Hi Balbir,

On 05/01/2016 09:05 PM, Balbir Singh wrote:

On 29/04/16 01:18, Christopher Covington wrote:

quoted

In order to share remap and unmap support for the VDSO with other
architectures without duplicating the code, we need a common name and type
for the address of the VDSO. An informal survey of the architectures
indicates unsigned long vdso is popular. Change the variable name in
powerpc from mm->context.vdso_base to simply mm->context.vdso.

Could you please provide additional details on why the remap/unmap operations are required?

The goal is to make checkpointing and restoring processes work on
several different architectures and ABIs, in the face of Address Space
Layout Randomization (ASLR) and other factors that might change the VDSO
virtual address from one exec() to the next.

Here's the patch adding PowerPC support:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=83d3f0e90c6c8f833e3da91917c243a916fda69e

This patch does rename, but should it abstract via a function acesss
to vmap field using arch_* operations? Not sure

I'm sorry, but I don't understand this question. Are you saying ARM,
Power etc. need VDSO unmap and remap log that behave differently? So far
I've found the differences to be stylistic rather than really affecting
generated code behavior.

Thanks,
Christopher Covington

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