/** * insn_get_displacement() - Get the displacement of instruction * @insn: &struct insn containing instruction * * If necessary, first collects the instruction up to and including the * SIB byte. * Displacement value is sign-expanded. */ void insn_get_displacement(struct insn *insn) { insn_byte_t mod, rm, base; if (insn->displacement.got) return; if (!insn->sib.got) insn_get_sib(insn); if (insn->modrm.nbytes) { /* * Interpreting the modrm byte: * mod = 00 - no displacement fields (exceptions below) * mod = 01 - 1-byte displacement field * mod = 10 - displacement field is 4 bytes, or 2 bytes if * address size = 2 (0x67 prefix in 32-bit mode) * mod = 11 - no memory operand * * If address size = 2... * mod = 00, r/m = 110 - displacement field is 2 bytes * * If address size != 2... * mod != 11, r/m = 100 - SIB byte exists * mod = 00, SIB base = 101 - displacement field is 4 bytes * mod = 00, r/m = 101 - rip-relative addressing, displacement * field is 4 bytes */ mod = X86_MODRM_MOD(insn->modrm.value); rm = X86_MODRM_RM(insn->modrm.value); base = X86_SIB_BASE(insn->sib.value); if (mod == 3) goto out; if (mod == 1) { insn->displacement.value = get_next(char, insn); insn->displacement.nbytes = 1; } else if (insn->addr_bytes == 2) {
/* * return the address being referenced be instruction * for rm=3 returning the content of the rm reg * for rm!=3 calculates the address using SIB and Disp */ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs) { unsigned long addr, base, indx; int addr_offset, base_offset, indx_offset; insn_byte_t sib; insn_get_modrm(insn); insn_get_sib(insn); sib = insn->sib.value; if (X86_MODRM_MOD(insn->modrm.value) == 3) { addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM); if (addr_offset < 0) goto out_err; addr = regs_get_register(regs, addr_offset); } else { if (insn->sib.nbytes) { base_offset = get_reg_offset(insn, regs, REG_TYPE_BASE); if (base_offset < 0) goto out_err; indx_offset = get_reg_offset(insn, regs, REG_TYPE_INDEX); if (indx_offset < 0) goto out_err; base = regs_get_register(regs, base_offset); indx = regs_get_register(regs, indx_offset); addr = base + indx * (1 << X86_SIB_SCALE(sib)); } else { addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM); if (addr_offset < 0) goto out_err; addr = regs_get_register(regs, addr_offset); } addr += insn->displacement.value; } return (void __user *)addr; out_err: return (void __user *)-1; }