On 05/10/2016 10:01 AM, Borislav Petkov wrote:
>> > pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d
>> > bytes, using '%s' format.\n",
>> > xfeatures_mask,
>> > - xstate_size,
>> > + kernel_xstate_size,
>> > cpu_has_xsaves ? "compacted" : "standard");
> I think we should dump user_xstate_size in the compacted case since it
> is != kernel_xstate_size.
Why? "kernel_xstate_size" is important to the kernel because it impacts
task_struct size.
But the kernel never actually stores "user_xstate_size" anywhere or
really ever even cares about it except when copying in/out of userspace.
"user_xstate_size" is also entirely enumerable in userspace with a
single cpuid instruction.
It's nice to dump out interesting data in dmesg, but I'm curious why you
think it's interesting.
