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Re: [RFC v2 00/12] powerpc: Memory Protection Keys

From Anshuman Khandual <khandual@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject Re: [RFC v2 00/12] powerpc: Memory Protection Keys
Date 2017-06-20 08:10 +0200
Message-ID <tUkwp-4RO-9@gated-at.bofh.it> (permalink)
References <tTd3X-1kp-3@gated-at.bofh.it> <tUjK1-4mm-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 06/20/2017 10:40 AM, Balbir Singh wrote:
> On Fri, 2017-06-16 at 20:52 -0700, Ram Pai wrote:
>> Memory protection keys enable applications to protect its
>> address space from inadvertent access or corruption from
>> itself.
> 
> I presume by itself you mean protection between threads?

Between threads due to race conditions or from the same thread
because of programming error.

> 
>>
>> The overall idea:
>>
>>  A process allocates a   key  and associates it with
>>  a  address  range  within    its   address   space.
> 
> OK, so this is per VMA?

Yeah but the same key can be given to multiple VMAs. Any
change will effect every VMA who got tagged by it.

> 
>>  The process  than  can  dynamically  set read/write 
>>  permissions on  the   key   without  involving  the 
>>  kernel.
> 
> This bit is not clear, how can the key be set without
> involving the kernel? I presume you mean the key is set

With pkey_mprotect() system call, all the effected PTEs get
tagged for once. Switching the permission happens just by
writing into the register on the fly.

> in the PTE's and the access protection values can be
> set without involving the kernel?

PTE setting happens once, access protection values can be
changed on the fly through register.

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[RFC v2 00/12] powerpc: Memory Protection Keys Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
  [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 09:00 +0200
      Re: [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 02:00 +0200
        Re: [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-21 05:20 +0200
          Re: [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 08:20 +0200
  [RFC v2 07/12] powerpc: Macro the mask used for checking DSI exception Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 07/12] powerpc: Macro the mask used for checking DSI  exception Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 10:20 +0200
      Re: [RFC v2 07/12] powerpc: Macro the mask used for checking DSI  exception Ram Pai <linuxram@us.ibm.com> - 2017-06-21 01:30 +0200
    Re: [RFC v2 07/12] powerpc: Macro the mask used for checking DSI exception "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-21 09:30 +0200
      Re: [RFC v2 07/12] powerpc: Macro the mask used for checking DSI  exception Ram Pai <linuxram@us.ibm.com> - 2017-06-21 11:20 +0200
  [RFC v2 04/12] powerpc: store and restore the pkey state across context switches. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
  [RFC v2 05/12] powerpc: Implementation for sys_mprotect_pkey() system call. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 05/12] powerpc: Implementation for sys_mprotect_pkey() system call. "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-21 09:20 +0200
  [RFC v2 11/12]Documentation: Documentation updates. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 11/12]Documentation: Documentation updates. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 08:20 +0200
      Re: [RFC v2 11/12]Documentation: Documentation updates. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 02:10 +0200
  [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 12:30 +0200
      Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 01:30 +0200
        Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-21 07:40 +0200
          Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 08:40 +0200
    Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed hpte pages. "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-21 08:50 +0200
      Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 11:40 +0200
    Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-22 11:10 +0200
      Re: [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-22 18:30 +0200
  [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused the exception. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused the exception. Michael Ellerman <mpe@ellerman.id.au> - 2017-06-19 13:10 +0200
      Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused  the exception. Ram Pai <linuxram@us.ibm.com> - 2017-06-19 20:00 +0200
        Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused  the exception. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 08:50 +0200
          Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused  the exception. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 02:00 +0200
      Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused  the exception. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 02:00 +0200
  [RFC v2 03/12] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 03/12] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call. Michael Ellerman <mpe@ellerman.id.au> - 2017-06-19 14:20 +0200
      Re: [RFC v2 03/12] powerpc: Implement sys_pkey_alloc and  sys_pkey_free system call. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 00:50 +0200
  [RFC v2 06/12] powerpc: Program HPTE key protection bits. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 06/12] powerpc: Program HPTE key protection bits. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 10:30 +0200
      Re: [RFC v2 06/12] powerpc: Program HPTE key protection bits. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 01:30 +0200
  [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-17 06:00 +0200
    Re: [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed  hpte pages. Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 13:00 +0200
      Re: [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 01:30 +0200
    Re: [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed hpte pages. "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-21 09:00 +0200
      Re: [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed  hpte pages. Ram Pai <linuxram@us.ibm.com> - 2017-06-21 22:20 +0200
    Re: [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K backed hpte pages. "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-06-21 09:00 +0200
  Re: [RFC v2 12/12]selftest: Updated protection key selftest Michael Ellerman <mpe@ellerman.id.au> - 2017-06-19 13:10 +0200
  Re: [RFC v2 00/12] powerpc: Memory Protection Keys Balbir Singh <bsingharora@gmail.com> - 2017-06-20 07:20 +0200
    Re: [RFC v2 00/12] powerpc: Memory Protection Keys Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 08:10 +0200
    Re: [RFC v2 00/12] powerpc: Memory Protection Keys Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-06-20 12:00 +0200
  Re: [RFC v2 12/12]selftest: Updated protection key selftest Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-06-20 08:30 +0200
    Re: [RFC v2 12/12]selftest: Updated protection key selftest Ram Pai <linuxram@us.ibm.com> - 2017-06-21 02:20 +0200

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