[CRIU] [PATCH 0/2] Tracking user space vDSO remaping
Christopher Covington
cov at codeaurora.org
Wed Mar 2 04:13:10 PST 2016
Hi,
On 03/20/2015 11:53 AM, Laurent Dufour wrote:
> CRIU is recreating the process memory layout by remapping the checkpointee
> memory area on top of the current process (criu). This includes remapping
> the vDSO to the place it has at checkpoint time.
>
> However some architectures like powerpc are keeping a reference to the vDSO
> base address to build the signal return stack frame by calling the vDSO
> sigreturn service. So once the vDSO has been moved, this reference is no
> more valid and the signal frame built later are not usable.
>
> This patch serie is introducing a new mm hook 'arch_remap' which is called
> when mremap is done and the mm lock still hold. The next patch is adding the
> vDSO remap and unmap tracking to the powerpc architecture.
>
> Laurent Dufour (2):
> mm: Introducing arch_remap hook
> powerpc/mm: Tracking vDSO remap
>
> arch/powerpc/include/asm/mmu_context.h | 35 +++++++++++++++++++++++++++++++-
> arch/s390/include/asm/mmu_context.h | 6 ++++++
> arch/um/include/asm/mmu_context.h | 5 +++++
> arch/unicore32/include/asm/mmu_context.h | 6 ++++++
> arch/x86/include/asm/mmu_context.h | 6 ++++++
> include/asm-generic/mm_hooks.h | 6 ++++++
> mm/mremap.c | 9 ++++++--
> 7 files changed, 70 insertions(+), 3 deletions(-)
We would like to be able to remap/unmap the VDSO on arm and arm64 as
well. When I proposed a patch with mmu_context.h and mmu-arch-hooks.h
changes to arm64 that were nearly identical to those done to powerpc,
Will Deacon reasonably suggested [1] attempting to combine the code and
provide generic VDSO accessors. Unfortunately, I no prior experience
with generic MM code. Can anyone advise on how to get started with that?
1. http://www.spinics.net/lists/linux-arm-msm/msg18441.html
Thanks,
Christopher Covington
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Qualcomm Innovation Center, Inc.
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