arch/sh/kernel/traps.c - maze/linux - Git at Google

 /* $Id: traps.c,v 1.17 2004/05/02 01:46:30 sugioka Exp $
  *
  *  linux/arch/sh/traps.c
  *
  *  SuperH version: Copyright (C) 1999 Niibe Yutaka
  *                  Copyright (C) 2000 Philipp Rumpf
  *                  Copyright (C) 2000 David Howells
  *                  Copyright (C) 2002, 2003 Paul Mundt
  */

 /*
  * 'Traps.c' handles hardware traps and faults after we have saved some
  * state in 'entry.S'.
  */
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
 #include <linux/timer.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/spinlock.h>
 #include <linux/module.h>
 #include <linux/kallsyms.h>

 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/atomic.h>
 #include <asm/processor.h>
 #include <asm/sections.h>

 #ifdef CONFIG_SH_KGDB
 #include <asm/kgdb.h>
 #define CHK_REMOTE_DEBUG(regs)                 	\
 {       					\
 	if (kgdb_debug_hook && !user_mode(regs))\
 		(*kgdb_debug_hook)(regs);       \
 }
 #else
 #define CHK_REMOTE_DEBUG(regs)
 #endif

 #ifdef CONFIG_CPU_SH2
 #define TRAP_RESERVED_INST	4
 #define TRAP_ILLEGAL_SLOT_INST	6
 #else
 #define TRAP_RESERVED_INST	12
 #define TRAP_ILLEGAL_SLOT_INST	13
 #endif

 /*
  * These constants are for searching for possible module text
  * segments.  VMALLOC_OFFSET comes from mm/vmalloc.c; MODULE_RANGE is
  * a guess of how much space is likely to be vmalloced.
  */
 #define VMALLOC_OFFSET (8*1024*1024)
 #define MODULE_RANGE (8*1024*1024)

 DEFINE_SPINLOCK(die_lock);

 void die(const char * str, struct pt_regs * regs, long err)
 {
 	static int die_counter;

 	console_verbose();
 	spin_lock_irq(&die_lock);
 	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 	CHK_REMOTE_DEBUG(regs);
 	show_regs(regs);
 	spin_unlock_irq(&die_lock);
 	do_exit(SIGSEGV);
 }

 static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
 {
 	if (!user_mode(regs))
 		die(str, regs, err);
 }

 static int handle_unaligned_notify_count = 10;

 /*
  * try and fix up kernelspace address errors
  * - userspace errors just cause EFAULT to be returned, resulting in SEGV
  * - kernel/userspace interfaces cause a jump to an appropriate handler
  * - other kernel errors are bad
  * - return 0 if fixed-up, -EFAULT if non-fatal (to the kernel) fault
  */
 static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
 {
 	if (!user_mode(regs))
 	{
 		const struct exception_table_entry *fixup;
 		fixup = search_exception_tables(regs->pc);
 		if (fixup) {
 			regs->pc = fixup->fixup;
 			return 0;
 		}
 		die(str, regs, err);
 	}
 	return -EFAULT;
 }

 /*
  * handle an instruction that does an unaligned memory access by emulating the
  * desired behaviour
  * - note that PC _may not_ point to the faulting instruction
  *   (if that instruction is in a branch delay slot)
  * - return 0 if emulation okay, -EFAULT on existential error
  */
 static int handle_unaligned_ins(u16 instruction, struct pt_regs *regs)
 {
 	int ret, index, count;
 	unsigned long *rm, *rn;
 	unsigned char *src, *dst;

 	index = (instruction>>8)&15;	/* 0x0F00 */
 	rn = &regs->regs[index];

 	index = (instruction>>4)&15;	/* 0x00F0 */
 	rm = &regs->regs[index];

 	count = 1<<(instruction&3);

 	ret = -EFAULT;
 	switch (instruction>>12) {
 	case 0: /* mov.[bwl] to/from memory via r0+rn */
 		if (instruction & 8) {
 			/* from memory */
 			src = (unsigned char*) *rm;
 			src += regs->regs[0];
 			dst = (unsigned char*) rn;
 			*(unsigned long*)dst = 0;

 #ifdef __LITTLE_ENDIAN__
 			if (copy_from_user(dst, src, count))
 				goto fetch_fault;

 			if ((count == 2) && dst[1] & 0x80) {
 				dst[2] = 0xff;
 				dst[3] = 0xff;
 			}
 #else
 			dst += 4-count;

 			if (__copy_user(dst, src, count))
 				goto fetch_fault;

 			if ((count == 2) && dst[2] & 0x80) {
 				dst[0] = 0xff;
 				dst[1] = 0xff;
 			}
 #endif
 		} else {
 			/* to memory */
 			src = (unsigned char*) rm;
 #if !defined(__LITTLE_ENDIAN__)
 			src += 4-count;
 #endif
 			dst = (unsigned char*) *rn;
 			dst += regs->regs[0];

 			if (copy_to_user(dst, src, count))
 				goto fetch_fault;
 		}
 		ret = 0;
 		break;

 	case 1: /* mov.l Rm,@(disp,Rn) */
 		src = (unsigned char*) rm;
 		dst = (unsigned char*) *rn;
 		dst += (instruction&0x000F)<<2;

 		if (copy_to_user(dst,src,4))
 			goto fetch_fault;
 		ret = 0;
  		break;

 	case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
 		if (instruction & 4)
 			*rn -= count;
 		src = (unsigned char*) rm;
 		dst = (unsigned char*) *rn;
 #if !defined(__LITTLE_ENDIAN__)
 		src += 4-count;
 #endif
 		if (copy_to_user(dst, src, count))
 			goto fetch_fault;
 		ret = 0;
 		break;

 	case 5: /* mov.l @(disp,Rm),Rn */
 		src = (unsigned char*) *rm;
 		src += (instruction&0x000F)<<2;
 		dst = (unsigned char*) rn;
 		*(unsigned long*)dst = 0;

 		if (copy_from_user(dst,src,4))
 			goto fetch_fault;
 		ret = 0;
  		break;

 	case 6:	/* mov.[bwl] from memory, possibly with post-increment */
 		src = (unsigned char*) *rm;
 		if (instruction & 4)
 			*rm += count;
 		dst = (unsigned char*) rn;
 		*(unsigned long*)dst = 0;

 #ifdef __LITTLE_ENDIAN__
 		if (copy_from_user(dst, src, count))
 			goto fetch_fault;

 		if ((count == 2) && dst[1] & 0x80) {
 			dst[2] = 0xff;
 			dst[3] = 0xff;
 		}
 #else
 		dst += 4-count;

 		if (copy_from_user(dst, src, count))
 			goto fetch_fault;

 		if ((count == 2) && dst[2] & 0x80) {
 			dst[0] = 0xff;
 			dst[1] = 0xff;
 		}
 #endif
 		ret = 0;
 		break;

 	case 8:
 		switch ((instruction&0xFF00)>>8) {
 		case 0x81: /* mov.w R0,@(disp,Rn) */
 			src = (unsigned char*) &regs->regs[0];
 #if !defined(__LITTLE_ENDIAN__)
 			src += 2;
 #endif
 			dst = (unsigned char*) *rm; /* called Rn in the spec */
 			dst += (instruction&0x000F)<<1;

 			if (copy_to_user(dst, src, 2))
 				goto fetch_fault;
 			ret = 0;
 			break;

 		case 0x85: /* mov.w @(disp,Rm),R0 */
 			src = (unsigned char*) *rm;
 			src += (instruction&0x000F)<<1;
 			dst = (unsigned char*) &regs->regs[0];
 			*(unsigned long*)dst = 0;

 #if !defined(__LITTLE_ENDIAN__)
 			dst += 2;
 #endif

 			if (copy_from_user(dst, src, 2))
 				goto fetch_fault;

 #ifdef __LITTLE_ENDIAN__
 			if (dst[1] & 0x80) {
 				dst[2] = 0xff;
 				dst[3] = 0xff;
 			}
 #else
 			if (dst[2] & 0x80) {
 				dst[0] = 0xff;
 				dst[1] = 0xff;
 			}
 #endif
 			ret = 0;
 			break;
 		}
 		break;
 	}
 	return ret;

  fetch_fault:
 	/* Argh. Address not only misaligned but also non-existent.
 	 * Raise an EFAULT and see if it's trapped
 	 */
 	return die_if_no_fixup("Fault in unaligned fixup", regs, 0);
 }

 /*
  * emulate the instruction in the delay slot
  * - fetches the instruction from PC+2
  */
 static inline int handle_unaligned_delayslot(struct pt_regs *regs)
 {
 	u16 instruction;

 	if (copy_from_user(&instruction, (u16 *)(regs->pc+2), 2)) {
 		/* the instruction-fetch faulted */
 		if (user_mode(regs))
 			return -EFAULT;

 		/* kernel */
 		die("delay-slot-insn faulting in handle_unaligned_delayslot", regs, 0);
 	}

 	return handle_unaligned_ins(instruction,regs);
 }

 /*
  * handle an instruction that does an unaligned memory access
  * - have to be careful of branch delay-slot instructions that fault
  *  SH3:
  *   - if the branch would be taken PC points to the branch
  *   - if the branch would not be taken, PC points to delay-slot
  *  SH4:
  *   - PC always points to delayed branch
  * - return 0 if handled, -EFAULT if failed (may not return if in kernel)
  */

 /* Macros to determine offset from current PC for branch instructions */
 /* Explicit type coercion is used to force sign extension where needed */
 #define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
 #define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)

 static int handle_unaligned_access(u16 instruction, struct pt_regs *regs)
 {
 	u_int rm;
 	int ret, index;

 	index = (instruction>>8)&15;	/* 0x0F00 */
 	rm = regs->regs[index];

 	/* shout about the first ten userspace fixups */
 	if (user_mode(regs) && handle_unaligned_notify_count>0) {
 		handle_unaligned_notify_count--;

 		printk("Fixing up unaligned userspace access in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
 		       current->comm,current->pid,(u16*)regs->pc,instruction);
 	}

 	ret = -EFAULT;
 	switch (instruction&0xF000) {
 	case 0x0000:
 		if (instruction==0x000B) {
 			/* rts */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0)
 				regs->pc = regs->pr;
 		}
 		else if ((instruction&0x00FF)==0x0023) {
 			/* braf @Rm */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0)
 				regs->pc += rm + 4;
 		}
 		else if ((instruction&0x00FF)==0x0003) {
 			/* bsrf @Rm */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0) {
 				regs->pr = regs->pc + 4;
 				regs->pc += rm + 4;
 			}
 		}
 		else {
 			/* mov.[bwl] to/from memory via r0+rn */
 			goto simple;
 		}
 		break;

 	case 0x1000: /* mov.l Rm,@(disp,Rn) */
 		goto simple;

 	case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
 		goto simple;

 	case 0x4000:
 		if ((instruction&0x00FF)==0x002B) {
 			/* jmp @Rm */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0)
 				regs->pc = rm;
 		}
 		else if ((instruction&0x00FF)==0x000B) {
 			/* jsr @Rm */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0) {
 				regs->pr = regs->pc + 4;
 				regs->pc = rm;
 			}
 		}
 		else {
 			/* mov.[bwl] to/from memory via r0+rn */
 			goto simple;
 		}
 		break;

 	case 0x5000: /* mov.l @(disp,Rm),Rn */
 		goto simple;

 	case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
 		goto simple;

 	case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
 		switch (instruction&0x0F00) {
 		case 0x0100: /* mov.w R0,@(disp,Rm) */
 			goto simple;
 		case 0x0500: /* mov.w @(disp,Rm),R0 */
 			goto simple;
 		case 0x0B00: /* bf   lab - no delayslot*/
 			break;
 		case 0x0F00: /* bf/s lab */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0) {
 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
 				if ((regs->sr & 0x00000001) != 0)
 					regs->pc += 4; /* next after slot */
 				else
 #endif
 					regs->pc += SH_PC_8BIT_OFFSET(instruction);
 			}
 			break;
 		case 0x0900: /* bt   lab - no delayslot */
 			break;
 		case 0x0D00: /* bt/s lab */
 			ret = handle_unaligned_delayslot(regs);
 			if (ret==0) {
 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
 				if ((regs->sr & 0x00000001) == 0)
 					regs->pc += 4; /* next after slot */
 				else
 #endif
 					regs->pc += SH_PC_8BIT_OFFSET(instruction);
 			}
 			break;
 		}
 		break;

 	case 0xA000: /* bra label */
 		ret = handle_unaligned_delayslot(regs);
 		if (ret==0)
 			regs->pc += SH_PC_12BIT_OFFSET(instruction);
 		break;

 	case 0xB000: /* bsr label */
 		ret = handle_unaligned_delayslot(regs);
 		if (ret==0) {
 			regs->pr = regs->pc + 4;
 			regs->pc += SH_PC_12BIT_OFFSET(instruction);
 		}
 		break;
 	}
 	return ret;

 	/* handle non-delay-slot instruction */
  simple:
 	ret = handle_unaligned_ins(instruction,regs);
 	if (ret==0)
 		regs->pc += 2;
 	return ret;
 }

 /*
  * Handle various address error exceptions
  */
 asmlinkage void do_address_error(struct pt_regs *regs,
 				 unsigned long writeaccess,
 				 unsigned long address)
 {
 	unsigned long error_code;
 	mm_segment_t oldfs;
 	u16 instruction;
 	int tmp;

 	asm volatile("stc       r2_bank,%0": "=r" (error_code));

 	oldfs = get_fs();

 	if (user_mode(regs)) {
 		local_irq_enable();
 		current->thread.error_code = error_code;
 		current->thread.trap_no = (writeaccess) ? 8 : 7;

 		/* bad PC is not something we can fix */
 		if (regs->pc & 1)
 			goto uspace_segv;

 		set_fs(USER_DS);
 		if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
 			/* Argh. Fault on the instruction itself.
 			   This should never happen non-SMP
 			*/
 			set_fs(oldfs);
 			goto uspace_segv;
 		}

 		tmp = handle_unaligned_access(instruction, regs);
 		set_fs(oldfs);

 		if (tmp==0)
 			return; /* sorted */

 	uspace_segv:
 		printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
 		force_sig(SIGSEGV, current);
 	} else {
 		if (regs->pc & 1)
 			die("unaligned program counter", regs, error_code);

 		set_fs(KERNEL_DS);
 		if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
 			/* Argh. Fault on the instruction itself.
 			   This should never happen non-SMP
 			*/
 			set_fs(oldfs);
 			die("insn faulting in do_address_error", regs, 0);
 		}

 		handle_unaligned_access(instruction, regs);
 		set_fs(oldfs);
 	}
 }

 #ifdef CONFIG_SH_DSP
 /*
  *	SH-DSP support gerg@snapgear.com.
  */
 int is_dsp_inst(struct pt_regs *regs)
 {
 	unsigned short inst;

 	/*
 	 * Safe guard if DSP mode is already enabled or we're lacking
 	 * the DSP altogether.
 	 */
 	if (!(cpu_data->flags & CPU_HAS_DSP) || (regs->sr & SR_DSP))
 		return 0;

 	get_user(inst, ((unsigned short *) regs->pc));

 	inst &= 0xf000;

 	/* Check for any type of DSP or support instruction */
 	if ((inst == 0xf000) || (inst == 0x4000))
 		return 1;

 	return 0;
 }
 #else
 #define is_dsp_inst(regs)	(0)
 #endif /* CONFIG_SH_DSP */

 extern int do_fpu_inst(unsigned short, struct pt_regs*);

 asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
 				unsigned long r6, unsigned long r7,
 				struct pt_regs regs)
 {
 	unsigned long error_code;
 	struct task_struct *tsk = current;

 #ifdef CONFIG_SH_FPU_EMU
 	unsigned short inst;
 	int err;

 	get_user(inst, (unsigned short*)regs.pc);

 	err = do_fpu_inst(inst, &regs);
 	if (!err) {
 		regs.pc += 2;
 		return;
 	}
 	/* not a FPU inst. */
 #endif

 #ifdef CONFIG_SH_DSP
 	/* Check if it's a DSP instruction */
  	if (is_dsp_inst(&regs)) {
 		/* Enable DSP mode, and restart instruction. */
 		regs.sr |= SR_DSP;
 		return;
 	}
 #endif

 	asm volatile("stc	r2_bank, %0": "=r" (error_code));
 	local_irq_enable();
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = TRAP_RESERVED_INST;
 	CHK_REMOTE_DEBUG(&regs);
 	force_sig(SIGILL, tsk);
 	die_if_no_fixup("reserved instruction", &regs, error_code);
 }

 #ifdef CONFIG_SH_FPU_EMU
 static int emulate_branch(unsigned short inst, struct pt_regs* regs)
 {
 	/*
 	 * bfs: 8fxx: PC+=d*2+4;
 	 * bts: 8dxx: PC+=d*2+4;
 	 * bra: axxx: PC+=D*2+4;
 	 * bsr: bxxx: PC+=D*2+4  after PR=PC+4;
 	 * braf:0x23: PC+=Rn*2+4;
 	 * bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
 	 * jmp: 4x2b: PC=Rn;
 	 * jsr: 4x0b: PC=Rn      after PR=PC+4;
 	 * rts: 000b: PC=PR;
 	 */
 	if ((inst & 0xfd00) == 0x8d00) {
 		regs->pc += SH_PC_8BIT_OFFSET(inst);
 		return 0;
 	}

 	if ((inst & 0xe000) == 0xa000) {
 		regs->pc += SH_PC_12BIT_OFFSET(inst);
 		return 0;
 	}

 	if ((inst & 0xf0df) == 0x0003) {
 		regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
 		return 0;
 	}

 	if ((inst & 0xf0df) == 0x400b) {
 		regs->pc = regs->regs[(inst & 0x0f00) >> 8];
 		return 0;
 	}

 	if ((inst & 0xffff) == 0x000b) {
 		regs->pc = regs->pr;
 		return 0;
 	}

 	return 1;
 }
 #endif

 asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
 				unsigned long r6, unsigned long r7,
 				struct pt_regs regs)
 {
 	unsigned long error_code;
 	struct task_struct *tsk = current;
 #ifdef CONFIG_SH_FPU_EMU
 	unsigned short inst;

 	get_user(inst, (unsigned short *)regs.pc + 1);
 	if (!do_fpu_inst(inst, &regs)) {
 		get_user(inst, (unsigned short *)regs.pc);
 		if (!emulate_branch(inst, &regs))
 			return;
 		/* fault in branch.*/
 	}
 	/* not a FPU inst. */
 #endif

 	asm volatile("stc	r2_bank, %0": "=r" (error_code));
 	local_irq_enable();
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = TRAP_RESERVED_INST;
 	CHK_REMOTE_DEBUG(&regs);
 	force_sig(SIGILL, tsk);
 	die_if_no_fixup("illegal slot instruction", &regs, error_code);
 }

 asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
 				   unsigned long r6, unsigned long r7,
 				   struct pt_regs regs)
 {
 	long ex;
 	asm volatile("stc	r2_bank, %0" : "=r" (ex));
 	die_if_kernel("exception", &regs, ex);
 }

 #if defined(CONFIG_SH_STANDARD_BIOS)
 void *gdb_vbr_vector;

 static inline void __init gdb_vbr_init(void)
 {
 	register unsigned long vbr;

 	/*
 	 * Read the old value of the VBR register to initialise
 	 * the vector through which debug and BIOS traps are
 	 * delegated by the Linux trap handler.
 	 */
 	asm volatile("stc vbr, %0" : "=r" (vbr));

 	gdb_vbr_vector = (void *)(vbr + 0x100);
 	printk("Setting GDB trap vector to 0x%08lx\n",
 	       (unsigned long)gdb_vbr_vector);
 }
 #endif

 void __init per_cpu_trap_init(void)
 {
 	extern void *vbr_base;

 #ifdef CONFIG_SH_STANDARD_BIOS
 	gdb_vbr_init();
 #endif

 	/* NOTE: The VBR value should be at P1
 	   (or P2, virtural "fixed" address space).
 	   It's definitely should not in physical address.  */

 	asm volatile("ldc	%0, vbr"
 		     : /* no output */
 		     : "r" (&vbr_base)
 		     : "memory");
 }

 void __init trap_init(void)
 {
 	extern void *exception_handling_table[];

 	exception_handling_table[TRAP_RESERVED_INST]
 		= (void *)do_reserved_inst;
 	exception_handling_table[TRAP_ILLEGAL_SLOT_INST]
 		= (void *)do_illegal_slot_inst;

 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) || \
     defined(CONFIG_SH_FPU_EMU)
 	/*
 	 * For SH-4 lacking an FPU, treat floating point instructions as
 	 * reserved. They'll be handled in the math-emu case, or faulted on
 	 * otherwise.
 	 */
 	/* entry 64 corresponds to EXPEVT=0x800 */
 	exception_handling_table[64] = (void *)do_reserved_inst;
 	exception_handling_table[65] = (void *)do_illegal_slot_inst;
 #endif

 	/* Setup VBR for boot cpu */
 	per_cpu_trap_init();
 }

 void show_stack(struct task_struct *tsk, unsigned long *sp)
 {
 	unsigned long *stack, addr;
 	unsigned long module_start = VMALLOC_START;
 	unsigned long module_end = VMALLOC_END;
 	int i = 1;

 	if (!tsk)
 		tsk = current;
 	if (tsk == current)
 		sp = (unsigned long *)current_stack_pointer;
 	else
 		sp = (unsigned long *)tsk->thread.sp;

 	stack = sp;

 	printk("\nCall trace: ");
 #ifdef CONFIG_KALLSYMS
 	printk("\n");
 #endif

 	while (!kstack_end(stack)) {
 		addr = *stack++;
 		if (((addr >= (unsigned long)_text) &&
 		     (addr <= (unsigned long)_etext)) ||
 		    ((addr >= module_start) && (addr <= module_end))) {
 			/*
 			 * For 80-columns display, 6 entry is maximum.
 			 * NOTE: '[<8c00abcd>] ' consumes 13 columns .
 			 */
 #ifndef CONFIG_KALLSYMS
 			if (i && ((i % 6) == 0))
 				printk("\n       ");
 #endif
 			printk("[<%08lx>] ", addr);
 			print_symbol("%s\n", addr);
 			i++;
 		}
 	}

 	printk("\n");
 }

 void show_task(unsigned long *sp)
 {
 	show_stack(NULL, sp);
 }

 void dump_stack(void)
 {
 	show_stack(NULL, NULL);
 }
 EXPORT_SYMBOL(dump_stack);
	/* $Id: traps.c,v 1.17 2004/05/02 01:46:30 sugioka Exp $
	*
	* linux/arch/sh/traps.c
	*
	* SuperH version: Copyright (C) 1999 Niibe Yutaka
	* Copyright (C) 2000 Philipp Rumpf
	* Copyright (C) 2000 David Howells
	* Copyright (C) 2002, 2003 Paul Mundt
	*/

	/*
	* 'Traps.c' handles hardware traps and faults after we have saved some
	* state in 'entry.S'.
	*/
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/ptrace.h>
	#include <linux/timer.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.h>
	#include <linux/init.h>
	#include <linux/delay.h>
	#include <linux/spinlock.h>
	#include <linux/module.h>
	#include <linux/kallsyms.h>

	#include <asm/system.h>
	#include <asm/uaccess.h>
	#include <asm/io.h>
	#include <asm/atomic.h>
	#include <asm/processor.h>
	#include <asm/sections.h>

	#ifdef CONFIG_SH_KGDB
	#include <asm/kgdb.h>
	#define CHK_REMOTE_DEBUG(regs) \
	{ \
	if (kgdb_debug_hook && !user_mode(regs))\
	(*kgdb_debug_hook)(regs); \
	}
	#else
	#define CHK_REMOTE_DEBUG(regs)
	#endif

	#ifdef CONFIG_CPU_SH2
	#define TRAP_RESERVED_INST 4
	#define TRAP_ILLEGAL_SLOT_INST 6
	#else
	#define TRAP_RESERVED_INST 12
	#define TRAP_ILLEGAL_SLOT_INST 13
	#endif

	/*
	* These constants are for searching for possible module text
	* segments. VMALLOC_OFFSET comes from mm/vmalloc.c; MODULE_RANGE is
	* a guess of how much space is likely to be vmalloced.
	*/
	#define VMALLOC_OFFSET (810241024)
	#define MODULE_RANGE (810241024)

	DEFINE_SPINLOCK(die_lock);

	void die(const char * str, struct pt_regs * regs, long err)
	{
	static int die_counter;

	console_verbose();
	spin_lock_irq(&die_lock);
	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
	CHK_REMOTE_DEBUG(regs);
	show_regs(regs);
	spin_unlock_irq(&die_lock);
	do_exit(SIGSEGV);
	}

	static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
	{
	if (!user_mode(regs))
	die(str, regs, err);
	}

	static int handle_unaligned_notify_count = 10;

	/*
	* try and fix up kernelspace address errors
	* - userspace errors just cause EFAULT to be returned, resulting in SEGV
	* - kernel/userspace interfaces cause a jump to an appropriate handler
	* - other kernel errors are bad
	* - return 0 if fixed-up, -EFAULT if non-fatal (to the kernel) fault
	*/
	static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
	{
	if (!user_mode(regs))
	{
	const struct exception_table_entry *fixup;
	fixup = search_exception_tables(regs->pc);
	if (fixup) {
	regs->pc = fixup->fixup;
	return 0;
	}
	die(str, regs, err);
	}
	return -EFAULT;
	}

	/*
	* handle an instruction that does an unaligned memory access by emulating the
	* desired behaviour
	* - note that PC _may not_ point to the faulting instruction
	* (if that instruction is in a branch delay slot)
	* - return 0 if emulation okay, -EFAULT on existential error
	*/
	static int handle_unaligned_ins(u16 instruction, struct pt_regs *regs)
	{
	int ret, index, count;
	unsigned long rm, rn;
	unsigned char src, dst;

	index = (instruction>>8)&15; /* 0x0F00 */
	rn = &regs->regs[index];

	index = (instruction>>4)&15; /* 0x00F0 */
	rm = &regs->regs[index];

	count = 1<<(instruction&3);

	ret = -EFAULT;
	switch (instruction>>12) {
	case 0: /* mov.[bwl] to/from memory via r0+rn */
	if (instruction & 8) {
	/* from memory */
	src = (unsigned char) rm;
	src += regs->regs[0];
	dst = (unsigned char*) rn;
	(unsigned long)dst = 0;

	#ifdef __LITTLE_ENDIAN__
	if (copy_from_user(dst, src, count))
	goto fetch_fault;

	if ((count == 2) && dst[1] & 0x80) {
	dst[2] = 0xff;
	dst[3] = 0xff;
	}
	#else
	dst += 4-count;

	if (__copy_user(dst, src, count))
	goto fetch_fault;

	if ((count == 2) && dst[2] & 0x80) {
	dst[0] = 0xff;
	dst[1] = 0xff;
	}
	#endif
	} else {
	/* to memory */
	src = (unsigned char*) rm;
	#if !defined(__LITTLE_ENDIAN__)
	src += 4-count;
	#endif
	dst = (unsigned char) rn;
	dst += regs->regs[0];

	if (copy_to_user(dst, src, count))
	goto fetch_fault;
	}
	ret = 0;
	break;

	case 1: /* mov.l Rm,@(disp,Rn) */
	src = (unsigned char*) rm;
	dst = (unsigned char) rn;
	dst += (instruction&0x000F)<<2;

	if (copy_to_user(dst,src,4))
	goto fetch_fault;
	ret = 0;
	break;

	case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
	if (instruction & 4)
	*rn -= count;
	src = (unsigned char*) rm;
	dst = (unsigned char) rn;
	#if !defined(__LITTLE_ENDIAN__)
	src += 4-count;
	#endif
	if (copy_to_user(dst, src, count))
	goto fetch_fault;
	ret = 0;
	break;

	case 5: /* mov.l @(disp,Rm),Rn */
	src = (unsigned char) rm;
	src += (instruction&0x000F)<<2;
	dst = (unsigned char*) rn;
	(unsigned long)dst = 0;

	if (copy_from_user(dst,src,4))
	goto fetch_fault;
	ret = 0;
	break;

	case 6: /* mov.[bwl] from memory, possibly with post-increment */
	src = (unsigned char) rm;
	if (instruction & 4)
	*rm += count;
	dst = (unsigned char*) rn;
	(unsigned long)dst = 0;

	#ifdef __LITTLE_ENDIAN__
	if (copy_from_user(dst, src, count))
	goto fetch_fault;

	if ((count == 2) && dst[1] & 0x80) {
	dst[2] = 0xff;
	dst[3] = 0xff;
	}
	#else
	dst += 4-count;

	if (copy_from_user(dst, src, count))
	goto fetch_fault;

	if ((count == 2) && dst[2] & 0x80) {
	dst[0] = 0xff;
	dst[1] = 0xff;
	}
	#endif
	ret = 0;
	break;

	case 8:
	switch ((instruction&0xFF00)>>8) {
	case 0x81: /* mov.w R0,@(disp,Rn) */
	src = (unsigned char*) &regs->regs[0];
	#if !defined(__LITTLE_ENDIAN__)
	src += 2;
	#endif
	dst = (unsigned char) rm; /* called Rn in the spec */
	dst += (instruction&0x000F)<<1;

	if (copy_to_user(dst, src, 2))
	goto fetch_fault;
	ret = 0;
	break;

	case 0x85: /* mov.w @(disp,Rm),R0 */
	src = (unsigned char) rm;
	src += (instruction&0x000F)<<1;
	dst = (unsigned char*) &regs->regs[0];
	(unsigned long)dst = 0;

	#if !defined(__LITTLE_ENDIAN__)
	dst += 2;
	#endif

	if (copy_from_user(dst, src, 2))
	goto fetch_fault;

	#ifdef __LITTLE_ENDIAN__
	if (dst[1] & 0x80) {
	dst[2] = 0xff;
	dst[3] = 0xff;
	}
	#else
	if (dst[2] & 0x80) {
	dst[0] = 0xff;
	dst[1] = 0xff;
	}
	#endif
	ret = 0;
	break;
	}
	break;
	}
	return ret;

	fetch_fault:
	/* Argh. Address not only misaligned but also non-existent.
	* Raise an EFAULT and see if it's trapped
	*/
	return die_if_no_fixup("Fault in unaligned fixup", regs, 0);
	}

	/*
	* emulate the instruction in the delay slot
	* - fetches the instruction from PC+2
	*/
	static inline int handle_unaligned_delayslot(struct pt_regs *regs)
	{
	u16 instruction;

	if (copy_from_user(&instruction, (u16 *)(regs->pc+2), 2)) {
	/* the instruction-fetch faulted */
	if (user_mode(regs))
	return -EFAULT;

	/* kernel */
	die("delay-slot-insn faulting in handle_unaligned_delayslot", regs, 0);
	}

	return handle_unaligned_ins(instruction,regs);
	}

	/*
	* handle an instruction that does an unaligned memory access
	* - have to be careful of branch delay-slot instructions that fault
	* SH3:
	* - if the branch would be taken PC points to the branch
	* - if the branch would not be taken, PC points to delay-slot
	* SH4:
	* - PC always points to delayed branch
	* - return 0 if handled, -EFAULT if failed (may not return if in kernel)
	*/

	/* Macros to determine offset from current PC for branch instructions */
	/* Explicit type coercion is used to force sign extension where needed */
	#define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
	#define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)

	static int handle_unaligned_access(u16 instruction, struct pt_regs *regs)
	{
	u_int rm;
	int ret, index;

	index = (instruction>>8)&15; /* 0x0F00 */
	rm = regs->regs[index];

	/* shout about the first ten userspace fixups */
	if (user_mode(regs) && handle_unaligned_notify_count>0) {
	handle_unaligned_notify_count--;

	printk("Fixing up unaligned userspace access in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
	current->comm,current->pid,(u16*)regs->pc,instruction);
	}

	ret = -EFAULT;
	switch (instruction&0xF000) {
	case 0x0000:
	if (instruction==0x000B) {
	/* rts */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0)
	regs->pc = regs->pr;
	}
	else if ((instruction&0x00FF)==0x0023) {
	/* braf @Rm */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0)
	regs->pc += rm + 4;
	}
	else if ((instruction&0x00FF)==0x0003) {
	/* bsrf @Rm */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0) {
	regs->pr = regs->pc + 4;
	regs->pc += rm + 4;
	}
	}
	else {
	/* mov.[bwl] to/from memory via r0+rn */
	goto simple;
	}
	break;

	case 0x1000: /* mov.l Rm,@(disp,Rn) */
	goto simple;

	case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
	goto simple;

	case 0x4000:
	if ((instruction&0x00FF)==0x002B) {
	/* jmp @Rm */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0)
	regs->pc = rm;
	}
	else if ((instruction&0x00FF)==0x000B) {
	/* jsr @Rm */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0) {
	regs->pr = regs->pc + 4;
	regs->pc = rm;
	}
	}
	else {
	/* mov.[bwl] to/from memory via r0+rn */
	goto simple;
	}
	break;

	case 0x5000: /* mov.l @(disp,Rm),Rn */
	goto simple;

	case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
	goto simple;

	case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
	switch (instruction&0x0F00) {
	case 0x0100: /* mov.w R0,@(disp,Rm) */
	goto simple;
	case 0x0500: /* mov.w @(disp,Rm),R0 */
	goto simple;
	case 0x0B00: /* bf lab - no delayslot*/
	break;
	case 0x0F00: /* bf/s lab */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0) {
	#if defined(CONFIG_CPU_SH4) \|\| defined(CONFIG_SH7705_CACHE_32KB)
	if ((regs->sr & 0x00000001) != 0)
	regs->pc += 4; /* next after slot */
	else
	#endif
	regs->pc += SH_PC_8BIT_OFFSET(instruction);
	}
	break;
	case 0x0900: /* bt lab - no delayslot */
	break;
	case 0x0D00: /* bt/s lab */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0) {
	#if defined(CONFIG_CPU_SH4) \|\| defined(CONFIG_SH7705_CACHE_32KB)
	if ((regs->sr & 0x00000001) == 0)
	regs->pc += 4; /* next after slot */
	else
	#endif
	regs->pc += SH_PC_8BIT_OFFSET(instruction);
	}
	break;
	}
	break;

	case 0xA000: /* bra label */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0)
	regs->pc += SH_PC_12BIT_OFFSET(instruction);
	break;

	case 0xB000: /* bsr label */
	ret = handle_unaligned_delayslot(regs);
	if (ret==0) {
	regs->pr = regs->pc + 4;
	regs->pc += SH_PC_12BIT_OFFSET(instruction);
	}
	break;
	}
	return ret;

	/* handle non-delay-slot instruction */
	simple:
	ret = handle_unaligned_ins(instruction,regs);
	if (ret==0)
	regs->pc += 2;
	return ret;
	}

	/*
	* Handle various address error exceptions
	*/
	asmlinkage void do_address_error(struct pt_regs *regs,
	unsigned long writeaccess,
	unsigned long address)
	{
	unsigned long error_code;
	mm_segment_t oldfs;
	u16 instruction;
	int tmp;

	asm volatile("stc r2_bank,%0": "=r" (error_code));

	oldfs = get_fs();

	if (user_mode(regs)) {
	local_irq_enable();
	current->thread.error_code = error_code;
	current->thread.trap_no = (writeaccess) ? 8 : 7;

	/* bad PC is not something we can fix */
	if (regs->pc & 1)
	goto uspace_segv;

	set_fs(USER_DS);
	if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
	/* Argh. Fault on the instruction itself.
	This should never happen non-SMP
	*/
	set_fs(oldfs);
	goto uspace_segv;
	}

	tmp = handle_unaligned_access(instruction, regs);
	set_fs(oldfs);

	if (tmp==0)
	return; /* sorted */

	uspace_segv:
	printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
	force_sig(SIGSEGV, current);
	} else {
	if (regs->pc & 1)
	die("unaligned program counter", regs, error_code);

	set_fs(KERNEL_DS);
	if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
	/* Argh. Fault on the instruction itself.
	This should never happen non-SMP
	*/
	set_fs(oldfs);
	die("insn faulting in do_address_error", regs, 0);
	}

	handle_unaligned_access(instruction, regs);
	set_fs(oldfs);
	}
	}

	#ifdef CONFIG_SH_DSP
	/*
	* SH-DSP support gerg@snapgear.com.
	*/
	int is_dsp_inst(struct pt_regs *regs)
	{
	unsigned short inst;

	/*
	* Safe guard if DSP mode is already enabled or we're lacking
	* the DSP altogether.
	*/
	if (!(cpu_data->flags & CPU_HAS_DSP) \|\| (regs->sr & SR_DSP))
	return 0;

	get_user(inst, ((unsigned short *) regs->pc));

	inst &= 0xf000;

	/* Check for any type of DSP or support instruction */
	if ((inst == 0xf000) \|\| (inst == 0x4000))
	return 1;

	return 0;
	}
	#else
	#define is_dsp_inst(regs) (0)
	#endif /* CONFIG_SH_DSP */

	extern int do_fpu_inst(unsigned short, struct pt_regs*);

	asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
	unsigned long r6, unsigned long r7,
	struct pt_regs regs)
	{
	unsigned long error_code;
	struct task_struct *tsk = current;

	#ifdef CONFIG_SH_FPU_EMU
	unsigned short inst;
	int err;

	get_user(inst, (unsigned short*)regs.pc);

	err = do_fpu_inst(inst, &regs);
	if (!err) {
	regs.pc += 2;
	return;
	}
	/* not a FPU inst. */
	#endif

	#ifdef CONFIG_SH_DSP
	/* Check if it's a DSP instruction */
	if (is_dsp_inst(&regs)) {
	/* Enable DSP mode, and restart instruction. */
	regs.sr \|= SR_DSP;
	return;
	}
	#endif

	asm volatile("stc r2_bank, %0": "=r" (error_code));
	local_irq_enable();
	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = TRAP_RESERVED_INST;
	CHK_REMOTE_DEBUG(&regs);
	force_sig(SIGILL, tsk);
	die_if_no_fixup("reserved instruction", &regs, error_code);
	}

	#ifdef CONFIG_SH_FPU_EMU
	static int emulate_branch(unsigned short inst, struct pt_regs* regs)
	{
	/*
	* bfs: 8fxx: PC+=d*2+4;
	* bts: 8dxx: PC+=d*2+4;
	* bra: axxx: PC+=D*2+4;
	* bsr: bxxx: PC+=D*2+4 after PR=PC+4;
	* braf:0x23: PC+=Rn*2+4;
	* bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
	* jmp: 4x2b: PC=Rn;
	* jsr: 4x0b: PC=Rn after PR=PC+4;
	* rts: 000b: PC=PR;
	*/
	if ((inst & 0xfd00) == 0x8d00) {
	regs->pc += SH_PC_8BIT_OFFSET(inst);
	return 0;
	}

	if ((inst & 0xe000) == 0xa000) {
	regs->pc += SH_PC_12BIT_OFFSET(inst);
	return 0;
	}

	if ((inst & 0xf0df) == 0x0003) {
	regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
	return 0;
	}

	if ((inst & 0xf0df) == 0x400b) {
	regs->pc = regs->regs[(inst & 0x0f00) >> 8];
	return 0;
	}

	if ((inst & 0xffff) == 0x000b) {
	regs->pc = regs->pr;
	return 0;
	}

	return 1;
	}
	#endif

	asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
	unsigned long r6, unsigned long r7,
	struct pt_regs regs)
	{
	unsigned long error_code;
	struct task_struct *tsk = current;
	#ifdef CONFIG_SH_FPU_EMU
	unsigned short inst;

	get_user(inst, (unsigned short *)regs.pc + 1);
	if (!do_fpu_inst(inst, &regs)) {
	get_user(inst, (unsigned short *)regs.pc);
	if (!emulate_branch(inst, &regs))
	return;
	/* fault in branch.*/
	}
	/* not a FPU inst. */
	#endif

	asm volatile("stc r2_bank, %0": "=r" (error_code));
	local_irq_enable();
	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = TRAP_RESERVED_INST;
	CHK_REMOTE_DEBUG(&regs);
	force_sig(SIGILL, tsk);
	die_if_no_fixup("illegal slot instruction", &regs, error_code);
	}

	asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
	unsigned long r6, unsigned long r7,
	struct pt_regs regs)
	{
	long ex;
	asm volatile("stc r2_bank, %0" : "=r" (ex));
	die_if_kernel("exception", &regs, ex);
	}

	#if defined(CONFIG_SH_STANDARD_BIOS)
	void *gdb_vbr_vector;

	static inline void __init gdb_vbr_init(void)
	{
	register unsigned long vbr;

	/*
	* Read the old value of the VBR register to initialise
	* the vector through which debug and BIOS traps are
	* delegated by the Linux trap handler.
	*/
	asm volatile("stc vbr, %0" : "=r" (vbr));

	gdb_vbr_vector = (void *)(vbr + 0x100);
	printk("Setting GDB trap vector to 0x%08lx\n",
	(unsigned long)gdb_vbr_vector);
	}
	#endif

	void __init per_cpu_trap_init(void)
	{
	extern void *vbr_base;

	#ifdef CONFIG_SH_STANDARD_BIOS
	gdb_vbr_init();
	#endif

	/* NOTE: The VBR value should be at P1
	(or P2, virtural "fixed" address space).
	It's definitely should not in physical address. */

	asm volatile("ldc %0, vbr"
	: /* no output */
	: "r" (&vbr_base)
	: "memory");
	}

	void __init trap_init(void)
	{
	extern void *exception_handling_table[];

	exception_handling_table[TRAP_RESERVED_INST]
	= (void *)do_reserved_inst;
	exception_handling_table[TRAP_ILLEGAL_SLOT_INST]
	= (void *)do_illegal_slot_inst;

	#if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) \|\| \
	defined(CONFIG_SH_FPU_EMU)
	/*
	* For SH-4 lacking an FPU, treat floating point instructions as
	* reserved. They'll be handled in the math-emu case, or faulted on
	* otherwise.
	*/
	/* entry 64 corresponds to EXPEVT=0x800 */
	exception_handling_table[64] = (void *)do_reserved_inst;
	exception_handling_table[65] = (void *)do_illegal_slot_inst;
	#endif

	/* Setup VBR for boot cpu */
	per_cpu_trap_init();
	}

	void show_stack(struct task_struct tsk, unsigned long sp)
	{
	unsigned long *stack, addr;
	unsigned long module_start = VMALLOC_START;
	unsigned long module_end = VMALLOC_END;
	int i = 1;

	if (!tsk)
	tsk = current;
	if (tsk == current)
	sp = (unsigned long *)current_stack_pointer;
	else
	sp = (unsigned long *)tsk->thread.sp;

	stack = sp;

	printk("\nCall trace: ");
	#ifdef CONFIG_KALLSYMS
	printk("\n");
	#endif

	while (!kstack_end(stack)) {
	addr = *stack++;
	if (((addr >= (unsigned long)_text) &&
	(addr <= (unsigned long)_etext)) \|\|
	((addr >= module_start) && (addr <= module_end))) {
	/*
	* For 80-columns display, 6 entry is maximum.
	* NOTE: '[<8c00abcd>] ' consumes 13 columns .
	*/
	#ifndef CONFIG_KALLSYMS
	if (i && ((i % 6) == 0))
	printk("\n ");
	#endif
	printk("[<%08lx>] ", addr);
	print_symbol("%s\n", addr);
	i++;
	}
	}

	printk("\n");
	}

	void show_task(unsigned long *sp)
	{
	show_stack(NULL, sp);
	}

	void dump_stack(void)
	{
	show_stack(NULL, NULL);
	}
	EXPORT_SYMBOL(dump_stack);