linux-kernel - Re: [PATCH] powerpc/vdso: Fix VDSO unmap check

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Message-ID: <375b927b-fa93-28cd-23b8-8afe264adb0c@csgroup.eu>
Date:   Wed, 9 Mar 2022 16:51:04 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Laurent Dufour <ldufour@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH] powerpc/vdso: Fix VDSO unmap check



Le 03/11/2020 à 18:13, Laurent Dufour a écrit :
> The check introduced by the commit 83d3f0e90c6c ("powerpc/mm: tracking vDSO
> remap") is wrong and is missing some partial unmaps of the VDSO.
> 
> To be complete the check needs the base and end address of the
> VDSO. Currently only the base is available in the mm_context of a task, but
> the end address can easily be computed because the size of VDSO is
> constant. However, there are 2 sizes for 32 or 64 bits task and they are
> stored in static variables in arch/powerpc/kernel/vdso.c.
> 
> Exporting a new function called vdso_pages() to get the number of pages of
> the VDSO based on the static variables from arch/powerpc/kernel/vdso.c.
> 
> Fixes: 83d3f0e90c6c ("powerpc/mm: tracking vDSO remap")
> 
> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
> Reported-by: Thomas Gleixner <tglx@...utronix.de>
> Suggested-by: Christophe Leroy <christophe.leroy@...roup.eu>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Cc: Paul Mackerras <paulus@...ba.org>
> ---
>   arch/powerpc/include/asm/mmu_context.h | 18 ++++++++++++++++--
>   arch/powerpc/kernel/vdso.c             | 14 ++++++++++++++
>   2 files changed, 30 insertions(+), 2 deletions(-)

This patch doesn't apply anymore.

In the meantime there's a pending series from Dmitry, so I'm wondering 
if it is worth rebasing this series or not.

Christophe