2008-04-04 05:51:41 +07:00
|
|
|
#include <linux/types.h>
|
|
|
|
|
|
|
|
#include "opcode.h"
|
|
|
|
|
|
|
|
static bool opcode_is_prefix(uint8_t b)
|
|
|
|
{
|
|
|
|
return
|
|
|
|
/* Group 1 */
|
|
|
|
b == 0xf0 || b == 0xf2 || b == 0xf3
|
|
|
|
/* Group 2 */
|
|
|
|
|| b == 0x2e || b == 0x36 || b == 0x3e || b == 0x26
|
2010-08-28 22:41:03 +07:00
|
|
|
|| b == 0x64 || b == 0x65
|
2008-04-04 05:51:41 +07:00
|
|
|
/* Group 3 */
|
|
|
|
|| b == 0x66
|
|
|
|
/* Group 4 */
|
|
|
|
|| b == 0x67;
|
|
|
|
}
|
|
|
|
|
2009-02-26 16:23:52 +07:00
|
|
|
#ifdef CONFIG_X86_64
|
2008-04-04 05:51:41 +07:00
|
|
|
static bool opcode_is_rex_prefix(uint8_t b)
|
|
|
|
{
|
|
|
|
return (b & 0xf0) == 0x40;
|
|
|
|
}
|
2009-02-26 16:23:52 +07:00
|
|
|
#else
|
|
|
|
static bool opcode_is_rex_prefix(uint8_t b)
|
|
|
|
{
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
#endif
|
2008-04-04 05:51:41 +07:00
|
|
|
|
|
|
|
#define REX_W (1 << 3)
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This is a VERY crude opcode decoder. We only need to find the size of the
|
|
|
|
* load/store that caused our #PF and this should work for all the opcodes
|
|
|
|
* that we care about. Moreover, the ones who invented this instruction set
|
|
|
|
* should be shot.
|
|
|
|
*/
|
|
|
|
void kmemcheck_opcode_decode(const uint8_t *op, unsigned int *size)
|
|
|
|
{
|
|
|
|
/* Default operand size */
|
|
|
|
int operand_size_override = 4;
|
|
|
|
|
|
|
|
/* prefixes */
|
|
|
|
for (; opcode_is_prefix(*op); ++op) {
|
|
|
|
if (*op == 0x66)
|
|
|
|
operand_size_override = 2;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* REX prefix */
|
|
|
|
if (opcode_is_rex_prefix(*op)) {
|
|
|
|
uint8_t rex = *op;
|
|
|
|
|
|
|
|
++op;
|
|
|
|
if (rex & REX_W) {
|
|
|
|
switch (*op) {
|
|
|
|
case 0x63:
|
|
|
|
*size = 4;
|
|
|
|
return;
|
|
|
|
case 0x0f:
|
|
|
|
++op;
|
|
|
|
|
|
|
|
switch (*op) {
|
|
|
|
case 0xb6:
|
|
|
|
case 0xbe:
|
|
|
|
*size = 1;
|
|
|
|
return;
|
|
|
|
case 0xb7:
|
|
|
|
case 0xbf:
|
|
|
|
*size = 2;
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
*size = 8;
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/* escape opcode */
|
|
|
|
if (*op == 0x0f) {
|
|
|
|
++op;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This is move with zero-extend and sign-extend, respectively;
|
|
|
|
* we don't have to think about 0xb6/0xbe, because this is
|
|
|
|
* already handled in the conditional below.
|
|
|
|
*/
|
|
|
|
if (*op == 0xb7 || *op == 0xbf)
|
|
|
|
operand_size_override = 2;
|
|
|
|
}
|
|
|
|
|
|
|
|
*size = (*op & 1) ? operand_size_override : 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
const uint8_t *kmemcheck_opcode_get_primary(const uint8_t *op)
|
|
|
|
{
|
|
|
|
/* skip prefixes */
|
|
|
|
while (opcode_is_prefix(*op))
|
|
|
|
++op;
|
|
|
|
if (opcode_is_rex_prefix(*op))
|
|
|
|
++op;
|
|
|
|
return op;
|
|
|
|
}
|