riscv64: define callee-saved frame layout.

Define which registers are saved/restored by different types of ART
callee-saved frames. This is based on the standard RISC-V calling
convention (https://github.com/riscv-non-isa/riscv-elf-psabi-doc) and
also ART internal convention (Quick ABI) that defines additional
ART-specific meaning of some registers (e.g. the ART thread register).

Test: lunch aosp_riscv64-userdebug && m dist

Co-authored-by: Ulya Trafimovich <skvadrik@google.com>
Change-Id: Ifd2fafcb94e7fac9da6bf41544c47d576bcc9560
4 files changed