diff options
Diffstat (limited to 'src/third_party/libdisasm/ia32_invariant.c')
| -rw-r--r-- | src/third_party/libdisasm/ia32_invariant.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/src/third_party/libdisasm/ia32_invariant.c b/src/third_party/libdisasm/ia32_invariant.c new file mode 100644 index 00000000..68ec153d --- /dev/null +++ b/src/third_party/libdisasm/ia32_invariant.c @@ -0,0 +1,313 @@ +#include <stdlib.h> +#include <string.h> + +#include "ia32_invariant.h" +#include "ia32_insn.h" +#include "ia32_settings.h" + +extern ia32_table_desc_t *ia32_tables; +extern ia32_settings_t ia32_settings; + +extern size_t ia32_table_lookup( unsigned char *buf, size_t buf_len, + unsigned int table, ia32_insn_t **raw_insn, + unsigned int *prefixes ); + + +/* -------------------------------- ModR/M, SIB */ +/* Convenience flags */ +#define MODRM_EA 1 /* ModR/M is an effective addr */ +#define MODRM_reg 2 /* ModR/M is a register */ + +/* ModR/M flags */ +#define MODRM_RM_SIB 0x04 /* R/M == 100 */ +#define MODRM_RM_NOREG 0x05 /* R/B == 101 */ +/* if (MODRM.MOD_NODISP && MODRM.RM_NOREG) then just disp32 */ +#define MODRM_MOD_NODISP 0x00 /* mod == 00 */ +#define MODRM_MOD_DISP8 0x01 /* mod == 01 */ +#define MODRM_MOD_DISP32 0x02 /* mod == 10 */ +#define MODRM_MOD_NOEA 0x03 /* mod == 11 */ +/* 16-bit modrm flags */ +#define MOD16_MOD_NODISP 0 +#define MOD16_MOD_DISP8 1 +#define MOD16_MOD_DISP16 2 +#define MOD16_MOD_REG 3 + +#define MOD16_RM_BXSI 0 +#define MOD16_RM_BXDI 1 +#define MOD16_RM_BPSI 2 +#define MOD16_RM_BPDI 3 +#define MOD16_RM_SI 4 +#define MOD16_RM_DI 5 +#define MOD16_RM_BP 6 +#define MOD16_RM_BX 7 + +/* SIB flags */ +#define SIB_INDEX_NONE 0x04 +#define SIB_BASE_EBP 0x05 +#define SIB_SCALE_NOBASE 0x00 + +/* Convenience struct for modR/M bitfield */ +struct modRM_byte { + unsigned int mod : 2; + unsigned int reg : 3; + unsigned int rm : 3; +}; + +/* Convenience struct for SIB bitfield */ +struct SIB_byte { + unsigned int scale : 2; + unsigned int index : 3; + unsigned int base : 3; +}; + +#ifdef WIN32 +static void byte_decode(unsigned char b, struct modRM_byte *modrm) { +#else +static inline void byte_decode(unsigned char b, struct modRM_byte *modrm) { +#endif + /* generic bitfield-packing routine */ + + modrm->mod = b >> 6; /* top 2 bits */ + modrm->reg = (b & 56) >> 3; /* middle 3 bits */ + modrm->rm = b & 7; /* bottom 3 bits */ +} +static int ia32_invariant_modrm( unsigned char *in, unsigned char *out, + unsigned int mode_16, x86_invariant_op_t *op) { + struct modRM_byte modrm; + struct SIB_byte sib; + unsigned char *c, *cin; + unsigned short *s; + unsigned int *i; + int size = 0; /* modrm byte is already counted */ + + + byte_decode(*in, &modrm); /* get bitfields */ + + out[0] = in[0]; /* save modrm byte */ + cin = &in[1]; + c = &out[1]; + s = (unsigned short *)&out[1]; + i = (unsigned int *)&out[1]; + + op->type = op_expression; + op->flags |= op_pointer; + if ( ! mode_16 && modrm.rm == MODRM_RM_SIB && + modrm.mod != MODRM_MOD_NOEA ) { + size ++; + byte_decode(*cin, (struct modRM_byte *)(void*)&sib); + + out[1] = in[1]; /* save sib byte */ + cin = &in[2]; + c = &out[2]; + s = (unsigned short *)&out[2]; + i = (unsigned int *)&out[2]; + + if ( sib.base == SIB_BASE_EBP && ! modrm.mod ) { + /* disp 32 is variant! */ + memset( i, X86_WILDCARD_BYTE, 4 ); + size += 4; + } + } + + if (! modrm.mod && modrm.rm == 101) { + if ( mode_16 ) { /* straight RVA in disp */ + memset( s, X86_WILDCARD_BYTE, 2 ); + size += 2; + } else { + memset( i, X86_WILDCARD_BYTE, 2 ); + size += 4; + } + } else if (modrm.mod && modrm.mod < 3) { + if (modrm.mod == MODRM_MOD_DISP8) { /* offset in disp */ + *c = *cin; + size += 1; + } else if ( mode_16 ) { + *s = (* ((unsigned short *) cin)); + size += 2; + } else { + *i = (*((unsigned int *) cin)); + size += 4; + } + } else if ( modrm.mod == 3 ) { + op->type = op_register; + op->flags &= ~op_pointer; + } + + return (size); +} + + +static int ia32_decode_invariant( unsigned char *buf, size_t buf_len, + ia32_insn_t *t, unsigned char *out, + unsigned int prefixes, x86_invariant_t *inv) { + + unsigned int addr_size, op_size, mode_16; + unsigned int op_flags[3] = { t->dest_flag, t->src_flag, t->aux_flag }; + int x, type, bytes = 0, size = 0, modrm = 0; + + /* set addressing mode */ + if (ia32_settings.options & opt_16_bit) { + op_size = ( prefixes & PREFIX_OP_SIZE ) ? 4 : 2; + addr_size = ( prefixes & PREFIX_ADDR_SIZE ) ? 4 : 2; + mode_16 = ( prefixes & PREFIX_ADDR_SIZE ) ? 0 : 1; + } else { + op_size = ( prefixes & PREFIX_OP_SIZE ) ? 2 : 4; + addr_size = ( prefixes & PREFIX_ADDR_SIZE ) ? 2 : 4; + mode_16 = ( prefixes & PREFIX_ADDR_SIZE ) ? 1 : 0; + } + + for (x = 0; x < 3; x++) { + inv->operands[x].access = (enum x86_op_access) + OP_PERM(op_flags[x]); + inv->operands[x].flags = (enum x86_op_flags) + (OP_FLAGS(op_flags[x]) >> 12); + + switch (op_flags[x] & OPTYPE_MASK) { + case OPTYPE_c: + size = (op_size == 4) ? 2 : 1; + break; + case OPTYPE_a: case OPTYPE_v: + size = (op_size == 4) ? 4 : 2; + break; + case OPTYPE_p: + size = (op_size == 4) ? 6 : 4; + break; + case OPTYPE_b: + size = 1; + break; + case OPTYPE_w: + size = 2; + break; + case OPTYPE_d: case OPTYPE_fs: case OPTYPE_fd: + case OPTYPE_fe: case OPTYPE_fb: case OPTYPE_fv: + case OPTYPE_si: case OPTYPE_fx: + size = 4; + break; + case OPTYPE_s: + size = 6; + break; + case OPTYPE_q: case OPTYPE_pi: + size = 8; + break; + case OPTYPE_dq: case OPTYPE_ps: case OPTYPE_ss: + case OPTYPE_pd: case OPTYPE_sd: + size = 16; + break; + case OPTYPE_m: + size = (addr_size == 4) ? 4 : 2; + break; + default: + break; + } + + type = op_flags[x] & ADDRMETH_MASK; + switch (type) { + case ADDRMETH_E: case ADDRMETH_M: case ADDRMETH_Q: + case ADDRMETH_R: case ADDRMETH_W: + modrm = 1; + bytes += ia32_invariant_modrm( buf, out, + mode_16, &inv->operands[x]); + break; + case ADDRMETH_C: case ADDRMETH_D: case ADDRMETH_G: + case ADDRMETH_P: case ADDRMETH_S: case ADDRMETH_T: + case ADDRMETH_V: + inv->operands[x].type = op_register; + modrm = 1; + break; + case ADDRMETH_A: case ADDRMETH_O: + /* pad with xF4's */ + memset( &out[bytes + modrm], X86_WILDCARD_BYTE, + size ); + bytes += size; + inv->operands[x].type = op_offset; + if ( type == ADDRMETH_O ) { + inv->operands[x].flags |= op_signed | + op_pointer; + } + break; + case ADDRMETH_I: case ADDRMETH_J: + /* grab imm value */ + if ((op_flags[x] & OPTYPE_MASK) == OPTYPE_v) { + /* assume this is an address */ + memset( &out[bytes + modrm], + X86_WILDCARD_BYTE, size ); + } else { + memcpy( &out[bytes + modrm], + &buf[bytes + modrm], size ); + } + + bytes += size; + if ( type == ADDRMETH_J ) { + if ( size == 1 ) { + inv->operands[x].type = + op_relative_near; + } else { + inv->operands[x].type = + op_relative_far; + } + inv->operands[x].flags |= op_signed; + } else { + inv->operands[x].type = op_immediate; + } + break; + case ADDRMETH_F: + inv->operands[x].type = op_register; + break; + case ADDRMETH_X: + inv->operands[x].flags |= op_signed | + op_pointer | op_ds_seg | op_string; + break; + case ADDRMETH_Y: + inv->operands[x].flags |= op_signed | + op_pointer | op_es_seg | op_string; + break; + case ADDRMETH_RR: + inv->operands[x].type = op_register; + break; + case ADDRMETH_II: + inv->operands[x].type = op_immediate; + break; + default: + inv->operands[x].type = op_unused; + break; + } + } + + return (bytes + modrm); +} + +size_t ia32_disasm_invariant( unsigned char * buf, size_t buf_len, + x86_invariant_t *inv ) { + ia32_insn_t *raw_insn = NULL; + unsigned int prefixes; + unsigned int type; + size_t size; + + /* Perform recursive table lookup starting with main table (0) */ + size = ia32_table_lookup( buf, buf_len, 0, &raw_insn, &prefixes ); + if ( size == INVALID_INSN || size > buf_len ) { + /* TODO: set errno */ + return 0; + } + + /* copy opcode bytes to buffer */ + memcpy( inv->bytes, buf, size ); + + /* set mnemonic type and group */ + type = raw_insn->mnem_flag & ~INS_FLAG_MASK; + inv->group = (enum x86_insn_group) (INS_GROUP(type)) >> 12; + inv->type = (enum x86_insn_type) INS_TYPE(type); + + /* handle operands */ + size += ia32_decode_invariant( buf + size, buf_len - size, raw_insn, + &buf[size - 1], prefixes, inv ); + + inv->size = size; + + return size; /* return size of instruction in bytes */ +} + +size_t ia32_disasm_size( unsigned char *buf, size_t buf_len ) { + x86_invariant_t inv = { {0} }; + return( ia32_disasm_invariant( buf, buf_len, &inv ) ); +} |