alignment.c

linux-2.6.15.6

/*
 *  linux/arch/arm/mm/alignment.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Modifications for ARM processor (c) 1995-2001 Russell King
 *  Thumb aligment 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/config.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/proc_fs.h>
#include <linux/init.h>

#include <asm/uaccess.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

static unsigned long ai_user;
static unsigned long ai_sys;
static unsigned long ai_skipped;
static unsigned long ai_half;
static unsigned long ai_word;
static unsigned long ai_dword;
static unsigned long ai_multi;
static int ai_usermode;

#ifdef CONFIG_PROC_FS
static const char *usermode_action[] = {
	"ignored",
	"warn",
	"fixup",
	"fixup+warn",
	"signal",
	"signal+warn"
};

static int
proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
		    void *data)
{
	char *p = page;
	int len;

	p += sprintf(p, "User:\t\t%lu\n", ai_user);
	p += sprintf(p, "System:\t\t%lu\n", ai_sys);
	p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
	p += sprintf(p, "Half:\t\t%lu\n", ai_half);
	p += sprintf(p, "Word:\t\t%lu\n", ai_word);
	if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
		p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
	p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
	p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
			usermode_action[ai_usermode]);

	len = (p - page) - off;
	if (len < 0)
		len = 0;

	*eof = (len <= count) ? 1 : 0;
	*start = page + off;

	return len;
}

static int proc_alignment_write(struct file *file, const char __user *buffer,
				unsigned long count, void *data)
{
	char mode;

	if (count > 0) {
		if (get_user(mode, buffer))
			return -EFAULT;
		if (mode >= '0' && mode <= '5')
			ai_usermode = mode - '0';
	}
	return count;
}

#endif /* CONFIG_PROC_FS */

union offset_union {
	unsigned long un;
	  signed long sn;
};

#define TYPE_ERROR	0
#define TYPE_FAULT	1
#define TYPE_LDST	2
#define TYPE_DONE	3

#ifdef __ARMEB__
#define BE		1
#define FIRST_BYTE_16	"mov	%1, %1, ror #8\n"
#define FIRST_BYTE_32	"mov	%1, %1, ror #24\n"
#define NEXT_BYTE	"ror #24"
#else
#define BE		0
#define FIRST_BYTE_16
#define FIRST_BYTE_32
#define NEXT_BYTE	"lsr #8"
#endif

#define __get8_unaligned_check(ins,val,addr,err)	\
	__asm__(					\
	"1:	"ins"	%1, [%2], #1\n"			\
	"2:\n"						\
	"	.section .fixup,\"ax\"\n"		\
	"	.align	2\n"				\
	"3:	mov	%0, #1\n"			\
	"	b	2b\n"				\
	"	.previous\n"				\
	"	.section __ex_table,\"a\"\n"		\
	"	.align	3\n"				\
	"	.long	1b, 3b\n"			\
	"	.previous\n"				\
	: "=r" (err), "=&r" (val), "=r" (addr)		\
	: "0" (err), "2" (addr))

#define __get16_unaligned_check(ins,val,addr)			\
	do {							\
		unsigned int err = 0, v, a = addr;		\
		__get8_unaligned_check(ins,v,a,err);		\
		val =  v << ((BE) ? 8 : 0);			\
		__get8_unaligned_check(ins,v,a,err);		\
		val |= v << ((BE) ? 0 : 8);			\
		if (err)					\
			goto fault;				\
	} while (0)

#define get16_unaligned_check(val,addr) \
	__get16_unaligned_check("ldrb",val,addr)

#define get16t_unaligned_check(val,addr) \
	__get16_unaligned_check("ldrbt",val,addr)

#define __get32_unaligned_check(ins,val,addr)			\
	do {							\
		unsigned int err = 0, v, a = addr;		\
		__get8_unaligned_check(ins,v,a,err);		\
		val =  v << ((BE) ? 24 :  0);			\
		__get8_unaligned_check(ins,v,a,err);		\
		val |= v << ((BE) ? 16 :  8);			\
		__get8_unaligned_check(ins,v,a,err);		\
		val |= v << ((BE) ?  8 : 16);			\
		__get8_unaligned_check(ins,v,a,err);		\
		val |= v << ((BE) ?  0 : 24);			\
		if (err)					\
			goto fault;				\
	} while (0)

#define get32_unaligned_check(val,addr) \
	__get32_unaligned_check("ldrb",val,addr)

#define get32t_unaligned_check(val,addr) \
	__get32_unaligned_check("ldrbt",val,addr)

#define __put16_unaligned_check(ins,val,addr)			\
	do {							\
		unsigned int err = 0, v = val, a = addr;	\
		__asm__( FIRST_BYTE_16				\
		"1:	"ins"	%1, [%2], #1\n"			\
		"	mov	%1, %1, "NEXT_BYTE"\n"		\
		"2:	"ins"	%1, [%2]\n"			\
		"3:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.align	2\n"				\
		"4:	mov	%0, #1\n"			\
		"	b	3b\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.align	3\n"				\
		"	.long	1b, 4b\n"			\
		"	.long	2b, 4b\n"			\
		"	.previous\n"				\
		: "=r" (err), "=&r" (v), "=&r" (a)		\
		: "0" (err), "1" (v), "2" (a));			\
		if (err)					\
			goto fault;				\
	} while (0)

#define put16_unaligned_check(val,addr)  \
	__put16_unaligned_check("strb",val,addr)

#define put16t_unaligned_check(val,addr) \
	__put16_unaligned_check("strbt",val,addr)

#define __put32_unaligned_check(ins,val,addr)			\
	do {							\
		unsigned int err = 0, v = val, a = addr;	\
		__asm__( FIRST_BYTE_32				\
		"1:	"ins"	%1, [%2], #1\n"			\
		"	mov	%1, %1, "NEXT_BYTE"\n"		\
		"2:	"ins"	%1, [%2], #1\n"			\
		"	mov	%1, %1, "NEXT_BYTE"\n"		\
		"3:	"ins"	%1, [%2], #1\n"			\
		"	mov	%1, %1, "NEXT_BYTE"\n"		\
		"4:	"ins"	%1, [%2]\n"			\
		"5:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.align	2\n"				\
		"6:	mov	%0, #1\n"			\
		"	b	5b\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.align	3\n"				\
		"	.long	1b, 6b\n"			\
		"	.long	2b, 6b\n"			\
		"	.long	3b, 6b\n"			\
		"	.long	4b, 6b\n"			\
		"	.previous\n"				\
		: "=r" (err), "=&r" (v), "=&r" (a)		\
		: "0" (err), "1" (v), "2" (a));			\
		if (err)					\
			goto fault;				\
	} while (0)

#define put32_unaligned_check(val,addr) \
	__put32_unaligned_check("strb", val, addr)

#define put32t_unaligned_check(val,addr) \
	__put32_unaligned_check("strbt", val, addr)

static void
do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
{
	if (!LDST_U_BIT(instr))
		offset.un = -offset.un;

	if (!LDST_P_BIT(instr))
		addr += offset.un;

	if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
		regs->uregs[RN_BITS(instr)] = addr;
}

static int
do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
{
	unsigned int rd = RD_BITS(instr);

	ai_half += 1;

	if (user_mode(regs))
		goto user;

	if (LDST_L_BIT(instr)) {
		unsigned long val;
		get16_unaligned_check(val, addr);

		/* signed half-word? */
		if (instr & 0x40)
			val = (signed long)((signed short) val);

		regs->uregs[rd] = val;
	} else
		put16_unaligned_check(regs->uregs[rd], addr);

	return TYPE_LDST;

 user:
	if (LDST_L_BIT(instr)) {
		unsigned long val;
		get16t_unaligned_check(val, addr);

		/* signed half-word? */
		if (instr & 0x40)
			val = (signed long)((signed short) val);

		regs->uregs[rd] = val;
	} else
		put16t_unaligned_check(regs->uregs[rd], addr);

	return TYPE_LDST;

 fault:
	return TYPE_FAULT;
}

static int
do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
		      struct pt_regs *regs)
{
	unsigned int rd = RD_BITS(instr);

	if (((rd & 1) == 1) || (rd == 14))
		goto bad;

	ai_dword += 1;

	if (user_mode(regs))
		goto user;

	if ((instr & 0xf0) == 0xd0) {
		unsigned long val;
		get32_unaligned_check(val, addr);
		regs->uregs[rd] = val;
		get32_unaligned_check(val, addr + 4);
		regs->uregs[rd + 1] = val;
	} else {
		put32_unaligned_check(regs->uregs[rd], addr);
		put32_unaligned_check(regs->uregs[rd + 1], addr + 4);
	}

	return TYPE_LDST;

 user:
	if ((instr & 0xf0) == 0xd0) {
		unsigned long val;
		get32t_unaligned_check(val, addr);
		regs->uregs[rd] = val;
		get32t_unaligned_check(val, addr + 4);
		regs->uregs[rd + 1] = val;
	} else {
		put32t_unaligned_check(regs->uregs[rd], addr);
		put32t_unaligned_check(regs->uregs[rd + 1], addr + 4);
	}

	return TYPE_LDST;
 bad:
	return TYPE_ERROR;
 fault:
	return TYPE_FAULT;
}

static int
do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
{
	unsigned int rd = RD_BITS(instr);

	ai_word += 1;

	if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
		goto trans;

	if (LDST_L_BIT(instr)) {
		unsigned int val;
		get32_unaligned_check(val, addr);
		regs->uregs[rd] = val;
	} else
		put32_unaligned_check(regs->uregs[rd], addr);
	return TYPE_LDST;

 trans:
	if (LDST_L_BIT(instr)) {
		unsigned int val;
		get32t_unaligned_check(val, addr);
		regs->uregs[rd] = val;
	} else
		put32t_unaligned_check(regs->uregs[rd], addr);
	return TYPE_LDST;

 fault:
	return TYPE_FAULT;
}

/*