linux-kernel - Re: [PATCH v2] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD

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Message-ID: <5a765e1bda8ec399a29dbdb195d15faa79c44273.camel@surriel.com>
Date:   Tue, 20 Aug 2019 12:56:20 -0400
From:   Rik van Riel <riel@...riel.com>
To:     Song Liu <songliubraving@...com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Kernel Team <Kernel-team@...com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Joerg Roedel <jroedel@...e.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v2] x86/mm/pti: in pti_clone_pgtable() don't increase
 addr by PUD_SIZE

On Tue, 2019-08-20 at 10:00 -0400, Song Liu wrote:
> 
> From 9ae74cff4faf4710a11cb8da4c4a3f3404bd9fdd Mon Sep 17 00:00:00
> 2001
> From: Song Liu <songliubraving@...com>
> Date: Mon, 19 Aug 2019 23:59:47 -0700
> Subject: [PATCH] x86/mm/pti: in pti_clone_pgtable(), increase addr
> properly
> 
> Before 32-bit support, pti_clone_pmds() always adds PMD_SIZE to addr.
> This behavior changes after the 32-bit support:  pti_clone_pgtable()
> increases addr by PUD_SIZE for pud_none(*pud) case, and increases
> addr by
> PMD_SIZE for pmd_none(*pmd) case. However, this is not accurate
> because
> addr may not be PUD_SIZE/PMD_SIZE aligned.
> 
> Fix this issue by properly rounding up addr to next PUD_SIZE/PMD_SIZE
> in these two cases.
> 
> Cc: stable@...r.kernel.org # v4.19+
> Fixes: 16a3fe634f6a ("x86/mm/pti: Clone kernel-image on PTE level for
> 32 bit")
> Signed-off-by: Song Liu <songliubraving@...com>
> Cc: Joerg Roedel <jroedel@...e.de>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Andy Lutomirski <luto@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>

This looks like it should do the trick!

Reviewed-by: Rik van Riel <riel@...riel.com>

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