Re: [PATCH v11 6/9] x86/cet: Add PTRACE interface for CET

From: Dave Hansen
Date: Thu Sep 03 2020 - 12:42:43 EST


On 9/3/20 9:32 AM, Andy Lutomirski wrote:
>> Taking the config register out of the init state is illogical, as is
>> writing to SSP while the config register is in its init state.
> What's so special about the INIT state? It's optimized by XSAVES, but
> it's just a number, right? So taking the register out of the INIT
> state is kind of like saying "gdb wanted to set xmm0 to (0,0,0,1), but
> it was in the INIT state to begin with", right?

Yeah, that's a good point. The init state shouldn't be special, as the
hardware is within its right to choose not to use the init optimization
at any time.