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/*
* xen/arch/arm/decode.c
*
* Instruction decoder
*
* Julien Grall <julien.grall@linaro.org>
* Copyright (C) 2013 Linaro Limited.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <xen/types.h>
#include <xen/sched.h>
#include <asm/current.h>
#include <asm/guest_access.h>
#include <xen/lib.h>
#include "decode.h"
static void update_dabt(struct hsr_dabt *dabt, int reg,
uint8_t size, bool_t sign)
{
dabt->reg = reg;
dabt->size = size;
dabt->sign = sign;
}
static int decode_thumb2(register_t pc, struct hsr_dabt *dabt, uint16_t hw1)
{
uint16_t hw2;
int rc;
uint16_t rt;
rc = raw_copy_from_guest(&hw2, (void *__user)(pc + 2), sizeof (hw2));
if ( rc )
return rc;
rt = (hw2 >> 12) & 0x7;
switch ( (hw1 >> 9) & 0xf )
{
case 12:
{
bool_t sign = !!(hw1 & (1 << 8));
bool_t load = !!(hw1 & (1 << 4));
if ( (hw1 & 0x0110) == 0x0100 )
/* NEON instruction */
goto bad_thumb2;
if ( (hw1 & 0x0070) == 0x0070 )
/* Undefined opcodes */
goto bad_thumb2;
/* Store/Load single data item */
if ( rt == 15 )
/* XXX: Rt == 15 is only invalid for store instruction */
goto bad_thumb2;
if ( !load && sign )
/* Store instruction doesn't support sign extension */
goto bad_thumb2;
update_dabt(dabt, rt, (hw1 >> 5) & 3, sign);
break;
}
default:
goto bad_thumb2;
}
return 0;
bad_thumb2:
gdprintk(XENLOG_ERR, "unhandled THUMB2 instruction 0x%x%x\n", hw1, hw2);
return 1;
}
static int decode_thumb(register_t pc, struct hsr_dabt *dabt)
{
uint16_t instr;
int rc;
rc = raw_copy_from_guest(&instr, (void * __user)pc, sizeof (instr));
if ( rc )
return rc;
switch ( instr >> 12 )
{
case 5:
{
/* Load/Store register */
uint16_t opB = (instr >> 9) & 0x7;
int reg = instr & 7;
switch ( opB & 0x3 )
{
case 0: /* Non-signed word */
update_dabt(dabt, reg, 2, 0);
break;
case 1: /* Non-signed halfword */
update_dabt(dabt, reg, 1, 0);
break;
case 2: /* Non-signed byte */
update_dabt(dabt, reg, 0, 0);
break;
case 3: /* Signed byte */
update_dabt(dabt, reg, 0, 1);
break;
}
break;
}
case 6:
/* Load/Store word immediate offset */
update_dabt(dabt, instr & 7, 2, 0);
break;
case 7:
/* Load/Store byte immediate offset */
update_dabt(dabt, instr & 7, 0, 0);
break;
case 8:
/* Load/Store halfword immediate offset */
update_dabt(dabt, instr & 7, 1, 0);
break;
case 9:
/* Load/Store word sp offset */
update_dabt(dabt, (instr >> 8) & 7, 2, 0);
break;
case 14:
if ( instr & (1 << 11) )
return decode_thumb2(pc, dabt, instr);
goto bad_thumb;
case 15:
return decode_thumb2(pc, dabt, instr);
default:
goto bad_thumb;
}
return 0;
bad_thumb:
gdprintk(XENLOG_ERR, "unhandled THUMB instruction 0x%x\n", instr);
return 1;
}
int decode_instruction(const struct cpu_user_regs *regs, struct hsr_dabt *dabt)
{
if ( is_pv32_domain(current->domain) && regs->cpsr & PSR_THUMB )
return decode_thumb(regs->pc, dabt);
/* TODO: Handle ARM instruction */
gdprintk(XENLOG_ERR, "unhandled ARM instruction\n");
return 1;
}
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