arch/openrisc/kernel/traps.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * OpenRISC traps.c
  *
  * Linux architectural port borrowing liberally from similar works of
  * others.  All original copyrights apply as per the original source
  * declaration.
  *
  * Modifications for the OpenRISC architecture:
  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  *
  *  Here we handle the break vectors not used by the system call
  *  mechanism, as well as some general stack/register dumping
  *  things.
  */

 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/kernel.h>
 #include <linux/extable.h>
 #include <linux/kmod.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
 #include <linux/timer.h>
 #include <linux/mm.h>
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>

 #include <asm/bug.h>
 #include <asm/fpu.h>
 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/unwinder.h>
 #include <asm/sections.h>

 int lwa_flag;
 static unsigned long __user *lwa_addr;

 asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector);
 asmlinkage void do_trap(struct pt_regs *regs, unsigned long address);
 asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address);
 asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address);
 asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address);
 asmlinkage void do_illegal_instruction(struct pt_regs *regs,
 				       unsigned long address);

 static void print_trace(void *data, unsigned long addr, int reliable)
 {
 	const char *loglvl = data;

 	pr_info("%s[<%p>] %s%pS\n", loglvl, (void *) addr, reliable ? "" : "? ",
 		(void *) addr);
 }

 static void print_data(unsigned long base_addr, unsigned long word, int i)
 {
 	if (i == 0)
 		pr_info("(%08lx:)\t%08lx", base_addr + (i * 4), word);
 	else
 		pr_info(" %08lx:\t%08lx", base_addr + (i * 4), word);
 }

 /* displays a short stack trace */
 void show_stack(struct task_struct *task, unsigned long *esp, const char *loglvl)
 {
 	if (esp == NULL)
 		esp = (unsigned long *)&esp;

 	pr_info("%sCall trace:\n", loglvl);
 	unwind_stack((void *)loglvl, esp, print_trace);
 }

 void show_registers(struct pt_regs *regs)
 {
 	int i;
 	int in_kernel = 1;
 	unsigned long esp;

 	esp = (unsigned long)(regs->sp);
 	if (user_mode(regs))
 		in_kernel = 0;

 	pr_info("CPU #: %d\n"
 		"   PC: %08lx    SR: %08lx    SP: %08lx\n",
 		smp_processor_id(), regs->pc, regs->sr, regs->sp);
 	pr_info("GPR00: %08lx GPR01: %08lx GPR02: %08lx GPR03: %08lx\n",
 		0L, regs->gpr[1], regs->gpr[2], regs->gpr[3]);
 	pr_info("GPR04: %08lx GPR05: %08lx GPR06: %08lx GPR07: %08lx\n",
 		regs->gpr[4], regs->gpr[5], regs->gpr[6], regs->gpr[7]);
 	pr_info("GPR08: %08lx GPR09: %08lx GPR10: %08lx GPR11: %08lx\n",
 		regs->gpr[8], regs->gpr[9], regs->gpr[10], regs->gpr[11]);
 	pr_info("GPR12: %08lx GPR13: %08lx GPR14: %08lx GPR15: %08lx\n",
 		regs->gpr[12], regs->gpr[13], regs->gpr[14], regs->gpr[15]);
 	pr_info("GPR16: %08lx GPR17: %08lx GPR18: %08lx GPR19: %08lx\n",
 		regs->gpr[16], regs->gpr[17], regs->gpr[18], regs->gpr[19]);
 	pr_info("GPR20: %08lx GPR21: %08lx GPR22: %08lx GPR23: %08lx\n",
 		regs->gpr[20], regs->gpr[21], regs->gpr[22], regs->gpr[23]);
 	pr_info("GPR24: %08lx GPR25: %08lx GPR26: %08lx GPR27: %08lx\n",
 		regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
 	pr_info("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
 		regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
 	pr_info("  RES: %08lx oGPR11: %08lx\n",
 		regs->gpr[11], regs->orig_gpr11);

 	pr_info("Process %s (pid: %d, stackpage=%08lx)\n",
 		current->comm, current->pid, (unsigned long)current);
 	/*
 	 * When in-kernel, we also print out the stack and code at the
 	 * time of the fault..
 	 */
 	if (in_kernel) {

 		pr_info("\nStack: ");
 		show_stack(NULL, (unsigned long *)esp, KERN_EMERG);

 		if (esp < PAGE_OFFSET)
 			goto bad_stack;

 		pr_info("\n");
 		for (i = -8; i < 24; i += 1) {
 			unsigned long word;

 			if (__get_user(word, &((unsigned long *)esp)[i])) {
 bad_stack:
 				pr_info(" Bad Stack value.");
 				break;
 			}

 			print_data(esp, word, i);
 		}

 		pr_info("\nCode: ");
 		if (regs->pc < PAGE_OFFSET)
 			goto bad;

 		for (i = -6; i < 6; i += 1) {
 			unsigned long word;

 			if (__get_user(word, &((unsigned long *)regs->pc)[i])) {
 bad:
 				pr_info(" Bad PC value.");
 				break;
 			}

 			print_data(regs->pc, word, i);
 		}
 	}
 	pr_info("\n");
 }

 /* This is normally the 'Oops' routine */
 void __noreturn die(const char *str, struct pt_regs *regs, long err)
 {

 	console_verbose();
 	pr_emerg("\n%s#: %04lx\n", str, err & 0xffff);
 	show_registers(regs);
 #ifdef CONFIG_JUMP_UPON_UNHANDLED_EXCEPTION
 	pr_emerg("\n\nUNHANDLED_EXCEPTION: entering infinite loop\n");

 	/* shut down interrupts */
 	local_irq_disable();

 	__asm__ __volatile__("l.nop   1");
 	do {} while (1);
 #endif
 	make_task_dead(SIGSEGV);
 }

 asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector)
 {
 	pr_emerg("Unable to handle exception at EA =0x%x, vector 0x%x",
 		 ea, vector);
 	die("Oops", regs, 9);
 }

 asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		int code = FPE_FLTUNK;
 #ifdef CONFIG_FPU
 		unsigned long fpcsr;

 		save_fpu(current);
 		fpcsr = current->thread.fpcsr;

 		if (fpcsr & SPR_FPCSR_IVF)
 			code = FPE_FLTINV;
 		else if (fpcsr & SPR_FPCSR_OVF)
 			code = FPE_FLTOVF;
 		else if (fpcsr & SPR_FPCSR_UNF)
 			code = FPE_FLTUND;
 		else if (fpcsr & SPR_FPCSR_DZF)
 			code = FPE_FLTDIV;
 		else if (fpcsr & SPR_FPCSR_IXF)
 			code = FPE_FLTRES;

 		/* Clear all flags */
 		current->thread.fpcsr &= ~SPR_FPCSR_ALLF;
 		restore_fpu(current);
 #endif
 		force_sig_fault(SIGFPE, code, (void __user *)regs->pc);
 	} else {
 		pr_emerg("KERNEL: Illegal fpe exception 0x%.8lx\n", regs->pc);
 		die("Die:", regs, SIGFPE);
 	}
 }

 asmlinkage void do_trap(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
 	} else {
 		pr_emerg("KERNEL: Illegal trap exception 0x%.8lx\n", regs->pc);
 		die("Die:", regs, SIGILL);
 	}
 }

 asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		/* Send a SIGBUS */
 		force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)address);
 	} else {
 		pr_emerg("KERNEL: Unaligned Access 0x%.8lx\n", address);
 		die("Die:", regs, address);
 	}

 }

 asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		/* Send a SIGBUS */
 		force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
 	} else {		/* Kernel mode */
 		pr_emerg("KERNEL: Bus error (SIGBUS) 0x%.8lx\n", address);
 		die("Die:", regs, address);
 	}
 }

 static inline int in_delay_slot(struct pt_regs *regs)
 {
 #ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
 	/* No delay slot flag, do the old way */
 	unsigned int op, insn;

 	insn = *((unsigned int *)regs->pc);
 	op = insn >> 26;
 	switch (op) {
 	case 0x00: /* l.j */
 	case 0x01: /* l.jal */
 	case 0x03: /* l.bnf */
 	case 0x04: /* l.bf */
 	case 0x11: /* l.jr */
 	case 0x12: /* l.jalr */
 		return 1;
 	default:
 		return 0;
 	}
 #else
 	return mfspr(SPR_SR) & SPR_SR_DSX;
 #endif
 }

 static inline void adjust_pc(struct pt_regs *regs, unsigned long address)
 {
 	int displacement;
 	unsigned int rb, op, jmp;

 	if (unlikely(in_delay_slot(regs))) {
 		/* In delay slot, instruction at pc is a branch, simulate it */
 		jmp = *((unsigned int *)regs->pc);

 		displacement = sign_extend32(((jmp) & 0x3ffffff) << 2, 27);
 		rb = (jmp & 0x0000ffff) >> 11;
 		op = jmp >> 26;

 		switch (op) {
 		case 0x00: /* l.j */
 			regs->pc += displacement;
 			return;
 		case 0x01: /* l.jal */
 			regs->pc += displacement;
 			regs->gpr[9] = regs->pc + 8;
 			return;
 		case 0x03: /* l.bnf */
 			if (regs->sr & SPR_SR_F)
 				regs->pc += 8;
 			else
 				regs->pc += displacement;
 			return;
 		case 0x04: /* l.bf */
 			if (regs->sr & SPR_SR_F)
 				regs->pc += displacement;
 			else
 				regs->pc += 8;
 			return;
 		case 0x11: /* l.jr */
 			regs->pc = regs->gpr[rb];
 			return;
 		case 0x12: /* l.jalr */
 			regs->pc = regs->gpr[rb];
 			regs->gpr[9] = regs->pc + 8;
 			return;
 		default:
 			break;
 		}
 	} else {
 		regs->pc += 4;
 	}
 }

 static inline void simulate_lwa(struct pt_regs *regs, unsigned long address,
 				unsigned int insn)
 {
 	unsigned int ra, rd;
 	unsigned long value;
 	unsigned long orig_pc;
 	long imm;

 	const struct exception_table_entry *entry;

 	orig_pc = regs->pc;
 	adjust_pc(regs, address);

 	ra = (insn >> 16) & 0x1f;
 	rd = (insn >> 21) & 0x1f;
 	imm = (short)insn;
 	lwa_addr = (unsigned long __user *)(regs->gpr[ra] + imm);

 	if ((unsigned long)lwa_addr & 0x3) {
 		do_unaligned_access(regs, address);
 		return;
 	}

 	if (get_user(value, lwa_addr)) {
 		if (user_mode(regs)) {
 			force_sig(SIGSEGV);
 			return;
 		}

 		if ((entry = search_exception_tables(orig_pc))) {
 			regs->pc = entry->fixup;
 			return;
 		}

 		/* kernel access in kernel space, load it directly */
 		value = *((unsigned long *)lwa_addr);
 	}

 	lwa_flag = 1;
 	regs->gpr[rd] = value;
 }

 static inline void simulate_swa(struct pt_regs *regs, unsigned long address,
 				unsigned int insn)
 {
 	unsigned long __user *vaddr;
 	unsigned long orig_pc;
 	unsigned int ra, rb;
 	long imm;

 	const struct exception_table_entry *entry;

 	orig_pc = regs->pc;
 	adjust_pc(regs, address);

 	ra = (insn >> 16) & 0x1f;
 	rb = (insn >> 11) & 0x1f;
 	imm = (short)(((insn & 0x2200000) >> 10) | (insn & 0x7ff));
 	vaddr = (unsigned long __user *)(regs->gpr[ra] + imm);

 	if (!lwa_flag || vaddr != lwa_addr) {
 		regs->sr &= ~SPR_SR_F;
 		return;
 	}

 	if ((unsigned long)vaddr & 0x3) {
 		do_unaligned_access(regs, address);
 		return;
 	}

 	if (put_user(regs->gpr[rb], vaddr)) {
 		if (user_mode(regs)) {
 			force_sig(SIGSEGV);
 			return;
 		}

 		if ((entry = search_exception_tables(orig_pc))) {
 			regs->pc = entry->fixup;
 			return;
 		}

 		/* kernel access in kernel space, store it directly */
 		*((unsigned long *)vaddr) = regs->gpr[rb];
 	}

 	lwa_flag = 0;
 	regs->sr |= SPR_SR_F;
 }

 #define INSN_LWA	0x1b
 #define INSN_SWA	0x33

 asmlinkage void do_illegal_instruction(struct pt_regs *regs,
 				       unsigned long address)
 {
 	unsigned int op;
 	unsigned int insn = *((unsigned int *)address);

 	op = insn >> 26;

 	switch (op) {
 	case INSN_LWA:
 		simulate_lwa(regs, address, insn);
 		return;

 	case INSN_SWA:
 		simulate_swa(regs, address, insn);
 		return;

 	default:
 		break;
 	}

 	if (user_mode(regs)) {
 		/* Send a SIGILL */
 		force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)address);
 	} else {		/* Kernel mode */
 		pr_emerg("KERNEL: Illegal instruction (SIGILL) 0x%.8lx\n",
 			 address);
 		die("Die:", regs, address);
 	}
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* OpenRISC traps.c
	*
	* Linux architectural port borrowing liberally from similar works of
	* others. All original copyrights apply as per the original source
	* declaration.
	*
	* Modifications for the OpenRISC architecture:
	* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
	* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
	*
	* Here we handle the break vectors not used by the system call
	* mechanism, as well as some general stack/register dumping
	* things.
	*/

	#include <linux/init.h>
	#include <linux/sched.h>
	#include <linux/sched/debug.h>
	#include <linux/sched/task_stack.h>
	#include <linux/kernel.h>
	#include <linux/extable.h>
	#include <linux/kmod.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/ptrace.h>
	#include <linux/timer.h>
	#include <linux/mm.h>
	#include <linux/kallsyms.h>
	#include <linux/uaccess.h>

	#include <asm/bug.h>
	#include <asm/fpu.h>
	#include <asm/io.h>
	#include <asm/processor.h>
	#include <asm/unwinder.h>
	#include <asm/sections.h>

	int lwa_flag;
	static unsigned long __user *lwa_addr;

	asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector);
	asmlinkage void do_trap(struct pt_regs *regs, unsigned long address);
	asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address);
	asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address);
	asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address);
	asmlinkage void do_illegal_instruction(struct pt_regs *regs,
	unsigned long address);

	static void print_trace(void *data, unsigned long addr, int reliable)
	{
	const char *loglvl = data;

	pr_info("%s[<%p>] %s%pS\n", loglvl, (void *) addr, reliable ? "" : "? ",
	(void *) addr);
	}

	static void print_data(unsigned long base_addr, unsigned long word, int i)
	{
	if (i == 0)
	pr_info("(%08lx:)\t%08lx", base_addr + (i * 4), word);
	else
	pr_info(" %08lx:\t%08lx", base_addr + (i * 4), word);
	}

	/* displays a short stack trace */
	void show_stack(struct task_struct task, unsigned long esp, const char *loglvl)
	{
	if (esp == NULL)
	esp = (unsigned long *)&esp;

	pr_info("%sCall trace:\n", loglvl);
	unwind_stack((void *)loglvl, esp, print_trace);
	}

	void show_registers(struct pt_regs *regs)
	{
	int i;
	int in_kernel = 1;
	unsigned long esp;

	esp = (unsigned long)(regs->sp);
	if (user_mode(regs))
	in_kernel = 0;

	pr_info("CPU #: %d\n"
	" PC: %08lx SR: %08lx SP: %08lx\n",
	smp_processor_id(), regs->pc, regs->sr, regs->sp);
	pr_info("GPR00: %08lx GPR01: %08lx GPR02: %08lx GPR03: %08lx\n",
	0L, regs->gpr[1], regs->gpr[2], regs->gpr[3]);
	pr_info("GPR04: %08lx GPR05: %08lx GPR06: %08lx GPR07: %08lx\n",
	regs->gpr[4], regs->gpr[5], regs->gpr[6], regs->gpr[7]);
	pr_info("GPR08: %08lx GPR09: %08lx GPR10: %08lx GPR11: %08lx\n",
	regs->gpr[8], regs->gpr[9], regs->gpr[10], regs->gpr[11]);
	pr_info("GPR12: %08lx GPR13: %08lx GPR14: %08lx GPR15: %08lx\n",
	regs->gpr[12], regs->gpr[13], regs->gpr[14], regs->gpr[15]);
	pr_info("GPR16: %08lx GPR17: %08lx GPR18: %08lx GPR19: %08lx\n",
	regs->gpr[16], regs->gpr[17], regs->gpr[18], regs->gpr[19]);
	pr_info("GPR20: %08lx GPR21: %08lx GPR22: %08lx GPR23: %08lx\n",
	regs->gpr[20], regs->gpr[21], regs->gpr[22], regs->gpr[23]);
	pr_info("GPR24: %08lx GPR25: %08lx GPR26: %08lx GPR27: %08lx\n",
	regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
	pr_info("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
	regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
	pr_info(" RES: %08lx oGPR11: %08lx\n",
	regs->gpr[11], regs->orig_gpr11);

	pr_info("Process %s (pid: %d, stackpage=%08lx)\n",
	current->comm, current->pid, (unsigned long)current);
	/*
	* When in-kernel, we also print out the stack and code at the
	* time of the fault..
	*/
	if (in_kernel) {

	pr_info("\nStack: ");
	show_stack(NULL, (unsigned long *)esp, KERN_EMERG);

	if (esp < PAGE_OFFSET)
	goto bad_stack;

	pr_info("\n");
	for (i = -8; i < 24; i += 1) {
	unsigned long word;

	if (__get_user(word, &((unsigned long *)esp)[i])) {
	bad_stack:
	pr_info(" Bad Stack value.");
	break;
	}

	print_data(esp, word, i);
	}

	pr_info("\nCode: ");
	if (regs->pc < PAGE_OFFSET)
	goto bad;

	for (i = -6; i < 6; i += 1) {
	unsigned long word;

	if (__get_user(word, &((unsigned long *)regs->pc)[i])) {
	bad:
	pr_info(" Bad PC value.");
	break;
	}

	print_data(regs->pc, word, i);
	}
	}
	pr_info("\n");
	}

	/* This is normally the 'Oops' routine */
	void __noreturn die(const char str, struct pt_regs regs, long err)
	{

	console_verbose();
	pr_emerg("\n%s#: %04lx\n", str, err & 0xffff);
	show_registers(regs);
	#ifdef CONFIG_JUMP_UPON_UNHANDLED_EXCEPTION
	pr_emerg("\n\nUNHANDLED_EXCEPTION: entering infinite loop\n");

	/* shut down interrupts */
	local_irq_disable();

	__asm__ __volatile__("l.nop 1");
	do {} while (1);
	#endif
	make_task_dead(SIGSEGV);
	}

	asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector)
	{
	pr_emerg("Unable to handle exception at EA =0x%x, vector 0x%x",
	ea, vector);
	die("Oops", regs, 9);
	}

	asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
	{
	if (user_mode(regs)) {
	int code = FPE_FLTUNK;
	#ifdef CONFIG_FPU
	unsigned long fpcsr;

	save_fpu(current);
	fpcsr = current->thread.fpcsr;

	if (fpcsr & SPR_FPCSR_IVF)
	code = FPE_FLTINV;
	else if (fpcsr & SPR_FPCSR_OVF)
	code = FPE_FLTOVF;
	else if (fpcsr & SPR_FPCSR_UNF)
	code = FPE_FLTUND;
	else if (fpcsr & SPR_FPCSR_DZF)
	code = FPE_FLTDIV;
	else if (fpcsr & SPR_FPCSR_IXF)
	code = FPE_FLTRES;

	/* Clear all flags */
	current->thread.fpcsr &= ~SPR_FPCSR_ALLF;
	restore_fpu(current);
	#endif
	force_sig_fault(SIGFPE, code, (void __user *)regs->pc);
	} else {
	pr_emerg("KERNEL: Illegal fpe exception 0x%.8lx\n", regs->pc);
	die("Die:", regs, SIGFPE);
	}
	}

	asmlinkage void do_trap(struct pt_regs *regs, unsigned long address)
	{
	if (user_mode(regs)) {
	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
	} else {
	pr_emerg("KERNEL: Illegal trap exception 0x%.8lx\n", regs->pc);
	die("Die:", regs, SIGILL);
	}
	}

	asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address)
	{
	if (user_mode(regs)) {
	/* Send a SIGBUS */
	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)address);
	} else {
	pr_emerg("KERNEL: Unaligned Access 0x%.8lx\n", address);
	die("Die:", regs, address);
	}

	}

	asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address)
	{
	if (user_mode(regs)) {
	/* Send a SIGBUS */
	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
	} else { /* Kernel mode */
	pr_emerg("KERNEL: Bus error (SIGBUS) 0x%.8lx\n", address);
	die("Die:", regs, address);
	}
	}

	static inline int in_delay_slot(struct pt_regs *regs)
	{
	#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
	/* No delay slot flag, do the old way */
	unsigned int op, insn;

	insn = ((unsigned int )regs->pc);
	op = insn >> 26;
	switch (op) {
	case 0x00: /* l.j */
	case 0x01: /* l.jal */
	case 0x03: /* l.bnf */
	case 0x04: /* l.bf */
	case 0x11: /* l.jr */
	case 0x12: /* l.jalr */
	return 1;
	default:
	return 0;
	}
	#else
	return mfspr(SPR_SR) & SPR_SR_DSX;
	#endif
	}

	static inline void adjust_pc(struct pt_regs *regs, unsigned long address)
	{
	int displacement;
	unsigned int rb, op, jmp;

	if (unlikely(in_delay_slot(regs))) {
	/* In delay slot, instruction at pc is a branch, simulate it */
	jmp = ((unsigned int )regs->pc);

	displacement = sign_extend32(((jmp) & 0x3ffffff) << 2, 27);
	rb = (jmp & 0x0000ffff) >> 11;
	op = jmp >> 26;

	switch (op) {
	case 0x00: /* l.j */
	regs->pc += displacement;
	return;
	case 0x01: /* l.jal */
	regs->pc += displacement;
	regs->gpr[9] = regs->pc + 8;
	return;
	case 0x03: /* l.bnf */
	if (regs->sr & SPR_SR_F)
	regs->pc += 8;
	else
	regs->pc += displacement;
	return;
	case 0x04: /* l.bf */
	if (regs->sr & SPR_SR_F)
	regs->pc += displacement;
	else
	regs->pc += 8;
	return;
	case 0x11: /* l.jr */
	regs->pc = regs->gpr[rb];
	return;
	case 0x12: /* l.jalr */
	regs->pc = regs->gpr[rb];
	regs->gpr[9] = regs->pc + 8;
	return;
	default:
	break;
	}
	} else {
	regs->pc += 4;
	}
	}

	static inline void simulate_lwa(struct pt_regs *regs, unsigned long address,
	unsigned int insn)
	{
	unsigned int ra, rd;
	unsigned long value;
	unsigned long orig_pc;
	long imm;

	const struct exception_table_entry *entry;

	orig_pc = regs->pc;
	adjust_pc(regs, address);

	ra = (insn >> 16) & 0x1f;
	rd = (insn >> 21) & 0x1f;
	imm = (short)insn;
	lwa_addr = (unsigned long __user *)(regs->gpr[ra] + imm);

	if ((unsigned long)lwa_addr & 0x3) {
	do_unaligned_access(regs, address);
	return;
	}

	if (get_user(value, lwa_addr)) {
	if (user_mode(regs)) {
	force_sig(SIGSEGV);
	return;
	}

	if ((entry = search_exception_tables(orig_pc))) {
	regs->pc = entry->fixup;
	return;
	}

	/* kernel access in kernel space, load it directly */
	value = ((unsigned long )lwa_addr);
	}

	lwa_flag = 1;
	regs->gpr[rd] = value;
	}

	static inline void simulate_swa(struct pt_regs *regs, unsigned long address,
	unsigned int insn)
	{
	unsigned long __user *vaddr;
	unsigned long orig_pc;
	unsigned int ra, rb;
	long imm;

	const struct exception_table_entry *entry;

	orig_pc = regs->pc;
	adjust_pc(regs, address);

	ra = (insn >> 16) & 0x1f;
	rb = (insn >> 11) & 0x1f;
	imm = (short)(((insn & 0x2200000) >> 10) \| (insn & 0x7ff));
	vaddr = (unsigned long __user *)(regs->gpr[ra] + imm);

	if (!lwa_flag \|\| vaddr != lwa_addr) {
	regs->sr &= ~SPR_SR_F;
	return;
	}

	if ((unsigned long)vaddr & 0x3) {
	do_unaligned_access(regs, address);
	return;
	}

	if (put_user(regs->gpr[rb], vaddr)) {
	if (user_mode(regs)) {
	force_sig(SIGSEGV);
	return;
	}

	if ((entry = search_exception_tables(orig_pc))) {
	regs->pc = entry->fixup;
	return;
	}

	/* kernel access in kernel space, store it directly */
	((unsigned long )vaddr) = regs->gpr[rb];
	}

	lwa_flag = 0;
	regs->sr \|= SPR_SR_F;
	}

	#define INSN_LWA 0x1b
	#define INSN_SWA 0x33

	asmlinkage void do_illegal_instruction(struct pt_regs *regs,
	unsigned long address)
	{
	unsigned int op;
	unsigned int insn = ((unsigned int )address);

	op = insn >> 26;

	switch (op) {
	case INSN_LWA:
	simulate_lwa(regs, address, insn);
	return;

	case INSN_SWA:
	simulate_swa(regs, address, insn);
	return;

	default:
	break;
	}

	if (user_mode(regs)) {
	/* Send a SIGILL */
	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)address);
	} else { /* Kernel mode */
	pr_emerg("KERNEL: Illegal instruction (SIGILL) 0x%.8lx\n",
	address);
	die("Die:", regs, address);
	}
	}