/*
 *  linux/arch/h8300/platform/h8300h/ptrace_h8300h.c
 *    ptrace cpu depend helper functions
 *
 *  Yoshinori Sato <ysato@users.sourceforge.jp>
 *
 * 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/linkage.h>
#include <linux/sched.h>
#include <asm/ptrace.h>

#define CCR_MASK 0x6f    /* mode/imask not set */
#define BREAKINST 0x5730 /* trapa #3 */

/* Mapping from PT_xxx to the stack offset at which the register is
   saved.  Notice that usp has no stack-slot and needs to be treated
   specially (see get_reg/put_reg below). */
static const int h8300_register_offset[] = {
        PT_REG(er1), PT_REG(er2), PT_REG(er3), PT_REG(er4),
        PT_REG(er5), PT_REG(er6), PT_REG(er0), PT_REG(orig_er0),
        PT_REG(ccr), PT_REG(pc)
};

/* read register */
long h8300_get_reg(struct task_struct *task, int regno)
{
        switch (regno) {
        case PT_USP:
                return task->thread.usp + sizeof(long)*2;
        case PT_CCR:
            return *(unsigned short *)(task->thread.esp0 + h8300_register_offset[regno]);
        default:
            return *(unsigned long *)(task->thread.esp0 + h8300_register_offset[regno]);
        }
}

/* write register */
int h8300_put_reg(struct task_struct *task, int regno, unsigned long data)
{
        unsigned short oldccr;
        switch (regno) {
        case PT_USP:
                task->thread.usp = data - sizeof(long)*2;
        case PT_CCR:
                oldccr = *(unsigned short *)(task->thread.esp0 + h8300_register_offset[regno]);
                oldccr &= ~CCR_MASK;
                data &= CCR_MASK;
                data |= oldccr;
                *(unsigned short *)(task->thread.esp0 + h8300_register_offset[regno]) = data;
                break;
        default:
                *(unsigned long *)(task->thread.esp0 + h8300_register_offset[regno]) = data;
                break;
        }
        return 0;
}

/* disable singlestep */
void h8300_disable_trace(struct task_struct *child)
{
        if((long)child->thread.breakinfo.addr != -1L) {
                *child->thread.breakinfo.addr = child->thread.breakinfo.inst;
                child->thread.breakinfo.addr = (unsigned short *)-1L;
        }
}

/* calculate next pc */
enum jump_type {none,    /* normal instruction */
                jabs,    /* absolute address jump */
                ind,     /* indirect address jump */
                ret,     /* return to subrutine */
                reg,     /* register indexed jump */
                relb,    /* pc relative jump (byte offset) */
                relw,    /* pc relative jump (word offset) */
               };

/* opcode decode table define
   ptn: opcode pattern
   msk: opcode bitmask
   len: instruction length (<0 next table index)
   jmp: jump operation mode */
struct optable {
        unsigned char bitpattern;
        unsigned char bitmask;
        signed char length;
        signed char type;
} __attribute__((aligned(1),packed));

#define OPTABLE(ptn,msk,len,jmp)   \
        {                          \
                .bitpattern = ptn, \
                .bitmask    = msk, \
                .length     = len, \
                .type       = jmp, \
        }

static const struct optable optable_0[] = {
        OPTABLE(0x00,0xff, 1,none), /* 0x00 */
        OPTABLE(0x01,0xff,-1,none), /* 0x01 */
        OPTABLE(0x02,0xfe, 1,none), /* 0x02-0x03 */
        OPTABLE(0x04,0xee, 1,none), /* 0x04-0x05/0x14-0x15 */
        OPTABLE(0x06,0xfe, 1,none), /* 0x06-0x07 */
        OPTABLE(0x08,0xea, 1,none), /* 0x08-0x09/0x0c-0x0d/0x18-0x19/0x1c-0x1d */
        OPTABLE(0x0a,0xee, 1,none), /* 0x0a-0x0b/0x1a-0x1b */
        OPTABLE(0x0e,0xee, 1,none), /* 0x0e-0x0f/0x1e-0x1f */
        OPTABLE(0x10,0xfc, 1,none), /* 0x10-0x13 */
        OPTABLE(0x16,0xfe, 1,none), /* 0x16-0x17 */
        OPTABLE(0x20,0xe0, 1,none), /* 0x20-0x3f */
        OPTABLE(0x40,0xf0, 1,relb), /* 0x40-0x4f */
        OPTABLE(0x50,0xfc, 1,none), /* 0x50-0x53 */
        OPTABLE(0x54,0xfd, 1,ret ), /* 0x54/0x56 */
        OPTABLE(0x55,0xff, 1,relb), /* 0x55 */
        OPTABLE(0x57,0xff, 1,none), /* 0x57 */
        OPTABLE(0x58,0xfb, 2,relw), /* 0x58/0x5c */
        OPTABLE(0x59,0xfb, 1,reg ), /* 0x59/0x5b */
        OPTABLE(0x5a,0xfb, 2,jabs), /* 0x5a/0x5e */
        OPTABLE(0x5b,0xfb, 2,ind ), /* 0x5b/0x5f */
        OPTABLE(0x60,0xe8, 1,none), /* 0x60-0x67/0x70-0x77 */
        OPTABLE(0x68,0xfa, 1,none), /* 0x68-0x69/0x6c-0x6d */
        OPTABLE(0x6a,0xfe,-2,none), /* 0x6a-0x6b */
        OPTABLE(0x6e,0xfe, 2,none), /* 0x6e-0x6f */
        OPTABLE(0x78,0xff, 4,none), /* 0x78 */
        OPTABLE(0x79,0xff, 2,none), /* 0x79 */
        OPTABLE(0x7a,0xff, 3,none), /* 0x7a */
        OPTABLE(0x7b,0xff, 2,none), /* 0x7b */
        OPTABLE(0x7c,0xfc, 2,none), /* 0x7c-0x7f */
        OPTABLE(0x80,0x80, 1,none), /* 0x80-0xff */
};

static const struct optable optable_1[] = {
        OPTABLE(0x00,0xff,-3,none), /* 0x0100 */
        OPTABLE(0x40,0xf0,-3,none), /* 0x0140-0x14f */
        OPTABLE(0x80,0xf0, 1,none), /* 0x0180-0x018f */
        OPTABLE(0xc0,0xc0, 2,none), /* 0x01c0-0x01ff */
};

static const struct optable optable_2[] = {
        OPTABLE(0x00,0x20, 2,none), /* 0x6a0?/0x6a8?/0x6b0?/0x6b8? */
        OPTABLE(0x20,0x20, 3,none), /* 0x6a2?/0x6aa?/0x6b2?/0x6ba? */
};

static const struct optable optable_3[] = {
        OPTABLE(0x69,0xfb, 2,none), /* 0x010069/0x01006d/014069/0x01406d */
        OPTABLE(0x6b,0xff,-4,none), /* 0x01006b/0x01406b */
        OPTABLE(0x6f,0xff, 3,none), /* 0x01006f/0x01406f */
        OPTABLE(0x78,0xff, 5,none), /* 0x010078/0x014078 */
};

static const struct optable optable_4[] = {
        OPTABLE(0x00,0x78, 3,none), /* 0x0100690?/0x01006d0?/0140690/0x01406d0?/0x0100698?/0x01006d8?/0140698?/0x01406d8? */
        OPTABLE(0x20,0x78, 4,none), /* 0x0100692?/0x01006d2?/0140692/0x01406d2?/0x010069a?/0x01006da?/014069a?/0x01406da? */
};

static const struct optables_list {
        const struct optable *ptr;
        int size;
} optables[] = {
#define OPTABLES(no)                                                   \
        {                                                              \
                .ptr  = optable_##no,                                  \
                .size = sizeof(optable_##no) / sizeof(struct optable), \
        }
        OPTABLES(0),
        OPTABLES(1),
        OPTABLES(2),
        OPTABLES(3),
        OPTABLES(4),

};

const unsigned char condmask[] = {
        0x00,0x40,0x01,0x04,0x02,0x08,0x10,0x20
};

static int isbranch(struct task_struct *task,int reson)
{
        unsigned char cond = h8300_get_reg(task, PT_CCR);
        /* encode complex conditions */
        /* B4: N^V
           B5: Z|(N^V)
           B6: C|Z */
        __asm__("bld #3,%w0\n\t"
                "bxor #1,%w0\n\t"
                "bst #4,%w0\n\t"
                "bor #2,%w0\n\t"
                "bst #5,%w0\n\t"
                "bld #2,%w0\n\t"
                "bor #0,%w0\n\t"
                "bst #6,%w0\n\t"
                :"=&r"(cond)::"cc");
        cond &= condmask[reson >> 1];
        if (!(reson & 1))
                return cond == 0;
        else
                return cond != 0;
}

static unsigned short *getnextpc(struct task_struct *child, unsigned short *pc)
{
        const struct optable *op;
        unsigned char *fetch_p;
        unsigned char inst;
        unsigned long addr;
        unsigned long *sp;
        int op_len,regno;
        op = optables[0].ptr;
        op_len = optables[0].size;
        fetch_p = (unsigned char *)pc;
        inst = *fetch_p++;
        do {
                if ((inst & op->bitmask) == op->bitpattern) {
                        if (op->length < 0) {
                                op = optables[-op->length].ptr;
                                op_len = optables[-op->length].size + 1;
                                inst = *fetch_p++;
                        } else {
                                switch (op->type) {
                                case none:
                                        return pc + op->length;
                                case jabs:
                                        addr = *(unsigned long *)pc;
                                        return (unsigned short *)(addr & 0x00ffffff);
                                case ind:
                                        addr = *pc & 0xff;
                                        return (unsigned short *)(*(unsigned long *)addr);
                                case ret:
                                        sp = (unsigned long *)h8300_get_reg(child, PT_USP);
                                        /* user stack frames
                                           |   er0  | temporary saved
                                           +--------+
                                           |   exp  | exception stack frames
                                           +--------+
                                           | ret pc | userspace return address
                                        */
                                        return (unsigned short *)(*(sp+2) & 0x00ffffff);
                                case reg:
                                        regno = (*pc >> 4) & 0x07;
                                        if (regno == 0)
                                                addr = h8300_get_reg(child, PT_ER0);
                                        else
                                                addr = h8300_get_reg(child, regno-1+PT_ER1);
                                        return (unsigned short *)addr;
                                case relb:
                                        if (inst == 0x55 || isbranch(child,inst & 0x0f))
                                                pc = (unsigned short *)((unsigned long)pc +
                                                                       ((signed char)(*fetch_p)));
                                        return pc+1; /* skip myself */
                                case relw:
                                        if (inst == 0x5c || isbranch(child,(*fetch_p & 0xf0) >> 4))
                                                pc = (unsigned short *)((unsigned long)pc +
                                                                       ((signed short)(*(pc+1))));
                                        return pc+2; /* skip myself */
                                }
                        }
                } else
                        op++;
        } while(--op_len > 0);
        return NULL;
}

/* Set breakpoint(s) to simulate a single step from the current PC.  */

void h8300_enable_trace(struct task_struct *child)
{
        unsigned short *nextpc;
        nextpc = getnextpc(child,(unsigned short *)h8300_get_reg(child, PT_PC));
        child->thread.breakinfo.addr = nextpc;
        child->thread.breakinfo.inst = *nextpc;
        *nextpc = BREAKINST;
}

asmlinkage void trace_trap(unsigned long bp)
{
        if ((unsigned long)current->thread.breakinfo.addr == bp) {
                h8300_disable_trace(current);
                force_sig(SIGTRAP,current);
        } else
                force_sig(SIGILL,current);
}