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

[Laurent Dufour]

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@xxxxxxxxxxxxx>
>> Reported-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Suggested-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
>> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Paul Mackerras <paulus@xxxxxxxxx>
>> ---
>>   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.