Re: [patch 09/31] x86/fpu: Do not inherit FPU context for CLONE_THREAD

Thomas Gleixner
2021-10-12T18:53:03Z

On Tue, Oct 12 2021 at 18:10, Borislav Petkov wrote:

> On Tue, Oct 12, 2021 at 02:00:11AM +0200, Thomas Gleixner wrote:
>> CLONE_THREAD does not have the guarantee of a true fork to inherit all
>> state. Especially the FPU state is meaningless for CLONE_THREAD.
>>
>> Just wipe out the minimal required state so restore on return to user space
>> let's the thread start with a clean FPU.
>
> This sentence reads weird, needs massaging.

The patch is wrong and needs to be removed. I just double checked
pthread_create() again and it says:

The new thread inherits the calling thread's floating-point environment
(fenv(3))

No idea where I was looking at a few days ago. :(

Thanks,

tglx