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decode: Replace T8+T72 with T16+T8E for R/M value

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This commit is contained in:
Alexis Engelke
2020-11-08 11:20:03 +01:00
parent 7d7e72746e
commit 9df6ac1788
2 changed files with 27 additions and 18 deletions
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15
decode.c
View File

@@ -30,8 +30,8 @@ typedef enum DecodeMode DecodeMode;
#define ENTRY_NONE 0
#define ENTRY_INSTR 1
#define ENTRY_TABLE256 2
#define ENTRY_TABLE8 3
#define ENTRY_TABLE72 4
#define ENTRY_TABLE16 3
#define ENTRY_TABLE8E 4
#define ENTRY_TABLE_PREFIX 5
#define ENTRY_TABLE_VEX 6
#define ENTRY_TABLE_ROOT 8
@@ -409,13 +409,12 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
}
// Then, walk through ModR/M-encoded opcode extensions.
if ((kind == ENTRY_TABLE8 || kind == ENTRY_TABLE72) && LIKELY(off < len))
{
if (kind == ENTRY_TABLE72 && (buffer[off] & 0xc0) == 0xc0)
ENTRY_UNPACK(table, kind, table[buffer[off++] - 0xb8]);
else
ENTRY_UNPACK(table, kind, table[(buffer[off] >> 3) & 7]);
if (kind == ENTRY_TABLE16 && LIKELY(off < len)) {
unsigned isreg = (buffer[off] & 0xc0) == 0xc0 ? 8 : 0;
ENTRY_UNPACK(table, kind, table[((buffer[off] >> 3) & 7) | isreg]);
}
if (kind == ENTRY_TABLE8E && LIKELY(off < len))
ENTRY_UNPACK(table, kind, table[buffer[off++] & 7]);
// For VEX prefix, we have to distinguish between VEX.W and VEX.L which may
// be part of the opcode.

30
parseinstrs.py
View File

@@ -202,8 +202,8 @@ class EntryKind(Enum):
NONE = 0
INSTR = 1
TABLE256 = 2
TABLE8 = 3
TABLE72 = 4
TABLE16 = 3
TABLE8E = 4
TABLE_PREFIX = 5
TABLE_VEX = 6
TABLE_ROOT = -1
@@ -215,8 +215,8 @@ class TrieEntry(NamedTuple):
TABLE_LENGTH = {
EntryKind.TABLE256: 256,
EntryKind.TABLE8: 8,
EntryKind.TABLE72: 72,
EntryKind.TABLE16: 16,
EntryKind.TABLE8E: 8,
EntryKind.TABLE_PREFIX: 4,
EntryKind.TABLE_VEX: 4,
EntryKind.TABLE_ROOT: 8,
@@ -296,10 +296,18 @@ class Opcode(NamedTuple):
prefix_val = ["NP", "66", "F3", "F2"].index(self.prefix)
opcode.append((EntryKind.TABLE_PREFIX, [prefix_val]))
if self.opcext:
opcext_kind = [EntryKind.TABLE8, EntryKind.TABLE72][self.opcext[0]]
opcext_val = self.opcext[1] - (0 if self.opcext[1] < 8 else 0xb8)
opcode.append((opcext_kind, [opcext_val]))
if self.extended:
opcext_val = self.opcext[1]
if not self.opcext[0]:
opcode.append((EntryKind.TABLE16, [opcext_val, opcext_val | 8]))
elif opcext_val < 8:
opcode.append((EntryKind.TABLE16, [opcext_val]))
else:
opcode.append((EntryKind.TABLE16, [((opcext_val - 0xc0) >> 3) | 8]))
if not self.extended:
opcode.append((EntryKind.TABLE8E, [opcext_val & 7]))
else:
opcode.append((EntryKind.TABLE8E, list(range(8))))
if self.extended and not self.opcext:
last_type, last_indices = opcode[-1]
opcode[-1] = last_type, [last_indices[0] + i for i in range(8)]
if self.vexl in ("0", "1") or self.rexw in ("0", "1"):
@@ -320,8 +328,10 @@ def format_opcode(opcode):
prefix += ["", "VEX."][byte >> 2]
elif kind == EntryKind.TABLE256:
opcode_string += "{:02x}".format(byte)
elif kind in (EntryKind.TABLE8, EntryKind.TABLE72):
opcode_string += "/{:x}".format(byte)
elif kind == EntryKind.TABLE16:
opcode_string += "/{:x}{}".format(byte & 7, "mr"[byte >> 3])
elif kind == EntryKind.TABLE8E:
opcode_string += "+rm={:x}".format(byte)
elif kind == EntryKind.TABLE_PREFIX:
if byte & 4:
prefix += "VEX."