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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2018-01-29 23:20:15 +0300
committerIngo Molnar <mingo@kernel.org>2018-02-05 23:34:50 +0300
commite61938a921a46347d7725badc40ec436ebfff977 (patch)
tree37e5a38337e0dd53e8bd6a622e101e277f146088
parent92485487ba834f6665ec13dfb2c69e80cd0c7c37 (diff)
downloadlinux-e61938a921a46347d7725badc40ec436ebfff977.tar.xz
locking: Introduce sync_core_before_usermode()
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 <mathieu.desnoyers@efficios.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Andrew Hunter <ahh@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> 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: H. Peter Anvin <hpa@zytor.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: Russell King <linux@armlinux.org.uk> 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/20180129202020.8515-7-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/sync_core.h21
-rw-r--r--init/Kconfig3
2 files changed, 24 insertions, 0 deletions
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 837adcf075d9..535421facea8 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