/* * Skip the prefixes of the instruction. */ static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn) { insn_attr_t attr; attr = inat_get_opcode_attribute((insn_byte_t)*insn); while (inat_is_legacy_prefix(attr)) { insn++; attr = inat_get_opcode_attribute((insn_byte_t)*insn); } #ifdef CONFIG_X86_64 if (inat_is_rex_prefix(attr)) insn++; #endif return insn; }
/** * insn_get_prefixes - scan x86 instruction prefix bytes * @insn: &struct insn containing instruction * * Populates the @insn->prefixes bitmap, and updates @insn->next_byte * to point to the (first) opcode. No effect if @insn->prefixes.got * is already set. */ void insn_get_prefixes(struct insn *insn) { struct insn_field *prefixes = &insn->prefixes; insn_attr_t attr; insn_byte_t b, lb; int i, nb; if (prefixes->got) return; nb = 0; lb = 0; b = peek_next(insn_byte_t, insn); attr = inat_get_opcode_attribute(b); while (inat_is_legacy_prefix(attr)) { /* Skip if same prefix */ for (i = 0; i < nb; i++) if (prefixes->bytes[i] == b) goto found; if (nb == 4) /* Invalid instruction */ break; prefixes->bytes[nb++] = b; if (inat_is_address_size_prefix(attr)) { /* address size switches 2/4 or 4/8 */ if (insn->x86_64) insn->addr_bytes ^= 12; else insn->addr_bytes ^= 6; } else if (inat_is_operand_size_prefix(attr)) { /* oprand size switches 2/4 */ insn->opnd_bytes ^= 6; } found: prefixes->nbytes++; insn->next_byte++; lb = b; b = peek_next(insn_byte_t, insn); attr = inat_get_opcode_attribute(b); } /* Set the last prefix */ if (lb && lb != insn->prefixes.bytes[3]) { if (unlikely(insn->prefixes.bytes[3])) { /* Swap the last prefix */ b = insn->prefixes.bytes[3]; for (i = 0; i < nb; i++) if (prefixes->bytes[i] == lb) prefixes->bytes[i] = b; } insn->prefixes.bytes[3] = lb; } /* Decode REX prefix */ if (insn->x86_64) { b = peek_next(insn_byte_t, insn); attr = inat_get_opcode_attribute(b); if (inat_is_rex_prefix(attr)) { insn->rex_prefix.value = b; insn->rex_prefix.nbytes = 1; insn->next_byte++; if (X86_REX_W(b)) /* REX.W overrides opnd_size */ insn->opnd_bytes = 8; } } insn->rex_prefix.got = 1; /* Decode VEX prefix */ b = peek_next(insn_byte_t, insn); attr = inat_get_opcode_attribute(b); if (inat_is_vex_prefix(attr)) { insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1); if (!insn->x86_64) { /* * In 32-bits mode, if the [7:6] bits (mod bits of * ModRM) on the second byte are not 11b, it is * LDS or LES. */ if (X86_MODRM_MOD(b2) != 3) goto vex_end; } insn->vex_prefix.bytes[0] = b; insn->vex_prefix.bytes[1] = b2; if (inat_is_vex3_prefix(attr)) { b2 = peek_nbyte_next(insn_byte_t, insn, 2); insn->vex_prefix.bytes[2] = b2; insn->vex_prefix.nbytes = 3; insn->next_byte += 3; if (insn->x86_64 && X86_VEX_W(b2)) /* VEX.W overrides opnd_size */ insn->opnd_bytes = 8; } else { insn->vex_prefix.nbytes = 2; insn->next_byte += 2; } } vex_end: insn->vex_prefix.got = 1; prefixes->got = 1; return; }