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e7615c9225
s390 trivially supports the ARCH_HAS_MEMBARRIER_SYNC_CORE requirements
since the used lpswe(y) instruction to return from any kernel context to
user space performs CPU serialization. This is very similar to arm, arm64
and powerpc.
See commit 70216e18e5 ("membarrier: Provide core serializing command,
*_SYNC_CORE") for further details.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
55 lines
1.8 KiB
Plaintext
55 lines
1.8 KiB
Plaintext
#
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# Feature name: membarrier-sync-core
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# Kconfig: ARCH_HAS_MEMBARRIER_SYNC_CORE
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# description: arch supports core serializing membarrier
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#
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# Architecture requirements
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#
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# * arm/arm64/powerpc/s390
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#
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# Rely on implicit context synchronization as a result of exception return
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# when returning from IPI handler, and when returning to user-space.
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#
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# * x86
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#
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# x86-32 uses IRET as return from interrupt, which takes care of the IPI.
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# However, it uses both IRET and SYSEXIT to go back to user-space. The IRET
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# instruction is core serializing, but not SYSEXIT.
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#
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# x86-64 uses IRET as return from interrupt, which takes care of the IPI.
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# However, it can return to user-space through either SYSRETL (compat code),
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# SYSRETQ, or IRET.
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#
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# Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely
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# instead on write_cr3() performed by switch_mm() to provide core serialization
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# after changing the current mm, and deal with the special case of kthread ->
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# uthread (temporarily keeping current mm into active_mm) by issuing a
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# sync_core_before_usermode() in that specific case.
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#
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-----------------------
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| arch |status|
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-----------------------
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| alpha: | TODO |
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| arc: | TODO |
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| arm: | ok |
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| arm64: | ok |
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| csky: | TODO |
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| hexagon: | TODO |
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| ia64: | TODO |
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| loongarch: | TODO |
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| m68k: | TODO |
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| microblaze: | TODO |
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| mips: | TODO |
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| nios2: | TODO |
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| openrisc: | TODO |
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| parisc: | TODO |
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| powerpc: | ok |
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| riscv: | TODO |
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| s390: | ok |
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| sh: | TODO |
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| sparc: | TODO |
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| um: | TODO |
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| x86: | ok |
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| xtensa: | TODO |
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-----------------------
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