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decode: Set address size when decoding prefixes

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This commit is contained in:
Alexis Engelke
2021-09-20 13:52:06 +02:00
parent a150822fe1
commit 1bd5f7c572
1 changed files with 4 additions and 9 deletions
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13
decode.c
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@@ -118,7 +118,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
unsigned prefix_rep = 0;
bool prefix_lock = false;
bool prefix_66 = false;
bool prefix_67 = false;
uint8_t addr_size = mode == DECODE_64 ? 8 : 4;
unsigned prefix_rex = 0;
int rex_off = -1;
instr->segment = FD_REG_NONE;
@@ -138,7 +138,7 @@ 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 0x65: instr->segment = FD_REG_GS; break;
case 0x66: prefix_66 = true; break;
case 0x67: prefix_67 = true; break;
case 0x67: addr_size = 2; break;
case 0xf0: prefix_lock = true; break;
case 0xf3: prefix_rep = 2; break;
case 0xf2: prefix_rep = 3; break;
@@ -159,7 +159,7 @@ 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 0x65: instr->segment = FD_REG_GS; break;
case 0x66: prefix_66 = true; break;
case 0x67: prefix_67 = true; break;
case 0x67: addr_size = 4; break;
case 0xf0: prefix_lock = true; break;
case 0xf3: prefix_rep = 2; break;
case 0xf2: prefix_rep = 3; break;
@@ -279,6 +279,7 @@ prefix_end:
const struct InstrDesc* desc = &descs[table_idx >> 2];
instr->type = desc->type;
instr->addrsz = addr_size;
instr->flags = prefix_rep == 2 ? FD_FLAG_REP :
prefix_rep == 3 ? FD_FLAG_REPNZ : 0;
if (mode == DECODE_64)
@@ -300,12 +301,6 @@ prefix_end:
if (prefix_rex & PREFIX_VEXL)
vec_size = 32;
// Compute address size.
uint8_t addr_size = mode == DECODE_64 ? 8 : 4;
if (UNLIKELY(prefix_67))
addr_size >>= 1;
instr->addrsz = addr_size;
__builtin_memset(instr->operands, 0, sizeof(instr->operands));
if (DESC_MODRM(desc) && UNLIKELY(off++ >= len))