This assert assumed all reads to EXEC_LO would be 64b, that is, we would always read the entire EXEC mask. This is invalid as some kernels read only the low 32b of EXEC. The write to EXEC_LO is also updated to handle 32b writes. Change-Id: Ifeb167578515bf112b1eab70bbf2201a5e936358 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29960 Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>