/*
* Skip the prefixes of the instruction.
*/
static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
{
insn_attr_t attr;
attr = inat_get_opcode_attribute((insn_byte_t)*insn);
while (inat_is_legacy_prefix(attr)) {
insn++;
attr = inat_get_opcode_attribute((insn_byte_t)*insn);
}
#ifdef CONFIG_X86_64
if (inat_is_rex_prefix(attr))
insn++;
#endif
return insn;
}
int inat_get_last_prefix_id(insn_byte_t last_pfx)
{
insn_attr_t lpfx_attr;
lpfx_attr = inat_get_opcode_attribute(last_pfx);
return inat_last_prefix_id(lpfx_attr);
}
/**
* insn_get_opcode - collect opcode(s)
* @insn: &struct insn containing instruction
*
* Populates @insn->opcode, updates @insn->next_byte to point past the
* opcode byte(s), and set @insn->attr (except for groups).
* If necessary, first collects any preceding (prefix) bytes.
* Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
* is already 1.
*/
void insn_get_opcode(struct insn *insn)
{
struct insn_field *opcode = &insn->opcode;
insn_byte_t op;
int pfx_id;
if (opcode->got)
return;
if (!insn->prefixes.got)
insn_get_prefixes(insn);
/* Get first opcode */
op = get_next(insn_byte_t, insn);
opcode->bytes[0] = op;
opcode->nbytes = 1;
/* Check if there is VEX prefix or not */
if (insn_is_avx(insn)) {
insn_byte_t m, p;
m = insn_vex_m_bits(insn);
p = insn_vex_p_bits(insn);
insn->attr = inat_get_avx_attribute(op, m, p);
if (!inat_accept_vex(insn->attr) && !inat_is_group(insn->attr))
insn->attr = 0; /* This instruction is bad */
goto end; /* VEX has only 1 byte for opcode */
}
insn->attr = inat_get_opcode_attribute(op);
while (inat_is_escape(insn->attr)) {
/* Get escaped opcode */
op = get_next(insn_byte_t, insn);
opcode->bytes[opcode->nbytes++] = op;
pfx_id = insn_last_prefix_id(insn);
insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
}
if (inat_must_vex(insn->attr))
insn->attr = 0; /* This instruction is bad */
end:
opcode->got = 1;
err_out:
return;
}
insn_attr_t inat_get_escape_attribute(insn_byte_t opcode, insn_byte_t last_pfx,
insn_attr_t esc_attr)
{
const insn_attr_t *table;
insn_attr_t lpfx_attr;
int n, m = 0;
n = inat_escape_id(esc_attr);
if (last_pfx) {
lpfx_attr = inat_get_opcode_attribute(last_pfx);
m = inat_last_prefix_id(lpfx_attr);
}
table = inat_escape_tables[n][0];
if (!table)
return 0;
if (inat_has_variant(table[opcode]) && m) {
table = inat_escape_tables[n][m];
if (!table)
return 0;
}
return table[opcode];
}
insn_attr_t inat_get_group_attribute(insn_byte_t modrm, insn_byte_t last_pfx,
insn_attr_t grp_attr)
{
const insn_attr_t *table;
insn_attr_t lpfx_attr;
int n, m = 0;
n = inat_group_id(grp_attr);
if (last_pfx) {
lpfx_attr = inat_get_opcode_attribute(last_pfx);
m = inat_last_prefix_id(lpfx_attr);
}
table = inat_group_tables[n][0];
if (!table)
return inat_group_common_attribute(grp_attr);
if (inat_has_variant(table[X86_MODRM_REG(modrm)]) && m) {
table = inat_group_tables[n][m];
if (!table)
return inat_group_common_attribute(grp_attr);
}
return table[X86_MODRM_REG(modrm)] |
inat_group_common_attribute(grp_attr);
}
/**
* insn_get_prefixes - scan x86 instruction prefix bytes
* @insn: &struct insn containing instruction
*
* Populates the @insn->prefixes bitmap, and updates @insn->next_byte
* to point to the (first) opcode. No effect if @insn->prefixes.got
* is already set.
*/
void insn_get_prefixes(struct insn *insn)
{
struct insn_field *prefixes = &insn->prefixes;
insn_attr_t attr;
insn_byte_t b, lb;
int i, nb;
if (prefixes->got)
return;
nb = 0;
lb = 0;
b = peek_next(insn_byte_t, insn);
attr = inat_get_opcode_attribute(b);
while (inat_is_legacy_prefix(attr)) {
/* Skip if same prefix */
for (i = 0; i < nb; i++)
if (prefixes->bytes[i] == b)
goto found;
if (nb == 4)
/* Invalid instruction */
break;
prefixes->bytes[nb++] = b;
if (inat_is_address_size_prefix(attr)) {
/* address size switches 2/4 or 4/8 */
if (insn->x86_64)
insn->addr_bytes ^= 12;
else
insn->addr_bytes ^= 6;
} else if (inat_is_operand_size_prefix(attr)) {
/* oprand size switches 2/4 */
insn->opnd_bytes ^= 6;
}
found:
prefixes->nbytes++;
insn->next_byte++;
lb = b;
b = peek_next(insn_byte_t, insn);
attr = inat_get_opcode_attribute(b);
}
/* Set the last prefix */
if (lb && lb != insn->prefixes.bytes[3]) {
if (unlikely(insn->prefixes.bytes[3])) {
/* Swap the last prefix */
b = insn->prefixes.bytes[3];
for (i = 0; i < nb; i++)
if (prefixes->bytes[i] == lb)
prefixes->bytes[i] = b;
}
insn->prefixes.bytes[3] = lb;
}
/* Decode REX prefix */
if (insn->x86_64) {
b = peek_next(insn_byte_t, insn);
attr = inat_get_opcode_attribute(b);
if (inat_is_rex_prefix(attr)) {
insn->rex_prefix.value = b;
insn->rex_prefix.nbytes = 1;
insn->next_byte++;
if (X86_REX_W(b))
/* REX.W overrides opnd_size */
insn->opnd_bytes = 8;
}
}
insn->rex_prefix.got = 1;
/* Decode VEX prefix */
b = peek_next(insn_byte_t, insn);
attr = inat_get_opcode_attribute(b);
if (inat_is_vex_prefix(attr)) {
insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
if (!insn->x86_64) {
/*
* In 32-bits mode, if the [7:6] bits (mod bits of
* ModRM) on the second byte are not 11b, it is
* LDS or LES.
*/
if (X86_MODRM_MOD(b2) != 3)
goto vex_end;
}
insn->vex_prefix.bytes[0] = b;
insn->vex_prefix.bytes[1] = b2;
if (inat_is_vex3_prefix(attr)) {
b2 = peek_nbyte_next(insn_byte_t, insn, 2);
insn->vex_prefix.bytes[2] = b2;
insn->vex_prefix.nbytes = 3;
insn->next_byte += 3;
if (insn->x86_64 && X86_VEX_W(b2))
/* VEX.W overrides opnd_size */
insn->opnd_bytes = 8;
} else {
insn->vex_prefix.nbytes = 2;
insn->next_byte += 2;
}
}
vex_end:
insn->vex_prefix.got = 1;
prefixes->got = 1;
return;
}
