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Message-ID: <7aa780b1-3bb5-ffa1-e8f1-defc13e5580c@linux.ibm.com>
Date:   Thu, 10 Mar 2022 17:18:29 +0100
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Subject: Re: [PATCH] powerpc/vdso: Fix VDSO unmap check
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To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        linuxppc-dev@lists.ozlabs.org
Cc:     linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
References: <20201103171336.98883-1-ldufour@linux.ibm.com>
 <375b927b-fa93-28cd-23b8-8afe264adb0c@csgroup.eu>
From:   Laurent Dufour <ldufour@linux.ibm.com>
In-Reply-To: <375b927b-fa93-28cd-23b8-8afe264adb0c@csgroup.eu>
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On 09/03/2022, 16:51:04, Christophe Leroy wrote:
> 
> 
> 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@linux.ibm.com>
>> Reported-by: Thomas Gleixner <tglx@linutronix.de>
>> Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.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.

I agee, the Dimitry's series looks better, addressing the issue in the
common code for all the architectures.

Laurent.