Introduce an architecture function that ensures the current CPU issues a core serializing instruction before returning to usermode.
This is needed for the membarrier "sync_core" command. Architectures defining the sync_core_before_usermode() static inline need to select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. Signed-off-by: Mathieu Desnoyers <[email protected]> CC: Thomas Gleixner <[email protected]> CC: Peter Zijlstra <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Paul E. McKenney <[email protected]> CC: Boqun Feng <[email protected]> CC: Andrew Hunter <[email protected]> CC: Maged Michael <[email protected]> CC: Avi Kivity <[email protected]> CC: Benjamin Herrenschmidt <[email protected]> CC: Paul Mackerras <[email protected]> CC: Michael Ellerman <[email protected]> CC: Dave Watson <[email protected]> CC: Ingo Molnar <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andrea Parri <[email protected]> CC: Russell King <[email protected]> CC: Greg Hackmann <[email protected]> CC: Will Deacon <[email protected]> CC: David Sehr <[email protected]> CC: Linus Torvalds <[email protected]> CC: [email protected] CC: [email protected] --- include/linux/processor.h | 6 ++++++ init/Kconfig | 3 +++ 2 files changed, 9 insertions(+) diff --git a/include/linux/processor.h b/include/linux/processor.h index dbc952eec869..866de5326d34 100644 --- a/include/linux/processor.h +++ b/include/linux/processor.h @@ -68,4 +68,10 @@ do { \ #endif +#ifndef CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE +static inline void sync_core_before_usermode(void) +{ +} +#endif + #endif /* _LINUX_PROCESSOR_H */ diff --git a/init/Kconfig b/init/Kconfig index 2d118b6adee2..30208da2221f 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1918,3 +1918,6 @@ config ASN1 functions to call on what tags. source "kernel/Kconfig.locks" + +config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE + bool -- 2.11.0
