Integer getSDA2Base() {
		if (sda2Base != null) {
			if (sda2Base == -1) {
				return null;
			}
			return sda2Base;
		}
		sda2Base = getBaseOffset("_SDA2_BASE_", ".sdata2", ".sbss2");
		if (sda2Base == -1) {
			getLog().appendMsg("ERROR: failed to establish _SDA2_BASE_");
			return null;
		}
		setRegisterContext("r2", BigInteger.valueOf(sda2Base));
		return sda2Base;
	}
Get or establish _SDA2_BASE_ value and apply as r2 context value to all memory blocks
with execute permission.
@return _SDA2_BASE_ offset or null if unable to determine or establish
Ghidra/Processors/PowerPC/src/main/java/ghidra/app/util/bin/format/elf/relocation/PowerPC_ElfRelocationContext.java