1. 01 5月, 2016 21 次提交
  2. 27 4月, 2016 1 次提交
    • C
      powerpc: Add support for userspace P9 copy paste · 8a649045
      Chris Smart 提交于
      The copy paste facility introduced in POWER9 provides an optimised
      mechanism for a userspace application to copy a cacheline. This is
      provided by a pair of instructions, copy and paste, while a third,
      cp_abort (copy paste abort), provides a clean up of the state in case of
      a failure.
      
      The copy instruction will read a 128 byte cacheline and store it in an
      internal buffer. The subsequent paste instruction will store this
      internal buffer to memory and set a CR field if the paste succeeds.
      
      Since the state of the copy paste buffer is internal (and not
      architecturally visible), in the unlikely event of a context switch, the
      state cannot be stored and the paste should therefore fail.
      
      The cp_abort instruction exists to fail and clean up any such
      interrupted copy paste sequence and is to be called by the kernel as
      part of the context switch. Doing so prevents data from a preceding copy
      in one process leaking into the paste of another.
      
      This code enables use of the cp_abort instruction if a supported
      processor is detected.
      
      NOTE: this is for userspace only, not in kernel, and does not deal
      with KVM guests.
      
      Patch created with much assistance from Michael Neuling
      <mikey@neuling.org>
      Signed-off-by: NChris Smart <chris@distroguy.com>
      Reviewed-by: NCyril Bur <cyrilbur@gmail.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      8a649045
  3. 21 4月, 2016 1 次提交
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