Re: [tip: x86/fpu] x86/fpu/xstate: Define new functions for clearing fpregs and xstates

[Dave Hansen]

On 12/1/22 04:58, Ivan Zahariev wrote:
> We are running 5.15.75 (LTS) but the problem started when we upgraded
> from 5.15.31 to 5.15.59 and is present ever since. I erroneously said
> that it's present into every 5.15.
> I didn't do my homework well and blamed the commit by Yu-cheng Yu. 
> But this commit never landed into 5.15, nor the fix commit that you>
> referred. There are no functions fpu__clear_all(), 
> copy_init_fpstate_to_fpregs(), copy_user_to_xstate() anywhere in the>
> sources of 5.15.75 or 5.15.31, so the 5.15 kernel is running with a 
> different FPU implementation.
It's also possible that the Ubuntu kernel folks pulled some FPU patches
into their 5.15 kernel from later upstream kernels, which is adding to
the confusion.  I think there may have been some effort to backport the
AMX work.

You might want to file a bug report with the Ubuntu folks.