Re: [PATCHv3 4/8] x86/mm: Handle LAM on context switch

From: Alexander Potapenko
Date: Fri Jun 17 2022 - 11:35:47 EST


On Fri, Jun 10, 2022 at 4:35 PM Kirill A. Shutemov
<kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
>
> Linear Address Masking mode for userspace pointers encoded in CR3 bits.
> The mode is selected per-thread. Add new thread features indicate that the
> thread has Linear Address Masking enabled.
>
> switch_mm_irqs_off() now respects these flags and constructs CR3
> accordingly.
>
> The active LAM mode gets recorded in the tlb_state.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>


> +#ifdef CONFIG_X86_64
> +static inline u64 mm_cr3_lam_mask(struct mm_struct *mm)
> +{
> + return mm->context.lam_cr3_mask;
> +}

Nit: can we have either "cr3_lam_mask" or "lam_cr3_mask" in both places?



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Alexander Potapenko
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