/*
 *  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 LDSTH_I_BIT(i)  (i & (1 << 22))         /* 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_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);
        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);

        if ((instr & 0x01f00ff0) == 0x01000090)
                goto swp;

        if ((instr & 0x90) != 0x90 || (instr & 0x60) == 0)
                goto bad;

        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;

 swp:
        printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
 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;
}

/*
 * LDM/STM alignment handler.
 *
 * There are 4 variants of this instruction:
 *
 * B = rn pointer before instruction, A = rn pointer after instruction
 *              ------ increasing address ----->
 *              |    | r0 | r1 | ... | rx |    |
 * PU = 01             B                    A
 * PU = 11        B                    A
 * PU = 00        A                    B
 * PU = 10             A                    B
 */
static int
do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
{
        unsigned int rd, rn, correction, nr_regs, regbits;
        unsigned long eaddr, newaddr;

        if (LDM_S_BIT(instr))
                goto bad;

        correction = 4; /* processor implementation defined */
        regs->ARM_pc += correction;

        ai_multi += 1;

        /* count the number of registers in the mask to be transferred */
        nr_regs = hweight16(REGMASK_BITS(instr)) * 4;

        rn = RN_BITS(instr);
        newaddr = eaddr = regs->uregs[rn];

        if (!LDST_U_BIT(instr))
                nr_regs = -nr_regs;
        newaddr += nr_regs;
        if (!LDST_U_BIT(instr))
                eaddr = newaddr;

        if (LDST_P_EQ_U(instr)) /* U = P */
                eaddr += 4;

        /* 
         * For alignment faults on the ARM922T/ARM920T the MMU  makes
         * the FSR (and hence addr) equal to the updated base address
         * of the multiple access rather than the restored value.
         * Switch this message off if we've got a ARM92[02], otherwise
         * [ls]dm alignment faults are noisy!
         */
#if !(defined CONFIG_CPU_ARM922T)  && !(defined CONFIG_CPU_ARM920T)
        /*
         * This is a "hint" - we already have eaddr worked out by the
         * processor for us.
         */
        if (addr != eaddr) {
                printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
                        "addr = %08lx, eaddr = %08lx\n",
                         instruction_pointer(regs), instr, addr, eaddr);
                show_regs(regs);
        }
#endif

        if (user_mode(regs)) {
                for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
                     regbits >>= 1, rd += 1)
                        if (regbits & 1) {
                                if (LDST_L_BIT(instr)) {
                                        unsigned int val;
                                        get32t_unaligned_check(val, eaddr);
                                        regs->uregs[rd] = val;
                                } else
                                        put32t_unaligned_check(regs->uregs[rd], eaddr);
                                eaddr += 4;
                        }
        } else {
                for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
                     regbits >>= 1, rd += 1)
                        if (regbits & 1) {
                                if (LDST_L_BIT(instr)) {
                                        unsigned int val;
                                        get32_unaligned_check(val, eaddr);
                                        regs->uregs[rd] = val;
                                } else
                                        put32_unaligned_check(regs->uregs[rd], eaddr);
                                eaddr += 4;
                        }
        }

        if (LDST_W_BIT(instr))
                regs->uregs[rn] = newaddr;
        if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
                regs->ARM_pc -= correction;
        return TYPE_DONE;

fault:
        regs->ARM_pc -= correction;
        return TYPE_FAULT;

bad:
        printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
        return TYPE_ERROR;
}

/*
 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
 * we can reuse ARM userland alignment fault fixups for Thumb.
 *
 * This implementation was initially based on the algorithm found in
 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
 *
 * NOTES:
 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
 *    decode, we return 0xdeadc0de. This should never happen under normal
 *    circumstances but if it does, we've got other problems to deal with
 *    elsewhere and we obviously can't fix those problems here.
 */

static unsigned long
thumb2arm(u16 tinstr)
{
        u32 L = (tinstr & (1<<11)) >> 11;

        switch ((tinstr & 0xf800) >> 11) {
        /* 6.5.1 Format 1: */
        case 0x6000 >> 11:                              /* 7.1.52 STR(1) */
        case 0x6800 >> 11:                              /* 7.1.26 LDR(1) */
        case 0x7000 >> 11:                              /* 7.1.55 STRB(1) */
        case 0x7800 >> 11:                              /* 7.1.30 LDRB(1) */
                return 0xe5800000 |
                        ((tinstr & (1<<12)) << (22-12)) |       /* fixup */
                        (L<<20) |                               /* L==1? */
                        ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
                        ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
                        ((tinstr & (31<<6)) >>                  /* immed_5 */
                                (6 - ((tinstr & (1<<12)) ? 0 : 2)));
        case 0x8000 >> 11:                              /* 7.1.57 STRH(1) */
        case 0x8800 >> 11:                              /* 7.1.32 LDRH(1) */
                return 0xe1c000b0 |
                        (L<<20) |                               /* L==1? */
                        ((tinstr & (7<<0)) << (12-0)) |         /* Rd */
                        ((tinstr & (7<<3)) << (16-3)) |         /* Rn */
                        ((tinstr & (7<<6)) >> (6-1)) |   /* immed_5[2:0] */
                        ((tinstr & (3<<9)) >> (9-8));    /* immed_5[4:3] */

        /* 6.5.1 Format 2: */
        case 0x5000 >> 11:
        case 0x5800 >> 11:
                {
                        static const u32 subset[8] = {
                                0xe7800000,             /* 7.1.53 STR(2) */
                                0xe18000b0,             /* 7.1.58 STRH(2) */
                                0xe7c00000,             /* 7.1.56 STRB(2) */
                                0xe19000d0,             /* 7.1.34 LDRSB */
                                0xe7900000,             /* 7.1.27 LDR(2) */
                                0xe19000b0,             /* 7.1.33 LDRH(2) */
                                0xe7d00000,             /* 7.1.31 LDRB(2) */
                                0xe19000f0              /* 7.1.35 LDRSH */
                        };
                        return subset[(tinstr & (7<<9)) >> 9] |
                            ((tinstr & (7<<0)) << (12-0)) |     /* Rd */
                            ((tinstr & (7<<3)) << (16-3)) |     /* Rn */
                            ((tinstr & (7<<6)) >> (6-0));       /* Rm */
                }

        /* 6.5.1 Format 3: */
        case 0x4800 >> 11:                              /* 7.1.28 LDR(3) */
                /* NOTE: This case is not technically possible. We're
                 *       loading 32-bit memory data via PC relative
                 *       addressing mode. So we can and should eliminate
                 *       this case. But I'll leave it here for now.
                 */
                return 0xe59f0000 |
                    ((tinstr & (7<<8)) << (12-8)) |             /* Rd */
                    ((tinstr & 255) << (2-0));                  /* immed_8 */

        /* 6.5.1 Format 4: */
        case 0x9000 >> 11:                              /* 7.1.54 STR(3) */
        case 0x9800 >> 11:                              /* 7.1.29 LDR(4) */
                return 0xe58d0000 |
                        (L<<20) |                               /* L==1? */
                        ((tinstr & (7<<8)) << (12-8)) |         /* Rd */
                        ((tinstr & 255) << 2);                  /* immed_8 */

        /* 6.6.1 Format 1: */
        case 0xc000 >> 11:                              /* 7.1.51 STMIA */
        case 0xc800 >> 11:                              /* 7.1.25 LDMIA */
                {
                        u32 Rn = (tinstr & (7<<8)) >> 8;
                        u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;

                        return 0xe8800000 | W | (L<<20) | (Rn<<16) |
                                (tinstr&255);
                }

        /* 6.6.1 Format 2: */
        case 0xb000 >> 11:                              /* 7.1.48 PUSH */
        case 0xb800 >> 11:                              /* 7.1.47 POP */
                if ((tinstr & (3 << 9)) == 0x0400) {
                        static const u32 subset[4] = {
                                0xe92d0000,     /* STMDB sp!,{registers} */
                                0xe92d4000,     /* STMDB sp!,{registers,lr} */
                                0xe8bd0000,     /* LDMIA sp!,{registers} */
                                0xe8bd8000      /* LDMIA sp!,{registers,pc} */
                        };
                        return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
                            (tinstr & 255);             /* register_list */
                }
                /* Else fall through for illegal instruction case */

        default:
                return 0xdeadc0de;
        }
}

static int
do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
        union offset_union offset;
        unsigned long instr = 0, instrptr;
        int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
        unsigned int type;
        mm_segment_t fs;
        unsigned int fault;
        u16 tinstr = 0;

        instrptr = instruction_pointer(regs);

        fs = get_fs();
        set_fs(KERNEL_DS);
        if thumb_mode(regs) {
                fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
                if (!(fault))
                        instr = thumb2arm(tinstr);
        } else
                fault = __get_user(instr, (u32 *)instrptr);
        set_fs(fs);

        if (fault) {
                type = TYPE_FAULT;
                goto bad_or_fault;
        }

        if (user_mode(regs))
                goto user;

        ai_sys += 1;

 fixup:

        regs->ARM_pc += thumb_mode(regs) ? 2 : 4;

        switch (CODING_BITS(instr)) {
        case 0x00000000:        /* ldrh or strh */
                if (LDSTH_I_BIT(instr))
                        offset.un = (instr & 0xf00) >> 4 | (instr & 15);
                else
                        offset.un = regs->uregs[RM_BITS(instr)];
                handler = do_alignment_ldrhstrh;
                break;

        case 0x04000000:        /* ldr or str immediate */
                offset.un = OFFSET_BITS(instr);
                handler = do_alignment_ldrstr;
                break;

        case 0x06000000:        /* ldr or str register */
                offset.un = regs->uregs[RM_BITS(instr)];

                if (IS_SHIFT(instr)) {
                        unsigned int shiftval = SHIFT_BITS(instr);

                        switch(SHIFT_TYPE(instr)) {
                        case SHIFT_LSL:
                                offset.un <<= shiftval;
                                break;

                        case SHIFT_LSR:
                                offset.un >>= shiftval;
                                break;

                        case SHIFT_ASR:
                                offset.sn >>= shiftval;
                                break;

                        case SHIFT_RORRRX:
                                if (shiftval == 0) {
                                        offset.un >>= 1;
                                        if (regs->ARM_cpsr & PSR_C_BIT)
                                                offset.un |= 1 << 31;
                                } else
                                        offset.un = offset.un >> shiftval |
                                                          offset.un << (32 - shiftval);
                                break;
                        }
                }
                handler = do_alignment_ldrstr;
                break;

        case 0x08000000:        /* ldm or stm */
                handler = do_alignment_ldmstm;
                break;

        default:
                goto bad;
        }

        type = handler(addr, instr, regs);

        if (type == TYPE_ERROR || type == TYPE_FAULT)
                goto bad_or_fault;

        if (type == TYPE_LDST)
                do_alignment_finish_ldst(addr, instr, regs, offset);

        return 0;

 bad_or_fault:
        if (type == TYPE_ERROR)
                goto bad;
        regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
        /*
         * We got a fault - fix it up, or die.
         */
        do_bad_area(current, current->mm, addr, fsr, regs);
        return 0;

 bad:
        /*
         * Oops, we didn't handle the instruction.
         */
        printk(KERN_ERR "Alignment trap: not handling instruction "
                "%0*lx at [<%08lx>]\n",
                thumb_mode(regs) ? 4 : 8,
                thumb_mode(regs) ? tinstr : instr, instrptr);
        ai_skipped += 1;
        return 1;

 user:
        ai_user += 1;

        if (ai_usermode & 1)
                printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
                       "Address=0x%08lx FSR 0x%03x\n", current->comm,
                        current->pid, instrptr,
                        thumb_mode(regs) ? 4 : 8,
                        thumb_mode(regs) ? tinstr : instr,
                        addr, fsr);

        if (ai_usermode & 2)
                goto fixup;

        if (ai_usermode & 4)
                force_sig(SIGBUS, current);
        else
                set_cr(cr_no_alignment);

        return 0;
}

/*
 * This needs to be done after sysctl_init, otherwise sys/ will be
 * overwritten.  Actually, this shouldn't be in sys/ at all since
 * it isn't a sysctl, and it doesn't contain sysctl information.
 * We now locate it in /proc/cpu/alignment instead.
 */
static int __init alignment_init(void)
{
#ifdef CONFIG_PROC_FS
        struct proc_dir_entry *res;

        res = proc_mkdir("cpu", NULL);
        if (!res)
                return -ENOMEM;

        res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
        if (!res)
                return -ENOMEM;

        res->read_proc = proc_alignment_read;
        res->write_proc = proc_alignment_write;
#endif

        hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
        hook_fault_code(3, do_alignment, SIGILL, "alignment exception");

        return 0;
}

fs_initcall(alignment_init);