alignment.c

/*
 *  linux/arch/arm/mm/alignment.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Modifications for ARM processor (c) 1995-2001 Russell King
 *  Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc.
 *  - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
 *    Copyright (C) 1996, Cygnus Software Technologies Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/moduleparam.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/uaccess.h>

#include <asm/cp15.h>
#include <asm/system_info.h>
#include <asm/unaligned.h>

#include "fault.h"

/*
 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
 * /proc/sys/debug/alignment, modified and integrated into
 * Linux 2.1 by Russell King
 *
 * Speed optimisations and better fault handling by Russell King.
 *
 * *** NOTE ***
 * This code is not portable to processors with late data abort handling.
 */
#define CODING_BITS(i)	(i & 0x0e000000)

#define LDST_I_BIT(i)	(i & (1 << 26))		/* Immediate constant	*/
#define LDST_P_BIT(i)	(i & (1 << 24))		/* Preindex		*/
#define LDST_U_BIT(i)	(i & (1 << 23))		/* Add offset		*/
#define LDST_W_BIT(i)	(i & (1 << 21))		/* Writeback		*/
#define LDST_L_BIT(i)	(i & (1 << 20))		/* Load			*/

#define LDST_P_EQ_U(i)	((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)

#define LDSTHD_I_BIT(i)	(i & (1 << 22))		/* double/half-word immed */
#define LDM_S_BIT(i)	(i & (1 << 22))		/* write CPSR from SPSR	*/

#define RN_BITS(i)	((i >> 16) & 15)	/* Rn			*/
#define RD_BITS(i)	((i >> 12) & 15)	/* Rd			*/
#define RM_BITS(i)	(i & 15)		/* Rm			*/

#define REGMASK_BITS(i)	(i & 0xffff)
#define OFFSET_BITS(i)	(i & 0x0fff)

#define IS_SHIFT(i)	(i & 0x0ff0)
#define SHIFT_BITS(i)	((i >> 7) & 0x1f)
#define SHIFT_TYPE(i)	(i & 0x60)
#define SHIFT_LSL	0x00
#define SHIFT_LSR	0x20
#define SHIFT_ASR	0x40
#define SHIFT_RORRRX	0x60

#define BAD_INSTR 	0xdeadc0de