[RFC v5 00/38] powerpc: Memory Protection Keys
linuxram at us.ibm.com
Mon Jul 10 16:05:44 AEST 2017
On Mon, Jul 10, 2017 at 11:13:23AM +0530, Anshuman Khandual wrote:
> On 07/06/2017 02:51 AM, 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
> > an address range within its address space.
> > The process then can dynamically set read/write
> > permissions on the key without involving the
> > kernel. Any code that violates the permissions
> > of 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 v5:
> > (1) reverted back to the old design -- store the
> > key in the pte, instead of bypassing it.
> > The v4 design slowed down the hash page path.
> > (2) detects key violation when kernel is told to
> > access user pages.
> > (3) further refined the patches into smaller consumable
> > units
> > (4) page faults handlers captures the faulting key
> > from the pte instead of the vma. This closes a
> > race between where the key update in the vma and
> > a key fault caused cause by the key programmed
> > in the pte.
> > (5) a key created with access-denied should
> > also set it up to deny write. Fixed it.
> > (6) protection-key number is displayed in smaps
> > the x86 way.
> Hello Ram,
> This patch series has now grown a lot. Do you have this
> hosted some where for us to pull and test it out ? BTW
> do you have data points to show the difference in
> performance between this version and the last one where
> we skipped the bits from PTE and directly programmed the
> HPTE entries looking into VMA bits.
No. I dont. I am hoping you can help me out with this.
More information about the Linuxppc-dev