According to the RISC-V Privileged Architecture Specification (20211203),
writing Initial or Clean to the FS field of mstatus may result in the FS
value getting set to Dirty in some implementations. This means we cannot
rely on reading back the same FS value after writing to mstatus.
Previously, the context restore code would:
1. Write an FS value to mstatus
2. Read mstatus again at a later point
3. Use the read FS value to determine FPU status
This change updates the context restore code to use the mstatus value
from the saved context instead of re-reading mstatus after writing to
it. This required chaning the location of the mstatus slot in the
context.
Fixes: https://github.com/FreeRTOS/FreeRTOS-Kernel/issues/1327
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
c8d31ddcff