/**
* 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) {
static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
enum reg_type type)
{
int regno = 0;
static const int regoff[] = {
offsetof(struct pt_regs, ax),
offsetof(struct pt_regs, cx),
offsetof(struct pt_regs, dx),
offsetof(struct pt_regs, bx),
offsetof(struct pt_regs, sp),
offsetof(struct pt_regs, bp),
offsetof(struct pt_regs, si),
offsetof(struct pt_regs, di),
#ifdef CONFIG_X86_64
offsetof(struct pt_regs, r8),
offsetof(struct pt_regs, r9),
offsetof(struct pt_regs, r10),
offsetof(struct pt_regs, r11),
offsetof(struct pt_regs, r12),
offsetof(struct pt_regs, r13),
offsetof(struct pt_regs, r14),
offsetof(struct pt_regs, r15),
#endif
};
int nr_registers = ARRAY_SIZE(regoff);
/*
* Don't possibly decode a 32-bit instructions as
* reading a 64-bit-only register.
*/
if (IS_ENABLED(CONFIG_X86_64) && !insn->x86_64)
nr_registers -= 8;
switch (type) {
case REG_TYPE_RM:
regno = X86_MODRM_RM(insn->modrm.value);
if (X86_REX_B(insn->rex_prefix.value) == 1)
regno += 8;
break;
case REG_TYPE_INDEX:
regno = X86_SIB_INDEX(insn->sib.value);
if (X86_REX_X(insn->rex_prefix.value) == 1)
regno += 8;
break;
case REG_TYPE_BASE:
regno = X86_SIB_BASE(insn->sib.value);
if (X86_REX_B(insn->rex_prefix.value) == 1)
regno += 8;
break;
default:
pr_err("invalid register type");
BUG();
break;
}
if (regno > nr_registers) {
WARN_ONCE(1, "decoded an instruction with an invalid register");
return -EINVAL;
}
return regoff[regno];
}
