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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
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@@ -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;
}