/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2012 Joshua M. Clulow <josh@sysmgr.org>
 * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
 */

#include <libdisasm.h>

#include "dis_tables.h"
#include "libdisasm_impl.h"

typedef struct dis_handle_i386 {
        int             dhx_mode;
        dis86_t         dhx_dis;
        uint64_t        dhx_end;
} dis_handle_i386_t;

/*
 * Returns true if we are near the end of a function.  This is a cheap hack at
 * detecting NULL padding between functions.  If we're within a few bytes of the
 * next function, or past the start, then return true.
 */
static int
check_func(void *data)
{
        dis_handle_t *dhp = data;
        uint64_t start;
        size_t len;

        if (dhp->dh_lookup(dhp->dh_data, dhp->dh_addr, NULL, 0, &start, &len)
            != 0)
                return (0);

        if (start < dhp->dh_addr)
                return (dhp->dh_addr > start + len - 0x10);

        return (1);
}

static int
get_byte(void *data)
{
        uchar_t byte;
        dis_handle_t *dhp = data;

        if (dhp->dh_read(dhp->dh_data, dhp->dh_addr, &byte, sizeof (byte)) !=
            sizeof (byte))
                return (-1);

        dhp->dh_addr++;

        return ((int)byte);
}

static int
do_lookup(void *data, uint64_t addr, char *buf, size_t buflen)
{
        dis_handle_t *dhp = data;

        return (dhp->dh_lookup(dhp->dh_data, addr, buf, buflen, NULL, NULL));
}

static void
dis_i386_handle_detach(dis_handle_t *dhp)
{
        dis_free(dhp->dh_arch_private, sizeof (dis_handle_i386_t));
        dhp->dh_arch_private = NULL;
}

static int
dis_i386_handle_attach(dis_handle_t *dhp)
{
        dis_handle_i386_t *dhx;

        /*
         * Validate architecture flags
         */
        if (dhp->dh_flags & ~(DIS_X86_SIZE16 | DIS_X86_SIZE32 | DIS_X86_SIZE64 |
            DIS_OCTAL | DIS_NOIMMSYM)) {
                (void) dis_seterrno(E_DIS_INVALFLAG);
                return (-1);
        }

        /*
         * Create and initialize the internal structure
         */
        if ((dhx = dis_zalloc(sizeof (dis_handle_i386_t))) == NULL) {
                (void) dis_seterrno(E_DIS_NOMEM);
                return (-1);
        }
        dhp->dh_arch_private = dhx;

        /*
         * Initialize x86-specific architecture structure
         */
        if (dhp->dh_flags & DIS_X86_SIZE16)
                dhx->dhx_mode = SIZE16;
        else if (dhp->dh_flags & DIS_X86_SIZE64)
                dhx->dhx_mode = SIZE64;
        else
                dhx->dhx_mode = SIZE32;

        if (dhp->dh_flags & DIS_OCTAL)
                dhx->dhx_dis.d86_flags = DIS_F_OCTAL;

        dhx->dhx_dis.d86_sprintf_func = dis_snprintf;
        dhx->dhx_dis.d86_get_byte = get_byte;
        dhx->dhx_dis.d86_sym_lookup = do_lookup;
        dhx->dhx_dis.d86_check_func = check_func;

        dhx->dhx_dis.d86_data = dhp;

        return (0);
}

static int
dis_i386_disassemble(dis_handle_t *dhp, uint64_t addr, char *buf,
    size_t buflen)
{
        dis_handle_i386_t *dhx = dhp->dh_arch_private;
        dhp->dh_addr = addr;

        /* DIS_NOIMMSYM might not be set until now, so update */
        if (dhp->dh_flags & DIS_NOIMMSYM)
                dhx->dhx_dis.d86_flags |= DIS_F_NOIMMSYM;
        else
                dhx->dhx_dis.d86_flags &= ~DIS_F_NOIMMSYM;

        if (dtrace_disx86(&dhx->dhx_dis, dhx->dhx_mode) != 0)
                return (-1);

        if (buf != NULL)
                dtrace_disx86_str(&dhx->dhx_dis, dhx->dhx_mode, addr, buf,
                    buflen);

        return (0);
}

/* ARGSUSED */
static int
dis_i386_max_instrlen(dis_handle_t *dhp)
{
        return (15);
}

/* ARGSUSED */
static int
dis_i386_min_instrlen(dis_handle_t *dhp)
{
        return (1);
}

static int
dis_i386_supports_flags(int flags)
{
        int archflags = flags & DIS_ARCH_MASK;

        if (archflags == DIS_X86_SIZE16 || archflags == DIS_X86_SIZE32 ||
            archflags == DIS_X86_SIZE64)
                return (1);

        return (0);
}

dis_arch_t dis_arch_i386 = {
        .da_supports_flags      = dis_i386_supports_flags,
        .da_handle_attach       = dis_i386_handle_attach,
        .da_handle_detach       = dis_i386_handle_detach,
        .da_disassemble         = dis_i386_disassemble,
        .da_min_instrlen        = dis_i386_min_instrlen,
        .da_max_instrlen        = dis_i386_max_instrlen,
};