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

   1 #
   2 # Feature name:          membarrier-sync-core
   3 #         Kconfig:       ARCH_HAS_MEMBARRIER_SYNC_CORE
   4 #         description:   arch supports core serializing membarrier
   5 #
   6 # Architecture requirements
   7 #
   8 # * arm/arm64
   9 #
  10 # Rely on implicit context synchronization as a result of exception return
  11 # when returning from IPI handler, and when returning to user-space.
  12 #
  13 # * x86
  14 #
  15 # x86-32 uses IRET as return from interrupt, which takes care of the IPI.
  16 # However, it uses both IRET and SYSEXIT to go back to user-space. The IRET
  17 # instruction is core serializing, but not SYSEXIT.
  18 #
  19 # x86-64 uses IRET as return from interrupt, which takes care of the IPI.
  20 # However, it can return to user-space through either SYSRETL (compat code),
  21 # SYSRETQ, or IRET.
  22 #
  23 # Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely
  24 # instead on write_cr3() performed by switch_mm() to provide core serialization
  25 # after changing the current mm, and deal with the special case of kthread ->
  26 # uthread (temporarily keeping current mm into active_mm) by issuing a
  27 # sync_core_before_usermode() in that specific case.
  28 #
  29     -----------------------
  30     |         arch |status|
  31     -----------------------
  32     |       alpha: | TODO |
  33     |         arc: | TODO |
  34     |         arm: |  ok  |
  35     |       arm64: |  ok  |
  36     |         c6x: | TODO |
  37     |        csky: | TODO |
  38     |       h8300: | TODO |
  39     |     hexagon: | TODO |
  40     |        ia64: | TODO |
  41     |        m68k: | TODO |
  42     |  microblaze: | TODO |
  43     |        mips: | TODO |
  44     |       nds32: | TODO |
  45     |       nios2: | TODO |
  46     |    openrisc: | TODO |
  47     |      parisc: | TODO |
  48     |     powerpc: | TODO |
  49     |       riscv: | TODO |
  50     |        s390: | TODO |
  51     |          sh: | TODO |
  52     |       sparc: | TODO |
  53     |          um: | TODO |
  54     |   unicore32: | TODO |
  55     |         x86: |  ok  |
  56     |      xtensa: | TODO |
  57     -----------------------