Re: [PATCH] x86, powerpc : pkey-mprotect must allow pkey-0

On Fri, Mar 09, 2018 at 09:19:53PM +1100, Michael Ellerman wrote:

Ram Pai [off-list ref] writes:
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Once an address range is associated with an allocated pkey, it cannot be
reverted back to key-0. There is no valid reason for the above behavior=

=2E  On

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the contrary applications need the ability to do so.

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Please explain this in much more detail. Is it an ABI change?

Not necessarily an ABI change. older binary applications  will continue
to work. It can be considered as a bug-fix.

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And why did we just notice this?

Yes. this was noticed by an application vendor.

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The patch relaxes the restriction.

Tested on powerpc and x86_64.

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Thanks, but please split the patch, one for each arch.

Will do.
RP