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decode: Move prefix before other opcode extensions

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This commit is contained in:
Alexis Engelke
2020-11-08 10:27:03 +01:00
parent 2e7e396325
commit 01e1587c5c
2 changed files with 15 additions and 15 deletions
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18
decode.c
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@@ -396,15 +396,6 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
if (LIKELY(off < len))
ENTRY_UNPACK(table, kind, table[buffer[off++]]);
// 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]);
}
// Handle mandatory prefixes (which behave like an opcode ext.).
if (kind == ENTRY_TABLE_PREFIX)
{
@@ -417,6 +408,15 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
ENTRY_UNPACK(table, kind, table[mandatory_prefix]);
}
// 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]);
}
// For VEX prefix, we have to distinguish between VEX.W and VEX.L which may
// be part of the opcode.
if (kind == ENTRY_TABLE_VEX)

12
parseinstrs.py
View File

@@ -288,6 +288,12 @@ class Opcode(NamedTuple):
opcode = []
opcode.append((EntryKind.TABLE_ROOT, [self.escape | self.vex << 2]))
opcode.append((EntryKind.TABLE256, [self.opc]))
if self.prefix:
if self.prefix == "NFx":
opcode.append((EntryKind.TABLE_PREFIX, [0, 1]))
else:
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)
@@ -295,12 +301,6 @@ class Opcode(NamedTuple):
if self.extended:
last_type, last_indices = opcode[-1]
opcode[-1] = last_type, [last_indices[0] + i for i in range(8)]
if self.prefix:
if self.prefix == "NFx":
opcode.append((EntryKind.TABLE_PREFIX, [0, 1]))
else:
prefix_val = ["NP", "66", "F3", "F2"].index(self.prefix)
opcode.append((EntryKind.TABLE_PREFIX, [prefix_val]))
if self.vexl in ("0", "1") or self.rexw in ("0", "1"):
rexw = {"0": [0], "1": [1<<0], "IG": [0, 1<<0]}[self.rexw or "IG"]
vexl = {"0": [0], "1": [1<<1], "IG": [0, 1<<1]}[self.vexl or "IG"]