Re: [PATCH v5 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack

Dave Hansen
2018-11-09T17:20:50Z

On 11/9/18 9:17 AM, Matthew Wilcox wrote:
>> But, later versions of the hardware have instructions that don't have
>> static offsets for the state components (when the XSAVES/XSAVEC
>> instructions are used). So, for those, the structure embedding isn't
>> used at *all* since some state might not be present.
> But *when present*, this structure is always aligned on an 8-byte
> boundary, right?

There's no guarantee of that.

There is an "aligned" attribute for each XSAVE state component, but I do
not believe it is set for anything yet.