08.03.2017 19:46, Andy Lutomirski пишет:
No no, since I meant prot mode, this is not what I need. I would never need to disable UMIP as to allow the prot mode apps to do SLDT. Instead it would be good to have an ability to provide a replacement for the dummy emulation that is currently being proposed for kernel. All is needed for this, is just to deliver a SIGSEGV.
That's what I meant. Turning off FIXUP_UMIP would leave UMIP on but turn off the fixup, so you'd get a SIGSEGV indicating #GP (or a vm86 GP exit).
But then I am confused with the word "compat" in your "COMPAT_MASK0_X86_UMIP_FIXUP" and "sys_adjust_compat_mask(int op, int word, u32 mask);"
Leaving UMIP on and only disabling a fixup doesn't sound like a compat option to me. I would expect compat to disable it completely.