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decode: Handle GPH, NOP and 3DNow in legacy block

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This commit is contained in:
Alexis Engelke
2023-03-24 11:30:12 +01:00
parent dac2ff1987
commit 513cc709a4
2 changed files with 42 additions and 34 deletions
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62
decode.c
View File

@@ -91,6 +91,7 @@ struct InstrDesc
#define DESC_LOCK(desc) (((desc)->operand_indices >> 11) & 1)
#define DESC_VSIB(desc) (((desc)->operand_indices >> 15) & 1)
#define DESC_OPSIZE(desc) (((desc)->reg_types >> 11) & 7)
#define DESC_LEGACY(desc) (((desc)->operand_sizes >> 8) & 1)
#define DESC_SIZE_FIX1(desc) (((desc)->operand_sizes >> 10) & 7)
#define DESC_SIZE_FIX2(desc) (((desc)->operand_sizes >> 13) & 3)
#define DESC_INSTR_WIDTH(desc) (((desc)->operand_sizes >> 15) & 1)
@@ -400,9 +401,7 @@ direct:
unsigned op_size;
unsigned op_size_alt = 0;
if (!(DESC_OPSIZE(desc) & 4)) {
if (DESC_OPSIZE(desc) == 1)
op_size = 1;
else if (mode == DECODE_64)
if (mode == DECODE_64)
op_size = ((prefix_rex & PREFIX_REXW) || DESC_OPSIZE(desc) == 3) ? 4 :
UNLIKELY(prefixes[PF_66] && !DESC_IGN66(desc)) ? 2 :
DESC_OPSIZE(desc) ? 4 :
@@ -632,7 +631,7 @@ direct:
// 2 = memory, address-sized, used for mov with moffs operand
FdOp* operand = &instr->operands[DESC_IMM_IDX(desc)];
operand->type = FD_OT_MEM;
operand->size = op_size;
operand->size = operand_sizes[(desc->operand_sizes >> 6) & 3];
operand->reg = FD_REG_NONE;
operand->misc = FD_REG_NONE;
@@ -722,31 +721,6 @@ direct:
}
}
if (instr->type == FDI_XCHG_NOP)
{
// Only 4890, 90, and 6690 are true NOPs.
if (instr->operands[0].reg == 0 && instr->operands[1].reg == 0)
{
instr->operands[0].type = FD_OT_NONE;
instr->operands[1].type = FD_OT_NONE;
instr->type = FDI_NOP;
}
else
{
instr->type = FDI_XCHG;
}
}
if (UNLIKELY(instr->type == FDI_3DNOW))
{
unsigned opc3dn = instr->imm;
if (opc3dn & 0x40)
return FD_ERR_UD;
uint64_t msk = opc3dn & 0x80 ? 0x88d144d144d14400 : 0x30003000;
if (!(msk >> (opc3dn & 0x3f) & 1))
return FD_ERR_UD;
}
skip_modrm:
if (UNLIKELY(prefixes[PF_LOCK])) {
if (!DESC_LOCK(desc) || instr->operands[0].type != FD_OT_MEM)
@@ -754,7 +728,10 @@ skip_modrm:
instr->flags |= FD_FLAG_LOCK;
}
if (UNLIKELY(op_size == 1 || instr->type == FDI_MOVSX || instr->type == FDI_MOVZX)) {
if (UNLIKELY(DESC_LEGACY(desc))) {
// Without REX prefix, convert one-byte GP regs to high-byte regs
// This actually only applies to SZ8/MOVSX/MOVZX; but no VEX-encoded
// instructions have a byte-sized GP register in the first two operands.
if (!(prefix_rex & PREFIX_REX)) {
for (int i = 0; i < 2; i++) {
FdOp* operand = &instr->operands[i];
@@ -765,10 +742,33 @@ skip_modrm:
operand->misc = FD_RT_GPH;
}
}
if (instr->type == FDI_XCHG_NOP) {
// Only 4890, 90, and 6690 are true NOPs.
if (instr->operands[0].reg == 0 && instr->operands[1].reg == 0) {
instr->operands[0].type = FD_OT_NONE;
instr->operands[1].type = FD_OT_NONE;
instr->type = FDI_NOP;
} else {
instr->type = FDI_XCHG;
}
}
if (UNLIKELY(instr->type == FDI_3DNOW)) {
unsigned opc3dn = instr->imm;
if (opc3dn & 0x40)
return FD_ERR_UD;
uint64_t msk = opc3dn & 0x80 ? 0x88d144d144d14400 : 0x30003000;
if (!(msk >> (opc3dn & 0x3f) & 1))
return FD_ERR_UD;
}
instr->operandsz = 0;
} else {
instr->operandsz = UNLIKELY(DESC_INSTR_WIDTH(desc)) ? op_size - 1 : 0;
}
instr->size = off;
instr->operandsz = UNLIKELY(DESC_INSTR_WIDTH(desc)) ? op_size - 1 : 0;
return off;
}

14
parseinstrs.py
View File

@@ -24,7 +24,8 @@ INSTR_FLAGS_FIELDS, INSTR_FLAGS_SIZES = zip(*[
("modreg_size", 2),
("vexreg_size", 2),
("imm_size", 2),
("unused2", 2),
("legacy", 1),
("unused2", 1),
("size_fix1", 3),
("size_fix2", 2),
("instr_width", 1),
@@ -274,12 +275,19 @@ class InstrDesc(NamedTuple):
raise Exception(f"conflicting vector operand sizes in {self}")
else: # either empty or GP operand size
dynsizes = [OpKind.SZ_OP]
if "SZ8" in self.flags: extraflags["opsize"] = 1
if "SZ8" in self.flags:
extraflags["opsize"] = 1
dynsizes = []
if "D64" in self.flags: extraflags["opsize"] = 2
if "F64" in self.flags: extraflags["opsize"] = 3
extraflags["instr_width"] = "INSTR_WIDTH" in self.flags
extraflags["lock"] = "LOCK" in self.flags
if "SZ8" in self.flags or mnem in ("MOVSX", "MOVZX", "XCHG_NOP", "3DNOW"):
if "SZ8" not in self.flags and "INSTR_WIDTH" in self.flags:
raise Exception("legacy instr with +w without SZ8")
extraflags["legacy"] = 1
imm_byte = self.imm_size(4) == 1
extraflags["imm_control"] = flags.imm_control | imm_byte
@@ -297,7 +305,7 @@ class InstrDesc(NamedTuple):
for i, opkind in enumerate(self.operands):
sz = self.OPKIND_SIZES[opkind.size] if opkind.size >= 0 else opkind.size
if opkind.kind == "IMM":
if imm_byte and sz not in (dynsizes[0], 1):
if imm_byte and sz not in [1] + dynsizes[:1]:
raise Exception(f"imm_byte with opsize {sz} in {self}")
extraflags[f"imm_size"] = sz == 1 if imm_byte else sizes.index(sz)
else: