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Commit 6a546c7e authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
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membarrier-sync-core: Document architecture support 



Ensure we gather architecture requirements about each architecture
supporting the "sync_core" membarrier command in a single file under
Documentation/features.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: David Sehr <sehr@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1518208256-22034-1-git-send-email-mathieu.desnoyers@efficios.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f1517df8

Documentation/features/sched/membarrier-sync-core/arch-support.txt

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+62 −0
Original line number Diff line number Diff line 
#

# Feature name:          membarrier-sync-core

#         Kconfig:       ARCH_HAS_MEMBARRIER_SYNC_CORE

#         description:   arch supports core serializing membarrier

#

# Architecture requirements

#

# * arm64

#

# Rely on eret context synchronization when returning from IPI handler, and

# when returning to user-space.

#

# * x86

#

# x86-32 uses IRET as return from interrupt, which takes care of the IPI.

# However, it uses both IRET and SYSEXIT to go back to user-space. The IRET

# instruction is core serializing, but not SYSEXIT.

#

# x86-64 uses IRET as return from interrupt, which takes care of the IPI.

# However, it can return to user-space through either SYSRETL (compat code),

# SYSRETQ, or IRET.

#

# Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely

# instead on write_cr3() performed by switch_mm() to provide core serialization

# after changing the current mm, and deal with the special case of kthread ->

# uthread (temporarily keeping current mm into active_mm) by issuing a

# sync_core_before_usermode() in that specific case.

#

    -----------------------

    |         arch |status|

    -----------------------

    |       alpha: | TODO |

    |         arc: | TODO |

    |         arm: | TODO |

    |       arm64: |  ok  |

    |    blackfin: | TODO |

    |         c6x: | TODO |

    |        cris: | TODO |

    |         frv: | TODO |

    |       h8300: | TODO |

    |     hexagon: | TODO |

    |        ia64: | TODO |

    |        m32r: | TODO |

    |        m68k: | TODO |

    |       metag: | TODO |

    |  microblaze: | TODO |

    |        mips: | TODO |

    |     mn10300: | TODO |

    |       nios2: | TODO |

    |    openrisc: | TODO |

    |      parisc: | TODO |

    |     powerpc: | TODO |

    |        s390: | TODO |

    |       score: | TODO |

    |          sh: | TODO |

    |       sparc: | TODO |

    |        tile: | TODO |

    |          um: | TODO |

    |   unicore32: | TODO |

    |         x86: |  ok  |

    |      xtensa: | TODO |

    -----------------------