path: root/arch/sh/kernel/traps.c

/*
 * 'traps.c' handles hardware traps and faults after we have saved some
 * state in 'entry.S'.
 *
 *  SuperH version: Copyright (C) 1999 Niibe Yutaka
 *                  Copyright (C) 2000 Philipp Rumpf
 *                  Copyright (C) 2000 David Howells
 *                  Copyright (C) 2002 - 2007 Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/io.h>
#include <linux/bug.h>
#include <linux/debug_locks.h>
#include <linux/kdebug.h>
#include <linux/limits.h>
#include <asm/system.h>
#include <asm/uaccess.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
# define TRAP_ADDRESS_ERROR	9
# ifdef CONFIG_CPU_SH2A
#  define TRAP_DIVZERO_ERROR	17
#  define TRAP_DIVOVF_ERROR	18
# endif
#else
#define TRAP_RESERVED_INST	12
#define TRAP_ILLEGAL_SLOT_INST	13
#endif

static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
{
	unsigned long p;
	int i;

	printk("%s(0x%08lx to 0x%08lx)\n", str, bottom, top);

	for (p = bottom & ~31; p < top; ) {
		printk("%04lx: ", p & 0xffff);

		for (i = 0; i < 8; i++, p += 4) {
			unsigned int val;

			if (p < bottom || p >= top)
				printk("         ");
			else {
				if (__get_user(val, (unsigned int __user *)p)) {
					printk("\n");
					return;
				}
				printk("%08x ", val);
			}
		}
		printk("\n");
	}
}

static 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);
	bust_spinlocks(1);

	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);

	CHK_REMOTE_DEBUG(regs);
	print_modules();
	show_regs(regs);

	printk("Process: %s (pid: %d, stack limit = %p)\n",
	       current->comm, current->pid, task_stack_page(current) + 1);

	if (!user_mode(regs) || in_interrupt())
		dump_mem("Stack: ", regs->regs[15], THREAD_SIZE +
			 (unsigned long)task_stack_page(current));

	bust_spinlocks(0);
	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);
}

/*
 * 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] =