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]> Acked-by: Peter Zijlstra (Intel) <[email protected]> CC: Thomas Gleixner <[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: Arnd Bergmann <[email protected]> CC: [email protected] CC: [email protected] --- Changes since v1: - Introduce include/linux/sync_core.h --- include/linux/sync_core.h | 21 +++++++++++++++++++++ init/Kconfig | 3 +++ 2 files changed, 24 insertions(+) create mode 100644 include/linux/sync_core.h diff --git a/include/linux/sync_core.h b/include/linux/sync_core.h new file mode 100644 index 000000000000..013da4b8b327 --- /dev/null +++ b/include/linux/sync_core.h @@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SYNC_CORE_H +#define _LINUX_SYNC_CORE_H + +#ifdef CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE +#include <asm/sync_core.h> +#else +/* + * This is a dummy sync_core_before_usermode() implementation that can be used + * on all architectures which return to user-space through core serializing + * instructions. + * If your architecture returns to user-space through non-core-serializing + * instructions, you need to write your own functions. + */ +static inline void sync_core_before_usermode(void) +{ +} +#endif + +#endif /* _LINUX_SYNC_CORE_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
