[v5 19/20] x86: Enable User-Mode Instruction Prevention

2017-03-03 Thread Ricardo Neri
User_mode Instruction Prevention (UMIP) is enabled by setting/clearing a bit in %cr4. It makes sense to enable UMIP at some point while booting, before user spaces come up. Like SMAP and SMEP, is not critical to have it enabled very early during boot. This is because UMIP is relevant only when

[v5 19/20] x86: Enable User-Mode Instruction Prevention

2017-03-03 Thread Ricardo Neri
User_mode Instruction Prevention (UMIP) is enabled by setting/clearing a bit in %cr4. It makes sense to enable UMIP at some point while booting, before user spaces come up. Like SMAP and SMEP, is not critical to have it enabled very early during boot. This is because UMIP is relevant only when