check for stack overruns early on and fix bug with modifying RFLAGS
check for stack overruns early on and fix bug with modifying RFLAGS

bradylee/nautilus_fs,haiyang1992/NautilusVirtio,yhx189/nautilus,haiyang1992/NautilusVirtio,yhx189/nautilus,yhx189/nautilus,bradylee/nautilus_fs,bradylee/nautilus_fs,haiyang1992/NautilusVirtio