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Re: [RFC v4 00/17] powerpc: Memory Protection Keys

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On Tue, 2017-06-27 at 03:11 -0700, Ram Pai wrote:
> Memory protection keys enable applications to protect its
> address space from inadvertent access or corruption from
> itself.
> 
> The overall idea:
> 
>  A process allocates a   key  and associates it with
>  a  address  range  within    its   address   space.
>  The process  than  can  dynamically  set read/write 
>  permissions on  the   key   without  involving  the 
>  kernel. Any  code that  violates   the  permissions
>  off the address space; as defined by its associated
>  key, will receive a segmentation fault.
> 
> This patch series enables the feature on PPC64 HPTE
> platform.
> 
> ISA3.0 section 5.7.13 describes the detailed specifications.
> 
> 
> Testing:
> 	This patch series has passed all the protection key
> 	tests available in  the selftests directory.
> 	The tests are updated to work on both x86 and powerpc.
> 
> version v4:
> 	(1) patches no more depend on the pte bits to program
> 		the hpte -- comment by Balbir
> 	(2) documentation updates
> 	(3) fixed a bug in the selftest.
> 	(4) unlike x86, powerpc lets signal handler change key
> 	    permission bits; the change will persist across
> 	    signal handler boundaries. Earlier we allowed
> 	    the signal handler to modify a field in the siginfo
> 	    structure which would than be used by the kernel
> 	    to program the key protection register (AMR)
>        		-- resolves a issue raised by Ben.
>     		"Calls to sys_swapcontext with a made-up context
> 	        will end up with a crap AMR if done by code who
> 	       	didn't know about that register".
> 	(5) these changes enable protection keys on 4k-page 
> 		kernel aswell.

I have not looked at the full series, but it seems cleaner than the original
one and the side-effect is that we can support 4k as well. Nice!

Balbir Singh.

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[RFC v4 00/17] powerpc: Memory Protection Keys Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
  [RFC v4 09/17] powerpc: call the hash functions with the correct pkey value Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
    Re: [RFC v4 09/17] powerpc: call the hash functions with the correct  pkey value "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-27 17:30 +0200
      Re: [RFC v4 09/17] powerpc: call the hash functions with the correct  pkey value Ram Pai <linuxram@us.ibm.com> - 2017-06-28 09:20 +0200
  [RFC v4 02/17] mm: ability to disable execute permission on a key at creation Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
    Re: [RFC v4 02/17] mm: ability to disable execute permission on a  key at creation Balbir Singh <bsingharora@gmail.com> - 2017-06-27 13:40 +0200
  [RFC v4 15/17] Documentation: Move protecton key documentation to arch neutral directory Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
  [RFC v4 03/17] x86: key creation with PKEY_DISABLE_EXECUTE disallowed Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
    Re: [RFC v4 03/17] x86: key creation with PKEY_DISABLE_EXECUTE  disallowed Balbir Singh <bsingharora@gmail.com> - 2017-06-27 13:40 +0200
  [RFC v4 04/17] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call Ram Pai <linuxram@us.ibm.com> - 2017-06-27 12:20 +0200
  Re: [RFC v4 00/17] powerpc: Memory Protection Keys Balbir Singh <bsingharora@gmail.com> - 2017-06-27 12:50 +0200

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