Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch 09/31] x86/fpu: Do not inherit FPU context for CLONE_THREAD | Date | Tue, 12 Oct 2021 21:01:45 +0200 |
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On Tue, Oct 12 2021 at 20:52, Thomas Gleixner wrote:
> 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. :(
But fenv(3) is not the FPU state. Duh!
Anyway. It's an optimization which we can do later still and not required for the cleanups here.
Thanks,
tglx
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