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decode: Store operand size logarithmic

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This commit is contained in:
Alexis Engelke
2022-11-25 13:17:40 +01:00
parent 1291603246
commit b817713ae8
2 changed files with 22 additions and 21 deletions
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37
decode.c
View File

@@ -120,7 +120,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
unsigned prefix_rep = 0; unsigned prefix_rep = 0;
bool prefix_lock = false; bool prefix_lock = false;
bool prefix_66 = false; bool prefix_66 = false;
uint8_t addr_size = mode == DECODE_64 ? 8 : 4; uint8_t addr_size = mode == DECODE_64 ? 3 : 2;
unsigned prefix_rex = 0; unsigned prefix_rex = 0;
int rex_off = -1; int rex_off = -1;
instr->segment = FD_REG_NONE; instr->segment = FD_REG_NONE;
@@ -140,7 +140,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
case 0x64: instr->segment = FD_REG_FS; break; case 0x64: instr->segment = FD_REG_FS; break;
case 0x65: instr->segment = FD_REG_GS; break; case 0x65: instr->segment = FD_REG_GS; break;
case 0x66: prefix_66 = true; break; case 0x66: prefix_66 = true; break;
case 0x67: addr_size = 2; break; case 0x67: addr_size = 1; break;
case 0xf0: prefix_lock = true; break; case 0xf0: prefix_lock = true; break;
case 0xf3: prefix_rep = 2; break; case 0xf3: prefix_rep = 2; break;
case 0xf2: prefix_rep = 3; break; case 0xf2: prefix_rep = 3; break;
@@ -161,7 +161,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
case 0x64: instr->segment = FD_REG_FS; break; case 0x64: instr->segment = FD_REG_FS; break;
case 0x65: instr->segment = FD_REG_GS; break; case 0x65: instr->segment = FD_REG_GS; break;
case 0x66: prefix_66 = true; break; case 0x66: prefix_66 = true; break;
case 0x67: addr_size = 4; break; case 0x67: addr_size = 2; break;
case 0xf0: prefix_lock = true; break; case 0xf0: prefix_lock = true; break;
case 0xf3: prefix_rep = 2; break; case 0xf3: prefix_rep = 2; break;
case 0xf2: prefix_rep = 3; break; case 0xf2: prefix_rep = 3; break;
@@ -292,16 +292,16 @@ prefix_end:
if (DESC_OPSIZE(desc) == 1) if (DESC_OPSIZE(desc) == 1)
op_size = 1; op_size = 1;
else if (mode == DECODE_64) else if (mode == DECODE_64)
op_size = ((prefix_rex & PREFIX_REXW) || DESC_OPSIZE(desc) == 3) ? 8 : op_size = ((prefix_rex & PREFIX_REXW) || DESC_OPSIZE(desc) == 3) ? 4 :
UNLIKELY(prefix_66 && !DESC_IGN66(desc)) ? 2 : UNLIKELY(prefix_66 && !DESC_IGN66(desc)) ? 2 :
DESC_OPSIZE(desc) ? 8 : DESC_OPSIZE(desc) ? 4 :
4; 3;
else else
op_size = UNLIKELY(prefix_66 && !DESC_IGN66(desc)) ? 2 : 4; op_size = UNLIKELY(prefix_66 && !DESC_IGN66(desc)) ? 2 : 3;
uint8_t vec_size = 16; uint8_t vec_size = 5;
if (prefix_rex & PREFIX_VEXL) if (prefix_rex & PREFIX_VEXL)
vec_size = 32; vec_size = 6;
for (unsigned i = 0; i < sizeof(instr->operands) / sizeof(FdOp); i++) for (unsigned i = 0; i < sizeof(instr->operands) / sizeof(FdOp); i++)
instr->operands[i] = (FdOp) {0}; instr->operands[i] = (FdOp) {0};
@@ -450,15 +450,16 @@ skip_modrm:
operand->reg = FD_REG_NONE; operand->reg = FD_REG_NONE;
operand->misc = FD_REG_NONE; operand->misc = FD_REG_NONE;
if (UNLIKELY(off + addr_size > len)) int moffsz = 1 << addr_size;
if (UNLIKELY(off + moffsz > len))
return FD_ERR_PARTIAL; return FD_ERR_PARTIAL;
if (addr_size == 2) if (moffsz == 2)
instr->disp = LOAD_LE_2(&buffer[off]); instr->disp = LOAD_LE_2(&buffer[off]);
if (addr_size == 4) if (moffsz == 4)
instr->disp = LOAD_LE_4(&buffer[off]); instr->disp = LOAD_LE_4(&buffer[off]);
if (LIKELY(addr_size == 8)) if (LIKELY(moffsz == 8))
instr->disp = LOAD_LE_8(&buffer[off]); instr->disp = LOAD_LE_8(&buffer[off]);
off += addr_size; off += moffsz;
} }
else if (UNLIKELY(imm_control == 3)) else if (UNLIKELY(imm_control == 3))
{ {
@@ -495,11 +496,11 @@ skip_modrm:
instr->type == FDI_SSE_INSERTQ)) instr->type == FDI_SSE_INSERTQ))
imm_size = 2; imm_size = 2;
else if (UNLIKELY(instr->type == FDI_JMPF || instr->type == FDI_CALLF)) else if (UNLIKELY(instr->type == FDI_JMPF || instr->type == FDI_CALLF))
imm_size = op_size + 2; imm_size = (1 << op_size >> 1) + 2;
else if (UNLIKELY(instr->type == FDI_ENTER)) else if (UNLIKELY(instr->type == FDI_ENTER))
imm_size = 3; imm_size = 3;
else if (instr->type == FDI_MOVABS) else if (instr->type == FDI_MOVABS)
imm_size = op_size; imm_size = (1 << op_size >> 1);
else else
imm_size = op_size == 2 ? 2 : 4; imm_size = op_size == 2 ? 2 : 4;
@@ -561,7 +562,7 @@ skip_modrm:
} }
uint8_t operand_sizes[4] = { uint8_t operand_sizes[4] = {
1 << DESC_SIZE_FIX1(desc) >> 1, 1 << DESC_SIZE_FIX2(desc), op_size, vec_size DESC_SIZE_FIX1(desc), DESC_SIZE_FIX2(desc) + 1, op_size, vec_size
}; };
for (int i = 0; i < 4; i++) for (int i = 0; i < 4; i++)
@@ -587,7 +588,7 @@ skip_modrm:
} }
instr->size = off; instr->size = off;
instr->operandsz = DESC_INSTR_WIDTH(desc) ? op_size : 0; instr->operandsz = DESC_INSTR_WIDTH(desc) ? op_size - 1 : 0;
return off; return off;
} }

6
fadec.h
View File

@@ -177,10 +177,10 @@ const char* fdi_name(FdInstrType ty);
/** Gets the specified segment override, or FD_REG_NONE for default segment. **/ /** Gets the specified segment override, or FD_REG_NONE for default segment. **/
#define FD_SEGMENT(instr) ((FdReg) (instr)->segment) #define FD_SEGMENT(instr) ((FdReg) (instr)->segment)
/** Gets the address size attribute of the instruction in bytes. **/ /** Gets the address size attribute of the instruction in bytes. **/
#define FD_ADDRSIZE(instr) ((instr)->addrsz) #define FD_ADDRSIZE(instr) (1 << (instr)->addrsz)
/** Gets the operation width in bytes of the instruction if this is not encoded /** Gets the operation width in bytes of the instruction if this is not encoded
* in the operands, for example for the string instruction (e.g. MOVS). **/ * in the operands, for example for the string instruction (e.g. MOVS). **/
#define FD_OPSIZE(instr) ((instr)->operandsz) #define FD_OPSIZE(instr) (1 << (instr)->operandsz)
/** Indicates whether the instruction was encoded with a REP prefix. Needed for: /** Indicates whether the instruction was encoded with a REP prefix. Needed for:
* (1) Handling the instructions MOVS, STOS, LODS, INS and OUTS properly. * (1) Handling the instructions MOVS, STOS, LODS, INS and OUTS properly.
* (2) Handling the instructions SCAS and CMPS, for which this means REPZ. **/ * (2) Handling the instructions SCAS and CMPS, for which this means REPZ. **/
@@ -201,7 +201,7 @@ const char* fdi_name(FdInstrType ty);
* actually needed operand size (that is, an instruction may/must only use * actually needed operand size (that is, an instruction may/must only use
* a smaller part than specified here). The real operand size is always * a smaller part than specified here). The real operand size is always
* fully recoverable in combination with the instruction type. **/ * fully recoverable in combination with the instruction type. **/
#define FD_OP_SIZE(instr,idx) ((instr)->operands[idx].size) #define FD_OP_SIZE(instr,idx) (1 << (instr)->operands[idx].size >> 1)
/** Gets the accessed register index of a register operand. Note that /only/ the /** Gets the accessed register index of a register operand. Note that /only/ the
* index is returned, no further interpretation of the index (which depends on * index is returned, no further interpretation of the index (which depends on
* the instruction type) is done. The register type can be fetched using * the instruction type) is done. The register type can be fetched using