0, $p0, #ITYPE_offVECTOR
+	andi	$p1, $p0, #NDS32_VECTOR_mskNONEXCEPTION
+	bnez	$p1, 1f
+	sethi	$lp, hi20(ret_from_exception)
+	ori	$lp, $lp, lo12(ret_from_exception)
+	sethi	$p1, hi20(exception_handlers)
+	ori	$p1, $p1, lo12(exception_handlers)
+	lw	$p1, [$p1+$p0<<2]
+	move	$r0, $p0
+	mfsr	$r1, $EVA
+	mfsr	$r2, $ITYPE
+	move	$r3, $sp
+	mfsr    $r4, $OIPC
+	/* enable gie if it is enabled in IPSW. */
+	mfsr	$r21, $PSW
+	andi	$r20, $r20, #PSW_mskGIE	/* r20 is $IPSW*/
+	or	$r21, $r21, $r20
+	mtsr	$r21, $PSW
+	dsb
+	jr	$p1
+
+	/* syscall */
+1:
+	addi	$p1, $p0, #-NDS32_VECTOR_offEXCEPTION
+	bnez	$p1, 2f
+	sethi	$lp, hi20(ret_from_exception)
+	ori	$lp, $lp, lo12(ret_from_exception)
+	sethi	$p1, hi20(exception_handlers)
+	ori	$p1, $p1, lo12(exception_handlers)
+	lwi	$p1, [$p1+#NDS32_VECTOR_offEXCEPTION<<2]
+	jr	$p1
+
+	/* interrupt */
+2:
+#ifdef CONFIG_TRACE_IRQFLAGS
+	jal     arch_trace_hardirqs_off
+#endif
+	move	$r0, $sp
+	sethi	$lp, hi20(ret_from_intr)
+	ori	$lp, $lp, lo12(ret_from_intr)
+	sethi	$p0, hi20(exception_handlers)
+	ori	$p0, $p0, lo12(exception_handlers)
+	lwi	$p0, [$p0+#NDS32_VECTOR_offINTERRUPT<<2]
+	jr	$p0
+
+	.macro	EXCEPTION_VECTOR_DEBUG
+	.align 4
+	mfsr     $p0, $EDM_CTL
+	andi     $p0, $p0, EDM_CTL_mskV3_EDM_MODE
+	tnez     $p0, SWID_RAISE_INTERRUPT_LEVEL
+	.endm
+
+	.macro	EXCEPTION_VECTOR
+	.align 4
+	sethi	 $p0, hi20(common_exception_handler)
+	ori	 $p0, $p0, lo12(common_exception_handler)
+	jral.ton $p0, $p0
+	.endm
+
+	.section	".text.init", #alloc, #execinstr
+	.global	exception_vector
+exception_vector:
+.rept 6
+	EXCEPTION_VECTOR
+.endr
+	EXCEPTION_VECTOR_DEBUG
+.rept 121
+	EXCEPTION_VECTOR
+.endr
+	.align 4
+	.global	exception_vector_end
+exception_vector_end:
diff --git a/arch/nds32/kernel/ex-exit.S b/arch/nds32/kernel/ex-exit.S
new file mode 100644
index 000000000000..03e4f7788a18
--- /dev/null
+++ b/arch/nds32/kernel/ex-exit.S
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/linkage.h>
+#include <asm/unistd.h>
+#include <asm/assembler.h>
+#include <asm/nds32.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+#include <asm/current.h>
+
+
+
+#ifdef CONFIG_HWZOL
+	.macro pop_zol
+	mtusr	$r14, $LB
+	mtusr	$r15, $LE
+	mtusr	$r16, $LC
+	.endm
+#endif
+
+	.macro	restore_user_regs_first
+	setgie.d
+	isb
+
+	addi	$sp, $sp, FUCOP_CTL_OFFSET
+
+	lmw.adm $r12, [$sp], $r24, #0x0
+	mtsr	$r12, $SP_USR
+	mtsr	$r13, $IPC
+#ifdef CONFIG_HWZOL
+	pop_zol
+#endif
+	mtsr	$r19, $PSW
+	mtsr	$r20, $IPSW
+	mtsr    $r21, $P_IPSW
+	mtsr	$r22, $P_IPC
+	mtsr	$r23, $P_P0
+	mtsr	$r24, $P_P1
+	lmw.adm $sp, [$sp], $sp, #0xe
+	.endm
+
+	.macro	restore_user_regs_last
+	pop	$p0
+	cmovn	$sp, $p0, $p0
+
+	iret
+	nop
+
+	.endm
+
+	.macro	restore_user_regs
+	restore_user_regs_first
+	lmw.adm $r0, [$sp], $r25, #0x0
+	addi	$sp, $sp, OSP_OFFSET
+	restore_user_regs_last
+	.endm
+
+	.macro	fast_restore_user_regs
+	restore_user_regs_first
+	lmw.adm $r1, [$sp], $r25, #0x0
+	addi	$sp, $sp, OSP_OFFSET-4
+	restore_user_regs_last
+	.endm
+
+#ifdef CONFIG_PREEMPT
+	.macro	preempt_stop
+	.endm
+#else
+	.macro	preempt_stop
+	setgie.d
+	isb
+	.endm
+#define	resume_kernel	no_work_pending
+#endif
+
+ENTRY(ret_from_exception)
+	preempt_stop
+ENTRY(ret_from_intr)
+
+/*
+ * judge Kernel or user mode
+ *
+ */
+	lwi	$p0, [$sp+(#IPSW_OFFSET)]	! Check if in nested interrupt
+	andi	$p0, $p0, #PSW_mskINTL
+	bnez	$p0, resume_kernel		! done with iret
+	j	resume_userspace
+
+
+/*
+ * This is the fast syscall return path.  We do as little as
+ * possible here, and this includes saving $r0 back into the SVC
+ * stack.
+ * fixed: tsk - $r25, syscall # - $r7, syscall table pointer - $r8
+ */
+ENTRY(ret_fast_syscall)
+	gie_disable
+	lwi	$r1, [tsk+#TSK_TI_FLAGS]
+	andi	$p1, $r1, #_TIF_WORK_MASK
+	bnez	$p1, fast_work_pending
+	fast_restore_user_regs			! iret
+
+/*
+ * Ok, we need to do extra processing,
+ * enter the slow path returning from syscall, while pending work.
+ */
+fast_work_pending:
+	swi	$r0, [$sp+(#R0_OFFSET)]		! what is different from ret_from_exception
+work_pending:
+	andi	$p1, $r1, #_TIF_NEED_RESCHED
+	bnez	$p1, work_resched
+
+	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME
+	beqz	$p1, no_work_pending
+
+	move	$r0, $sp			! 'regs'
+	gie_enable
+	bal	do_notify_resume
+	b       ret_slow_syscall
+work_resched:
+	bal	schedule			! path, return to user mode
+
+/*
+ * "slow" syscall return path.
+ */
+ENTRY(resume_userspace)
+ENTRY(ret_slow_syscall)
+	gie_disable
+	lwi	$p0, [$sp+(#IPSW_OFFSET)]	! Check if in nested interrupt
+	andi	$p0, $p0, #PSW_mskINTL
+	bnez	$p0, no_work_pending		! done with iret
+	lwi	$r1, [tsk+#TSK_TI_FLAGS]
+	andi	$p1, $r1, #_TIF_WORK_MASK
+	bnez	$p1, work_pending		! handle work_resched, sig_pend
+
+no_work_pending:
+#ifdef CONFIG_TRACE_IRQFLAGS
+	lwi	$p0, [$sp+(#IPSW_OFFSET)]
+	andi	$p0, $p0, #0x1
+	la	$r10, trace_hardirqs_off
+	la	$r9, trace_hardirqs_on
+	cmovz	$r9, $p0, $r10
+	jral	$r9
+#endif
+	restore_user_regs			! return from iret
+
+
+/*
+ * preemptive kernel
+ */
+#ifdef CONFIG_PREEMPT
+resume_kernel:
+	gie_disable
+	lwi	$t0, [tsk+#TSK_TI_PREEMPT]
+	bnez	$t0, no_work_pending
+need_resched:
+	lwi	$t0, [tsk+#TSK_TI_FLAGS]
+	andi	$p1, $t0, #_TIF_NEED_RESCHED
+	beqz	$p1, no_work_pending
+
+	lwi	$t0, [$sp+(#IPSW_OFFSET)]	! Interrupts off?
+	andi	$t0, $t0, #1
+	beqz	$t0, no_work_pending
+
+	jal	preempt_schedule_irq
+	b	need_resched
+#endif
+
+/*
+ * This is how we return from a fork.
+ */
+ENTRY(ret_from_fork)
+	bal	schedule_tail
+	beqz	$r6, 1f				! r6 stores fn for kernel thread
+	move	$r0, $r7			! prepare kernel thread arg
+	jral	$r6
+1:
+	lwi	$r1, [tsk+#TSK_TI_FLAGS]		! check for syscall tracing
+	andi	$p1, $r1, #_TIF_WORK_SYSCALL_LEAVE	! are we tracing syscalls?
+	beqz	$p1, ret_slow_syscall
+	move    $r0, $sp
+	bal	syscall_trace_leave
+	b	ret_slow_syscall
diff --git a/arch/nds32/kernel/stacktrace.c b/arch/nds32/kernel/stacktrace.c
new file mode 100644
index 000000000000..bc70113c0e84
--- /dev/null
+++ b/arch/nds32/kernel/stacktrace.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+
+void save_stack_trace(struct stack_trace *trace)
+{
+	save_stack_trace_tsk(current, trace);
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+	unsigned long *fpn;
+	int skip = trace->skip;
+	int savesched;
+
+	if (tsk == current) {
+		__asm__ __volatile__("\tori\t%0, $fp, #0\n":"=r"(fpn));
+		savesched = 1;
+	} else {
+		fpn = (unsigned long *)thread_saved_fp(tsk);
+		savesched = 0;
+	}
+
+	while (!kstack_end(fpn) && !((unsigned long)fpn & 0x3)
+	       && (fpn >= (unsigned long *)TASK_SIZE)) {
+		unsigned long lpp, fpp;
+
+		lpp = fpn[-1];
+		fpp = fpn[FP_OFFSET];
+		if (!__kernel_text_address(lpp))
+			break;
+
+		if (savesched || !in_sched_functions(lpp)) {
+			if (skip) {
+				skip--;
+			} else {
+				trace->entries[trace->nr_entries++] = lpp;
+				if (trace->nr_entries >= trace->max_entries)
+					break;
+			}
+		}
+		fpn = (unsigned long *)fpp;
+	}
+}
diff --git a/arch/nds32/kernel/traps.c b/arch/nds32/kernel/traps.c
new file mode 100644
index 000000000000..8828b4aeb72b
--- /dev/null
+++ b/arch/nds32/kernel/traps.c
@@ -0,0 +1,442 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/module.h>
+#include <linux/personality.h>
+#include <linux/kallsyms.h>
+#include <linux/hardirq.h>
+#include <linux/kdebug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/uaccess.h>
+
+#include <asm/proc-fns.h>
+#include <asm/unistd.h>
+
+#include <linux/ptrace.h>
+#include <nds32_intrinsic.h>
+
+extern void show_pte(struct mm_struct *mm, unsigned long addr);
+
+/*
+ * Dump out the contents of some memory nicely...
+ */
+void dump_mem(const char *lvl, unsigned long bottom, unsigned long top)
+{
+	unsigned long first;
+	mm_segment_t fs;
+	int i;
+
+	/*
+	 * We need to switch to kernel mode so that we can use __get_user
+	 * to safely read from kernel space.  Note that we now dump the
+	 * code first, just in case the backtrace kills us.
+	 */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	pr_emerg("%s(0x%08lx to 0x%08lx)\n", lvl, bottom, top);
+
+	for (first = bottom & ~31; first < top; first += 32) {
+		unsigned long p;
+		char str[sizeof(" 12345678") * 8 + 1];
+
+		memset(str, ' ', sizeof(str));
+		str[sizeof(str) - 1] = '\0';
+
+		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
+			if (p >= bottom && p < top) {
+				unsigned long val;
+				if (__get_user(val, (unsigned long *)p) == 0)
+					sprintf(str + i * 9, " %08lx", val);
+				else
+					sprintf(str + i * 9, " ????????");
+			}
+		}
+		pr_emerg("%s%04lx:%s\n", lvl, first & 0xffff, str);
+	}
+
+	set_fs(fs);
+}
+
+EXPORT_SYMBOL(dump_mem);
+
+static void dump_instr(struct pt_regs *regs)
+{
+	unsigned long addr = instruction_pointer(regs);
+	mm_segment_t fs;
+	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
+	int i;
+
+	return;
+	/*
+	 * We need to switch to kernel mode so that we can use __get_user
+	 * to safely read from kernel space.  Note that we now dump the
+	 * code first, just in case the backtrace kills us.
+	 */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	pr_emerg("Code: ");
+	for (i = -4; i < 1; i++) {
+		unsigned int val, bad;
+
+		bad = __get_user(val, &((u32 *) addr)[i]);
+
+		if (!bad) {
+			p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
+		} else {
+			p += sprintf(p, "bad PC value");
+			break;
+		}
+	}
+	pr_emerg("Code: %s\n", str);
+
+	set_fs(fs);
+}
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#include <linux/ftrace.h>
+static void
+get_real_ret_addr(unsigned long *addr, struct task_struct *tsk, int *graph)
+{
+	if (*addr == (unsigned long)return_to_handler) {
+		int index = tsk->curr_ret_stack;
+
+		if (tsk->ret_stack && index >= *graph) {
+			index -= *graph;
+			*addr = tsk->ret_stack[index].ret;
+			(*graph)++;
+		}
+	}
+}
+#else
+static inline void
+get_real_ret_addr(unsigned long *addr, struct task_struct *tsk, int *graph)
+{
+}
+#endif
+
+#define LOOP_TIMES (100)
+static void __dump(struct task_struct *tsk, unsigned long *base_reg)
+{
+	unsigned long ret_addr;
+	int cnt = LOOP_TIMES, graph = 0;
+	pr_emerg("Call Trace:\n");
+	if (!IS_ENABLED(CONFIG_FRAME_POINTER)) {
+		while (!kstack_end(base_reg)) {
+			ret_addr = *base_reg++;
+			if (__kernel_text_address(ret_addr)) {
+				get_real_ret_addr(&ret_addr, tsk, &graph);
+				print_ip_sym(ret_addr);
+			}
+			if (--cnt < 0)
+				break;
+		}
+	} else {
+		while (!kstack_end((void *)base_reg) &&
+		       !((unsigned long)base_reg & 0x3) &&
+		       ((unsigned long)base_reg >= TASK_SIZE)) {
+			unsigned long next_fp;
+#if !defined(NDS32_ABI_2)
+			ret_addr = base_reg[0];
+			next_fp = base_reg[1];
+#else
+			ret_addr = base_reg[-1];
+			next_fp = base_reg[FP_OFFSET];
+#endif
+			if (__kernel_text_address(ret_addr)) {
+				get_real_ret_addr(&ret_addr, tsk, &graph);
+				print_ip_sym(ret_addr);
+			}
+			if (--cnt < 0)
+				break;
+			base_reg = (unsigned long *)next_fp;
+		}
+	}
+	pr_emerg("\n");
+}
+
+void dump_stack(void)
+{
+	unsigned long *base_reg;
+	if (!IS_ENABLED(CONFIG_FRAME_POINTER))
+		__asm__ __volatile__("\tori\t%0, $sp, #0\n":"=r"(base_reg));
+	else
+		__asm__ __volatile__("\tori\t%0, $fp, #0\n":"=r"(base_reg));
+	__dump(NULL, base_reg);
+}
+
+EXPORT_SYMBOL(dump_stack);
+
+void show_stack(struct task_struct *tsk, unsigned long *sp)
+{
+	unsigned long *base_reg;
+
+	if (!tsk)
+		tsk = current;
+	if (!IS_ENABLED(CONFIG_FRAME_POINTER)) {
+		if (tsk != current)
+			base_reg = (unsigned long *)(tsk->thread.cpu_context.sp);
+		else
+			__asm__ __volatile__("\tori\t%0, $sp, #0\n":"=r"(base_reg));
+	} else {
+		if (tsk != current)
+			base_reg = (unsigned long *)(tsk->thread.cpu_context.fp);
+		else
+			__asm__ __volatile__("\tori\t%0, $fp, #0\n":"=r"(base_reg));
+	}
+	__dump(tsk, base_reg);
+	barrier();
+}
+
+DEFINE_SPINLOCK(die_lock);
+
+/*
+ * This function is protected against re-entrancy.
+ */
+void die(const char *str, struct pt_regs *regs, int err)
+{
+	struct task_struct *tsk = current;
+	static int die_counter;
+
+	console_verbose();
+	spin_lock_irq(&die_lock);
+	bust_spinlocks(1);
+
+	pr_emerg("Internal error: %s: %x [#%d]\n", str, err, ++die_counter);
+	print_modules();
+	pr_emerg("CPU: %i\n", smp_processor_id());
+	show_regs(regs);
+	pr_emerg("Process %s (pid: %d, stack limit = 0x%p)\n",
+		 tsk->comm, tsk->pid, task_thread_info(tsk) + 1);
+
+	if (!user_mode(regs) || in_interrupt()) {
+		dump_mem("Stack: ", regs->sp,
+			 THREAD_SIZE + (unsigned long)task_thread_info(tsk));
+		dump_instr(regs);
+		dump_stack();
+	}
+
+	bust_spinlocks(0);
+	spin_unlock_irq(&die_lock);
+	do_exit(SIGSEGV);
+}
+
+EXPORT_SYMBOL(die);
+
+void die_if_kernel(const char *str, struct pt_regs *regs, int err)
+{
+	if (user_mode(regs))
+		return;
+
+	die(str, regs, err);
+}
+
+int bad_syscall(int n, struct pt_regs *regs)
+{
+	siginfo_t info;
+
+	if (current->personality != PER_LINUX) {
+		send_sig(SIGSEGV, current, 1);
+		return regs->uregs[0];
+	}
+
+	info.si_signo = SIGILL;
+	info.si_errno = 0;
+	info.si_code = ILL_ILLTRP;
+	info.si_addr = (void __user *)instruction_pointer(regs) - 4;
+
+	force_sig_info(SIGILL, &info, current);
+	die_if_kernel("Oops - bad syscall", regs, n);
+	return regs->uregs[0];
+}
+
+void __pte_error(const char *file, int line, unsigned long val)
+{
+	pr_emerg("%s:%d: bad pte %08lx.\n", file, line, val);
+}
+
+void __pmd_error(const char *file, int line, unsigned long val)
+{
+	pr_emerg("%s:%d: bad pmd %08lx.\n", file, line, val);
+}
+
+void __pgd_error(const char *file, int line, unsigned long val)
+{
+	pr_emerg("%s:%d: bad pgd %08lx.\n", file, line, val);
+}
+
+extern char *exception_vector, *exception_vector_end;
+void __init trap_init(void)
+{
+	return;
+}
+
+void __init early_trap_init(void)
+{
+	unsigned long ivb = 0;
+	unsigned long base = PAGE_OFFSET;
+
+	memcpy((unsigned long *)base, (unsigned long *)&exception_vector,
+	       ((unsigned long)&exception_vector_end -
+		(unsigned long)&exception_vector));
+	ivb = __nds32__mfsr(NDS32_SR_IVB);
+	/* Check platform support. */
+	if (((ivb & IVB_mskNIVIC) >> IVB_offNIVIC) < 2)
+		panic
+		    ("IVIC mode is not allowed on the platform with interrupt controller\n");
+	__nds32__mtsr((ivb & ~IVB_mskESZ) | (IVB_valESZ16 << IVB_offESZ) |
+		      IVB_BASE, NDS32_SR_IVB);
+	__nds32__mtsr(INT_MASK_INITAIAL_VAL, NDS32_SR_INT_MASK);
+
+	/*
+	 * 0x800 = 128 vectors * 16byte.
+	 * It should be enough to flush a page.
+	 */
+	cpu_cache_wbinval_page(base, true);
+}
+
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+		  int error_code, int si_code)
+{
+	struct siginfo info;
+
+	tsk->thread.trap_no = ENTRY_DEBUG_RELATED;
+	tsk->thread.error_code = error_code;
+
+	memset(&info, 0, sizeof(info));
+	info.si_signo = SIGTRAP;
+	info.si_code = si_code;
+	info.si_addr = (void __user *)instruction_pointer(regs);
+	force_sig_info(SIGTRAP, &info, tsk);
+}
+
+void do_debug_trap(unsigned long entry, unsigned long addr,
+		   unsigned long type, struct pt_regs *regs)
+{
+	if (notify_die(DIE_OOPS, "Oops", regs, addr, type, SIGTRAP)
+	    == NOTIFY_STOP)
+		return;
+
+	if (user_mode(regs)) {
+		/* trap_signal */
+		send_sigtrap(current, regs, 0, TRAP_BRKPT);
+	} else {
+		/* kernel_trap */
+		if (!fixup_exception(regs))
+			die("unexpected kernel_trap", regs, 0);
+	}
+}
+
+void unhandled_interruption(struct pt_regs *regs)
+{
+	siginfo_t si;
+	pr_emerg("unhandled_interruption\n");
+	show_regs(regs);
+	if (!user_mode(regs))
+		do_exit(SIGKILL);
+	si.si_signo = SIGKILL;
+	si.si_errno = 0;
+	force_sig_info(SIGKILL, &si, current);
+}
+
+void unhandled_exceptions(unsigned long entry, unsigned long addr,
+			  unsigned long type, struct pt_regs *regs)
+{
+	siginfo_t si;
+	pr_emerg("Unhandled Exception: entry: %lx addr:%lx itype:%lx\n", entry,
+		 addr, type);
+	show_regs(regs);
+	if (!user_mode(regs))
+		do_exit(SIGKILL);
+	si.si_signo = SIGKILL;
+	si.si_errno = 0;
+	si.si_addr = (void *)addr;
+	force_sig_info(SIGKILL, &si, current);
+}
+
+extern int do_page_fault(unsigned long entry, unsigned long addr,
+			 unsigned int error_code, struct pt_regs *regs);
+
+/*
+ * 2:DEF dispatch for TLB MISC exception handler
+*/
+
+void do_dispatch_tlb_misc(unsigned long entry, unsigned long addr,
+			  unsigned long type, struct pt_regs *regs)
+{
+	type = type & (ITYPE_mskINST | ITYPE_mskETYPE);
+	if ((type & ITYPE_mskETYPE) < 5) {
+		/* Permission exceptions */
+		do_page_fault(entry, addr, type, regs);
+	} else
+		unhandled_exceptions(entry, addr, type, regs);
+}
+
+void do_revinsn(struct pt_regs *regs)
+{
+	siginfo_t si;
+	pr_emerg("Reserved Instruction\n");
+	show_regs(regs);
+	if (!user_mode(regs))
+		do_exit(SIGILL);
+	si.si_signo = SIGILL;
+	si.si_errno = 0;
+	force_sig_info(SIGILL, &si, current);
+}
+
+#ifdef CONFIG_ALIGNMENT_TRAP
+extern int unalign_access_mode;
+extern int do_unaligned_access(unsigned long addr, struct pt_regs *regs);
+#endif
+void do_dispatch_general(unsigned long entry, unsigned long addr,
+			 unsigned long itype, struct pt_regs *regs,
+			 unsigned long oipc)
+{
+	unsigned int swid = itype >> ITYPE_offSWID;
+	unsigned long type = itype & (ITYPE_mskINST | ITYPE_mskETYPE);
+	if (type == ETYPE_ALIGNMENT_CHECK) {
+#ifdef CONFIG_ALIGNMENT_TRAP
+		/* Alignment check */
+		if (user_mode(regs) && unalign_access_mode) {
+			int ret;
+			ret = do_unaligned_access(addr, regs);
+
+			if (ret == 0)
+				return;
+
+			if (ret == -EFAULT)
+				pr_emerg
+				    ("Unhandled unaligned access exception\n");
+		}
+#endif
+		do_page_fault(entry, addr, type, regs);
+	} else if (type == ETYPE_RESERVED_INSTRUCTION) {
+		/* Reserved instruction */
+		do_revinsn(regs);
+	} else if (type == ETYPE_TRAP && swid == SWID_RAISE_INTERRUPT_LEVEL) {
+		/* trap, used on v3 EDM target debugging workaround */
+		/*
+		 * DIPC(OIPC) is passed as parameter before
+		 * interrupt is enabled, so the DIPC will not be corrupted
+		 * even though interrupts are coming in
+		 */
+		/*
+		 * 1. update ipc
+		 * 2. update pt_regs ipc with oipc
+		 * 3. update pt_regs ipsw (clear DEX)
+		 */
+		__asm__ volatile ("mtsr %0, $IPC\n\t"::"r" (oipc));
+		regs->ipc = oipc;
+		if (regs->pipsw & PSW_mskDEX) {
+			pr_emerg
+			    ("Nested Debug exception is possibly happened\n");
+			pr_emerg("ipc:%08x pipc:%08x\n",
+				 (unsigned int)regs->ipc,
+				 (unsigned int)regs->pipc);
+		}
+		do_debug_trap(entry, addr, itype, regs);
+		regs->ipsw &= ~PSW_mskDEX;
+	} else
+		unhandled_exceptions(entry, addr, type, regs);
+}
diff --git a/arch/nds32/mm/alignment.c b/arch/nds32/mm/alignment.c
new file mode 100644
index 000000000000..b96a01b10ca7
--- /dev/null
+++ b/arch/nds32/mm/alignment.c
@@ -0,0 +1,576 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/proc_fs.h>
+#include <linux/uaccess.h>
+#include <linux/sysctl.h>
+#include <asm/unaligned.h>
+
+#define DEBUG(enable, tagged, ...)				\
+	do{							\
+		if (enable) {					\
+			if (tagged)				\
+			pr_warn("[ %30s() ] ", __func__);	\
+			pr_warn(__VA_ARGS__);			\
+		}						\
+	} while (0)
+
+#define RT(inst)	(((inst) >> 20) & 0x1FUL)
+#define RA(inst)	(((inst) >> 15) & 0x1FUL)
+#define RB(inst)	(((inst) >> 10) & 0x1FUL)
+#define SV(inst)	(((inst) >> 8) & 0x3UL)
+#define IMM(inst)	(((inst) >> 0) & 0x3FFFUL)
+
+#define RA3(inst)	(((inst) >> 3) & 0x7UL)
+#define RT3(inst)	(((inst) >> 6) & 0x7UL)
+#define IMM3U(inst)	(((inst) >> 0) & 0x7UL)
+
+#define RA5(inst)	(((inst) >> 0) & 0x1FUL)
+#define RT4(inst)	(((inst) >> 5) & 0xFUL)
+
+#define __get8_data(val,addr,err)	\
+	__asm__(					\
+	"1:	lbi.bi	%1, [%2], #1\n"			\
+	"2:\n"						\
+	"	.pushsection .text.fixup,\"ax\"\n"	\
+	"	.align	2\n"				\
+	"3:	movi	%0, #1\n"			\
+	"	j	2b\n"				\
+	"	.popsection\n"				\
+	"	.pushsection __ex_table,\"a\"\n"	\
+	"	.align	3\n"				\
+	"	.long	1b, 3b\n"			\
+	"	.popsection\n"				\
+	: "=r" (err), "=&r" (val), "=r" (addr)		\
+	: "0" (err), "2" (addr))
+
+#define get16_data(addr, val_ptr)				\
+	do {							\
+		unsigned int err = 0, v, a = addr;		\
+		__get8_data(v,a,err);				\
+		*val_ptr =  v << 0;				\
+		__get8_data(v,a,err);				\
+		*val_ptr |= v << 8;				\
+		if (err)					\
+			goto fault;				\
+		*val_ptr = le16_to_cpu(*val_ptr);		\
+	} while(0)
+
+#define get32_data(addr, val_ptr)				\
+	do {							\
+		unsigned int err = 0, v, a = addr;		\
+		__get8_data(v,a,err);				\
+		*val_ptr =  v << 0;				\
+		__get8_data(v,a,err);				\
+		*val_ptr |= v << 8;				\
+		__get8_data(v,a,err);				\
+		*val_ptr |= v << 16;				\
+		__get8_data(v,a,err);				\
+		*val_ptr |= v << 24;				\
+		if (err)					\
+			goto fault;				\
+		*val_ptr = le32_to_cpu(*val_ptr);		\
+	} while(0)
+
+#define get_data(addr, val_ptr, len)				\
+	if (len == 2)						\
+		get16_data(addr, val_ptr);			\
+	else							\
+		get32_data(addr, val_ptr);
+
+#define set16_data(addr, val)					\
+	do {							\
+		unsigned int err = 0, *ptr = addr ;		\
+		val = le32_to_cpu(val);				\
+		__asm__(					\
+                "1:	sbi.bi 	%2, [%1], #1\n"			\
+                "	srli 	%2, %2, #8\n"			\
+                "2:	sbi	%2, [%1]\n"			\
+		"3:\n"						\
+		"	.pushsection .text.fixup,\"ax\"\n"	\
+		"	.align	2\n"				\
+		"4:	movi	%0, #1\n"			\
+		"	j	3b\n"				\
+		"	.popsection\n"				\
+		"	.pushsection __ex_table,\"a\"\n"	\
+		"	.align	3\n"				\
+		"	.long	1b, 4b\n"			\
+		"	.long	2b, 4b\n"			\
+		"	.popsection\n"				\
+		: "=r" (err), "+r" (ptr), "+r" (val)		\
+		: "0" (err)					\
+		);						\
+		if (err)					\
+			goto fault;				\
+	} while(0)
+
+#define set32_data(addr, val)					\
+	do {							\
+		unsigned int err = 0, *ptr = addr ;		\
+		val = le32_to_cpu(val);				\
+		__asm__(					\
+                "1:	sbi.bi 	%2, [%1], #1\n"			\
+                "	srli 	%2, %2, #8\n"			\
+                "2:	sbi.bi 	%2, [%1], #1\n"			\
+                "	srli 	%2, %2, #8\n"			\
+                "3:	sbi.bi 	%2, [%1], #1\n"			\
+                "	srli 	%2, %2, #8\n"			\
+                "4:	sbi 	%2, [%1]\n"			\
+		"5:\n"						\
+		"	.pushsection .text.fixup,\"ax\"\n"	\
+		"	.align	2\n"				\
+		"6:	movi	%0, #1\n"			\
+		"	j	5b\n"				\
+		"	.popsection\n"				\
+		"	.pushsection __ex_table,\"a\"\n"	\
+		"	.align	3\n"				\
+		"	.long	1b, 6b\n"			\
+		"	.long	2b, 6b\n"			\
+		"	.long	3b, 6b\n"			\
+		"	.long	4b, 6b\n"			\
+		"	.popsection\n"				\
+		: "=r" (err), "+r" (ptr), "+r" (val)		\
+		: "0" (err)					\
+		);						\
+		if (err)					\
+			goto fault;				\
+	} while(0)
+#define set_data(addr, val, len)				\
+	if (len == 2)						\
+		set16_data(addr, val);				\
+	else							\
+		set32_data(addr, val);
+#define NDS32_16BIT_INSTRUCTION	0x80000000
+
+extern pte_t va_present(struct mm_struct *mm, unsigned long addr);
+extern pte_t va_kernel_present(unsigned long addr);
+extern int va_readable(struct pt_regs *regs, unsigned long addr);
+extern int va_writable(struct pt_regs *regs, unsigned long addr);
+
+int unalign_access_mode = 0, unalign_access_debug = 0;
+
+static inline unsigned long *idx_to_addr(struct pt_regs *regs, int idx)
+{
+	/* this should be consistent with ptrace.h */
+	if (idx >= 0 && idx <= 25)	/* R0-R25 */
+		return &regs->uregs[0] + idx;
+	else if (idx >= 28 && idx <= 30)	/* FP, GP, LP */
+		return &regs->fp + (idx - 28);
+	else if (idx == 31)	/* SP */
+		return &regs->sp;
+	else
+		return NULL;	/* cause a segfault */
+}
+
+static inline unsigned long get_inst(unsigned long addr)
+{
+	return be32_to_cpu(get_unaligned((u32 *) addr));
+}
+
+static inline unsigned long sign_extend(unsigned long val, int len)
+{
+	unsigned long ret = 0;
+	unsigned char *s, *t;
+	int i = 0;
+
+	val = cpu_to_le32(val);
+
+	s = (void *)&val;
+	t = (void *)&ret;
+
+	while (i++ < len)
+		*t++ = *s++;
+
+	if (((*(t - 1)) & 0x80) && (i < 4)) {
+
+		while (i++ <= 4)
+			*t++ = 0xff;
+	}
+
+	return le32_to_cpu(ret);
+}
+
+static inline int do_16(unsigned long inst, struct pt_regs *regs)
+{
+	int imm, regular, load, len, addr_mode, idx_mode;
+	unsigned long unaligned_addr, target_val, source_idx, target_idx,
+	    shift = 0;
+	switch ((inst >> 9) & 0x3F) {
+
+	case 0x12:		/* LHI333    */
+		imm = 1;
+		regular = 1;
+		load = 1;
+		len = 2;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x10:		/* LWI333    */
+		imm = 1;
+		regular = 1;
+		load = 1;
+		len = 4;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x11:		/* LWI333.bi */
+		imm = 1;
+		regular = 0;
+		load = 1;
+		len = 4;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x1A:		/* LWI450    */
+		imm = 0;
+		regular = 1;
+		load = 1;
+		len = 4;
+		addr_mode = 5;
+		idx_mode = 4;
+		break;
+	case 0x16:		/* SHI333    */
+		imm = 1;
+		regular = 1;
+		load = 0;
+		len = 2;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x14:		/* SWI333    */
+		imm = 1;
+		regular = 1;
+		load = 0;
+		len = 4;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x15:		/* SWI333.bi */
+		imm = 1;
+		regular = 0;
+		load = 0;
+		len = 4;
+		addr_mode = 3;
+		idx_mode = 3;
+		break;
+	case 0x1B:		/* SWI450    */
+		imm = 0;
+		regular = 1;
+		load = 0;
+		len = 4;
+		addr_mode = 5;
+		idx_mode = 4;
+		break;
+
+	default:
+		return -EFAULT;
+	}
+
+	if (addr_mode == 3) {
+		unaligned_addr = *idx_to_addr(regs, RA3(inst));
+		source_idx = RA3(inst);
+	} else {
+		unaligned_addr = *idx_to_addr(regs, RA5(inst));
+		source_idx = RA5(inst);
+	}
+
+	if (idx_mode == 3)
+		target_idx = RT3(inst);
+	else
+		target_idx = RT4(inst);
+
+	if (imm)
+		shift = IMM3U(inst) * len;
+
+	if (regular)
+		unaligned_addr += shift;
+
+	if (load) {
+		if (!access_ok(VERIFY_READ, (void *)unaligned_addr, len))
+			return -EACCES;
+
+		get_data(unaligned_addr, &target_val, len);
+		*idx_to_addr(regs, target_idx) = target_val;
+	} else {
+		if (!access_ok(VERIFY_WRITE, (void *)unaligned_addr, len))
+			return -EACCES;
+		target_val = *idx_to_addr(regs, target_idx);
+		set_data((void *)unaligned_addr, target_val, len);
+	}
+
+	if (!regular)
+		*idx_to_addr(regs, source_idx) = unaligned_addr + shift;
+	regs->ipc += 2;
+
+	return 0;
+fault:
+	return -EACCES;
+}
+
+static inline int do_32(unsigned long inst, struct pt_regs *regs)
+{
+	int imm, regular, load, len, sign_ext;
+	unsigned long unaligned_addr, target_val, shift;
+
+	unaligned_addr = *idx_to_addr(regs, RA(inst));
+
+	switch ((inst >> 25) << 1) {
+
+	case 0x02:		/* LHI       */
+		imm = 1;
+		regular = 1;
+		load = 1;
+		len = 2;
+		sign_ext = 0;
+		break;
+	case 0x0A:		/* LHI.bi    */
+		imm = 1;
+		regular = 0;
+		load = 1;
+		len = 2;
+		sign_ext = 0;
+		break;
+	case 0x22:		/* LHSI      */
+		imm = 1;
+		regular = 1;
+		load = 1;
+		len = 2;
+		sign_ext = 1;
+		break;
+	case 0x2A:		/* LHSI.bi   */
+		imm = 1;
+		regular = 0;
+		load = 1;
+		len = 2;
+		sign_ext = 1;
+		break;
+	case 0x04:		/* LWI       */
+		imm = 1;
+		regular = 1;
+		load = 1;
+		len = 4;
+		sign_ext = 0;
+		break;
+	case 0x0C:		/* LWI.bi    */
+		imm = 1;
+		regular = 0;
+		load = 1;
+		len = 4;
+		sign_ext = 0;
+		break;
+	case 0x12:		/* SHI       */
+		imm = 1;
+		regular = 1;
+		load = 0;
+		len = 2;
+		sign_ext = 0;
+		break;
+	case 0x1A:		/* SHI.bi    */
+		imm = 1;
+		regular = 0;
+		load = 0;
+		len = 2;
+		sign_ext = 0;
+		break;
+	case 0x14:		/* SWI       */
+		imm = 1;
+		regular = 1;
+		load = 0;
+		len = 4;
+		sign_ext = 0;
+		break;
+	case 0x1C:		/* SWI.bi    */
+		imm = 1;
+		regular = 0;
+		load = 0;
+		len = 4;
+		sign_ext = 0;
+		break;
+
+	default:
+		switch (inst & 0xff) {
+
+		case 0x01:	/* LH        */
+			imm = 0;
+			regular = 1;
+			load = 1;
+			len = 2;
+			sign_ext = 0;
+			break;
+		case 0x05:	/* LH.bi     */
+			imm = 0;
+			regular = 0;
+			load = 1;
+			len = 2;
+			sign_ext = 0;
+			break;
+		case 0x11:	/* LHS       */
+			imm = 0;
+			regular = 1;
+			load = 1;
+			len = 2;
+			sign_ext = 1;
+			break;
+		case 0x15:	/* LHS.bi    */
+			imm = 0;
+			regular = 0;
+			load = 1;
+			len = 2;
+			sign_ext = 1;
+			break;
+		case 0x02:	/* LW        */
+			imm = 0;
+			regular = 1;
+			load = 1;
+			len = 4;
+			sign_ext = 0;
+			break;
+		case 0x06:	/* LW.bi     */
+			imm = 0;
+			regular = 0;
+			load = 1;
+			len = 4;
+			sign_ext = 0;
+			break;
+		case 0x09:	/* SH        */
+			imm = 0;
+			regular = 1;
+			load = 0;
+			len = 2;
+			sign_ext = 0;
+			break;
+		case 0x0D:	/* SH.bi     */
+			imm = 0;
+			regular = 0;
+			load = 0;
+			len = 2;
+			sign_ext = 0;
+			break;
+		case 0x0A:	/* SW        */
+			imm = 0;
+			regular = 1;
+			load = 0;
+			len = 4;
+			sign_ext = 0;
+			break;
+		case 0x0E:	/* SW.bi     */
+			imm = 0;
+			regular = 0;
+			load = 0;
+			len = 4;
+			sign_ext = 0;
+			break;
+
+		default:
+			return -EFAULT;
+		}
+	}
+
+	if (imm)
+		shift = IMM(inst) * len;
+	else
+		shift = *idx_to_addr(regs, RB(inst)) << SV(inst);
+
+	if (regular)
+		unaligned_addr += shift;
+
+	if (load) {
+
+		if (!access_ok(VERIFY_READ, (void *)unaligned_addr, len))
+			return -EACCES;
+
+		get_data(unaligned_addr, &target_val, len);
+
+		if (sign_ext)
+			*idx_to_addr(regs, RT(inst)) =
+			    sign_extend(target_val, len);
+		else
+			*idx_to_addr(regs, RT(inst)) = target_val;
+	} else {
+
+		if (!access_ok(VERIFY_WRITE, (void *)unaligned_addr, len))
+			return -EACCES;
+
+		target_val = *idx_to_addr(regs, RT(inst));
+		set_data((void *)unaligned_addr, target_val, len);
+	}
+
+	if (!regular)
+		*idx_to_addr(regs, RA(inst)) = unaligned_addr + shift;
+
+	regs->ipc += 4;
+
+	return 0;
+fault:
+	return -EACCES;
+}
+
+int do_unaligned_access(unsigned long addr, struct pt_regs *regs)
+{
+	unsigned long inst;
+	int ret = -EFAULT;
+	mm_segment_t seg = get_fs();
+
+	inst = get_inst(regs->ipc);
+
+	DEBUG((unalign_access_debug > 0), 1,
+	      "Faulting addr: 0x%08lx, pc: 0x%08lx [inst: 0x%08lx ]\n", addr,
+	      regs->ipc, inst);
+
+	set_fs(USER_DS);
+
+	if (inst & NDS32_16BIT_INSTRUCTION)
+		ret = do_16((inst >> 16) & 0xffff, regs);
+	else
+		ret = do_32(inst, regs);
+	set_fs(seg);
+
+	return ret;
+}
+
+#ifdef CONFIG_PROC_FS
+
+static struct ctl_table alignment_tbl[3] = {
+	{
+	 .procname = "enable",
+	 .data = &unalign_access_mode,
+	 .maxlen = sizeof(unalign_access_mode),
+	 .mode = 0666,
+	 .proc_handler = &proc_dointvec
+	}
+	,
+	{
+	 .procname = "debug_info",
+	 .data = &unalign_access_debug,
+	 .maxlen = sizeof(unalign_access_debug),
+	 .mode = 0644,
+	 .proc_handler = &proc_dointvec
+	}
+	,
+	{}
+};
+
+static struct ctl_table nds32_sysctl_table[2] = {
+	{
+	 .procname = "unaligned_acess",
+	 .mode = 0555,
+	 .child = alignment_tbl},
+	{}
+};
+
+static struct ctl_path nds32_path[2] = {
+	{.procname = "nds32"},
+	{}
+};
+
+/*
+ * Initialize nds32 alignment-correction interface
+ */
+static int __init nds32_sysctl_init(void)
+{
+	register_sysctl_paths(nds32_path, nds32_sysctl_table);
+	return 0;
+}
+
+__initcall(nds32_sysctl_init);
+#endif /* CONFIG_PROC_FS */