Re: [PATCHv3 6/8] x86/mm: Provide ARCH_GET_UNTAG_MASK and ARCH_ENABLE_TAGGED_ADDR

Andy Lutomirski
2022-06-28T23:42:48Z

On 6/10/22 07:35, Kirill A. Shutemov wrote:

> + /* Update CR3 to get LAM active */
> + switch_mm(current->mm, current->mm, current);

Can you at least justify this oddity? When changing an LDT, we use a
dedicated mechanism. Is there a significant benefit to abusing
switch_mm for this?

Also, why can't we enable LAM on a multithreaded process? We can change
an LDT, and the code isn't even particularly complicated.