linux-kernel - Re: [PATCH] [v2] x86/doc: add PTI description

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Date:   Fri, 5 Jan 2018 10:43:28 +0900
From:   Hector Martin 'marcan' <marcan@...can.st>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Cc:     x86@...nel.org
Subject: Re: [PATCH] [v2] x86/doc: add PTI description

On 2018-01-05 09:24, Dave Hansen wrote:
> +			Not specifying this option nothing is equivalent to
> +			pti=auto.

-nothing

> +Page Table Isolation (pti, previously known as KAISER[1]) is a
> +countermeasure against attacks on kernel address information such
> +as the "Meltdown" approach[2].

It's not really just address information, but any data. Maybe "attacks
that leak kernel memory"?

> +To avoid leaking address information, we create an new, independent

Same issue here. Also an -> a.

> +copy of the page tables which are used only when running userspace

are -> is. The copy is singular.

> +applications.  When the kernel is entered via syscalls, interrupts or
> +exceptions, page tables are switched to the full "kernel" copy.  When

"the page tables".

> +crippled by setting the NX bit in the top level.  This ensures
> +that if a kernel->user CR3 switch is missed that userspace will
> +crash immediately upon executing its first instruction.

"that userspace" -> "then userspace"

-- 
Hector Martin "marcan" (marcan@...can.st)
Public Key: https://mrcn.st/pub