# Linux Kernel Module Cheat

##### 30.2.3.2. ARMv8 aarch64 ret instruction

Example: userland/arch/aarch64/ret.S

ARMv8 AArch64 only:

- there is no BX in AArch64 since no Thumb to worry about, so it is called just BR

- the RET instruction was added in addition to BR, with the following differences:

  - provides a hint that this is a function call return

  - has a default argument X30 if none is given. This is where BL puts the return value.

See also: https://stackoverflow.com/questions/32304646/arm-assembly-branch-to-address-inside-register-or-memory/54145818#54145818